Difference Between Embryonic and Adult Stem Cells:
There are significant biological differences between human, embryonic, and adult
stem cells. Embryonic stem cells can be isolated from embryos with relative ease
and have an unlimited ability to self-renew and proliferate in culture in huge
numbers for many generations. Further, they are the only stem cell lines known
to be undifferentiated and pluripotent that are available for study. This means
that they are more likely to generate a wider range of cell types. Such
characteristics, in combination, give embryonic stem cells a remarkably broad
therapeutic potential. Yet the availability of human embryos for the production
of stem cells is limited and subject to considerable ethical controversy and legal
restrictions. Many of the existing stem cell lines are incompletely characterized
and may not be robust or stable in their properties.
Adult stem cells, in contrast, are found in low numbers in the human body, can
be difficult to obtain, do not expand readily in culture, and may be capable of
differentiation into only a limited number of cell types. It seems likely that a few
known adult stem cells exhibit stem cell plasticity and can differentiate into cell
types outside their usual path. Such adult stem cells would need somehow to be
isolated, expanded, and then efficiently reprogrammed onto a new pathway of
differentiation if they were to be used to treat patients. This extra
reprogramming step makes the development of specialized cells from adult stem
cells more complicated than from embryonic stem cells.
Totipotency is the ability of a single cell to divide and produce all of the
differentiated cells in an organism, and example totipotent cells are spores and
zygotes. In the spectrum of cell potency, totipotency represents the cell with the
greatest differentiation potential.
Pluripotency refers to a stem cell that has the potential to differentiate into any
of the three germ layers: endoderm (interior stomach lining, gastrointestinal
tract, the lungs), mesoderm (muscle, bone, blood, urogenital), or ectoderm
(epidermal tissues and nervous system).
Multipotency describes progenitor cells which have the gene activation potential
to differentiate int