[Hematopoietic stem cell transplantation]

Recent development of chemotherapy enabled us to cure patients with malignancies including leukemia, malignant lymphoma, choriocarcinoma, ovarian cancer, breast cancer and so on. In order to obtain the definite effect, the quantities of chemotherapeutic agents should be increased and the major lethal side effect caused by bone marrow failure should be avoided. For this purpose, hematopoietic stem cells derived from either bone marrow or peripheral blood can be used for the rapid recovery of neutropenia and thrombocytopenia. We prepared stem cells both from bone marrow and peripheral blood by anti-CD34 monoclonal antibody bound on magnetic beads column and administered into severe combined immunodeficiency (SCID) mouse. Four and 20 weeks after transplantation, mononuclear cells bearing human hematopoietic antigens and human immunoglobulin G were appeared in the circulation, suggesting that stem cells from peripheral blood also possess long-standing capability of maturation as well as those from bone marrow. We next conducted clinical study of high dose chemotherapy combined with peripheral blood stem cell transplantation for patients with poor risk choriocarcioma. By this treatment, 4 complete response (CR) and 4 partial response (PR) were obtained, whereas 2 progressive disease (PD), 1 no change (NC) and 5 PR were obtained by the previous conventional chemotherapies. The results obtained were promising and this treatment regimen may become a good modality for the complete treatment of chemotherapy curable tumors.