Biomedical Engineering Reference
In-Depth Information
of the adult cell into a human egg whose nucleus has been removed. This process is
somatic cell nuclear transfer. In this procedure, the resulting embryo is implanted in a
woman and carried to birth. Therapeutic cloning begins with the same procedure as
reproductive cloning. Whereas the goal of reproductive cloning is to produce a baby,
the goal of therapeutic cloning is to produce ESCs for research or treatment.
12.6.7.3 There is Law that Could Apply to ESCR Originally attached to the 1995
Health and Human Services (HHS) appropriations bill, the “Dickey Amendment”
has prohibited federal funding of “any research in which a human embryo or
embryos are destroyed, discarded or knowingly subjected to risk of injury or death.”
Unfortunately, there are no laws to protect preembryos (embryos younger than 14
days old) or that prohibit private individuals, research firms, or pharmaceutical
companies from forming, manipulating, or destroying stem cells, human clones, or
embryos.
12.6.7.4 ESCR Currently has Major Disadvantages One minor complication is
that use of human ESCs requires lifelong use of drugs to prevent rejection of the
tissue. Another more serious disadvantage is that using ESCs can produce tumors
from rapid growth when injected into adult patients. A third disadvantage reported in
the March 8, 2001, New England Journal of Medicine was of tragic side effects from
an experiment involving the insertion of fetal brain cells into the brains of patients
with Parkinson's disease. Results included uncontrollable movements, including
writhing, twisting, head jerking, arm flailing, and constant chewing. Fourth, a recent
report in the Journal Science reported that mice cloned from ESCs were genetically
defective. Finally, the research may be hampered because many of the existing stem
cell lines were grown with the necessary help of mouse cells. If any of this research is
to turn into treatments, it will need approval from the FDA, which requires special
safeguards to prevent transmission of animal diseases to people. It is unclear how
many of these cell lines were developed with the safeguards in place. This leads to a
host of problems related to transgenic issues.
12.6.8 Challenges Remain for Stem Cell Therapies
There are many challenges to making stem cell therapies, such as regenerative
medicine, actually work in a therapeutic setting. We might be able to harvest stem
cells, from either blastocysts or by creating pluripotent cells from already differenti-
ated tissues, but that is really only the beginning of a medically viable process. After
a cell line is cultured in a maintainable way, the following questions remain:
How to direct differentiation into the desired tissue type and optimizing growth
conditions and the physical environment for cell cultures or for growing organs
for transplantation
How to inject and transport stem cells to the target location in the body
Finding ways to generate induced pluripotent stem cells without inducing
tumor formation in future recipients of stem cell therapies.
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