Xenobiotic kidney organogenesis: a new avenue for renal transplantation.

Currently many efforts are being made to apply regenerative medicine to clinical renal diseases. It has been suggested that some renal diseases which maintain renal structure can be treated by infusion of stem cells isolated from the bone marrow or adult kidney. However such cell-based therapy cannot be applied to the treatment of chronic renal disease, in which renal structure, including the kidney scaffold, is totally disrupted. Therefore, absolute kidney regeneration is needed to rebuild a whole functional kidney de novo and eliminate the requirement for dialysis. However, due to the anatomical complexity of the kidney and the need for communication between each cell to fulfill renal function, the kidney has been labeled as the most difficult organ to regenerate. Only a small number of groups are investigating the potential for reconstructing an organized and functional kidney structure, and, among them, we are using the developing xenoembryo as an organ factory for this purpose. Here we review the challenges faced in developing a whole functional kidney de novo and discuss the obstacles which must be overcome before clinical use is possible.