0090-9556/10/3810-1623–1635$20.00
DRUG METABOLISM AND DISPOSITION
Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
DMD 38:1623–1635, 2010
Vol. 38, No. 10
33571/3623600
Printed in U.S.A.
Minireview
The Role of the Placenta in Fetal Exposure to Xenobiotics:
Importance of Membrane Transporters and Human Models for
Transfer Studies
Caroline Prouillac and Sylvaine Lecoeur
Métabolisme et Toxicologie Comparée des Xénobiotiques (UMR 1233 INRA), VetAgroSup, Marcy l’Etoile, France
Received March 26, 2010; accepted July 6, 2010
The placenta is a key organ in fetal growth and development
because it controls maternal-to-fetal exchanges of nutrients and
hormones. It also interferes with drug delivery to the fetus by
expressing active membrane transporters and xenobiotic metabolism enzymes. Developing strategies to understand the role of the
placenta in drug delivery is a challenge in toxicology. Despite
common physiological functions, the placentas of different species are heterogeneous in their morphology and in their expression
of membrane transporters and metabolizing proteins. These characteristics raise the difficulty of obtaining a good representative
model of human placental transfer. To date, different in vitro, in
vivo, and ex vivo tools have been used to elucidate transport and
metabolism processes in the human placenta. This study recapitulates the typical features of human placenta and then presents
the placental enzymes of xenobiotic metabolism, ATP-binding cassette transporters, solute carrier transporters, and their role in
fetal exposure to xenobiotics. The study also compares the characteristics of different models of human placenta, in terms of
membrane localization of transporters, and the expression of xenobiotic metabolism enzymes. The use of these models for toxicological studies, in particular xenobiotic transfer, is described,
and the advantages and limits of each model are summarized.
Introduction
plasma membrane of the syncytium. On the opposite side, the basal
membrane faces the fetal circulation and lacks microvillar projections.
Both sides of the syncytium are not only structurally distinct, but they
also differ in the localization of transporters, enzymes, and hormone
receptors. The current knowledge about the existence of different
systems, including plasma membrane carriers, biotransforming enzymes, and export pumps, that determine the selectivity and efficacy
of the so-called placental barrier is underlined. A good understanding
of the molecular bases of these processes and their regulation is
crucial for predicting the risk of fetal exposure to active agents.
In addition to drug exposure, which can be voluntarily limited during
pregnancy, fetal exposure to food contaminants is characterized by
chronic exposure to low doses. Very little information is available on fetal
exposure to these pollutants and their long-term effects. Drug transporters
are involved in the regulation of the chemical environment of the fetus by
selectively transporting and removing toxic substrates. Thus, placental
epithelia expressing xenobiotic metabolism enzymes and protein transporters are very helpful models for the in vitro study of quantitative and
qualitative transfers of molecules to the fetus.
The placenta is a key organ for the growth and development of the
embryo and fetus during pregnancy: this semipermeable barrier separates the mother and the fetus and regulates the exchange of nutrients, gases, waste, and endogenous and foreign molecules between
maternal and fetal circulations. It has traditionally been considered as
a highly permeable organ for a large variety of substances with
diverse molecular structures that are readily able to cross it from the
maternal blood to reach the fetus. Indeed, proof of fetal exposure to
maternal intake occurred for the first time with the thalidomide
disaster in 1957 to 1961. As a result, experts recommend the limited
use of drugs during pregnancy, if possible.
The human placenta barrier consists of a single limiting layer of
multinuclear cells, which are known as syncytiotrophoblasts (Enders
and Blankenship, 1999). A microvillous brush border membrane, in
direct contact with maternal blood, constitutes the maternal-facing
Article, publication date, and citation information can be found at
http://dmd.aspetjournals.org.
doi:10.1124/dmd.110.033571.
ABBREVIATIONS: P450, cytochrome P450; ABC, ATP-binding cassette; MDR1, ABCB1, multidrug resistance-associated proteins; P-gp,
P-glycoprotein; PSC833, 6-{(2S,4R,6E)-4-methyl-2-(methylamino)-3-oxo-6-octenoic} cyclosporine D. GG918, N-{4-[2-(1,2,3,4-tetrahydro-6,7dimethoxy-2-isoquinolinyl)-ethyl]-phenyl}-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamine; MRPs, ABCCs, multidrug resistance proteins;
BCRP, ABCG2, breast cancer resistance proteins; PhIP, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine; SLC, solute carrier; OATP, organic
anion-transporting polypeptide; OAT, organic anion transporter; OCT, organic cation transporter; OCTN, organic cation/carnitine transporter;
SERT, serotonin transporter; NET, norepinephrin transporter; MCT, monocarboxylate transporter; ENT, equilibrative nucleoside transporter; FR␣,
folate receptor alpha; RFC-1, reduced folate carrier 1; PCFT/HCP1, proton-coupled folate transporter/heme carrier protein 1; hCG, human
chorionic gonadotropin; IFN, interferon; IL, interleukin; ASCT, amino acid transporter; SNP, single nucleotide polymorphism.
1623
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ABSTRACT:
1624
PROUILLAC AND LECOEUR
Different experimental trophoblast systems are available, including
immortalized cell lines, which are derived from normal and malignant
tissues. In this review, we present a synthesis on xenobiotic metabolism
enzymes and transporters in the placenta and update the different experimental models potentially available for the study of the barrier function.
Physiological Function of the Human Placental Barrier
Umbilical cord
a
Fetus
Fetal poron
Enzymes of Xenobiotic Metabolism Content
The human placenta contains a wealth of enzymatic machinery
responsible for both phase I and phase II reactions (Table 1). However, data on the contribution of placental biotranformations in the
conversion of xenobiotics into potential toxic metabolites are very
scarce. Compared with the liver, placental metabolism seems to be
minor and does not limit the extent of xenobiotic passage across the
placenta (Pasanen, 1999). Several cytochromes P450 (P450s), including CYP1, CYP2, and CYP3, have been isolated from the placenta.
These proteins are largely responsible for the detoxification of drugs and
toxins. However, the members and the quantity of P450s vary as a
function of placental development, length of gestation, and maternal
health status (Hakkola et al., 1996a,b). Expression and activities of
human P450 enzymes decline during gestation from the first trimester
of pregnancy to the second and third trimesters (Syme et al., 2004). In
the placenta, a large number of enzymes are involved in progesterone
and estrogen synthesis from fetal and maternal precursors (Pasqualini,
2005; Smuc and Rizner, 2009). Enzymes involved in steroid hormone
metabolism are sulfatase (Salido et al., 1990), 3␤-hydroxysteroid
dehydrogenase (Lachance et al., 1990), aromatase, and 17␤-hydroxysteroid dehydrogenase (type 1 and type 2) (Luu-The et al., 1989).
CYP19 and CYP11A are the major isoforms expressed (mRNA
quantification) (Nishimura et al., 2003). Human placenta contains a
few forms of phase II enzymes: glutathione S-transferase ␣ and ␲
(Pacifici and Rane, 1981; Pasanen et al., 1997), epoxide hydrolase
(Pacifici and Rane, 1983), N-acetyltranferase (Derewlany et al.,
1994), and sulfotransferases isoforms such as SULT1A1 and
Umbilical artery
Umbilical vein
Amnioc
cavity
Chorionic villous
Chorion
Uterine myometrium
uterus
Amnioc fluid
Intervillous space
Uterine
i endometrium
d
i
Maternal poron
b
Chorionic villous
Maternal ssue
Conjoncval ssue
SCT
CT
Intervillous
space
I ll
Intervillous
space
Syncytotrophoblast
(SCT)
Maternal
erythrocyte
Fetal capillary
Cytotrophoblast (CT)
Umbilical artery
Umbilical vein
chorion
FIG. 1. Schematic drawing of human placental structure. a, transverse section through a full-term placenta. b, localization and
structure of human placental barrier.
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Smilar to other primate species, the human placenta is hemochorial
and characterized by direct contact between maternal blood and
trophoblast (Fig. 1a). The human placenta is divided into functional
vascular units called cotyledons. Within the cotyledon, the villus tree
contains a barrier that separates maternal circulation from fetal circulation. The layer of tissue that separates maternal and fetal circulation
is composed of the endothelium of fetal capillaries and the trophoblast, which contains the villus strom, the cytotrophoblasts, and the
syncytiotrophoblast. The thickness of the syncytiotrophoblast layer
decreases during gestation, the cytotrophoblast becomes discontinuous, and exchange processes between mother and fetus are facilitated
(van der Aa et al., 1998) (Fig. 1b).
The major function of the placenta is the transfer of nutrients that
support embryonic and fetal growth and development. During early
gestation, the placenta mediates the implantation of the embryo in the
uterus and produces hormones that prevent the end of the ovarian
cycle. The luteinizing hormone and the human chorionic gonadotrophin have a stimulating action on estrogen and progesterone synthesis
by the placenta (Pasqualini and Kincl, 1985). After implantation, the
placenta regulates the supply of nutrients and oxygen to the fetus. It
also produces angiogenic factors, vasodilators, growth hormones,
placental lactogens, and different hormones, all of which stimulate
maternal blood cell production, increase blood volume, regulate appetite, etc. Other functions of the placenta are immune function (Ig
transfer), removal of waste or toxic products from the fetus, and
metabolism. The presence of metabolism enzymes and transport systems in the placenta makes these functions possible.
1625
PLACENTAL TRANSPORTERS AND MODELS FOR TRANSFER STUDIES
TABLE 1
Metabolism enzyme expression as a function of pregnancy stage and placental models
First trimester of pregnancy
Full-term placenta
Jeg-3 cells
BeWo cells
mRNA Level
Protein Level
Enzyme Activity
⫹⫹
⫹
⫺
⫺
⫹
⫹
⫹
⫹
⫹⫹
⫺
⫺
⫺
⫺
⫺
⫹
⫹
⫹
⫹
⫺
⫹
⫹⫹
⫹⫹
⫹
⫺
nd
⫺
⫺
nd
⫹
⫹
⫹
⫹
nd
nd
nd
nd
nd
⫺
⫺
⫺
⫺
⫺
nd
nd
nd
⫹
nd
⫹
nd
nd
nd
nd
nd
nd
⫹
nd
nd
nd
nd
nd
⫺
⫺
⫺
⫺
⫺
nd
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
⫹
nd
nd
nd
⫹
nd
nd
⫹
⫹
nd
nd
⫹
nd
nd
nd
⫹
⫹
⫹
⫹
⫹
nd
nd
⫹
Reference
Hakkola et al., 1996b
Schuetz et al., 1993
Pasanen et al., 1997
Bièche et al., 2007
Hakkola et al., 1996a
Pasanen et al., 1997
Nishimura et al., 2003
Nakanishi et al., 2002
Pelkonen et al., 1984
Pavek et al., 2007
Nakanishi et al., 2002
Samson et al., 2009
Smuc and Rizner, 2009
Avery et al., 2003
Pavek et al., 2007
Nakanishi et al., 2002
nd, no data available; HSD, hydroxysteroid dehydrogenase type 1.
⫹, positive signal.
⫹⫹, strong positive signal.
⫺, negative result.
SULT1A3 (Mitra and Audus, 2009). UDP-Glucuronyltransferase isoforms, such as UGT1A and UGT2B, are also expressed (Collier et al.,
2002a,b). Data on enzymes of xenobiotic metabolism contents in
placenta cell lines are very scarce compared to those for the whole
organ: only a few P450s, including CYP19, and hydroxysteroid
deshydrogenase enzymes have been reported (Table 1).
Membrane Transport in Placenta
Transplacental Transfer of Xenobiotics. The transfer of molecules between maternal and fetal circulation occurs across the endothelial-syncytial membrane of the placenta. Drug permeation can be
influenced by numerous factors: drug properties (degree of ionization,
lipophilicity, protein binding, molecular weight); placental characteristics (blood flow, concentration gradient of the drug across the
barrier, pH gradient, thinning and aging barrier with advancement of
pregnancy, increasing surface area as pregnancy progesses, developing metabolism, protein gradients); and maternal and fetal factors
(fetal growth and development, fetal metabolism, fetal tissue binding,
maternal metabolism, maternal health condition) (Poulsen et al.,
2009). Most of the drugs crossing the human placenta diffuse passively. In this case, placental blood flow, pH of maternal and fetal
blood, physicochemical characteristics of the compounds, and protein
binding determine a drug’s ability to cross placental membranes
(Pacifici and Nottoli, 1995; Audus, 1999). Facilitated diffusion,
phagocytosis, and pinocytosis are less important routes of placental
drug transfer (Syme et al., 2004).
In 1998, the report of carrier-mediated transport of xenobiotics in
the placenta stressed the role of ATP-binding cassette (ABC) transporters in this organ (Lankas et al., 1998). Depending on the localization of these transporters in the apical (maternal facing brush
border membrane) and basal (fetal facing basal membrane) membrane
of the syncytiotrophoblast, the substrates are preferentially transported
either in maternal circulation or in fetal circulation (Unadkat et al.,
2004). Placental xenobiotic transporters and their polarized distribution are summarized in Table 2.
ABC Transporters
P-Glycoprotein (MDR1, ABCB1). The placental barrier had been
commonly considered as a permeable barrier, until a study was
published by Lankas et al. (1998). These authors stressed the role of
P-glycoprotein (P-gp) in the mouse placenta by exposing pregnant
dams, which contained a spontaneous mutation in the mdr1 gene, to
the teratogenic isomer of avermectin [1.5 mg/(kg 䡠 day), oral administration, 6 –15 days gestation], which is a substrate of P-gp. They
demonstrated that the degree of chemical exposure to fetuses within
each litter was inversely related to the expression of placental P-gp,
linking the fetal genotype to pharmacokinetic changes and subsequently to developmental toxicity.
