Background: In Japan, solid organ transplantation (Tx) medicine has been advancing in its own unique way. Historically, Tx relied on related-living-donors for cultural and legal reasons. Although deceased, adult donor Tx in Japan was lawfully started in 1997, brain-dead children could not be organ donors until 2010. Since then, the number of pediatric organ donors has been gradually increasing, despite the low number overall. Also, the monitoring system for donor-derived infection (DDI) has been limited in Japan, possibly due to the better accessibility of medical information from related living donors. However, the increasing number of deceased-donor Tx cases may alter the clinical outcome of pediatric Tx and the risk of DDI. Accordingly, a more careful monitoring system for DDI, which has not been fully established in Japan, may be needed.
Hence, this study aimed to investigate the current status of pediatric Tx and associated DDIs in Japan.
Methods: We extracted the information from the Tx database in Japan managed by several Tx societies to summarize the number of historical pediatric Tx cases and focus on their primary diagnosis and donor source. Also, publications related to DDI were systematically reviewed in English and Japanese literature.
Results: At the time of data collection in July 2022, there have been 60 heart and 22 small bowel pediatric Tx cases in Japan. In contrast, there are 1516 kidney and 3453 liver pediatric Tx cases. Of those, only 197 (13%) kidney Tx cases and 79 (2%) liver Tx cases underwent deceased-donor Tx. There have been a small number of case reports and original studies reporting DDIs related to the transmission of multidrug-resistant organisms, Epstein-Barr virus, cytomegalovirus, and hepatitis B virus, but no cases of DDI attributable to locally endemic pathogens, including mycobacteria and human T cell leukemia virus type 1.
Discussion: Living-donor Tx remains the majority of Tx type in some countries, especially in pediatric Tx, to meet the urgent need for Tx. Although the planned living-donor Tx may allow full risk assessment of DDI in some cases, there is always a risk of unexpected/unrecognized DDI. Monitoring systems adopted in many countries, where deceased-donor Tx is more common, may be needed with the increase of deceased-donor Tx cases in the countries where living-donor Tx has been dominant.