Fetal-to-fetal kidney transplantation in utero.

Potter sequence consists of various symptoms associated with renal dysplasia. For bilateral renal agenesis, there is no hope of survival. As a novel therapeutic approach for Potter sequence, we develop a unique approach of "transplantation of fetal kidneys from a different species during the fetal stage." In this study, we first validate the approach using allogeneic transplantation. Fetal kidneys with bladders from green fluorescent protein-expressing rats (embryonic day 14.0-16.5) are subcutaneously transplanted into allogeneic rat fetuses in utero (embryonic day 18.0-18.5). After birth, the transplanted fetal kidneys are confirmed to have urine production capability. Furthermore, long-term (up to 150 days) urine production is sustained. Next, we perform xenotransplantation. The transplantation of mouse fetal kidneys into rat fetuses in utero leads to the maturation of renal tissue structures. We demonstrate organ transplantation into in utero fetuses using fetal kidneys as donor organs for fetal therapy.