This report presents the Japanese status of organ procurement from deceased donors for organ transplantation in 2022 within the COVID-19 pandemic in Japan. The Act on Organ Transplantation was established in July, 1997 and amended in June, 2009. After the enforcement of the amended Act on Organ Transplantation in July 2010, the number of brain-dead donors vastly increased. But the total numbers of deceased donors for organ transplantation were almost the same from 2015 to 2018. In 2019 the total number increased to 125. But within the COVID-19 pandemic, the number decreased to 77 in 2020, and to 76 in 2021, and increased to 108 in 2022. In this situation, the numbers of brain-dead donors in 2020 and 2021 were kept almost the same from 2015 to 2018, but increased slightly in 2022. The Japan Society for Transplantation would like to express its deepest gratitude to those who have expressed their willingness to donate their organs despite the difficult circumstances, to the families who have agreed to donate their organs, and to the medical staff, other related people, and transplant coordinators who have been involved in organ donation in order to respond to their wishes.

A total of 1,782 kidney transplants including 1,584 from living donors, 28 from non-heart-beating donors and 170 from heart-beating donors were performed in 2022 in Japan. The data obtained from the Japanese Renal Transplant Registry are shown and analyzed in this annual report. The characteristics of recipients and donors such as relationships, original diseases, duration of dialysis therapy, blood transfusion, status of viral antigens and antibodies, pretransplant complications, causes of death of deceased donors, ischemic time and histocompatibilities are described. In addition, immunosuppressants used initially and other treatments are analyzed. We also report the results of a follow-up survey for recipients and living donors.

Since the Organ Transplantation Act was passed in October 1997, a total of 704 heart transplantations (HTx) have been performed in Japan as of December, 2022. After the Revised Transplant Act came into effect in July 2010, the number of brain-dead organ donation increased and 84 HTx were performed in 2019. In 2020 and 2021, the number of HTx decreased due to the COVID-19 pandemic. However, in 2022, the severity and fatality rate associated with COVID-19 decreased, and the number of HTx increased to 79. The mean waiting time as status 1 continuously increased to 1,877 days in adults. After approval of the use of an implantable continuous-flow ventricular assist device (iVAD) for bridge-to-transplant (BTT) in 2011, BTT cases using iVAD increased. In 2022, 70 of 71 adult cases were supported by iVADs. In 2022, 8 children underwent HTx, 7 of whom were BTT cases using the EXCOR VAD and 1 was treated with intravenous inotropic drugs. Most patients underwent a modified bicaval method of operation with Celsior for cardiac preservation, and all recipients were administered triple therapy with calcineurin inhibitor (cyclosporine or tacrolimus), mycophenolate mofetil, and a steroid as an initial immunosuppressive regimen. Patient survival at 5, 10 and 15 years was 92.9%, 88.8% and 79.7%, respectively, which is superior to that of the international registry. This surveillance documented that the results of HTx in Japan were excellent despite a severe shortage of donors and long waiting times with VAD as BTT.

【Objective】 This paper presents the 19th official registry report on lung transplantation in Japan, conducted by the Japanese Society of Lung and Heart-Lung Transplantation since 2005.

【Design and Methods】 The study analyzed data from cadaveric lung transplantation, living-donor lung transplantation, and heart-lung transplantation performed until the end of 2022. The data included transplant numbers, recipient survival rates, functional and working statuses, and causes of death. Survival rates were calculated using the Kaplan-Meier method.

【Results】 By the end of 2022, a total of 752 cadaveric lung transplantations (398 single, 354 bilateral), 284 living-donor lung transplantations, and 3 heart-lung transplantations were performed. The number of cadaveric lung transplants reached a record high of 108 in 2022. The 5-year and 10-year survival rates for cadaveric lung transplantations were 73.9% and 62.6%, respectively, surpassing international registry data. The survival rates for living-donor transplantations were similar to those of cadaveric lung transplantation, with 73.5% and 62.1%. All three heart-lung transplant recipients are alive. Approximately 80% of cadaveric lung transplant recipients achieved an mMRC scale grade of 0 or 1, as did approximately 75% of living-donor lung transplant recipients. Infections were the leading cause of death after lung transplantation, while deaths related to chronic lung allograft dysfunction, malignancy, and post-transplantation lymphoproliferative disease have increased in recent years.

【Conclusion】 The outcomes of lung transplantation in Japan have been satisfactory. Since the implementation of the modified Japanese transplantation law in July 2010, the number of cadaveric lung transplantations has increased. Although the number of transplants decreased in 2020 due to the COVID-19 pandemic, it recovered in 2021 and reached a record high in 2022. The Japanese Society of Lung and Heart-Lung Transplantation will continue to provide annual reports on Japanese lung transplantations.

A total of 518 cases of pancreas transplantation from deceased and living-related donors were performed in 21 institutions in Japan between April 2000 and the end of 2022. The following donor- and recipient-related factors were analyzed in the 491 cases from deceased donors out of the total 518 cases: age and gender of donor and recipient, cause of death, history of diabetes and hemodialysis, waiting period, total cold ischemic time, operative procedure, immunosuppression and posttransplant survival rates of patient and graft. Based on the analyses, the current status of pancreas transplantation in Japan is herein described. The patient survival after the transplantation was 95.5%, 94.2% and 92.2% at 1, 3, and 5 years, respectively. The pancreas graft survival in cases with simultaneous pancreas and kidney transplantation (SPK) was 87.9%, 84.6%, and 82.9% at 1, 3, and 5 years, respectively. The pancreas graft survival in cases with pancreas after kidney transplantation (PAK) (82.3%, 70.7%, and 59.6% at 1, 3, and 5 years, respectively) and pancreas transplantation alone (PTA) (67.7%, 33.9%, and 20.3% at 1, 3, and 5 years) was significantly poorer than for SPK. The main cause of pancreas graft loss was graft thrombus in SPK cases, while it was chronic rejection in PAK and PTA cases. In conclusion, we confirmed the current status of pancreas transplantation in Japan. While the posttransplant outcome was favorable, it is necessary to overcome graft thrombus in SPK cases and chronic rejection in PAK and PTA cases for improving the posttransplant outcomes.