Other studies confirmed the involvement of P-gp in the limited fetal
penetration of various potentially harmful or therapeutic compounds
such as digoxin, saquinavir, paclitaxel (study performed in P-gpdeficient mice) (Smit et al., 1999), and indinavir (study using an in
Downloaded from dmd.aspetjournals.org at ASPET Journals on June 18, 2017
JAR cells
P450 Isoform
CYP1A1
CYP1A2
CYP2A
CYP2B
CYP2D6
CYP3A4
CYP3A5
CYP3A7
CYP1A1
CYP1A2
CYP2A6/7
CYP 2B6/7
CYP2C8–19
CYP2D6
CYP2E1
CYP2F1
CYP3A4
CYP3A5
CYP3A7
CYP4B1
CYP11A1
CYP19
CYP19
No data for other cytochromes
CYP1B1
CYP2C9
CYP3A4
CYP19
3␤-HSD1
17␤-HSD1–12
CYP1A1
CYP1A2
CYP2C9
CYP3A4
CYP19
1626
PROUILLAC AND LECOEUR
TABLE 2
Comparison of the polarized distribution and relative expression at mRNA/protein level (immunohistochemistry, Western blot, and functionality) of placental
transporters relevant to drug disposition across the maternal-fetal interface
Localization
Transporter
Brush border (maternal facing) P-gp (MDR1)
membrane
Unknown or controversial
localization
⫹⫹/⫹
BeWo
⫹/⫹
Jeg-3
JAR
⫹/⫹
⫹⫹/⫹
MRP2
⫹/⫹
⫹⫹/⫹
MRP8
BCRP
⫹/nd
⫹/⫹
⫹/nd
⫹⫹/nd
⫹/nd
⫹⫹/⫹⫹
⫹/⫹ ⫹⫹/⫹
OATP1A2 (OATP-A)
OATP1B1 (OATP-C)
OATP3A1 (OATP-D)
OATP4A1 (OATP-E)
OCTN1/SLC22A4
OCTN2/SLC22A5
NaDC3
hENT1/SLC29A1
MCT-4/SLC16A4
FR␣
PCFT (SLC46A1)
RFC-1 (SLC19A1)
SERT
NET
MDR3
MRP5
OATP2B1 (OATP-B)
OAT4
RFC-1 (SLC19A1)
OCT3
MCT-1/SLC16A1
MRP1
⫹/nd ⫹⫹/⫺
⫹/nd
⫹/nd
⫹/nd
⫹/nd
nd/nd
nd/nd
⫹/nd
nd/nd
nd/nd
nd/⫹
nd/nd
nd/nd
⫹/⫹
nd/nd
nd/nd
⫹/⫹
⫹/⫹
nd/nd
nd/⫹
nd/nd
nd/nd
nd/⫹
⫹/⫹
nd/nd
⫹/⫹
nd/nd
nd/nd
⫹/⫹
⫹/⫹
nd/nd
⫹/⫹
⫹/nd
nd/nd
⫹/⫹
⫹/nd
nd/nd
⫹/⫹
⫹/⫹
nd/nd
⫹/⫹
nd/nd
nd/nd
⫹/⫹⫹ ⫹a/⫹
⫹a/nd
⫹⫹/⫹
⫹a/nd
nd/nd
⫹⫹/⫹⫹
⫹/nd
⫹/nd
⫹⫹/⫹
nd/nd
nd/nd
⫹/⫹
⫹/⫹
nd/nd
⫹/⫹
⫺/nd
nd/nd
⫹/⫹
nd/nd
nd/nd
⫹/⫹
⫹⫹/⫹⫹ ⫹⫹/⫹
MRP3
⫹⫹/⫹
MRP4
⫹/nd
MCT-8
⫹/⫹
MCT3, MCT5, MCT7
⫹/nd
hENT2/SLC29A2
nd/⫹
⫹/nd
⫹/nd
nd/⫹
nd/nd
nd/nd
⫹/nd
⫹⫹/nd
nd/nd
nd/nd
nd/nd
⫹/nd
nd/nd
nd/nd
nd/nd
nd/nd
nd/nd
nd/nd
nd/nd
nd/nd
⫹/nd
nd/nd
nd/nd
⫹/⫹
nd/nd
⫹a/⫹⫹
nd/nd
⫹/nd
nd/nd
nd/nd
nd/nd
nd/nd
⫹/⫹
⫹/nd
⫹/nd
nd/nd
nd/nd
nd/nd
Reference
St-Pierre et al., 2000; Patel et al., 2003; Evseenko et al., 2006
Pascolo et al., 2000; St-Pierre et al., 2000; Evseenko et al., 2006;
Serrano et al., 2007; Prouillac et al., 2009
Serrano et al., 2007
Maliepaard et al., 2001; Evseenko et al., 2006; Yeboah et al., 2006
Patel et al., 2003; Ugele et al., 2003; Serrano et al., 2007
Patel et al., 2003; Ugele et al., 2003; Serrano et al., 2007
Patel et al., 2003; Ugele et al., 2003; Serrano et al., 2007
Sato et al., 2003
Tamai et al., 1997; Ganapathy et al., 2005
Lahjouji et al., 2004; Rytting and Audus, 2005, 2007
Wang et al., 2000
Barros et al., 1995; Yasuda et al., 2008
Settle et al., 2004
Yasuda et al., 2008; Solanky et al., 2009
Yasuda et al., 2008; Solanky et al., 2009
Yasuda et al., 2008; Solanky et al., 2009
Prasad et al., 1996
Bzoskie et al., 1997
Patel et al., 2003; Evseenko et al., 2006
Pascolo et al. 2003; Meyer zu Schwabedissen et al., 2005
St-Pierre et al., 2002; Grube et al., 2007; Serrano et al., 2007
Cha et al., 2000; Ugele et al., 2003
Yasuda et al., 2008; Solanky et al., 2009
Sata et al., 2005
Settle et al., 2004
St-Pierre et al., 2000; Nagashige et al., 2003; Evseenko et al., 2006
St-Pierre et al., 2000
Serrano et al., 2007
Utoguchi et al., 1999; Chan et al., 2006
Price et al., 1998; Settle et al., 2004
Barros et al., 1995
nd, no data available.
a
limit detection.
⫹, positive signal.
⫹⫹, strong positive signal.
⫺, negative result.
vitro model of human placenta perfusion) (Sudhakaran et al., 2007).
Indeed, Smit et al. (1999) used mice with a targeted disruption of
mdr1a and mdr1b genes. mdr1a(⫹/–)/1b(⫹/–) females were mated
with mdr1a(⫹/–)/1b(⫹/–) males to obtain fetuses of three genotypes
[mdr1a(⫹/⫹)/1b(⫹/⫹), mdr1a(⫹/–)/1b(⫹/–), and mdr1a(–/–)/
1b(–/–)] in a single mother. Intravenous administration of a single
dose of P-gp substrate digoxin, saquinavir, and paclitaxel to pregnant
dams (gestation day 15) revealed that 2.4, 7, and 16 times more drug,
respectively, crossed the placenta and entered the mdr1a(⫺/⫺)/
1b(⫺/⫺) fetus, compared with the wild-type [mdr1a(⫹/⫹)/1b(⫹/⫹)]
fetus. This study also demonstrated that P-gp activity was completely
inhibited by oral administration of the P-gp blockers PSC833 and
GG918 to heterozygous mothers, indicating that P-gp function in the
placenta can be cancelled by pharmacological means.
ABCB1 mRNA is strongly expressed in the human placenta, which
is comparable with mRNA levels in the intestine and liver (Bremer et
al., 1992). Protein expression, confirmed by immunohistochemical
studies, is located on the maternal side of the trophoblast layer
(St-Pierre et al., 2000) and on the syncytiotrophoblast microvillous
border of the first-trimester and term placentas (MacFarland et al.,
1994; Nakamura et al., 1997).
The mRNA expression of MDR3 (MDR1 homolog, ABCB4) has
also been reported in human term and preterm placenta by Patel et al.
(2003). These results were confirmed by Evseenko et al. (2006a), who
identified MDR3 protein in the basolateral membrane of the syncytium of the term placenta and suggested that MDR3 mediated the
vectorial transport of substrates toward the fetus. MDR3 functions as
a lipid translocator and may also interact with pharmaceutical drugs
(Kimura et al., 2007). Although an overexpression of MDR3 was
reported in resistant tumor cells (Scheffer et al., 2000), the role of
MDR3 in multidrug resistance is probably minor and remains to be
confirmed.
Multidrug Resistance-Associated Proteins. The human term placenta expresses at least three members of the MRP family: MRP1,
MRP2, and MRP3 (St-Pierre et al., 2000). The localization of MRP1
has been studied using human placental brush-border, basal membrane vesicles and immunohistochemical studies, but the results are
controversial, because both apical (St-Pierre et al., 2000) and basal
(Nagashige et al., 2003) localization have been reported. MRP2 was
clearly detected by both immunofluorescence and Western blotting in
the apical membranes of syncytiotrophoblasts, whereas immunoblotting suggested an apical localization facing the maternal blood of
MRP3 (St-Pierre et al., 2000). MRPs mRNA have been identified in
placental cell lines: MRP1 and MRP2 transcripts were found in the
human choriocarcinoma cell line BeWo (Pascolo et al., 2000; Prouillac et al., 2009). Serrano et al. (2007) also reported the comparative
mRNA expression of members of the MRP family (MRP1, MRP2,
MRP3, MRP4) in human trophoblast and choriocarcinoma cells
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Basal (fetal facing) membrane
Placenta
PLACENTAL TRANSPORTERS AND MODELS FOR TRANSFER STUDIES
Solute Carrier Transporters
Organic Anion-Transporting Polypeptides. Members of the organic anion-transporting polypeptides (OATP/SLCO) are expressed
in the placenta (OATP1A2, OATP1B1, OATP-2B1, OATP-3A1,
OATP-4A1). These proteins are involved in the Na⫹-independent
uptake of bile acids in hepatocytes. As shown in vitro in transfected
epithelial cells, OATP2B1 could be involved in the transepithelial
transport of steroid sulfates in human placenta (Grube et al., 2007).
The role of other OATPs in placental drug transport is not well
known, although they could transport drugs such as methotrexate,
antibiotics, and nonsteroidal anti-inflammatory drugs (Ugele et al.,
2003; Mikkaichi et al., 2004).
Organic Anion Transporters. Organic anion transporter (OAT)-4
is the most expressed OAT. It is located in cytotrophoblast membranes and the basal surfaces of syncytiotrophoblasts (Cha et al.,
2000; Ugele et al., 2003). Although it is involved in the transport of
steroid sulfates that allow estrogen synthesis in the placenta, it is also
a multispecific xenobiotic transporter that could interact with environmental toxins and drugs (You, 2004a,b) and contribute to fetal
exposure to xenobiotics.
Organic Cation Transporters. Different organic cation transporters have been identified in the human placenta. The organic cation/
carnitine transporter 1 (OCTN1), a member of a subfamily of OCTs
(SLC22A subfamily), is expressed on the apical side of human syncytiotrophoblasts (Tamai et al., 1997; Ganapathy et al., 2005).
OCTN2 is also present on the maternal side (microvillous membrane)
of trophoblast cells, as shown by Lahjouji et al. (2004). OCTN2
transports L-carnitine in a Na⫹-dependent manner, from maternal
circulation to fetal circulation. It can also mediate the transport of
drugs such as antidepressants, amphetamines, and ␤-lactam antibiotics (Grube et al., 2005). OCT3 is a Na⫹- and Cl⫺-independent
monoamine transporter that is mostly found in the placenta (Kekuda
et al., 1998). OCT3 transcript and protein have been detected at the
basal membrane of human trophoblast cells (Sata et al., 2005). Because it shows a high affinity for monoamines (serotonin, dopamine,
norepinephrine, and histamine), human OCT3 is considered to be an
extraneuronal monoamine transporter. However, antidepressants (desipramine, imipramine, amphetamines) could also interact with
OCT3.
Monoamine Transporters. The serotonin transporter (SERT) and
the norepinephrin transporter (NET) have been identified in the placenta at the maternal facing membrane (Prasad et al., 1996; Bzoskie
et al., 1997). Both SERT and NET proteins are functionally active in
the human placenta at term. Because these transporters critically
regulate extracellular monoamine concentrations, they could play a
role in maintaining homeostasis in amniotic fluid and fetal circulation
(Prasad et al., 1994a): they clear the maternal blood of excessive
amounts of catecholamines and serotonine, preventing preeclampsia
(Bottalico et al., 2004). In addition, the monoamine oxidases A, which
allow the intracellular degradation of monoamines after uptake from
the extracellular space, are less expressed and less active in placentas
from preeclamptic pregnancies (Kaaja et al., 1999; Carrasco et al.,
2000; Sivasubramaniam et al., 2002). Monoamine transporters have
been involved in the adverse effects of cocaine and amphetamines,
because they are cellular targets for these abusable drugs that block
catecholamine transport (Ramamoorthy et al., 1995; Prasad et al.,
1996; Bzoskie et al., 1997).
