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Role of Stem Cells Derived from Unfertilized Embryos
Using unfertilized human oocytes as a source for stem cell is less controversial
than using fertilized embryos; it avoids the ethical concerns surrounding human
ESC research. Without the contribution from a sperm, the oocyte has a unique
advantage of homozygosity, which renders its derivatives less immunogenic and
provides a broader match with different MHC phenotypes. In addition, stem
cells derived from unfertilized oocytes could also be selected for homozygosity
of a drug response gene, a disease gene, or a cancer gene from a female carrier
and, therefore, could provide a model and business rationale for drug testing and
drug discovery. For example, a collection of stem cells homozygous for different
drug metabolizing gene variants could be used to prescreen a drug for its pro-
spective toxicity and effi cacy in the population. A cancer progression model can
be established by differentiating stem cells homozygous for a cancer gene to the
cancer tissue types, leading to the identifi cation of biomarkers of cancer pro-
gression and drugs for cancer prevention. Furthermore, these homozygous stem
cells could be used in facilitating linkage studies and in verifying the function
of a SNP.
Cloning and Personalized Cell Therapy
Cloning is the procedure used to create a cell or organism that is genetically identi-
cal to an existing cell or organism. The underlying biological mechanism of cloning
is the reprogramming of the nuclei of specialized adult cells to become the nuclei of
new embryonic cells. Cloning cells in the laboratory is a routine procedure used to
produce life-saving therapeutic proteins such as human insulin for the treatment of
diabetes. Potential further applications of cloning can improve treatments for ill-
nesses stroke, Parkinson’s disease and heart disease. Human therapeutic cloning
provides a potentially limitless source of cells for cell therapy and tissue engineer-
ing. Cloning helps to overcome the problem with transplants of either cells or organs
as the immune system recognizes them as foreign. But a patient’s body will not
reject cells if they are genetically identical to him or her.
The promise of cloning is that it could be used to create stem cells that are essen-
tially the patient’s own. An embryo would be cloned from one of the patient’s own
cells, and destroyed when it was a few days old to produce stem cells. These cells
could be chemically guided to become whatever bits of tissue needed replacement –
insulin-producing beta-islet cells for diabetics, dopamine-rich neurons for
Parkinson’s disease, heart tissue. This would be considered as personalized cell
therapy.
9 Personalized Biological Therapies