[Cord blood transplantation: current status and new perspectives].

Cord blood (CB) has been an alternative stem cell source for patients with a wide variety of hematological diseases. When compared with unrelated bone marrow transplantation (u-BMT), obvious advantages of CB are the rapid availability and tolerance of 2 HLA antigen mismatch, which have increased the chances of transplantation for patients who lack a suitable donor or need urgent transplantation. Although higher rates of engraftment failure as compared to other stem cell sources after cord blood transplantation (CBT) have been a serious concern, the mechanisms underlying these failures have gradually been clarified by analyzing accumulated clinical data, thereby contributing to improvement of engraftment. Recent large-scale retrospective comparisons of clinical outcomes between CBT and u-BMT from HLA-matched donors have obtained comparable results, and moreover, results of CBT have been promising even in elderly patients and those in non-remission status. This review describes the current status of CBT and problems to be solved, along with discussion of developing strategies aimed at improving patient outcomes.