Cell therapy (also called cellular therapy or cytotherapy) is therapy in which cellular material is injected into a patient, this generally means intact, living cells. Two distinct categories of cell therapy are recognized. The first category is cell therapy in mainstream medicine. This is the subject of intense research and the basis of potential therapeutic benefit, i.e., (a) Allogeneic Cell Therapy (b) Human embryonic stem cells (c) Neural Stem Cell Therapy (d) Mesenchymal Stem Cell Therapy (e) Hematopoietic stem cell transplantation The second category is in alternative medicine, and perpetuates the practice of injecting animal materials in an attempt to cure disease. This practice, according to the American Cancer Society, is not backed by any medical evidence of effectiveness, and can have deadly consequences.