 Patients who receive blood stem cell transplants HSCT, also called bone marrow transplants, to treat their cancer are at risk for serious complications, which may sometimes be fatal. The more common, serious ones are relapse return of their disease, body organ injury from the intensity of the chemotherapy given prior to their transplant, and a serious complication called graft versus host disease GVHD. GVHD is a form of rejection, where the transplanted cells of the donor attack the recipients body as foreign, and do damage to organs and tissues. 