These cells are derived from the blastocyst stage (Image) of an
embryo and are pluripotent (can differentiate into any body cell). Therefore
they have a wide range of clinical applications from spinal cord repair to skin
regeneration, however they have many negative characteristics mainly concerned
with ethics. It is unethical to destroy a human embryo for the collection of hESCs
although recently collection of hESCs from early stage blastocysts has been
implemented which doesn’t destroy the embryo but still requires culturing
(growing) with existing hESC lines. Additionally embryos used for the
collection of hESCs are leftover from IVF treatments and would not form an
organism. The question of ethics is complicated and all opinions must be
considered and it’s left to the reader to make their own decision.
Other problems of hESC in regenerative medicine include the
development of immunogenicity with differentiation when using allogeneic (from
an unrelated individual) sources. Simply put, as a hESC differentiates into the
desired cell types they gain the potential to elicit an immune response causing
rejection similar to that seen in organ transplants, therefore
immunosuppressive drugs are required which possess their own problems. The use
of autologous (from the same individual) hESCs would prevent this reaction
however unless hESCs are stored from birth these are not available. Also the
pluripotency increases the chances of differentiation towards undesired cell
type which could have adverse effects upon implantation and is not easily
solved.
To grow or culture hESCs requires unique condition such as a
supportive layer of mouse embryonic fibroblasts and signalling to maintain
pluripotency which isn’t always effective.
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