We often hear about stem cells and its
undergoing research in the news, without fully
understanding what it is about.
Stem cells are biological cells found in
almost all multicellular organisms 1 and are characterized by their
three special properties: self-renewal, differentiation and their unspecialised
nature 2. Each stem cell has the potential to remain a stem cell
or turn into a cell type with a specialised function such as a red blood cell.
There are three different types of stem cells
which can determine how many different cell types they can develop into, in the
All stem cells have the potential to develop
into different cell types, but totipotent
cells can develop into any cell type, which makes them ideal for cell and gene
therapies as well as tissue engineering for transplants and replacement of
diseased cells 3. When a single celled sperm and egg unite, they
form a zygote cell, which is essentially a totipotent cell, as they have the
potential to develop into any cell found in the human body. Just after 4 days,
the fertilised egg will lose its totipotency (total potential) and matures to
become more specialised stem cells called pluripotent stem cells.
Pluripotent cells can
give rise to any type of cell in the body, including all of the more than 200 different
cell types, except those needed to support and develop a fetus in the womb.
Embryonic stem cells are considered pluripotent and so are induced pluripotent
stem cells that have been reprogrammed from adult tissues. Adult stem cells are
committed to becoming a cell from their tissue of origin, and can’t form other
cell types therefore also called tissue-specific stem cells 4.
Stem cells that can give rise only to a small
number of different cell types are called multipotent.
Although multipotent stem cell can
give rise to other types of cells, it is limited in its ability to
differentiate. An example could be bone marrow as it can give rise to all blood
cell types but not any other types.
You can use stem cells to treat or prevent a disease
through stem-cell therapy which promotes the reparative response of diseased,
dysfunctional or injured tissue using stem cells or their derivatives 5.
Usually bone marrow transplant is used for this but umbilical cords can also be
used. This can be used to combat the limited supply
of donor organs by using cells instead.
stem cells are grown in a lab where they are manipulated to specialise in a
specific types of cells, such as blood cells. Next, this is injected into
someone, where it is needed. For
example, if the person has heart disease, the cells could be injected into the
heart muscle. The healthy transplanted heart cells could then contribute to
repairing defective heart muscle.
stem cells can also be made to differentiate into different cell types which
will retain more similarity to the tissue of interest as they offer a far more
accurate and efficient model with which to discover and test new drugs.
Further, if a disease has a genetic component, embryotic stem cells could be
generated with the particular genetic mutation. These cells could be made to
differentiate into diseased tissue before drugs are tested on them.
there are ethical dilemmas about using human embryos. Some believe that the
embryo is, in a sense, as much a human being as a new-born baby and that its
destruction, even in its early stages, is unethical as it can still bear new
life. Others see the human need for the embryotic stem cells, but they think
the human embryo is more than just nameless cells, and yet it is not the same
as a baby.
Every day, research
is undergoing into stem cells and there are bound to be clashes from both
sides, each with a valid argument. However, as we advance, as science advances,
it will surely lead to a better future.
1. Hima Bindu A and Srilatha B (2011) Potency of Various Types
of Stem Cells and their Transplantation. J Stem Cell Res
2. Jeevani T (2011) Stemcell
Transplantation- Types, Risks and Benefits. J Stem Cell Res Ther 1: 114.
3. Murnaghan I (2017) Totipotent Stem Cells © ExploreStemCells 2000-2017
© 2015 California Institute for Regenerative Medicine
5Stem cells: What they are and what they do
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