Transplantation of embryonic kidneys.

The number of kidney allotransplants performed per year is limited by the availability of human donor organs. Xenotransplantation of a vascularized organ, such as the kidney, as an alternative to allotransplantation presents formidable immunological challenges. One novel solution to this conundrum is to use embryonic kidneys taken from animal donors early during organogenesis when metanephroi can be transplanted in 'cellular' form. We and others have shown that developing embryonic kidneys (metanephroi) transplanted into the omentum of animal hosts undergo differentiation and growth in situ, become vascularized by blood vessels of host origin and exhibit excretory function. Metanephroi can be stored for up to 3 days in vitro prior to transplantation with no impairment in growth or function post-implantation. Metanephroi can be transplanted across both concordant (rat to mouse) and highly disparate/discordant (pig to rodent) xenogeneic barriers. This review summarizes experimental data relating to the transplantation of embryonic kidneys.