Stem cell therapy is an intervention strategy that introduces new adult stem cells into damaged tissue in order to treat disease or injury. Many medical researchers believe that stem cell therapies have the potential to change the face of human disease and alleviate suffering. The ability of stem cells to self-renew and give rise to subsequent generations with variable degrees of differentiation capacities,  offers significant potential for generation of tissues that can potentially replace diseased and damaged areas in the body, with minimal risk of rejection and side effects.
A number of stem cell therapies exist, but most are at experimental stages, costly or controversial, with the notable exception of bone-marrow transplantation.  Medical researchers anticipate that adult and embryonic stem cells will soon be able to treat cancer, Type 1 diabetes mellitus, Parkinson’s disease, Huntington’s disease, Celiac disease, cardiac failure, muscle damage and neurological disorders, and many others.  Nevertheless, before stem cell therapeutics can be applied in the clinical setting, more research is necessary to understand stem cell behavior upon transplantation as well as the mechanisms of stem cell interaction with the diseased/injured microenvironment.
For over 30 years, bone-marrow, and more recently, umbilical-cord blood stem cells, have been used to treat cancer patients with conditions such as leukaemia and lymphoma.
During chemotherapy, most growing cells are killed by the cytotoxic agents. These agents, however, cannot discriminate between the leukaemia or neoplastic cells, and the hematopoietic stem cells within the bone marrow. It is this side effect of conventional chemotherapy strategies that the stem cell transplant attempts to reverse; a donor’s healthy bone marrow reintroduces functional stem cells to replace the cells lost in the host’s body during therapy.