Umbilical cord blood transplantation (UCBT), which was originally investigated as an alternative to bone marrow or peripheral blood transplantations of related or unrelated donors, is now being performed widely. The annual number of UCBT surpasses that of unrelated BM or PB transplantations. Moreover, UCBT has reportedly shown almost equivalent outcomes as that of the others. Although the incidence of relapse after UCBT is reportedly lower than that of others, it has a higher incidence of non-relapse mortality, which is one of the main obstacles that need to be overcome to improve the outcomes. Failed or delayed engraftment and associated infections, as well as alloimmune-related complications, such as pre-engraftment immune reactions or acute graft-versus-host disease, need to be overcome urgently. However, alloimmune reactions could play a role in reducing the incidence of relapse, and a risk-adapted approach needs to be established.

 Graft-versus-host disease (GVHD) is a potentially life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-SCT); GVHD prophylaxis using immunosuppressants, such as calcineurin inhibitors, is essential for the success of allo-SCT. However, profound immunosuppression can lead to tumor relapse and infectious complications. Therefore, it is necessary to develop a novel management strategy that does not rely on immunosuppressants for GVHD. Emerging evidence has demonstrated that there are tissue-specific mechanisms that maintain tissue homeostasis against damage caused by immune response and inflammation. These mechanisms are disrupted after allo-SCT due to conditioning regimens and/or GVHD. Moreover, it is also suggested that the impairment of these mechanisms may lead to the development, exacerbation, and refractoriness of GVHD. In this review, we summarize recent findings pertaining to tissue-intrinsic mechanisms that maintain tissue homeostasis, with a focus on the intestine.

 Unrelated cord blood transplantation is one of the well-established methods of allogeneic transplantation. The number of cord blood transplantations is increasing in Japan but decreasing in the United States and Europe due to the rise of related haploidentical transplantation. In order to examine whether race affects the outcomes of cord blood transplantations, prognostic factors for cord blood transplantation in Japan and Europe were compared, and the prognostic factors were found to be similar except for human leukocyte antigen (HLA). This may be why cord blood is preferred as an alternative source of hematopoietic stem cells in Japan. Recently, the usefulness of cord blood transplantation for patients with high risk of recurrence of hematologic malignancies has been demonstrated. Moreover, cord blood transplantation is of increasing research interest due to improved results from pre-transplant conditioning regimens and from randomized controlled trials on expanded cord blood in Europe and the United States.

 A retrospective investigation was conducted on the employment status of 30 patients who had received allogeneic hematopoietic stem cell transplantation (allo SCT) over a 10-year period (2009-2019). Of the 30 patients, 80% started work which was comparable to the employment rate of the general young adult population. The median time frame to start work (including part-time), after allo SCT was 410 days (90 to 1,760 days). 8 of 24 patients (33%) began work within 1 year and 18 patients (75%) began work within 2 years. 20 out of 24 patients (83%) began work with post-transplant complications. These patients required regular hospital visits for evaluation and treatment for their conditions.

 In cooperation with the Kinki branch office of the Japan Marrow Donor Program, we verified the problems in current coordination and constructed a WEB system to provide a notification of the harvest schedule at each hospital. After introducing this system, the median time between donor selection and collection and actual transplant were 70-78 days in 2013-2016 and 57-63 days in 2017-2020 without refusal. The collection rate in the first-choice week of patients increased 29-38% in 2013-2016, to 32% in 2017, and 63-73% in 2018-2020. Additionally, the role of the hematopoietic cell transplant coordinator was important for improving the efficiency of collection and reducing the workload of hematologists. This system helped improve the efficiency of harvesting. In contrast, there was disparity in the harvest experience of various hospitals. In the future, the development of teaching harvest techniques and skills to improve donor safety will be an important problem.

 Thymoglobulin is an anti-human thymocyte immunoglobulin preparation made of purified polyclonal antibodies derived from rabbits. It is approved for clinical use in Japan as an immunosuppressant treatment for a pre-treatment before hematopoietic stem cell transplant (HSCT) and in the treatment of post-HSCT acute graft-versus-host disease (GVHD); it is also approved to treat moderate to severe aplastic anemia and acute rejection after kidney, hepatic, cardiac, pulmonary, pancreatic or small intestinal transplant. Post-launch, a drug use surveillance and a special drug use surveillance were conducted in thymoglobulin-treated patients in order to understand the safety and effectiveness profiles in real-world medical practice. There were no new safety concerns associated with thymoglobulin use; no notable or unexpected adverse reactions were recognized. Regarding effectiveness, significant differences were found in some of the patient characteristics by examining factors which influence the response rate in the patients with acute GVHD after HSCT or pre-treatment of HSCT. These results were consistent with those from Phase Ⅱ clinical trials and domestic clinical studies.

 Sinusoidal obstruction syndrome (SOS) is a fatal complication of hematopoietic stem cell transplantation. We report two cases of SOS where early defibrotide (DF) initiation led to recovery. The first case was that of a 49-year-old woman with Philadelphia chromosome-positive acute lymphoblastic leukemia. In the first complete remission, she underwent human leukocyte antigen (HLA) 2 antigen-mismatched cord blood transplantation, using a conditioning regimen with busulfan and cyclophosphamide. Organ damage and weight gain were observed on day 27 after transplantation, and she was diagnosed with SOS. DF was initiated on day 28 and her symptoms and collected data improved by day 54. The second case was that of a 67-year-old man with adult T-cell leukemia/lymphoma. In the first complete remission, he underwent HLA-matched unrelated peripheral blood hematopoietic stem cell transplantation, using a conditioning regimen with fludarabine and melphalan. Red blood cell fragmentation and transfusion-refractory thrombocytopenia were observed on day 8, followed by ascites and liver dysfunction. He was diagnosed with SOS and DF was administered on day 24. His conditions improved by day 36. Further studies are required to determine the appropriate timing of DF initiation.