Monocarboxylate Transporters. There are several isoforms of
monocarboxylate transporters (MCT1, MCT3, MCT4, MCT5, MCT7,
MCT8) (Price et al., 1998; Settle et al., 2004) and dicarboxylate
transporters (NaDC3) (Wang et al., 2000) in the placenta. These
proton-coupled transporters are essential for the transport of lactate,
ketone bodies, and other monocarboxylates through the plasma membrane. They may contribute to the net transport of lactate through the
placental barrier (Nagai et al., 2010). MCT8 could be involved in the
transport of thyroid hormones and implicated in the development of
trophoblast cells and the fetus (Chan et al., 2006). Other substrates are
benzoic acid, acetic acid, acetylsalicylic acid, and antibiotic cefdinir
(Utoguchi et al., 1999).
Equilibrative Nucleoside Transporters. Both Na⫹-independent
equilibrative nucleoside transporters, ENT1 and ENT2, are expressed
in the placenta (Barros et al., 1995). Physiological substrates of these
transporters are purine and pyrimidine nucleosides, but a number of
anticancer nucleoside analogs are also substrates (Griffiths et al.,
1997).
Folate Transporters. Because folates are essential nutrients for
cell division and growth, folates’ deficiencies by insufficient dietary
intake could impair fetal development. In addition to their involve-
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(BeWo, Jeg-3, JAR). MRP1, MRP2, and MRP3 are known to mediate
the transport of various glucuronides, including estradiol and biblirubin, and handle various xenobiotics and their metabolites as substrates
(for a review, see Deeley et al., 2006). However, their role in the
placenta has not been clearly established. It is probably related to the
efflux of polar conjugates of xenobiotics or metabolites of endogenous compounds as steroid conjugates.
Protein and mRNA expression, localization, and the function of
MRP5 in human placenta have been studied by Pascolo et al. (2003)
and Meyer zu Schwabedissen et al. (2005). Although it is mostly
located in the basal membrane of syncytiotrophoblasts, and in and
around fetal vessels, MRP5 has also been detected in the apical
membrane. MRP5 acts as an export pump for cyclic nucleotides,
especially cGMP, which play a major role in cytotrophoboblast differentiation. Although the role of MRP5 in this process is still unknown, MRP5 has been shown to confer resistance to nucleobase and
nucleoside analogs, used in anticancer and antiviral therapy, by cellular export of nucleoside monophosphate (Wijnholds et al., 2000).
Breast Cancer Resistance Protein. Evidence of a BCRP-mediated
transport in the placenta was highlighted by Jonker et al. (2000).
Using P-gp-deficient pregnant mice, the authors demonstrated that the
coadministration (at gestation day 15) of Bcrp1 inhibitor elacridar (50
mg/kg, oral administration) increased the fetal concentration of topotecan (a BCRP/Bcrp1 substrate) after drug administration (1 mg/kg,
oral administration). Other in vivo studies using Bcrp1-knockout mice
demonstrated the transport activity of placental bcrp1 (Enokizono et
al., 2007; Zhang et al., 2007) and its role in limiting fetal exposure to
phytoestrogen (30 ␮mol/kg genistein, coumestrol, or daidzein, oral
administration, 2 weeks gestation) and nitrofurantoin (5 mg/kg, retroorbital injection, 2 weeks of gestation). The fetoprotective function of
BCRP was highlighted by studies using a human placental perfusion
model, which demonstrated an increase in the fetal-to-maternal concentration ratio of glyburide (100 ng/ml perfusion) (Pollex et al.,
2008) and PhIP (2 ␮M perfusion) (Myllynen et al., 2008) after
pharmacological inhibition of BCRP. The limitation of fetal glyburide
distribution by BCRP was also confirmed in mice by Zhou et al.
(2008) and in vesicles of human brush border by Gedeon et al. (2008).
The expression of BCRP mRNA is known to be higher in human
placenta than in other organs (Allikmets et al., 1998). The corresponding protein is expressed in the apical membrane of syncytiotrophoblasts and in the fetal vessels of chorionic villi (Maliepaard et al.,
2001; Evseenko et al., 2006a; Yeboah et al., 2006). BCRP structure
(substrate selectivity and localization in the placenta) suggest that, like
P-gp, it may have a protective role in removing cytotoxic drugs from
fetal tissues.
1627
1628
PROUILLAC AND LECOEUR
Variation of Transporter Expression during Pregnancy
The continuous development of placenta defines different stages of
pregnancy and results in modifications of permeability, which potentially lead to modulation of fetal exposure. Among ABC transporters,
ABCG2, ABCB1, ABCB33, and ABCC1 have been shown to vary
during pregnancy.
ABCG2. Different in vivo studies have shown a clear variation in
ABCG2 expression as gestation progresses. Indeed, BCRP protein
expression and mRNA increased 2-fold in a group of preterm placentas (28 ⫾ 1 week of pregnancy, 15 placentas), compared with term
placentas (39 ⫾ 2 week of pregnancy, 29 placentas) (Meyer zu
Schwabedissen et al., 2006). On the contrary, Yeboah et al. (2006)
examined BCRP in placental tissues at week 6 to 41 of pregnancy and
reported an increase in protein expression at term, although mRNA
levels did not change as gestation progressed. In the rat placenta, a
decrease in the expression of Bcrp1 (mRNA and protein) from the
mid-stage to the end of gestation was observed (Yasuda et al., 2005).
Bcrp1 mRNA expression increased 3-fold on the 15th day of gestation
compared with the 21st day (Cygalova et al., 2008). In agreement with
the latter study, two recent studies on mouse placenta reported peaked
Bcrp1 levels on the 15th gestation day (Wang et al., 2006) and a
gestation-dependent decrease in the mRNA expression of Bcrp1 from
the 9th to the 18th day of gestation (Kalabis et al., 2007).
ABCB1, ABCB3. The mean expression of P-gp measured by
Western blotting analysis in early (13–14 gestation week) compared
with late (full-term) placentas was found to be 2-fold higher (Gil et al.,
2005; Sun et al., 2005). In agreement with this finding, Mathias et al.
(2005) demonstrated that the P-gp expression protein decreased dramatically as pregnancy proceeded and was lowest at term. On the
other hand, Novotna et al. (2004) showed increasing expression of
P-gp in rat syncytiotrophoblasts from the 11th to the 18th day of
pregnancy. This result was in agreement with a possible role in fetal
protection soon after the establishment of chorioallantoic placenta and
until the end of pregnancy. Unlike human MDR1, human MDR3 was
more abundantly expressed in the last stage of gestation (Patel et al.,
2003).
Existing data strongly suggest that ABCG2 and ABCB1 play an
important role in protecting the fetus against the potential toxicity of
drugs, xenobiotics, and metabolites. The decrease in ABCG2 and
ABCB1 at the end of gestation could be related to higher fetal susceptibility to xenobiotic toxicity in the last part of gestation and higher fetal
protection against xenobiotics early in pregnancy. Indeed, the fetus is
most vulnerable to xenobiotic toxicity during organogenesis.
ABCC1. In a study using placental samples (cytotrophoblasts and
endothelial cells), MRP1 expression was increased 4-fold in the third
trimester, compared with the first trimester (Pascolo et al., 2003).
MRP1 was also increased 20-fold in polarized BeWo cells, compared
with nonpolarized cells.
OATPs. Among SLC transporters, OATP1A2 and OATP3A1 were
down-regulated between the first and third trimester of pregnancy
(Patel et al., 2003).
The discrepancies observed in rats, mice, and humans suggested
different mechanisms in the regulation of transporter expression
among these species. However, the molecular mechanisms underlying
the modulation of placental ABC and SLC transporters by pregnancy
have not been elucidated yet.
Folate Transporters. An increase in the expression levels of FR␣,
RFC, and PCFT and the progress of gestation in rat placenta have
been shown and could play an important role in the response to
increased need by placenta and fetus for folate during development
(Yasuda et al., 2008).
Due to obvious ethical reasons, studies of fetal risk from maternal
exposure to chemicals and pharmaceuticals are not performed in
humans. In addition to in vivo/ex vivo models, cell lines have been
developed to provide important knowledge on the transplacental
transfer in humans of new chemical substances and on environmental
exposures to hazardous compounds. The use of nondifferentiated
models, such as choriocarcinoma cell lines, is also an alternative in the
study of the expression of transporters during early stages of gestation.
The Use of Cell Lines as Placental Barrier Models
The properties and main uses of these cell lines are summarized in
Table 3.
Human Choriocarcinoma Cell Lines
BeWo Cell Line. The BeWo cell line (Patillo and Gey, 1968),
developed from a malignant gestational choriocarcinoma of the fetal
placenta, displays morphological and biochemical enzymes of trophoblasts, which show hormonal secretion properties (hCG, progesterone,
placental lactogen) (Pattillo et al., 1979; Nickel and Cattini, 1991) and
cytokine expression [IFN␣, IFN␤, IL10 (Bennett et al., 1996), IL6 and
IL8 (Fujisawa et al., 2000), and IL4 (Sacks et al., 2001)].
The BeWo cell line is widely used as a model system to study
trophoblast differentiation (Hussa et al., 1974; Vogt et al., 1997; Xu et
al., 1999; Rao et al., 2003; Rote, 2005), placental metabolism, and
nutrient and drug distribution across the placental barrier (van der
Ende et al., 1989; Furesz et al., 1993; Moe et al., 1994; Prasad et al.,
1996; Eaton and Sooranna, 1998; Way et al., 1998; Ellinger et al.,
1999; Ushigome et al., 2000; Shah et al., 1999; Takahashi et al., 2001;
Vardhana and Illsley, 2002; Schmid et al., 2003). BeWo cells form a
confluent polarized monolayer on a permeable support, as shown by
the development of a transepithelial electric resistance and a high
density of microvilli on the apical surface of the monolayer (Liu et al.,
1997). The b24 and b30 BeWo clones (developed by Dr. Alan
Schwartz, Washington University School of Medicine, St. Louis, MO)
have shown better monolayer-forming ability than the original BeWo
clone available from the American Type Culture Collection (Manassas, VA) (Bode et al., 2006). This finding contradicts studies by Parry
et al. (2006) and Mark and Waddell (2006) who used the BeWo clone
from American Type Culture Collection as a representative model of
transepithelial barrier. The ability of cells to form a monolayer on a
permeable support depends on the formation of tight junctions. Many
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ment in folate transport, these transporters could interact with a
variety of antifolates used in the treatment of cancer and immune
disorders.
Folate receptor alpha (FR␣), localized on the apical side of human
placental villi, could be invoved in folate uptake from maternal blood
to the placenta (Prasad et al., 1994b; Yasuda et al., 2008). Reduced
folate carrier (RFC-1; SLC19A1) is distributed to both the microvillous plasma membrane of the syncytiotrophoblast and the basal syncytiotrophoblast in term placenta (Yasuda et al., 2008; Solanky et al.,
2010), and it mediates bidirectional reduced folate transport. More
recently, a heme carrier protein 1 (PCFT/HCP1, SLC46A1) implicated in folate transport has been characterized in the apical side of the
trophoblast.
Most studies on the placental expression of transporters have been
performed in various models that representated different stages of
gestation. Therefore, it is very difficult to compare the levels of
expression from one stage of gestation to another. Data on the expression of transporters throughout gestation are necessary to understand their importance in fetal development. Indeed, the expression of
numerous transporters varies during pregnancy.
Gene expression
Physiological stimuli, hormone secretion,
apoptosis, parasites, virus
(Abbasi et al., 2003; Kilani et al, 2007)
Apoptosis
(Saulsbury et al., 2008)
(Hemming et al., 2001)
(Mitchell et al., 1995; Bode et al., 2006)
(Liu et al., 1997)
Transplacental transport of drug
(Saunders, 2009)
Trophoblast differentiation
(Nampoothiri et al., 2007)
Use
Ability to form confluent monolayer
on permeable support
(Bode et al., 2006;
Hardman at al., 2007)
Gene expression
(Rena et al., 2009)
Controversial
Controversial
Controversial
Progesterone, ␤-hCG, steroids
(Morrish et al., 1997)
Progesterone, ␤-hCG,
steroids
(Kato and Braunstein, 1991)
Early placental trophoblast
Morphological differentiation
(Borges et al., 2003)
Not spontaneously
(forskolin, cAMP analog)
Only biochemical
differentiation
(Al-Nasiry et al., 2006)
Progesterone, ␤-hCG,
steroids
(Chou, 1982)
Hormonal secretion
Undifferentiated cytotrophoblasts
mononucleated and proliferative
Not spontaneously
(forskolin, cAMP analog)
Biochemical and morphological
differentiation
(Al-Nasiry et al., 2006)
Progesterone, ␤-hCG,
steroids, placental lactogen
(Pattillo et al., 1979; Nickel and Cattini,
1991; Prouillac et al., 2009)
Yes
Differentiation
Derived from BeWo
Spontaneously
(Morrish et al., 1997)
Normal trophoblast contamination by other
cell types (endothelial cells, etc.)
Choriocarcinoma cells
Choriocarcinoma cells derived
from BeWo
Mononucleated and proliferative
Choriocarcinoma cells
Origin
Jeg-3
BeWo
TABLE 3
Properties and use of placental cell lines
1629
factors such as the choice of media (essential nutrients and growth
factors), seeding density, extent of cell confluency, exposure time,
environmental conditions, and choice of permeable insert (diameter,
pore size, supporting matrix) may influence tight junction development. Validity of the monolayer is assessed by measuring transepithelial electrical resistance and determining the transfer of paracellular
markers (inulin, sucrose, fluorescein, fluorescein isothiocyanatedextran, Lucifer yellow) (Liu at al., 1997; Konsoula and Barile, 2005).
