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Shvoong Home>Science>Bioengineering & Biotechnology>Embryonic and adult stem cells Summary

Embryonic and adult stem cells

Article Summary   by:TishaHriday     Original Author: TishaHriday
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Embryonic and adult stem cells


Human embryonic and adult stem cells each have advantages and
disadvantages regarding potential use for cell-based regenerative therapies. Of
course, adult and embryonic stem cells differ in the number and type of
differentiated cells types they can become. Embryonic stem cells can become all
cell types of the body because they are pluripotent. Adult stem cells are
generally limited to differentiating into different cell types of their tissue
of origin. However, some evidence suggests that adult stem cell plasticity may
exist, increasing the number of cell types a given adult stem cell can become.

Large numbers of embryonic stem cells can be relatively easily grown in
culture, while adult stem cells are rare in mature tissues and methods for
expanding their numbers in cell culture have not yet been worked out. This is
an important distinction, as large numbers of cells are needed for stem cell
replacement therapies.

A potential advantage of using stem cells from an adult is that the patient''''s
own cells could be expanded in culture and then reintroduced into the patient.
The use of the patient''''s own adult stem cells would mean that the cells would
not be rejected by the immune system. This represents a significant advantage as
immune rejection is a difficult problem that can only be circumvented with
immunosuppressive drugs.

Embryonic stem cells from a donor introduced into a patient could cause
transplant rejection. However, whether the recipient would reject donor
embryonic stem cells has not been determined in human experiments.

The unique potential contribution of human
embryonic stem cells to therapies is a product of both their longevity and
their capacity to produce a wide range of specialized cells in the laboratory. By
contrast, adult stem cells that are grown in the laboratory appear to have much
shorter lifespan than embryonic stem cells. This reduces their capacity to form
new cell types. Stem cells can also be obtained from aborted fetuses and
umbilical cord blood, but it is not clear whether the full range of cell types
that are required for treatments could eventually be generated from these
sources alone.

The unique potential contribution of human
embryonic stem cells to therapies is a product of both their longevity and
their capacity to produce a wide range of specialized cells in the laboratory.
By contrast, adult stem cells that are grown in the laboratory appear to have
much shorter lifespan than embryonic stem cells. This reduces their capacity to
form new cell types. Stem cells can also be obtained from aborted fetuses and
umbilical cord blood, but it is not clear whether the full range of cell types
that are required for treatments could eventually be generated from these
sources alone.

In theory, embryonic stem cells could be used to
replace any part of the body damaged by accident or illness. That could lead to
cures for such recalcitrant diseases as Parkinson''''s, Alzheimer''''s and diabetes.
Some scientists believe the cells might eventually allow those who are
paralyzed to walk again.

But many feel such medical miracles would be tainted, because scientists must
destroy human embryos to make these cells. To those who believe an embryo has
the rights of a person, this is akin to murder.

Embryo-derived cells are only one type of stem cell. Others are found in
umbilical cord blood, or even in specific organs like bone marrow or the brain.
But these other types do not appear to be as flexible as those taken from
embryos. Another advantage for the embryonic cells: Unlike other types of
cells, they can probably reproduce forever.

Some researchers believe that the process used to clone animals might be
important in stem cell research. Researchers would clone one of the patient''''s
own cells. They would destroy the embryo used in the process, creating stem
cells that would not be reject
Published: February 27, 2008   
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