Available online at www.ijpbr.org
ISSN: 2394 - 3726
Int. J. Phar. & Biomedi. Rese. 2015, 2 (2): 41-44
Review on Life Cell - Stem Cells
Mohsina Syedy*
Dept. of Life Science, Career Point University, Kota (Rajasthan)
*Corresponding Author E-mail: [email protected]
ABSTRACT
Stem cells are undifferentiated cells present in all multicellular organisms, having potency to
differentiate into all kind of body cells. Stem cells possess self-renewal, totipotency and plasticity.
Embryonic stem cells possess totipotency, the adult stem cells possess multipotency and differential
plasticity which can be exploited for future generation of therapeutic options. By their successful use
various kinds of diseases can be treated like cancer, diabetes and congenital diseases also. Cell
based therapy might become commercial in coming years. This review is an attempt to explore the
basic knowledge about stem cells.
Key words: Embryonic stem cells, plasticity, totipotency, congenital diseases.
INTRODUCTION
Stem cells are undifferentiated or unspecialized cells present in the multicellular organism’s body with
remarkable ability of self differentiation. These differentiated stem cells play an important role in tissue
repair and homeostasis. Stem cells are distinguished from other cell lines by two important features. First,
they are undifferentiated cells capable of self-renewing through mitotic cell division. Second, under
laboratory conditions, they can be induced to become tissue-specific or organ specific cells with special
functions. In some organs, like bone marrow and gut, stem cells continuously divide to repair their
damaged parts. However, in other organs, like heart and pancreas it can only divide under special
conditions.
Scientists are working on stem cells to screen new drugs and also know the fact that what makes stem
cells different from specialized cell types. And how can they be helpful in congenital defects.
Types of stem cells- stem cells are of two types.
1) Embryonic stem cells
Embryonic stem cells (ESCs) are derived from 4 to 11 days old embryos called blastocysts. They are best
grown embryos obtained from invitro fertilization (IVF) centers. They are totipotent in nature and capable
of differentiating into any type of cells. ESCs are referred as immortal because they can be multiplied and
maintained in an undifferentiated state for ever. These stem cells have the highest potential to regenerate
and repair diseased tissue and organs in the body. [1,2] However, the therapeutic benefit of ESCs is
bogged by a controversy owing to the belief that the process of extraction of stem cells from an embryo
destroys the embryo itself and some view this as taking life, thereby, raising moral and ethical concerns.
Further, it is difficult to control the growth and differentiation of the embryonic stem cell posing risk of
tumorogenicity and teratoma formation. While research is on to overcome some of these shortfalls as of
now, ESCs are not so far used therapeutically and have only remained an excellent platform for research.
2) Adult stem cells
Adult stem cells (ASCs) or somatic stem cells (SSCs) are found throughout the body in most adult tissues
like brain, bone marrow, blood, blood vessles, skeletal muscles, skin, and liver.
Copyright © 2015; IJPBR
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Mohsina Syedy
Int. J. Phar. & Biomedi. Rese. 2015, 2 (2): 41-44
ISSN: 2394 – 3726
They remain in non-dividing state for several years. They are multipotent in nature and can be
differentiated into more than one cell type but not all. [3] ASCs possess plasticity- ability to expand
beyond its potential. For example, dental pulp stem cells not only develop into tooth tissue but also have
the ability to differentiate into neuronal tissue.
Classification of Adult stem cells based on their originOn the basis of origin ASCs are of two typesa) Hemopoetic stem cells (HSCs)- they are unique cells and are obtained either from blood and cord.
[4]
b) Mesenchymal stem cells (MSCs)- they are multipotent stomal cells and can differentiate into a
variety of cell types like bone cells [5], cartilage cells [6], muscle cells [7] and fat cells [8].
Fig. 1
Mechanism of Action of stem cellsWhen called into action following an injury, a stem cell self-renews – undergoes cell division and gives
rise to one daughter stem cell and one progenitor cell. A progenitor cell is an intermediate cell type
formed before it achieves a fully differentiated state. It is regarded as committed to differentiating along a
particular cellular developmental pathway of stem cells:
Stem cell → Stem cell + Progenitor cell → Differentiated cell
Characteristics of stem cellsStem cells have two fundamental properties they are:1) Self- renewal- they have ability to divide mitoticaly without differentiation.