Improvements in islet transplantation outcomes were achieved using anti-thymocyte globulin as an induction therapy, and eventually, in 2020, islet transplantation obtained coverage under Japanese national health insurance. Unfortunately, due to the onset of the COVID-19 pandemic, no cases of islet transplantation were performed in that year. However, in 2022, six islet transplantation procedures were successfully conducted for five cases of type 1 diabetes, following two cases in 2021. In this report, we present the clinical islet transplantations performed in 2022, along with the recent performance status of pancreas transplantation, which shares the pancreatic graft from brain-dead donors with islet transplantation.

Thirty two intestinal transplants for 38 patients were performed since 1996 in 6 institutions. There were 29 deceased donor and 13 living donor transplants. Primary causes of intestinal transplants were short gut syndrome (n=19), intestinal mobility function disorder (n=17), others (n=2) and re- transplantation (n=4). One-year patient survival was 92%, and 10-year patient survival was 59%. They were excellent results for a standard therapeutic option for intestinal failure if patients fail to maintain total parental nutrition.

Hematopoietic stem cell transplantation (HSCT) offers potentially curative treatment for a wide range of otherwise fatal hematologic disorders, and the number of HSCTs has continued to increase over the last 30 years; more than 5,500 allogeneic and autologous HSCTs have been performed annually in recent years. A constant increase of allogeneic HSCTs for older (aged over 50) patients, and an increase in the variety of donor/stem cell sources such as cord blood from unrelated donors have led to this constant increase of HSCT in Japan. The transplant survival outcome also continues to improve and the assets for the improvement include better supportive care, innovative transplant approaches, and the considerable contribution of a well-established transplant outcome registry to a variety of clinical studies.

【Objective】 The screening and prophylactic measures of latent tuberculosis (TB) infection (LTBI) before transplantation are of importance for organ transplant recipients. There are few data on the prevalence of LTBI in living donor kidney transplant candidates in Japan. We investigated the prevalence of LTBI and the effectiveness of prophylactic measures for LTBI.

【Design】 Case series study.

【Methods】 Forty-three living donor kidney transplant candidates who were screened for LTBI using T-SPOT were investigated. LTBI was diagnosed as T-SPOT positive along with no symptoms, no active TB lesions on Computed Tomography (CT), and no apparent history of TB. Patients diagnosed with LTBI received Isoniazid 5 mg/kg/day 6 months before transplantation.

【Results】 Five out of 43 patients were diagnosed with LTBI. Four patients were from high-risk countries for TB and another lived in Japan. They received Isoniazid and no one developed active TB after transplantation.

【Conclusion】 Screening and prophylactic measures for LTBI before transplantation were empirically effective not only to prevent active TB but also to ensure the favorable outcome of kidney transplantation.

【Objective】 To ensure the sustained continuity of organ transplantation healthcare in Japan, the establishment of an efficient transport system for instruments and materials, the implementation of a specialized division of labor within organ retrieval surgeries, and the preparation of internal institutional environments for potential increases in transplantation cases are considered requisite.

【Methods】 To illuminate the existing circumstances both domestically and internationally, an empirical investigation through surveys was conducted as part of a specialized project in health and labor sciences.

【Results】 Responses were garnered from 121 domestic institutions (comprising 11 specializing in cardiac, 11 in pulmonary, 31 in hepatic, 22 in pancreatic, 66 in renal, and 10 in intestinal treatments) and 29 international establishments (including 6 for pulmonary, 23 for hepatic, 13 for pancreatic, 14 for renal, and 5 for intestinal, with instances of duplication). Overseas, in contrast to Japan, a well-defined division of labor within organ retrieval surgeries was established, and an extensive engagement of internists was evident from the immediate post-transplantation phase to post-discharge medical care. Furthermore, the simultaneous implementation of multi-organ transplantations within a single facility was commonly practiced.

【Conclusion】 Considering the projected rise in organ donation figures, it was deemed imperative to advance the refinement of domestic institutional infrastructure and to conduct further comprehensive data acquisition to accomplish the sustainability of transplant medicine.

【Objectives】 This is the second survey conducted with the aim of understanding the actual situation of intravenous immunoglobulin (IVIG) therapy in pancreas transplantation in Japan, following the first survey that focused on all organ transplantation.

【Methods】 A second survey on the efficacy and safety of this procedure was conducted, including four cases from four institutions in which IVIG was used to treat antibody-mediated rejection (ABMR) after pancreas transplantation from April 2001 to March 2022.

【Results】 Although a pancreatic graft biopsy was performed in only one case, a kidney graft biopsy was conducted in the other two cases to diagnose ABMR. On or after the diagnosis of rejection, an immunological examination revealed positivity for donor-specific antibodies at some point during the observation period in all cases. To treat ABMR, 0.38 to 1.03 g/kg of IVIG was administered to each recipient. The pancreatic graft prognosis after ABMR was graft loss in only one of the four cases, although one of the graft survival cases required resumption of insulin therapy because of severe deterioration of insulin secretion from the pancreatic graft after the episode of ABMR. No adverse events were observed in any of the four cases.

【Conclusion】 ABMR after pancreas transplantation was associated with a poor pancreatic graft prognosis. However, IVIG therapy has shown the potential to control ABMR and avoid graft loss. In addition, no adverse events were observed in this survey.