BeWo monolayers have been used for transport studies, but the latter
all report different cell culture conditions (Saunders, 2009).
The BeWo cells consist of undifferentiated cytotrophoblasts with
few syncytialized cells (Wice et al., 1990). Their differentiation into
syncytiotrophoblasts does not occur spontaneously, but the syncytialization process can be induced by forskolin or 8-bromoadenosine
38,58-cyclic monophosphate treatment (Borges et al., 2003). For this
reason, BeWo cells are used for studies on the maturation of trophoblasts: they can model either cytotrophoblasts of early gestation or
syncytiotrophoblasts of late gestation. Treatments with syncytium
inducers result in an increase of monolayer permeability (Liu et al.,
1997), which can be a disadvantage for transfer studies.
BeWo cells constitute a good model for studying the fusion process
that occurs during syncytium formation. Envelope proteins such as
syncytin-1, derived from human endogenous retroviruses, seem to
play an essential role in these cellular fusion events (see the review by
Pötgens et al., 2004). Syncytin-1 expression is up-regulated after
stimulating the fusion of primary cytotrophoblast into syncytia by
forskolin, a cAMP analog. Vargas et al. (2009) recently demonstrated
a more important role for syncytin-2 in trophoblast fusion, showing
that syncytin-1 expression changed slightly in BeWo on stimulation,
compared with syncytin-2 fluctuation. Moreover, using two different
targeted small interfering RNAs for each transcript, the authors demonstrated that a reduction of syncytin-2 expression led to a significant
decrease in the number of BeWo cell fusions. Two amino acid
transporters ASCT1 and ASCT2 expressed in trophoblast are potential
receptors of syncytin-1. The receptor of syncytin-2 protein is also
placenta-specific (Esnault et al., 2008).
ABC efflux transporters, including P-gp, MRPs and BCRP, are
expressed in BeWo cells (Table 2). The pattern of expression is
similar to that of syncytiotrophoblasts isolated from human placenta.
BCRP is highly expressed in BeWo cells, whereas P-gp transcript and
protein are minimally expressed or even absent. Both transporters are
localized predominantly in the apical plasma membrane and show
efflux activity. mRNA of MRP1, MRP2, MRP3, MRP5, and MRP8
are variably expressed, depending on differentiation status (Pascolo et
al., 2000, 2003; Serrano et al., 2007). Folate transporters (Yasuda et
al., 2008) and OCTN2 (Rytting and Audus, 2005, 2007) are present,
whereas OAT and MCT expression has not been reported up to now.
Expression of ABC transporters (BCRP, MRP1, MRP2) is modulated
by cell differentiation (Evseenko et al., 2006b; Prouillac et al., 2009).
BeWo cells are stable, easily maintained by trypsinization, and
form a confluent monolayer on a permeable support in a relatively
short period of time (4 –5 days). These advantages make this cell line
an attractive in vitro model for studying trans-trophoblast transport
and drug metabolism (Poulsen et al., 2009), as shown by numerous
studies on the transport of digoxin, vinblastine, vincristine (Ushigome
et al., 2000), opioides peptides (Ampasavate et al., 2002), iron
(Heaton et al., 2008), and cholesterol (Schmid et al., 2003) (Table 4).
JAR and JEG-3 Cell Lines. JAR and JEG-3 cell lines, derived
from choriocarcinoma cell lines, are used in studies of placental
function including differentiation, invasion, hypoxia/oxidative stress
response, endocrinology, maternal fetal immunology, and transplacental transfer. The JEG-3 cells possess many of the biological and
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JAR
Primary Placental Cells
PLACENTAL TRANSPORTERS AND MODELS FOR TRANSFER STUDIES
1630
nd
nd
Caffeine, glyphosate,
benzoic acidr
nd
Food
contaminant
Opioid peptides,o vincristine,
vinblastine, digoxin,p
monocarboxylic acidq
Riboflavind
Antibiotics, antacid,
antidiabetic
Cocaine, alcohol,
nicotine, morphine
HIV inhibitors,
antidepressants,
Medicinal drugs
Abused agents
Anesthetics, antiepileptic,
heart condition
Pregnancy related
treatmenta,b
Caffeine, glyphosate,
benzoic acid,s PhIPt
Valproic acidn
Antiviral drugs, antimitotic, colchicines,
HIV inhibitors, antidepressants,
antibiotics, antacid, antidiabetic,
Anesthetics, antiepileptic, heart
conditiona
Levofloxacinc
nd
Amino acid,e glucose,f glucocorticoids,g
folic acid,g fatty acid,h transferrin,i
serotonin,j bilirubin,j choline,k IgG,k
cholesterol,l leptinm
nd
nd
nd
Physiological
molecules
Intracellular Accumulation
nd, no data available.
a
Rama Sastry, 1999; b Myren et al., 2007; c Polachek et al., 2010; d Huang and Swaan, 2001; e Jones et al., 2006; f Vardhana and Illsley, 2002; g Takahashi et al., 2001; h Liu et al., 1997; i van der Ende, 1990; j Pascolo et al., 2001; k Ellinger et al., 1999;
Schmid et al., 2003; m Wyrwoll et al., 2005; n Utoguchi and Audus, 2000; o Ampasavate et al., 2002; p Ushigome et al., 2000; q Utoguchi et al., 1999; r Poulsen et al., 2009; s Mose et al., 2008; t Myllynen et al., 2008; u Hardman et al., 2007; v Keating et
al., 2006; w Feinshtein et al., 2010.
l
nd
Nitrofurantoinw
nd
nd
Folic acidv
Copperu
Intracellular
Accumulation
Intracellular
Accumulation
Vectorial Transport
Jeg-3
BeWo
In Vivo Transplacental Transfer
Perfused Human Placenta
TABLE 4
biochemical characteristics of syncytiotrophoblasts, although they are
mononucleated and proliferative (Matsuo and Strauss, 1994). They
produce placental hormones (progesterone, hCG, steroids) (Chou,
1982; Kato and Braunstein, 1991) and express various enzymes (Sun
et al., 1998; Tremblay et al., 1999). Although they show biochemical
differentiation, such as increased hCG secretion, JEG-3 cells do not
morphologically differentiate with forskolin treatment (Al-Nasiry et
al., 2006). However, JEG-3 cells have a lower rate of proliferation and
a higher degree of differentiation than BeWo and JAR cells (White et
al., 1988; Aplin et al., 1992; Borges et al., 2003; Kitano et al., 2004).
Compared with cytotrophoblast cells stemming from isolated human placenta, JAR cells are more similar to nondifferentiated cytotrophoblasts (Evseenko et al., 2006a). The JAR cell line is probably an
unsuitable model for studies of transepithelial transport (Mitchell et
al., 1995), exactly like JEG-3 cells, if one refers to the few studies
reporting the use of JEG-3 as a model for vectorial transepithelial
transport (Hardman et al., 2007). Indeed, the ability of both cell lines
to form a polarized monolayer is controversial (Bode et al., 2006). The
transcriptional profile and protein expression of many transporters, in
particular export pumps (P-gp, MRPs, and BCRP) and organic anion
transporters (OATPs), show quantitative variation in both cell lines
(Table 2) (Serrano et al., 2007).
Human Primary Cells
Primary cell lines of undifferentiated cytotrophoblasts can be produced from human placenta. Unless primary cells are allowed to
differentiate, they represent early stages of gestation. These nonproliferative, multinucleated cells are able to syncytialize spontaneously.
They form aggregates with large intercellular spaces, which make
studies of polarized transport of xenobiotics impossible when they are
grown on semipermeable membranes (Yui et al., 1994; Liu et al.,
1997). Hemmings et al. (2001) reported that primary cytotrophoblasts
formed tight junctions after three successive cycles of seeding and
differentiation. Although this method produced multiple overlapping
layers of syncytialized cells, areas of microvillar projections were
formed on the apical surface and functioned as a barrier to low- and
high-molecular-weight molecules. In addition to the fact that obtaining a reproducible cell population may be tricky, primary cell lines
also have high contamination levels and are not viable for many
passages. These cell lines are mostly used in investigations involving
parasites or virus (Abbasi et al., 2003).
Other Models for Placental Transfer Studies
Experimental models have to replicate the full features and functionality of in vivo trophoblast cells. For obvious ethical reasons, in
vivo experimentation of placental drug transport in humans cannot be
performed. Therefore, the risk assessment of fetal injury (teratogenic
and fetotoxic potential of xenobiotics) from maternal exposure to
xenobiotics is based on results from animal studies. Animal models
provide the advantages of a complete physiological system. However,
interspecies differences in placental morphology and length of gestation demand caution when assuming that the maternal-to-fetal transfer
of substances observed in animal models will be observed in the same
way in humans (Moe, 1995; Enders and Blankenship, 1999). For these
reasons, mechanisms of placental transport, metabolism, and placental
toxicity are best investigated in models of human origin (Myllynen
and Vähäkangas, 2002). Primates such as rhesus macaques and baboons have also been used to evaluate the transfer of compounds
because their hemochorial placentation is similar to that of humans
(Patterson et al., 2000). An original study has recently reported the use
of positron emission tomography imaging to monitor the placental
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Studies of therapeutic agents, abused drugs and food contaminants transfer using in vivo and in vitro models of placenta
Vectorial
Transport
JAR
Vectorial
Transport
PROUILLAC AND LECOEUR
PLACENTAL TRANSPORTERS AND MODELS FOR TRANSFER STUDIES
specificity, saturability) of transporters, but it does not reflect the in
vivo situation, due to a lack of regulatory factors.
Conclusions and Perspectives
The expression of both ATP and SLC transporters has been demonstrated in many polarized epithelial barriers (i.e., kidney, liver,
blood-brain barrier, intestine, lung, etc.) and many different species.
Cellular localization combined with knowledge of the protein function
gives insight into the role of these proteins in the accumulation and
removal of specific substrates from the cells at each barrier. However,
despite the considerable efforts invested in studying these transporters, few works have been dedicated to the cellular localization of these
transporters in the placenta. Moreover, too little information is available on the mechanisms of fetal exposure to pollutants and the role of
the placenta in this exposure.
First, placental models efficient for studying xenobiotic transport
are far from being fully characterized. Better knowledge of cell
properties (content in xenobiotic metabolism enzymes and transporters, number of passage, phenotype, differentiation) is required, and
several external factors must be considered and optimized (Audus et
al., 1990):
• culture conditions (culture medium composition, cell seeding density, stage of differentiation)
• permeable support characteristics (diameter, pore size, supporting
matrix such as collagen)
• transport study conditions (transport medium composition, pH, temperature, etc.)
• diffusion apparatus (stirring or not)
In vitro placental transfer studies show high variability, occasionally leading to controversial results. Further investigation into transporter activity and membrane localization in the polarized placental
epithelium will help to define the physiological and pharmacological
functions of transporters in placental cells.
Second, the modulation of the expression of placental transporters
may influence their role. In addition to variation of expression due to
the gestation stage, in vivo genetic variability may also exist in
xenobiotic transport by placenta. Variability is due to the presence of
single nucleotide polymorphisms (SNPs), as has been shown for ABC
transporter expression. This genetic polymorphism has been described
for placental mdr1 (Tanabe et al., 2001) and bcrp (Kobayashi et al.,
2005) and is associated with altered P-glycoprotein expression (Hitzl
et al., 2004). However, it remains to be determined whether these
SNPs influence the pharmacokinetic and dynamic properties of clinically useful drugs. Rahi et al. (2008) reported that although SNPs
altered the expression levels of P-gp in the human placenta, they did
not have an effect on P-gp-mediated placental transfer of saquinavir.
On the contrary, recent studies have shown that some homozygous
mdr1 variants (C1236T, C3245T) are associated with an increase in
placental P-gp efflux of paclitaxel (Hemauer et al., 2010). Transfected
cell lines expressing the polymorphic variant (Q141K) of ABCG2
exhibit altered placental pharmacokinetics of glyburide (Pollex et al.,
2010). Further investigations are needed to define the significance of
SNPs in the placental transport of xenobiotics.
Third, in addition to the trophoblast cells, human fetal membranes
such as the amnion, chorion, and yolk sac may constitute an additional
site of drug transfer in pregnant humans and rodents. Data are very
scarce on transporter expression and function in these fetal annexes.
The amnion can be considered as a barrier that separates maternal and
fetal compartments and expresses functional transporter proteins such
as MRPs and BCRP (Aye et al., 2007), as well as the chorion, which
expresses BCRP (Yeboah et al., 2008). RFC protein is expressed in
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P-gp function during pregnancy in nonhuman primates (Chung et al.,
2010).
Feto-Maternal Blood Concentration Ratio. Human maternal and
umbilical cord blood are simultaneously sampled during labor. Further analysis for the presence of compounds constitutes a simple and
ethical method that illustrates the drug concentration between both
circulations. However, the lack of comparison with a proper reference
compound, the difficulties in evaluating the influence of placental
metabolism on drug transfer, and the lack of information on drug
distribution and accumulation in tissue are definite drawbacks (Levy,
1981; Waddell and Marlowe, 1981; Chamberlain, 1986; Simone et al.,
1994).
