Stem cells are cells
found in all multi-cellular organisms. They are
characterized by the ability to renew themselves through
mitotic cell division and differentiate into a diverse
range of specialized cell types. Research in the stem
cell field grew out of findings by Canadian scientists
Ernest A. McCulloch and James E. Till in the 1960s.
The two broad types of mammalian stem cells are:
embryonic stem cells that are isolated from the inner
cell mass of blastocysts, and adult stem cells that are
found in adult tissues. In a developing embryo, stem
cells can differentiate into all of the specialized
embryonic tissues. In adult organisms, stem cells and
progenitor cells act as a repair system for the body,
replenishing specialized cells, but also maintain the
normal turnover of regenerative organs, such as blood,
skin, or intestinal tissues.
Stem cells can now
be grown and transformed into specialized cells with
characteristics consistent with cells of various tissues
such as muscles or nerves through cell culture. Highly
plastic adult stem cells from a variety of sources,
including umbilical cord blood and bone marrow, are
routinely used in medical therapies. Embryonic cell
lines and autologous embryonic stem cells generated
through therapeutic cloning have also been proposed as
promising candidates for future therapies.
Medical researchers believe that stem cell therapy has
the potential to dramatically change the treatment of
human disease. A number of adult stem cell therapies
already exist, particularly bone marrow transplants that
are used to treat leukemia. In the future, medical
researchers anticipate being able to use technologies
derived from stem cell research to treat a wider variety
of diseases including cancer, Parkinson's disease,
spinal cord injuries, Amyotrophic lateral sclerosis,
multiple sclerosis, and muscle damage, amongst a number
of other impairments and conditions. However, there
still exists a great deal of social and scientific
uncertainty surrounding stem cell research, which could
possibly be overcome through public debate and future
research, and further education of the public.
One concern of treatment is the possible risk that
transplanted stem cells could form tumors and have the
possibility of becoming cancerous if cell division
continues uncontrollably.
Stem cells, however,
are already studied extensively. While some scientists
are hesitant to associate the therapeutic potential of
stem cells as the first goal of the research, they find
the investigation of stem cells as a goal worthy in
itself.
Information
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