Requirements for Hematopoietic Stem Cell Engraftment and Graft Engineering: Role of Facilitating Cells
I. INTRODUCTION Since the first successful bone marrow transplants were carried out almost 40 years ago, bone marrow transplantation (BMT) is now the preferred therapy in the treatment of a number of hematological malignancies (1). It was during the early period of BMT that the importance of histocompatibility antigens became evident. The establishment of human leukocyte antigen (HLA) typing has made the selection of major histocompatibility complex (MHC)–identical or MHC-compatible allogeneic donor/recipient pairs possible (2,3). In spite of these advances, there remain two major limitations to BMT for leukemia: (1) graft-versus-host disease (GVHD) and (2) failure of engraftment. In addition, the observation that the incidence of GVHD is highly correlated with the degree of genetic disparity between donor and recipient currently prohibits the expansion of the limited donor pool.