Human Coelocentesis. This alternative to fetal blood sampling was
introduced in 1991 (Jauniaux et al., 1991). It consists of sampling
from human exocoelomic and amniotic fluid by transvaginal puncture
at weeks 6 to 10 and weeks 7 to 12, respectively (Jauniaux and Gulbis,
2000). This method does not allow building a kinetic model, which is
necessary to extrapolate quantitative drug transfer.
Perfused Single Human Placental Cotyledon Model. The technique of ex vivo perfusion of human placenta was first described by
Panigel et al. (1967), then modified by Schneider et al. (1972). It is
commonly used to investigate the mechanism and predict the rate of
transfer of drugs through the placenta in vivo (Bourget et al., 1995).
This model has been used to elucidate the mechanisms of placental
transfer of HIV protease inhibitors and antiepileptic drugs (Forestier
et al., 2001; Myllynen et al., 2003). Ethical problems are minimal
because this technique is noninvasive and placentas are discarded or
incinerated after birth. The critical point of the model is that it does
not represent the first trimester placenta, when the fetus’ susceptibility
to toxic hazards is high. However, because placental thickness and the
number of cell layers decrease at the end of pregnancy, it is possible
that the term placenta might be more sensitive to environmental
agents than first anticipated (Vähäkangas and Myllynen, 2006). Another disadvantage is possible underestimation of the contribution
made by transporters and metabolism during pregnancy, because
transporters and metabolism differ between first trimester and fullterm placenta. Interindividual variation also raises the question of the
number of placentas that have to be perfused to validate the method.
However, the influence of placental metabolism, the preferential direction of transport, and the presence of overall active transport can be
evaluated. Results are generally compared with data on reference
compounds such as inulin or antipyrine.
Human Trophoblast Tissue Preparations. Tissue explants can be
used to study the transport of substances from the maternal circulation
into the syncytiotrophoblast, as well as the metabolism, endocrine
function, enzyme function, cellular proliferation, and differentiation in
the placenta at early gestation or near term (Miller et al., 2005). This
method requires careful consideration of the potential contribution of
mesenchymal and endothelial cells to the metabolic process (Syme et
al., 2004). Moreover, a recent publication has reported the limits of
this model: the functional characterization of individual transporters is
difficult, due to the lack of selective substrates and/or specific inhibitors. Furthermore, the authors suggested the presence of compensatory regulatory mechanisms, which could explain the difficulty of
performing a good kinetic transfer study (Vaidya et al., 2009).
Membrane Vesicles. Isolated membrane vesicles can be obtained
from either the membrane of the brush border or the basal surface of
the trophoblast. Therefore, the study of transport mechanisms is
possible in both fetal and maternal plasma membranes (Murer and
Kinne, 1980; Bissonnette, 1982). This model enables the characterization of expression and functionality (susceptibility to inhibitors,
1631
1632
PROUILLAC AND LECOEUR
the yolk sac (Maddox et al., 2003), and the existence of xenobiotic
efflux transporters in extraembryonic fetal membranes has recently
been demonstrated in mice (Kalabis et al., 2007; Aleksunes et al.,
2008). It is now necessary to study the contribution of fetal membranes in the transfer of xenobiotics between the mother and the fetus,
which opens up a new field of research.
ABC and SLC proteins are able to transport nutrients as well as xenobiotics. These xenobiotics may compete with the physiological substrates of the
placental transporters and interfere with the delivery of nutrients to the fetus.
Future studies should deal with the possibility of an interaction that alters
exchanges between fetus and mother. Exchange modulation may have consequences on the growth and development of the fetus, a crucial stage in
which small alterations may lead to long-term modulation of metabolic
regulation and programming.
References
Downloaded from dmd.aspetjournals.org at ASPET Journals on June 18, 2017
Abbasi M, Kowalewska-Grochowska K, Bahar MA, Kilani RT, Winkler-Lowen B, and Guilbert
LJ (2003) Infection of placental trophoblasts by Toxoplasma gondii. J Infect Dis 188:608 –
616.
Aleksunes LM, Cui Y, and Klaassen CD (2008) Prominent expression of xenobiotic efflux
transporters in mouse extraembryonic fetal membranes compared with placenta. Drug Metab
Dispos 36:1960 –1970.
Allikmets R, Schriml LM, Hutchinson A, Romano-Spica V, and Dean M (1998) A human
placenta-specific ATP-binding cassette gene (ABCP) on chromosome 4q22 that is involved in
multidrug resistance. Cancer Res 58:5337–5339.
Al-Nasiry S, Spitz B, Hanssens M, Luyten C, and Pijnenborg R (2006) Differential effects of
inducers of syncytialization and apoptosis on BeWo and JEG-3 choriocarcinoma cells. Hum
Reprod 21:193–201.
Ampasavate C, Chandorkar GA, Vander Velde DG, Stobaugh JF, and Audus KL (2002)
Transport and metabolism of opioid peptides across BeWo cells, an in vitro model of the
placental barrier. Int J Pharm 233:85–98.
Aplin JD, Sattar A, and Mould AP (1992) Variant choriocarcinoma (BeWo) cells that differ in
adhesion and migration on fibronectin display conserved patterns of integrin expression. J Cell
Sci 103:435– 444.
Audus KL, Bartel RL, Hidalgo IJ, Borchardt RT (1990) The use of cultured epithelial and
endothelial cells for drug transport and metabolism studies. Pharm Res 7:435– 451.
Audus KL (1999) Controlling drug delivery across the placenta. Eur J Pharm Sci 8:161–165.
Avery ML, Meek CE, and Audus KL (2003) The presence of inducible cytochrome P450 types
1A1 and 1A2 in the BeWo cell line. Placenta 24:45–52.
Aye IL, Paxton JW, Evseenko DA, and Keelan JA (2007) Expression, localization and activity
of ATP binding cassette (ABC) family of drug transporters in human amnion membranes.
Placenta 28:868 – 877.
Barros LF, Yudilevich DL, Jarvis SM, Beaumont N, Young JD, and Baldwin SA (1995)
Immunolocalisation of nucleoside transporters in human placental trophoblast and endothelial
cells: evidence for multiple transporter isoforms. Pflugers Arch 429:394 –399.
Bennett WA, Lagoo-Deenadayalan S, Brackin MN, Hale E, and Cowan BD (1996) Cytokine
expression by models of human trophoblast as assessed by a semiquantitative reverse transcription-polymerase chain reaction technique. Am J Reprod Immunol 36:285–294.
Bièche I, Narjoz C, Asselah T, Vacher S, Marcellin P, Lidereau R, Beaune P, and de Waziers I
(2007) Reverse transcriptase-PCR quantification of mRNA levels from cytochrome (CYP)1,
CYP2 and CYP3 families in 22 different human tissues. Pharmacogenet Genomics 17:731–
742.
Bissonnette JM (1982) Review article: membrane vesicles from trophoblast cells as models for
placental exchange studies. Placenta 3:99 –106.
Bode CJ, Jin H, Rytting E, Silverstein PS, Young AM, and Audus KL (2006) In vitro models for
studying trophoblast transcellular transport. Methods Mol Med 122:225–239.
Borges M, Bose P, Frank HG, Kaufmann P, and Pötgens AJ (2003) A two-colour fluorescence
assay for the measurement of syncytial fusion between trophoblast-derived cell lines. Placenta
24:959 –964.
Bottalico B, Larsson I, Brodszki J, Hernandez-Andrade E, Casslén B, Marsál K, and Hansson SR
(2004) Norepinephrine transporter (NET), serotonin transporter (SERT), vesicular monoamine
transporter (VMAT2) and organic cation transporters (OCT1, 2 and EMT) in human placenta
from pre-eclamptic and normotensive pregnancies. Placenta 25:518 –529.
Bourget P, Roulot C, and Fernandez H (1995) Models for placental transfer studies of drugs. Clin
Pharmacokinet 28:161–180.
Bremer S, Hoof T, Wilke M, Busche R, Scholte B, Riordan JR, Maass G, and Tümmler B (1992)
Quantitative expression patterns of multidrug-resistance P-glycoprotein (MDR1) and differentially spliced cystic-fibrosis transmembrane-conductance regulator mRNA transcripts in
human epithelia. Eur J Biochem 206:137–149.
Bzoskie L, Yen J, Tseng YT, Blount L, Kashiwai K, and Padbury JF (1997) Human placental
norepinephrine transporter mRNA: expression and correlation with fetal condition at birth.
Placenta 18:205–210.
Carrasco G, Cruz MA, Dominguez A, Gallardo V, Miguel P, and González C (2000) The
expression and activity of monoamine oxidase A, but not of the serotonin transporter, is
decreased in human placenta from pre-eclamptic pregnancies. Life Sci 67:2961–2969.
Cha SH, Sekine T, Kusuhara H, Yu E, Kim JY, Kim DK, Sugiyama Y, Kanai Y, and Endou H
(2000) Molecular cloning and characterization of multispecific organic anion transporter 4
expressed in the placenta. J Biol Chem 275:4507– 4512.
Chamberlain G (1986) Placental transfer of drugs. Clin Exp Obstet Gynecol 13:107–112.
Chan SY, Franklyn JA, Pemberton HN, Bulmer JN, Visser TJ, McCabe CJ, and Kilby MD
(2006) Monocarboxylate transporter 8 expression in the human placenta: the effects of severe
intrauterine growth restriction. J Endocrinol 189:465– 471.
Chou JY (1982) Effects of retinoic acid on differentiation of choriocarcinoma cells in vitro.
J Clin Endocrinol Metab 54:1174 –1180.
Chung FS, Eyal S, Muzi M, Link JM, Mankoff DA, Kaddoumi A, O’Sullivan F, Hsiao P, and
Unadkat JD (2010) Positron emission tomography imaging of tissue P-glycoprotein activity
during pregnancy in the non-human primate. Br J Pharmacol 159:394 – 404.
Collier AC, Ganley NA, Tingle MD, Blumenstein M, Marvin KW, Paxton JW, Mitchell MD, and
Keelan JA (2002a) UDP-glucuronyltransferase activity, expression and cellular localization in
human placenta at term. Biochem Pharmacol 63:409 – 419.
Collier AC, Tingle MD, Paxton JW, Mitchell MD, and Keelan JA (2002b) Metabolizing enzyme
localization and activities in the first trimester human placenta: the effect of maternal and
gestational age, smoking and alcohol consumption. Hum Reprod 17:2564 –2572.
Cygalova L, Ceckova M, Pavek P, and Staud F (2008) Role of breast cancer resistance protein
(Bcrp/Abcg2) in fetal protection during gestation in rat. Toxicol Lett 178:176 –180.
Deeley RG, Westlake C, and Cole SP (2006) Transmembrane transport of endo- and xenobiotics
by mammalian ATP-binding cassette multidrug resistance proteins. Physiol Rev 86:849 – 899.
Derewlany LO, Knie B, and Koren G (1994) Arylamine N-acetyltransferase activity of the
human placenta. J Pharmacol Exp Ther 269:756 –760.
Eaton BM and Sooranna SR (1998) Regulation of the choline transport system in superfused
microcarrier cultures of BeWo cells. Placenta 19:663– 669.
Ellinger I, Schwab M, Stefanescu A, Hunziker W, and Fuchs R (1999) IgG transport across
trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta. Eur
J Immunol 29:733–744.
Enders AC and Blankenship TN (1999) Comparative placental structure. Adv Drug Deliv Rev
38:3–15.
Enokizono J, Kusuhara H, and Sugiyama Y (2007) Effect of breast cancer resistance protein
(Bcrp/Abcg2) on the disposition of phytoestrogens. Mol Pharmacol 72:967–975.
Esnault C, Priet S, Ribet D, Vernochet C, Bruls T, Lavialle C, Weissenbach J, and Heidmann T
(2008) A placenta-specific receptor for the fusogenic, endogenous retrovirus-derived, human
syncytin-2. Proc Natl Acad Sci USA 105:17532–17537.
Evseenko D, Paxton JW, and Keelan JA (2006a) Active transport across the human placenta:
impact on drug efficacy and toxicity. Expert Opin Drug Metab Toxicol 2:51– 69.
Evseenko DA, Paxton JW, and Keelan JA (2006b) ABC drug transporter expression and
functional activity in trophoblast-like cell lines and differentiating primary trophoblast. Am J
Physiol Regul Integr Comp Physiol 290:R1357–R1365.
Feinshtein V, Holcberg G, Amash A, Erez N, Rubin M, Sheiner E, Polachek H, and Ben-Zvi Z
(2010) Nitrofurantoin transport by placental choriocarcinoma JAr cells: involvement of BCRP,
OATP2B1 and other MDR transporters. Arch Gynecol Obstet 281:1037–1044.
Forestier F, de Renty P, Peytavin G, Dohin E, Farinotti R, and Mandelbrot L (2001) Maternalfetal transfer of saquinavir studied in the ex vivo placental perfusion model. Am J Obstet
Gynecol 185:178 –181.
Fujisawa K, Nasu K, Arima K, Sugano T, Narahara H, and Miyakawa I (2000) Production of
interleukin (IL)-6 and IL-8 by a choriocarcinoma cell line, BeWo. Placenta 21:354 –360.
Furesz TC, Smith CH, and Moe AJ (1993) ASC system activity is altered by development of cell
polarity in trophoblast from human placenta. Am J Physiol 265:C212–C217.
Ganapathy V, Zhuang L, Devoe LD, and Prasad PD (2005) Expression of OCTN1 in placental
brush border membrane and its interaction with antidepressants. J Soc Gynecol Invest 12:
180A.
