The field of hematopoietic stem cell transplantation is rapidly evolving. Realization that hematopoietic stem cells give rise to the immune compartment has resulted in clinical trials of hematopoietic stem cell transplantation for patients with autoimmune diseases. Allogeneic hematopoietic transplants are a form of adoptive immunotherapy resulting in beneficial graft versus tumor effects. Large numbers of hematopoietic cells can be collected with ease. Therefore, a renewable source of cells for ex vivo genetic manipulations is readily available. Multiple trials combining hematopoietic...