Current status and future aspects of kidney transplantation in Japan

Abstract In Japan, there are very few cases of organ donation, including kidneys. The number of deceased donor kidney transplants (DDKTs) is much less than that of other developed Asian and Western countries, although donation after brain death is increasing slowly. Living donor kidney transplants (LDKTs) are more popular than DDKTs in Japan. However, the number of LDKTs per million population was still less than that in Korea, the UK, and the USA. Living donor ABO-incompatible kidney transplants have been performed in Japan since 1989, and long-term outcomes proved similar to those for ABO-compatible kidney transplants. Preemptive kidney transplants comprised 30% of LDKTs. In spite of the small number of kidney transplants, patient, and graft survival rates in Japan are superior to those of any other country. The infusion of regulatory T cells may induce immunotolerance in kidney transplants although acute rejection frequently occurred when immunosuppression was withdrawn and anti-donor-specific antibodies (DSAs) production could not always be suppressed. Combined kidney and bone marrow transplantation may induce immunotolerance, although a few recipients produced DSA. Kidney regeneration has become a reality. Nephron progenitor cells have been generated from human-induced pluripotent stem cells, readily reconstituting three-dimensional nephrons, including vascularized glomeruli with podocytes. The niche method has been used to generate kidney, urinary tract, and bladder tissue. Many Japanese scientists are researching kidney regeneration, and a kidney regenerated from a recipient’s cells could be transplanted without immunosuppression in the near future