Gedeon C, Anger G, Piquette-Miller M, and Koren G (2008) Breast cancer resistance protein:
mediating the trans-placental transfer of glyburide across the human placenta. Placenta
29:39 – 43.
Gil S, Saura R, Forestier F, and Farinotti R (2005) P-Glycoprotein expression of the human
placenta during pregnancy. Placenta 26:268 –270.
Griffiths M, Beaumont N, Yao SY, Sundaram M, Boumah CE, Davies A, Kwong FY, Coe I,
Cass CE, Young JD, et al. (1997) Cloning of a human nucleoside transporter implicated in the
cellular uptake of adenosine and chemotherapeutic drugs. Nat Med 3:89 –93.
Grube M, Reuther S, Meyer Zu Schwabedissen H, Köck K, Draber K, Ritter CA, Fusch C,
Jedlitschky G, and Kroemer HK (2007) Organic anion transporting polypeptide 2B1 and breast
cancer resistance protein interact in the transepithelial transport of steroid sulfates in human
placenta. Drug Metab Dispos 35:30 –35.
Grube M, Schwabedissen HM, Draber K, Präger D, Möritz KU, Linnemann K, Fusch C,
Jedlitschky G, and Kroemer HK (2005) Expression, localization, and function of the carnitine
transporter octn2 (slc22a5) in human placenta. Drug Metab Dispos 33:31–37.
Hakkola J, Pasanen M, Hukkanen J, Pelkonen O, Mäenpää J, Edwards RJ, Boobis AR, and
Raunio H (1996a) Expression of xenobiotic-metabolizing cytochrome P450 forms in human
full-term placenta. Biochem Pharmacol 51:403– 411.
Hakkola J, Raunio H, Purkunen R, Pelkonen O, Saarikoski S, Cresteil T, and Pasanen M (1996b)
Detection of cytochrome P450 gene expression in human placenta in first trimester of
pregnancy. Biochem Pharmacol 52:379 –383.
Hardman B, Michalczyk A, Greenough M, Camakaris J, Mercer JF, and Ackland ML (2007)
Hormonal regulation of the Menkes and Wilson copper-transporting ATPases in human
placental Jeg-3 cells. Biochem J 402:241–250.
Heaton SJ, Eady JJ, Parker ML, Gotts KL, Dainty JR, Fairweather-Tait SJ, McArdle HJ, Srai KS,
and Elliott RM (2008) The use of BeWo cells as an in vitro model for placental iron transport.
Am J Physiol Cell Physiol 295:C1445–C1453.
Hemauer SJ, Nanovskaya TN, Abdel-Rahman SZ, Patrikeeva SL, Hankins GD, and Ahmed MS
(2010) Modulation of human placental P-glycoprotein expression and activity by MDR1 gene
polymorphisms. Biochem Pharmacol 79:921–925.
Hemmings DG, Lowen B, Sherburne R, Sawicki G, and Guilbert LJ (2001) Villous trophoblasts
cultured on semi-permeable membranes form an effective barrier to the passage of high and
low molecular weight particles. Placenta 22:70 –79.
Hitzl M, Schaeffeler E, Hocher B, Slowinski T, Halle H, Eichelbaum M, Kaufmann P, Fritz P,
Fromm MF, and Schwab M (2004) Variable expression of P-glycoprotein in the human
placenta and its association with mutations of the multidrug resistance 1 gene (MDR1,
ABCB1). Pharmacogenetics 14:309 –318.
Huang SN and Swaan PW (2001) Riboflavin uptake in human trophoblast-derived BeWo cell
monolayers: cellular translocation and regulatory mechanisms. J Pharmacol Exp Ther 298:
264 –271.
Hussa RO, Story MT, and Pattillo RA (1974) Cyclic adenosine monophosphate stimulates
secretion of human chorionic gonadotropin and estrogens by human trophoblast in vitro. J Clin
Endocrinol Metab 38:338 –340.
PLACENTAL TRANSPORTERS AND MODELS FOR TRANSFER STUDIES
Moe AJ, Furesz TC, and Smith CH (1994) Functional characterization of L-alanine transport in
a placental choriocarcinoma cell line (BeWo). Placenta 15:797– 802.
Morrish DW, Dakour J, Li H, Xiao J, Miller R, Sherburne R, Berdan RC, and Guilbert LJ (1997)
In vitro cultured human term cytotrophoblast: a model for normal primary epithelial cells
demonstrating a spontaneous differentiation programme that requires EGF for extensive
development of syncytium. Placenta 18:577–585.
Mose T, Kjaerstad MB, Mathiesen L, Bo Nielsen J, Edelfors S, and Knudsen LE (2008) Placental
passage of benzoic acid, caffeine, and glyphosate in an ex-vivo human perfusion system. J
Toxicol Env Health A 71:984 –991.
Murer H and Kinne R (1980) The use of isolated membrane vesicles to study epithelial transport
processes. J Membr Biol 55:81–95.
Myllynen P, Kummu M, Kangas T, Ilves M, Immonen E, Rysä J, Pirilä R, Lastumäki A, and
Vähäkangas KH (2008) ABCG2/BCRP decreases the transfer of a food-born chemical carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in perfused term human
placenta. Toxicol Appl Pharmacol 232:210 –217.
Myllynen PK, Pienimaki PK, and Vähäkangas KH (2003) Transplacental passage of lamotrigine
in a human placental perfusion system in vitro and in maternal and cord blood in vivo. Eur
J Clin Pharmacol 58:677– 682.
Myllynen P and Vähäkangas K (2002) An examination of whether human placental perfusion
allows accurate prediction of placental drug transport: studies with diazepam. J Pharmacol
Toxicol Methods 48:131–138.
Myren M, Mose T, Mathiesen L, and Knudsen LE (2007) The human placenta–an alternative for
studying foetal exposure. Toxicol In Vitro 21:1332–1340.
Nagai A, Takebe K, Nio-Kobayashi J, Takahashi-Iwanaga H, and Iwanaga T (2010) Cellular
expression of the monocarboxylate transporter (MCT) family in the placenta of mice. Placenta
31:126 –133.
Nagashige M, Ushigome F, Koyabu N, Hirata K, Kawabuchi M, Hirakawa T, Satoh S, Tsukimori
K, Nakano H, Uchiumi T, et al. (2003) Basal membrane localization of MRP1 in human
placental trophoblast. Placenta 24:951–958.
Nakamura Y, Ikeda S, Furukawa T, Sumizawa T, Tani A, Akiyama S, and Nagata Y (1997)
Function of P-glycoprotein expressed in placenta and mole. Biochem Biophys Res Commun
235:849 – 853.
Nakanishi T, Kohroki J, Suzuki S, Ishizaki J, Hiromori Y, Takasuga S, Itoh N, Watanabe Y,
Utoguchi N, and Tanaka K (2002) Trialkyltin compounds enhance human CG secretion and
aromatase activity in human placental choriocarcinoma cells. J Clin Endocrinol Metab
87:2830 –2837.
Nampoothiri L, Neelima PS, and Rao AJ (2007) Proteomic profiling of forskolin-induced
differentiated BeWo cells: an in-vitro model of cytotrophoblast differentiation. Reprod Biomed
Online 14:477– 487.
Nickel BE and Cattini PA (1991) Tissue-specific expression and thyroid hormone regulation of
the endogenous placental growth hormone variant and chorionic somatomammotropin genes
in a human choriocarcinoma cell line. Endocrinology 128:2353–2359.
Nishimura M, Yaguti H, Yoshitsugu H, Naito S, and Satoh T (2003) Tissue distribution of
mRNA expression of human cytochrome P450 isoforms assessed by high-sensitivity real-time
reverse transcription PCR. Yakugaku Zasshi 123:369 –375.
Novotna M, Libra A, Kopecky M, Pavek P, Fendrich Z, Semecky V, and Staud F (2004)
P-Glycoprotein expression and distribution in the rat placenta during pregnancy. Reprod
Toxicol 18:785–792.
Pacifici GM and Nottoli R (1995) Placental transfer of drugs administered to the mother. Clin
Pharmacokinet 28:235–269.
Pacifici GM and Rane A (1981) Glutathione S-epoxidetransferase in the human placenta at
different stages of pregnancy. Drug Metab Dispos 9:472– 475.
Pacifici GM and Rane A (1983) Epoxide hydrolase in the human placenta at different stages of
pregnancy. Dev Pharmacol Ther 6:83–93.
Panigel M, Pascaud M, and Brun JL (1967) Radioangiographic study of circulation in the villi
and intervillous space of isolated human placental cotyledon kept viable by perfusion.
J Physiol (Paris) 59:277.
Parry S, Zhang J, Koi H, Arechavaleta-Velasco F, and Elovitz MA (2006) Transcytosis of
Human immunodeficiency virus 1 across the placenta is enhanced by treatment with tumour
necrosis factor alpha. J Gen Virol 87:2269 –2278.
Pasanen M (1999) The expression and regulation of drug metabolism in human placenta. Adv
Drug Deliv Rev 38:81–97.
Pasanen M, Helin-Martikainen HL, Pelkonen O, and Kirkinen P (1997) Intrahepatic cholestasis
of pregnancy impairs the activities of human placental xenobiotic and steroid metabolizing
enzymes in vitro. Placenta 18:37– 41.
Pascolo L, Fernetti C, Garcia-Mediavilla MV, Ostrow JD, and Tiribelli C (2001) Mechanism for
the transport of unconjugated bilirubin in human trophoblastic BeWo cells. FEBS Lett
495:94 –99.
Pascolo L, Fernetti C, Pirulli D, Bogoni S, Garcia-Mediavilla MV, Spano A, Amoroso A, and
Crovella S (2000) Detection of MRP1 mRNA in human tumors and tumor cell lines by in situ
RT-PCR. Biochem Biophy Res Commun 275:466 – 471.
Pascolo L, Fernetti C, Pirulli D, Crovella S, Amoroso A, and Tiribelli C (2003) Effects of
maturation on RNA transcription and protein expression of four MRP genes in human placenta
and in BeWo cells. Biochem Biophys Res Commun 303:259 –265.
Pasqualini JR (2005) Enzymes involved in the formation and transformation of steroid hormones
in the fetal and placental compartments. J Steroid Biochem Mol Biol 97:401– 415.
Pasqualini JR and Kincl FA (1985) Biosynthesis of metabolism of different hormones in the fetal
placental compartments, in Hormones and the Fetus (Pasqualini JR and Kincl FA eds) vol I,
pp 73–172, Pergamon Press, Oxford.
Patel P, Weerasekera N, Hitchins M, Boyd CA, Johnston DG, and Williamson C (2003) Semi
quantitative expression analysis of MDR3, FIC1, BSEP, OATP-A, OATP-C, OATP-D,
OATP-E and NTCP gene transcripts in 1st and 3rd trimester human placenta. Placenta
24:39 – 44.
Pattillo RA and Gey GO (1968) The establishment of a cell line of human hormone-synthesizing
trophoblastic cells in vitro. Cancer Res 28:1231–1236.
Pattillo RA, Hussa RO, Ruckert AC, Kurtz JW, Cade JM, and Rinke ML (1979) Human
chorionic gonadotropin in BeWo trophoblastic cells after 12 years in continuous culture:
retention of intact human chorionic gonadotropin secretion in mechanically versus enzymedispersed cells. Endocrinology 105:967–974.
Patterson TA, Binienda ZK, Newport GD, Lipe GW, Gillam MP, Slikker W Jr, and Sandberg JA
Downloaded from dmd.aspetjournals.org at ASPET Journals on June 18, 2017
Jauniaux E and Gulbis B (2000) In vivo investigation of placental transfer early in human
pregnancy. Eur J Obstet Gynecol Reprod Biol 92:45– 49.
Jauniaux E, Jurkovic D, Gulbis B, Gervy C, Ooms HA, and Campbell S (1991) Biochemical
composition of exocoelomic fluid in early human pregnancy. Obstet Gynecol 78:1124 –1128.
Jones HN, Ashworth CJ, Page KR, and McArdle HJ (2006) Expression and adaptive regulation
of amino acid transport system A in a placental cell line under amino acid restriction.
Reproduction 131:951–960.
Jonker JW, Smit JW, Brinkhuis RF, Maliepaard M, Beijnen JH, Schellens JH, and Schinkel AH
(2000) Role of breast cancer resistance protein in the bioavailability and fetal penetration of
topotecan. J Natl Cancer Inst 92:1651–1656.
Kaaja RJ, Moore MP, Yandle TG, Ylikorkala O, Frampton CM, and Nicholls MG (1999) Blood
pressure and vasoactive hormones in mild preeclampsia and normal pregnancy. Hypertens
Pregnancy 18:173–187.
Kalabis GM, Petropoulos S, Gibb W, and Matthews SG (2007) Breast cancer resistance protein
(Bcrp1/Abcg2) in mouse placenta and yolk sac: ontogeny and its regulation by progesterone.
Placenta 28:1073–1081.
Kato Y and Braunstein GD (1991) Retinoic acid stimulates placental hormone secretion by
choriocarcinoma cell lines in vitro. Endocrinology 128:401– 407.
Keating E, Lemos C, Azevedo I, and Martel F (2006) Comparison of folic acid uptake
characteristics by human placental choriocarcinoma cells at acidic and physiological pH. Can
J Physiol Pharmacol 84:247–255.
