Biomedical Engineering Reference
In-Depth Information
in addition to their restricted developmental potential, other factors
make adult stem cells less attractive than esCs for regenerative medicine
research. Adult stem cells are difficult to isolate because they are intermin-
gled with large numbers of other cell types. secondly, when grown outside
the body, adult stem cells usually die after a few divisions and spontane-
ously differentiate into the specialized cell types of the tissues from which
they came.
Despite the difficulties in working with adult stem cells, researchers
continue efforts to improve harvesting techniques and to expand the de-
velopmental potential of adult stem cells grown in the laboratory. These
labors are producing some progress for stem cells obtained from umbili-
cal cord and menstrual blood; placental, fat, neural, lung, mammary, bone
marrow, and testicular tissue; and the lining of the nasal cavity. recently,
researchers in Germany and south Korea made adult stem cells from the
human nervous system pluripotent by modifying them genetically, work
considered later in this chapter.
Adult stem cells have helped persons with injuries and diseases for many
years. for example, when patients receive skin grafts, they rely on adult
stem cells in the healthy skin tissue to help repair the injury. When can-
cer patients receive bone marrow transplants after chemotherapy, they de-
pend on hemopoietic stem cells to replace blood-generating cells killed by
the chemotherapeutic drugs.
even though adult stem cells may not have the clinical value of esCs,
continued research on adult stem cells is desirable for at least three rea-
sons. first, it could lead to regenerative treatments for specific organs. for
example, adult stem cell-derived progenitor cells from bladder tissue have
already been used to grow functional, new bladders; and in 2008 an inter-
national team of doctors and researchers from spain, italy, and england
used a patient's bone marrow cells to provide her with a new windpipe.
second, adult stem cells do not carry the controversial ethical issues that
esCs do since they can be harvested from tissue biopsies or recently de-
ceased persons. no human embryos are needed to obtain adult stem cells.
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