الفهرس 
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Abstract
Stem cell is defined as an undifferentiated cell that has
continuous proliferative ability. Additional characteristics
include the ability to repopulate a tissue or organ after
transplantation and the potential to be serially transplanted.
Stem cells have been categorized according to their
origin into: Embryonic, fetal, adult and HSCs (including cells
of other types).
Although ESCs proved to give rise to cells derived from
all the three germ layers, but still this high differentiation
capacity has the disadvantage of forming teratomas. As well as
the high ethical concerns it raises about methods of obtaining
these cells and the moral status of the embryos involved in this
research. These concerns are much more less for other sources.
The study of HSCs is one of the most exciting and
rapidly advancing researches in the medical field today. HSCs
will be one of the most powerful tools for healing. HSCs were
obtained from BM, peripheral blood and UCB which begins to
flourish now with the development of UCB banks but its
application and its cost-effectiveness is still questionable. SCT nowadays carry a great hope for many diseases that
before were thought to be non-curable. With great success in
certain malignant and hematological diseases such as; leukemia,
lymphoma, neuroblastoma, aplastic anemia, thalassemia and
sickle cell disease.
On the other hand, more research is required for SCT to
be applicable for a great variety of diseases as; type I DM, brain
damage, cancer, spinal cord injury, Parkinson’s disease,
cardiovascular diseases, blindness and metabolic diseases.
Complications of SCT are numerous. Infectious
complications are frequent and include bacterial, fungal and
viral infections. Immuno-suppression with break down of skin and mucosal barriers, decreased immunoglobin production and impairment of cell mediated immunity are predisposing factors.
GVHD represents one of the major complications of
allogeneic SCT. It is an immunologic reaction of donor Tlymphocytes
against recipient tissue. It may be acute or chronic.
Other complications include veno-occlusive disease,
cataract, diarrhea, mucositis, pneumonitis and endocrine
disorders.