Kekuda R, Prasad PD, Wu X, Wang H, Fei YJ, Leibach FH, and Ganapathy V (1998) Cloning
and functional characterization of a potential-sensitive, polyspecific organic cation transporter
(OCT3) most abundantly expressed in placenta. J Bio Chem 273:15971–15979.
Kilani RT, Mackova M, Davidge ST, Winkler-Lowen B, Demianczuk N, and Guilbert LJ (2007)
Endogenous tumor necrosis factor alpha mediates enhanced apoptosis of cultured villous
trophoblasts from intrauterine growth-restricted placentae. Reproduction 133:257–264.
Kimura Y, Morita SY, Matsuo M, and Ueda K (2007) Mechanism of multidrug recognition by
MDR1/ABCB1. Cancer Sci 98:1303–1310.
Kitano T, Iizasa H, Hwang IW, Hirose Y, Morita T, Maeda T, and Nakashima E (2004)
Conditionally immortalized syncytiotrophoblast cell lines as new tools for study of the
blood-placenta barrier. Biol Pharm Bull 27:753–759.
Kobayashi D, Ieiri I, Hirota T, Takane H, Maegawa S, Kigawa J, Suzuki H, Nanba E, Oshimura
M, Terakawa N, et al. (2005) Functional assessment of ABCG2 (BCRP) gene polymorphisms
to protein expression in human placenta. Drug Metab Dispos 33:94 –101.
Konsoula R and Barile FA (2005) Correlation of in vitro cytotoxicity with paracellular permeability in Caco-2 cells. Toxicol In Vitro 19:675– 684.
Lachance Y, Luu-The V, Labrie C, Simard J, Dumont M, de Launoit Y, Guerin S, Leblanc G,
and Labrie F (1990) Characterization of human 3-beta-hydroxysteroid dehydrogenase/delta5delta4-isomerase gene and its expression in mammalian cells. J Biol Chem 265:20469 –20475.
Lahjouji K, Elimrani I, Lafond J, Leduc L, Qureshi IA, and Mitchell GA (2004) L-Carnitine
transport in human placental brush-border membranes is mediated by the sodium-dependent
organic cation transporter OCTN2. Am J Physiol Cell Physiol 287:C263–C269.
Lankas GR, Wise D, Cartwright C, Pippert T, and Umbenhauer DR (1998) Placental Pglycoprotein deficiency enhances susceptibility to chemically induced birth defects in mice.
Reprod Toxicol 12:457– 463.
Levy G (1981) Pharmacokinetics of fetal and neonatal exposure to drugs. Obstet Gynecol
58:9S–16S.
Liu F, Soares MJ, and Audus KL (1997) Permeability properties of monolayers of the human
trophoblast cell line BeWo. Am J Physiol 273:C1596 –C1604.
Luu-The V, Labrie C, Zhao HF, Couët J, Lachance Y, Simard J, Leblanc G, Côté J, Bérubé D,
and Gagné R, et al. (1989) Characterization of cDNAs for human estradiol 17 betadehydrogenase and assignment of the gene to chromosome 17: evidence of two mRNA species
with distinct 5⬘-termini in human placenta. Mol Endocrinol 3:1301–1309.
MacFarland A, Abramovich DR, Ewen SW, and Pearson CK (1994) Stage-specific distribution
of P-glycoprotein in first-trimester and full-term human placenta. Histochem J 26:417– 423.
Maddox DM, Manlapat A, Roon P, Prasad P, Ganapathy V, and Smith SB (2003) Reduced-folate
carrier (RFC) is expressed in placenta and yolk sac, as well as in cells of the developing
forebrain, hindbrain, neural tube, craniofacial region, eye, limb buds and heart. BMC Dev Biol
3:6 –14.
Maliepaard M, Scheffer GL, Faneyte IF, van Gastelen MA, Pijnenborg AC, Schinkel AH, van De
Vijver MJ, Scheper RJ, and Schellens JH (2001) Subcellular localization and distribution of
the breast cancer resistance protein transporter in normal human tissues. Cancer Res 61:3458 –
3464.
Mark PJ and Waddell BJ (2006) P-glycoprotein restricts access of cortisol and dexamethasone to
the glucocorticoid receptor in placental BeWo cells. Endocrinology 147:5147–5152.
Mathias AA, Hitti J, and Unadkat JD (2005) P-Glycoprotein and breast cancer resistance protein
expression in human placentae of various gestational ages. Am J Physiol Regul Integr Comp
Physiol 289:R963–R969.
Matsuo H and Strauss JF 3rd (1994) Peroxisome proliferators and retinoids affect JEG-3
choriocarcinoma cell function. Endocrinology 135:1135–1145.
Meyer zu Schwabedissen HE, Grube M, Dreisbach A, Jedlitschky G, Meissner K, Linnemann K,
Fusch C, Ritter CA, Völker U, and Kroemer HK (2006) Epidermal growth factor-mediated
activation of the map-kinase cascade results in altered expression and function of ABCG2
(BCRP). Drug Metab Dispos 34:524 –533.
Meyer zu Schwabedissen HE, Grube M, Heydrich B, Linnemann K, Fusch C, Kroemer HK, and
Jedlitschky G (2005) Expression, localization, and function of MRP5 (ABCC5), a transporter
for cyclic nucleotides, in human placenta and cultured human trophoblasts: effects of gestational age and cellular differentiation. Am J Pathol 166:39 – 47.
Mikkaichi T, Suzuki T, Tanemoto M, Ito S, and Abe T (2004) The organic anion transporter
(OATP) family. Drug Metab Pharmacokinet 19:171–179.
Miller RK, Genbacev O, Turner MA, Aplin JD, Caniggia I, and Huppertz B (2005) Human
placental explants in culture: approaches and assessments. Placenta 26:439 – 448.
Mitchell AM, Yap AS, Payne EJ, Manley SW, and Mortimer RH (1995) Characterization of cell
polarity and epithelial junctions in the choriocarcinoma cell line, JAR. Placenta 16:31–39.
Mitra P and Audus KL (2009) Expression and functional activities of selected sulfotransferase
isoforms in BeWo cells and primary cytotrophoblast cells. Biochem Pharmacol 78:1475–
1482.
Moe AJ (1995) Placental amino acid transport. Am J Physiol 268:C1321–C1331.
1633
1634
PROUILLAC AND LECOEUR
transport and glucose transporters in the human choriocarcinoma cell line, BeWo. Placenta
20:651– 659.
Simone C, Derewlany LO, and Koren G (1994) Drug transfer across the placenta. Considerations
in treatment and research. Clin Perinatol 21:463– 481.
Sivasubramaniam SD, Finch CC, Billett MA, Baker PN, and Billett EE (2002) Monoamine
oxidase expression and activity in human placentae from pre-eclamptic and normotensive
pregnancies. Placenta 23:163–171.
Smit JW, Huisman MT, van Tellingen O, Wiltshire HR, and Schinkel AH (1999) Absence or
pharmacological blocking of placental P-glycoprotein profoundly increases fetal drug exposure. J Clin Invest 104:1441–1447.
Smuc T and Rizner TL (2009) Expression of 17beta-hydroxysteroid dehydrogenases and other
estrogen-metabolizing enzymes in different cancer cell lines. Chem Biol Interact 178:228 –
233.
Solanky N, Requena Jimenez A, D’Souza SW, Sibley CP, and Glazier JD (2010) Expression of
folate transporters in human placenta and implications for homocysteine metabolism. Placenta
31:134 –143.
St-Pierre MV, Hagenbuch B, Ugele B, Meier PJ, and Stallmach T (2002) Characterization of an
organic anion-transporting polypeptide (OATP-B) in human placenta. J Clin Endocrinol
Metab 87:1856 –1863.
St-Pierre MV, Serrano MA, Macias RI, Dubs U, Hoechli M, Lauper U, Meier PJ, and Marin JJ
(2000) Expression of members of the multidrug resistance protein family in human term
placenta. Am J Physiol Regul Integr Comp Physiol 279:R1495–R1503.
Sudhakaran S, Rayner CR, Li J, Kong DCM, Gude NM, and Nation RL (2007) Inhibition of
placental P-gylcoprotein: impact on indinavir transfer to the fetus. Br J Clin Pharmacol
65:667– 673.
Sun M, Kingdom J, Baczyk D, Lye SJ, Matthews SG, and Gibb W (2005) Expression of the
multidrug resistance P-glycoprotein (ABCB1 glycoprotein) in the human placenta decreases
with advancing gestation. Placenta 27:602– 607.
Sun T, Zhao Y, Mangelsdorf DJ, and Simpson ER (1998) Characterization of a region upstream
of exon I.1 of the human CYP19 (aromatase) gene that mediates regulation by retinoids in
human choriocarcinoma cells. Endocrinology 139:1684 –1691.
Syme MR, Paxton JW, and Keelan JA (2004) Drug transfer and metabolism by the human
placenta. Clin Pharmacokinet 43:487–514.
Takahashi T, Utoguchi N, Takara A, Yamamoto N, Nakanishi T, Tanaka K, Audus KL, and
Watanabe Y (2001) Carrier-mediated transport of folic acid in BeWo cell monolayers as a
model of the human trophoblast. Placenta 22:863– 869.
Tamai I, Yabuuchi H, Nezu J, Sai Y, Oku A, Shimane M, and Tsuji A (1997) Cloning and
characterization of a novel human pH-dependent organic cation transporter, OCTN1. FEBS
Lett 419:107–111.
Tanabe M, Ieiri I, Nagata N, Inoue K, Ito S, Kanamori Y, Takahashi M, Kurata Y, Kigawa J,
Higuchi S, et al. (2001) Expression of P-glycoprotein in human placenta: relation to genetic
polymorphism of the multidrug resistance (MDR)-1 gene. J Pharmacol Exp Ther 297:1137–
1143.
Tremblay J, Hardy DB, Pereira LE, and Yang K (1999) Retinoic acid stimulates the expression
of 11beta-hydroxysteroid dehydrogenase type 2 in human choriocarcinoma JEG-3 cells. Biol
Reprod 60:541–545.
Ugele B, St-Pierre MV, Pihusch M, Bahn A, and Hantschmann P (2003) Characterization and
identification of steroid sulfate transporters of human placenta. Am J Physiol Endocrinol
Metab 284:E390 –E398.
Unadkat JD, Dahlin A, and Vijay S (2004) Placental drug transporters. Curr Drug Metab
5:125–131.
Ushigome F, Takanaga H, Matsuo H, Yanai S, Tsukimori K, Nakano H, Uchiumi T, Nakamura
T, Kuwano M, Ohtani H, et al. (2000) Human placental transport of vinblastine, vincristine,
digoxin and progesterone: contribution of P-glycoprotein. Eur J Pharmacol 408:1–10.
Utoguchi N, Magnusson M, and Audus KL (1999) Carrier-mediated transport of monocarboxylic
acids in BeWo cell monolayers as a model of the human trophoblast. J Pharm Sci 88:1288 –
1292.
Utoguchi N and Audus KL (2000) Carrier-mediated transport of valproic acid in BeWo cells, a
human trophoblast cell line. Int J Pharm 195:115–124.
Utoguchi N, Chandorkar GA, Avery M, and Audus KL (2000) Functional expression of
P-glycoprotein in primary cultures of human cytotrophoblasts and BeWo cells. Reprod Toxicol
14:217–224.
Vähäkangas K and Myllynen P (2006) Experimental methods to study human transplacental
exposure to genotoxic agents. Mutat Res 608:129 –135.
Vaidya SS, Walsh SW, and Gerk PM (2009) Formation and efflux of ATP-binding cassette
transporter substrate 2,4-dinitrophenyl-S-glutathione from cultured human term placental
villous tissue fragments. Mol Pharm 6:1689 –1702.
van der Aa EM, Copius Peereboom-Stegeman JHJ, Noordhoek J, Gribnau FWJ, Russel FGM
(1998) Mechanisms of drug transfer across the human placenta. Pharm World Sci 20:139 –148.
van der Ende A, du Maine A, Schwartz AL, and Strous GJ (1989) Effect of ATP depletion and
temperature on the transferrin-mediated uptake and release of iron by BeWo choriocarcinoma
cells. Biochem J 259:685– 692.
van der Ende A, du Maine A, Schwartz AL, and Strous GJ (1990) Modulation of transferrinreceptor activity and recycling after induced differentiation of BeWo choriocarcinoma cells.
Biochem J 270:451– 457.
Vardhana PA and Illsley NP (2002) Transepithelial glucose transport and metabolism in BeWo
choriocarcinoma cells. Placenta 23:653– 660.
Vargas A, Moreau J, Landry S, LeBellego F, Toufaily C, Rassart E, Lafond J, and Barbeau B
(2009) Syncytin-2 plays an important role in the fusion of human trophoblast cells. J Mol Biol
392:301–318.
Vogt E, Ng AK, and Rote NS (1997) Antiphosphatidylserine antibody removes annexin-V and
facilitates the binding of prothrombin at the surface of a choriocarcinoma model of trophoblast
differentiation. Am J Obstet Gynecol 177:964 –972.
Waddell WJ and Marlowe C (1981) Transfer of drugs across the placenta. Pharmacol Ther
14:375–390.
Wang H, Fei YJ, Kekuda R, Yang-Feng TL, Devoe LD, Leibach FH, Prasad PD, and Ganapathy
V (2000) Structure, function, and genomic organization of human Na⫹-dependent highaffinity dicarboxylate transporter. Am J Physiol Cell Physiol 278:C1019 –C1030.