Two mechanisms exist to ensure that a stem cell population is maintained:
1. Obligatory asymmetric replication: a stem cell divides into one mother cell that is identical to the
original stem cell, and another daughter cell that is differentiated.
2. Stochastic differentiation: when one stem cell develops into two differentiated daughter cells,
another stem cell undergoes mitosis and produces two stem cells identical to the original.
2) Potency- ability of stem cells to differentiate into specialized cell types. Stem cells are either
pluripotent, totipotent and multipotent.
Totipotent stem cells can differentiate into extra embryonic and embryonic cell types. Such cells can
produce a whole new vital organism. [9] These cells are produced from the fusion of an egg and sperm
cell. Cells produced by the first few divisions of the fertilized egg are also totipotent [10].
Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells, [9].
i.e. cells derived from any of the three germ layers [11].
Multipotent stem cells can differentiate into a number of cell types [9].
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Mohsina Syedy
Int. J. Phar. & Biomedi. Rese. 2015, 2 (2): 41-44
ISSN: 2394 – 3726
3) Plasticity: mesenchymal stem cells (MSCs) have plasticity and can undergo differentiation. The trigger
for plasticity is stress or tissue injury which upregulates the stem cells and releases chemoattractants and
growth factors.
Stem cell : Research- stem cell research is now a days in very demand. Its research give extraordinary
benifites some of them are:• They are helpful to understand genome data mining, human embryonic gene expression.
• They serve to study biological processes which help in understanding human developmental
disorders like birth defects, cancers, etc.
• They are new means of creating human disease models for drug discovery and development. It
serves as an alternative to animal toxicology thereby hastening the drug to the market [12].
• The most crucial and exciting of all stem cell uses is cell-based therapy.
Cell-based therapy
Adult stem cells have been used in pilot studies as potential cell-based therapy for various diseases. The
following stem cell characteristics make them good candidates for cell-based therapy: [13, 14]
1. Potential to be harvested from patients
2. High capacity of cell proliferation in culture
3. Ease of manipulation to replace existing nonfunctional genes via gene splicing methods
4. Ability to migrate to host target tissues.
5. Ability to integrate into host tissues and interact with the surrounding tissues.
Stem cell: benefits: stem cells provide various benefits for health and medicine areas. Some benefits are:
Human welfare and stem cellsScientists are studying on stem cells to know their potential in the formation of specialized cells that
makes humans. Many congenital diseases occur because of defects in the differentiation processes of
cells. By understanding of the development that happen in normal cells during differentiation will help
scientist to find their cure.
Stem cells and cell – based therapiesStem cells act as a source for the production of new cells and tissues for medical therapies. By using these
viable cells various diseases can be treated. Some of them are:
• Parkinson’s disease
• Type I diabetes
• Arthritis
• Burn victims
• Cardiovascular disease
Potential to reverse diseasesBy the use of stem cells various diseases can be reversed because they provide renewable source of
replacement cells.
Heart Attack - For example, a patient who has suffered from a heart attack and sustained heart damage
could have the damaged tissue replaced by healthy new muscle cells.
Parkinson's disease - The destruction of brain cells in conditions such as Parkinson's disease can
hopefully be reversed with the replacement of new, healthy and functioning brain cells.
Genetic Defects - Even more promising is the potential to address genetic defects that are present from
birth by restoring function and health with the introduction of normal healthy cells that do not have these
defects.
Stem cells and Drug TestingStem cells also serve an important benefit for the pharmaceutical area. New discovered drugs can be
tested on stem cells to assess their safety. After their successful results they can be tested on animals and
human models.
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Mohsina Syedy
Int. J. Phar. & Biomedi. Rese. 2015, 2 (2): 41-44
ISSN: 2394 – 3726
CONCLUSION
Stem cells are very important cells of the body. And they can be drived from body itself. Stem cell
therapies serve unlimited medical, dental and health applications. While there are several barriers that
need to be broken down before this novel therapy can be translated from lab to clinics, it is certain that the
future is going to be exciting for all of us. Stem cell therapy has brought in a lot of optimistic hope
amongst researchers, doctors, and not to forget the patients who are the chief beneficiary of this
innovation. Stem cells regenerate hope and not all that is happening in research is hype.
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