[Introduction and the current status of unrelated peripheral blood stem cells transplantation in Japan]

In other countries, unrelated donor peripheral blood stem cell transplantation (PBSCT) is more prevalent than bone marrow transplantation; however, in Japan, it was introduced in 2010 after confirming the safety of donors. PBSCT does not require blood donation, general anesthesia, or frequent bone marrow aspiration of the donor. After PBSCT, numerous hematopoietic cells can prompt blood recovery and engraftment, which has enabled reduced intensity transplantation in elderly patients and patients with concurrent diseases, such as infection. In addition, GVL effect by a large number of donor lymphocytes is expected, however, chronic GVHD is a major concern. When introducing PBSCT in Japan, manuals were drafted considering the short-term safety of donors, and data were collected on the occurrence of long- and short-term adverse events. A randomized trial reported no difference in the survival rate between bone marrow transplantation and PBSCT at 5 years; however, it revealed that QOL was better in the former. PB is a essential transplant source option, and attempts are being made to overcome chronic GVHD. PBSC contains abundant stem cells, progenitor cells, and immunocompetent cells and is indispensable for the development of cell therapy for blood diseases in the future.