Wang H, Wu X, Hudkins K, Mikheev A, Zhang H, Gupta A, Unadkat JD, and Mao Q (2006)
Expression of the breast cancer resistance protein (Bcrp1/Abcg2) in tissues from pregnant
Downloaded from dmd.aspetjournals.org at ASPET Journals on June 18, 2017
(2000) Transplacental pharmacokinetics and fetal distribution of 2⬘,3⬘-didehydro-3⬘deoxythymidine (d4T) and its metabolites in late-term rhesus macaques. Teratology 62:93–99.
Pavek P, Cerveny L, Svecova L, Brysch M, Libra A, Vrzal R, Nachtigal P, Staud F, Ulrichova
J, Fendrich Z, et al. (2007) Examination of glucocorticoid receptor alpha-mediated transcriptional regulation of P-glycoprotein, CYP3A4, and CYP2C9 genes in placental trophoblast cell
lines. Placenta 28:1004 –1011.
Pelkonen O, Vähäkangas K, Kärki NT, and Sotaniemi EA (1984) Genetic and environmental
regulation of aryl hydrocarbon hydroxylase in man: studies with liver, lung, placenta, and
lymphocytes. Toxicol Pathol 12:256 –260.
Polachek H, Holcberg G, Polachek J, Rubin M, Feinshtein V, Sheiner E, and Ben-Zvi Z (2010)
Carrier-mediated uptake of Levofloxacin by BeWo cells, a human trophoblast cell line. Arch
Gynecol Obstet 281:833– 838.
Pollex EK, Anger G, Hutson J, Koren G, and Piquette-Miller M (2010) Breast cancer resistance
protein (BCRP)-mediated glyburide transport: effect of the C421A/Q141K BCRP singlenucleotide polymorphism. Drug Metab Dispos 38:740 –744.
Pollex EK, Lubetsky A, and Koren G (2008) The role of placental breast cancer resistance
protein in the efflux of glyburide across the human placenta. Placenta 29:743–747.
Pötgens AJ, Drewlo S, Kokozidou M, and Kaufmann P (2004) Syncytin: the major regulator of
trophoblast fusion? Recent developments and hypotheses on its action. Hum Reprod Update
10:487– 496.
Poulsen MS, Rytting E, Mose T, and Knudsen LE (2009) Modeling placental transport:
correlation of in vitro BeWo cell permeability and ex vivo human placental perfusion. Toxicol
In Vitro 23:1380 –1386.
Prasad PD, Leibach FH, Mahesh VB, and Ganapathy V (1994a) Human placenta as a target organ
for cocaine action: interaction of cocaine with the placental serotonin transporter. Placenta
15:267–278.
Prasad PD, Ramamoorthy S, Moe AJ, Smith CH, Leibach FH, and Ganapathy V (1994b)
Selective expression of the high-affinity isoform of the folate receptor (FR-alpha) in the human
placental syncytiotrophoblast and choriocarcinoma cells. Biochim Biophys Acta 1223:71–75.
Prasad PD, Ramamoorthy S, Moe AJ, Smith CH, Leibach FH, and Ganapathy V (1996)
Functional expression of the plasma membrane serotonin transporter but not the vesicular
monoamine transporter in human placental trophoblasts and choriocarcinoma cells. Placenta
17:201–207.
Price NT, Jackson VN, and Halestrap AP (1998) Cloning and sequencing of four new mammalian monocarboxylate transporter (MCT) homologues confirms the existence of a transporter
family with an ancient past. Biochem J 329 (Pt 2):321–328.
Prouillac C, Videmann B, Mazallon M, and Lecoeur S (2009) Induction of cells differentiation
and ABC transporters expression by a myco-estrogen, zearalenone, in human choriocarcinoma
cell line (BeWo). Toxicology 263:100 –107.
Rahi M, Heikkinen T, Hakkola J, Hakala K, Wallerman O, Wadelius M, Wadelius C, and Laine
K (2008) Influence of adenosine triphosphate and ABCB1 (MDR1) genotype on the Pglycoprotein-dependent transfer of saquinavir in the dually perfused human placenta. Hum Exp
Toxicol 27:65–71.
Ramamoorthy JD, Ramamoorthy S, Leibach FH, and Ganapathy V (1995) Human placental
monoamine transporters as targets for amphetamines. Am J Obstet Gynecol 173:1782–1787.
Rama Sastry BV (1999) Techniques to study human placental transport. Adv Drug Deliv Rev
38:17–39.
Rao RM, Rama S, and Rao AJ (2003) Changes in T-plastin expression with human trophoblast
differentiation. Reprod Biomed Online 7:235–242.
Rena V, Angeletti S, Panzetta-Dutari G, and Genti-Raimondi S (2009) Activation of beta-catenin
signalling increases StarD7 gene expression in JEG-3 cells. Placenta 30:876 – 883.
Rote NS (2005) Intercellular fusion of BeWo. Placenta 26:686.
Rytting E and Audus KL (2005) Novel organic cation transporter 2-mediated carnitine uptake in
placental choriocarcinoma (BeWo) cells. J Pharmacol Exp Ther 312:192–198.
Rytting E and Audus KL (2007) Effects of low oxygen levels on the expression and function of
transporter OCTN2 in BeWo cells. J Pharm Pharmacol 59:1095–1102.
Sacks GP, Clover LM, Bainbridge DR, Redman CW, and Sargent IL (2001) Flow cytometric
measurement of intracellular Th1 and Th2 cytokine production by human villous and extravillous cytotrophoblast. Placenta 22:550 –559.
Salido EC, Yen PH, Barajas L, and Shapiro LJ (1990) Steroid sulfatase expression in human
placenta: immunocytochemistry and in situ hybridization study. J Clin Endocrinol Metab
70:1564 –1567.
Samson M, Labrie F, and Luu-The V (2009) Specific estradiol biosynthetic pathway in choriocarcinoma (JEG-3) cell line. J Steroid Biochem Mol Biol 116:154 –159.
Sata R, Ohtani H, Tsujimoto M, Murakami H, Koyabu N, Nakamura T, Uchiumi T, Kuwano M,
Nagata H, Tsukimori K, et al. (2005) Functional analysis of organic cation transporter 3
expressed in human placenta. J Pharmacol Exp Ther 315:888 – 895.
Saulsbury MD, Heyliger SO, Wang K, and Round D (2008) Characterization of chlorpyrifosinduced apoptosis in placental cells. Toxicology 244:98 –110.
Saunders M (2009) Transplacental transport of nanomaterials. Wiley Interdiscip Rev Nanomed
Nanobiotechnol 1:671– 684.
Scheffer GL, Kool M, Heijn M, de Haas M, Pijenborg ACLM, Wijnholds J, van Helvoort A, de
Jong MC, Hooijberg JH, Mol CA, et al. (2000) Specific detection of multidrug resistance
proteins MRP1, MRP2, MRP3, MRP5, and MDR3 P-glycoprotein with a panel of monoclonal
antibodies. Cancer Res 60:5269 –5277.
Schmid KE, Davidson WS, Myatt L, and Woollett LA (2003) Transport of cholesterol across a
BeWo cell monolayer: implications for net transport of sterol from maternal to fetal circulation. J Lipid Res 44:1909 –1918.
Schneider H, Panigel M, and Dancis J (1972) Transfer across the perfused human placenta of
antipyrine, sodium and leucine. Am J Obstet Gynecol 114:822– 828.
Schuetz JD, Kauma S, and Guzelian PS (1993) Identification of the fetal liver cytochrome
CYP3A7 in human endometrium and placenta. J Clin Invest 92:1018 –1024.
Serrano MA, Macias RIR, Briz O, Monte MJ, Blazquez AG, Williamson C, Kubitz R, and Marin
JJ (2007) Expression in human trophoblast and choriocarcinoma cell lines, BeWo, Jeg-3 and
JAr of genes involved in the hepatobiliary-like excretory function of the placenta. Placenta
28:107–117.
Settle P, Mynett K, Speake P, Champion E, Doughty IM, Sibley CP, D’Souza SW, and Glazier
J (2004) Polarized lactate transporter activity and expression in the syncytiotrophoblast of the
term human placenta. Placenta 25:496 –504.
Shah SW, Zhao H, Low SY, Mcardle HJ, and Hundal HS (1999) Characterization of glucose
PLACENTAL TRANSPORTERS AND MODELS FOR TRANSFER STUDIES
Address correspondence to: Sylvaine Lecoeur, Métabolisme et Toxicologie
Comparée des Xénobiotiques (UMR 1233 INRA), VetAgroSup, Campus Vétérinaire de Lyon, 1 avenue Bourgelat, 69280 Marcy l’Etoile, France. E-mail:
[email protected]
Caroline Prouillac is an assistant professor at
the Veterinary Campus of Lyon, Marcy l’Etoile,
France. She has a Doctor of Pharmacy degree
from the University Victor Segalen of Bordeaux,
France. She received a Master’s Degree in Toxicology in 2003 and obtained a Ph.D. in Biology
and Health in 2007 from the University Paul
Sabatier of Toulouse, France. Current research
interests include the effect and the toxicity of
environmental and food contaminants on placental development, and the role of this organ in the
fetal exposure to xenobiotics.
Sylvaine Lecoeur is Director of Research at
the National Institute of Agronomic Research,
Veterinary Campus of Lyon, Marcy l’Etoile,
France. She obtained a Doctor of Veterinary
Medicine degree from the University Paul Sabatier of Toulouse, France. She received a Master’s Degree in Toxicology in 1992 and a Ph.D. in
Toxicology in 1996 from the University Rene Descartes of Paris, France. Current research interests
include the role of ABC transporters in the toxicity
of environmental and food contaminants such as
mycotoxins and phytoestrogens.
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mice: effects of pregnancy and correlations with nuclear receptors. Am J Physiol Endocrinol
Metab 291:E1295–E1304.
Way BA, Furesz TC, Schwarz JK, Moe AJ, and Smith CH (1998) Sodium-independent lysine
uptake by the BeWo choriocarcinoma cell line. Placenta 19:323–328.
White TE, Saltzman RA, Di Sant’Agnese PA, Keng PC, Sutherland RM, and Miller RK (1988)
Human choriocarcinoma (JAr) cells grown as multicellular spheroids. Placenta 9:583–598.
Wice B, Menton D, Geuze H, and Schwartz AL (1990) Modulators of cyclic AMP metabolism
induce syncytiotrophoblast formation in vitro. Exp Cell Res 186:306 –316.
Wijnholds J, Mol CA, van Deemter L, de Haas M, Scheffer GL, Baas F, Beijnen JH, Scheper
RJ, Hatse S, De Clercq E, et al. (2000) Multidrug-resistance protein 5 is a multispecific
organic anion transporter able to transport nucleotide analogs. Proc Natl Acad Sci USA
97:7476 –7481.
Wyrwoll CS, Mark PJ, and Waddell BJ (2005) Directional secretion and transport of leptin and
expression of leptin receptor isoforms in human placental BeWo cells. Mol Cell Endocrinol
241:73–79.
Xu B, Lin L, and Rote NS (1999) Identification of a stress-induced protein during human
trophoblast differentiation by differential display analysis. Biol Reprod 61:681– 686.
Yasuda S, Hasui S, Kobayashi M, Itagaki S, Hirano T, and Iseki K (2008) The mechanism of
carrier-mediated transport of folates in BeWo cells: the involvement of heme carrier protein 1
in placental folate transport. Biosci Biotechnol Biochem 72:329 –334.
Yasuda S, Itagaki S, Hirano T, and Iseki K (2005) Expression level of ABCG2 in the placenta
decreases from the mid stage to the end of gestation. Biosci Biotechnol Biochem 69:1871–
1876.
Yeboah D, Kalabis GM, Sun M, Ou RC, Matthews SG, and Gibb W (2008) Expression and
localisation of breast cancer resistance protein (BCRP) in human fetal membranes and decidua
and the influence of labour at term. Reprod Fertil Dev 20:328 –334.
Yeboah D, Sun M, Kingdom J, Baczyk D, Lye SJ, Matthews SG, and Gibb W (2006) Expression
of breast cancer resistance protein (BCRP/ABCG2) in human placenta throughout gestation
and at term before and after labor. Can J Physiol Pharmacol 84:1251–1258.
You G (2004a) The role of organic ion transporters in drug disposition: an update. Curr Drug
Metab 5:55– 62.
You G (2004b) Towards an understanding of organic anion transporters: structure-function
relationships. Med Res Rev 24:762–774.
Yui J, Garcia-Lloret M, Brown AJ, Berdan RC, Morrish DW, Wegmann TG, and Guilbert LJ
(1994) Functional, long-term cultures of human term trophoblasts purified by columnelimination of CD9 expressing cells. Placenta 15:231–246.
Zhang Y, Wang H, Unadkat JD, and Mao Q (2007) Breast cancer resistance protein 1 limits fetal
distribution of nitrofurantoin in the pregnant mouse. Drug Metab Dispos 35:2154 –2158.
Zhou L, Naraharisetti SB, Wang H, Unadkat JD, Hebert MF, and Mao Q (2008) The breast
cancer resistance protein (Bcrp1/Abcg2) limits fetal distribution of glyburide in the
pregnant mouse: an Obstetric-Fetal Pharmacology Research Unit Network and University
of Washington Specialized Center of Research Study. Mol Pharmacol 73:949 –959.
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