Stem Cell Research and Human Cloning
What is all the fuss about?
Ray Campbell
Director, Queensland Bioethics Centre
1. A Quote
“Human nature itself lies on the operating table, ready for alteration, for eugenic
and neuropsychic ‘enhancement’, for wholesale redesign. In leading laboratories,
academic and industrial, new creators are confidently amassing their powers and
quietly honing their skills, while on the street their evangelists are zealously
prophesying a posthuman future. For anyone who cares about preserving our
humanity, the time has come to pay attention.” (Leon Kass, Life, Liberty and the Defense of
Dignity)
2. Some Questions
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What does it mean to treat nascent human life as raw material to be
exploited as a mere natural resource?
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What does it mean to blur the lines between procreation and manufacture?
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What are the likely future possibilities emerging from our current decisions?
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Can we control where this project is taking us, so as to reap the benefits
without losing our humanity? If so, how? (Leon Kass)
3. Stem Cells
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A generic cell which can a) continue to proliferate and b) give rise to
specialised cells
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Totipotent stems cells: can give rise to every cell in the human body -- the
single cell zygote and the very early embryo
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Pluripotent: can give rise to many different specialised cells
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Multipotent: generates cells for a particular type of tissue
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Unipotent: able to form only one differentiated type
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The process of moving from one to the other is differentiation
4. Kinds of Stem Cells
4.1 Adult stem cells (post natal)
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Able to produce exact copies of themselves and differentiated daughter cells
Stem Cell Research and Human Cloning
Queensland Bioethics Centre
http://bne.catholic.net.au/qbc
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Said to be multipotent
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More pliable than first believed -- possibility of transdifferentiation -pluripotent
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Difficult to find, but more being identified
Resource: http://www.stemcellresearch.org
4.1.1 More recent developments with adult stem cells
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Baby teeth as source of stem cells
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Use of olfactory tissue
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Olfactory neurons
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Olfactory stem cells
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Olfactory ensheathing cells – producing insulating myelin sheaths
(see: http://www.gu.edu.au/er/development/content_icmt_adultstem.html)
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Therapies using them already exist – cancers, autoimmune disease, stroke,
heart attack, skin, bone and cartilage deformities, spinal injury(?)
4.2 Foetal stem cells
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Taken from foetal tissue
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Make up the bulk of the tissue
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Thought to be capable of generating whole organs
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Generally not rejected to the same extent as post-natal tissue
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Obtained from aborted or miscarried foetuses.
4.3 Umbilical cord blood and placenta tissue stem cells
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Good source of stem cells particularly for bone marrow
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Less chance of rejection
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Cord blood banks
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To date, limited application
4.4 Embryonic stem cells
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Cells which have not yet differentiated -- pluripotent
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Hailed as possible source for many cures -- but none to date
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Obtained by destroying an embryo
Stem Cell Research and Human Cloning
Queensland Bioethics Centre
http://bne.catholic.net.au/qbc
4.4.1 Obtaining embryonic stem cells
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from existing “spare” embryos from IVF process – destroys the embryo
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through cloning and then destroying the embryo
5. What is a clone?
"one or a group of genetically identical cells, organisms, or plants derived by
vegetative reproduction from a single parent." Dorland's Illustrated Medical Dictionary (29th
edition)
"member of group of organisms produced asexually from one individual”,
The
Australian Pocket Oxford Dictionary
5.1 Three types of human cloning
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Replicating genetic & cellular material e.g. DNA fragments, particular cells
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Splitting of human embryo -- blastomere separation
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Somatic cell nuclear transfer
5.2 Human Cloning Possibilities
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Human somatic cell transfer to an enucleated human ovum (actually fusion
of a human somatic cell with an enucleated human ovum);
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Human somatic cell nuclear transfer to an enucleated human embryo;
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Human somatic cell transfer to an enucleated animal ovum;
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Human somatic cell nuclear transfer to an enucleated animal embryo;
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Transfer of chromosomes from more than one human individual to a human
or animal enucleated ovum or embryo;
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“Fertilisation” of a human ovum by chromosomes from a human somatic
cell;
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Fusion of ova from two different women or from the same woman;
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Parthenogenesis
5.3 When is a clone a clone?
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Most of Dolly’s (the sheep cloned in 1997) mitochondria (99.5%) came from
the egg = 37 genes
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In humans this would mean 1% of DNA would not be the same as the donor
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Nuclear genetic identity, not total
Stem Cell Research and Human Cloning
Queensland Bioethics Centre
http://bne.catholic.net.au/qbc
5.4 Developmental problems with clones
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Inefficiency -- only 2% to 4% of mammalian clones are long term survivors
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Poor Imprinting -- molecular mechanism through which genes inside sperm
and egg cells are turned on or off in preparation for early embryonic and
fetal development
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Need for a large number of eggs – hence some advocate the use of animal
eggs for human cloning
5.5 Reproductive cloning and “therapeutic” cloning
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Reproductive cloning -- cloning for the sake of bringing a genetically
identical person to birth;
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Therapeutic cloning -- supposedly for some therapeutic purpose
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In what sense is this a valid distinction? -- a distinction based upon further
purposes of the actual cloning
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Universal Declaration on the Human Genome and Human Rights, 1997
states that practices such as “reproductive cloning of human beings shall not
be permitted”.
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The Declaration makes no reference to “therapeutic” cloning
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The relevant distinction was between cloning human beings and cloning
parts.
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A false distinction
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All human cloning is embryo cloning
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All human cloning is experimental
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A misuse of the term “therapeutic”
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never used for research destructive of the subject
5.6 The Issues
The Current Legislation:
Research Involving Embryos Act and Prohibition of Human Cloning Act 2002
5.7 Purpose of the Acts
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REA: “to address concerns, including ethical concerns, about scientific
developments in relation to human reproduction and the utilisation of
human embryos by regulating activities that involve the use of certain
human embryos created by assisted reproductive technology.”
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Notice it is “use of human embryos” not “respect for” or “care of”.
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PHCA: “to address concerns, including ethical concerns, about scientific
developments in relation to human reproduction and the utilisation of
human embryos by prohibiting certain practices.”
Stem Cell Research and Human Cloning
Queensland Bioethics Centre
http://bne.catholic.net.au/qbc
5.8 The Act and embryonic stem cells
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Nowhere in the Act is there mention of embryonic stem cells. The reference
is in the explanatory memorandum
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The Act permits destructive research on human embryos providing certain
conditions are met. – Nowhere is this research limited to the harvesting of
stem cells.
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The majority of approvals already granted are not for obtaining stem cells
5.9 The Issue
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The Act permits destructive research on human embryos – some embryos
are things to be “used”
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Why not all embryos? Why not foetuses?
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Why not comatose people at the other end of life?
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The challenge to be rationally consistent
5.10 Current Situation
Lockhart Review and Report
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While claiming that embryos should only be created for reproductive
purposes, there is no mechanism to ensure this
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Wants to redefine the embryo
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Wants to allow cloning for research purposes
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Would permit many of the practices currently forbidden
(See the “Status of the Embryo” factsheet on our website for more:
http://bne.catholic.net.au/qbc/resources_topics.php)
Stem Cell Research and Human Cloning
Queensland Bioethics Centre
http://bne.catholic.net.au/qbc