Regenerative therapy in nephrology. Repair or construction?

Animal experiments and analyses of human renal tissues show that regeneration of degraded renal tubules is caused by adjacent surviving tubules. Differentiation, migration, proliferation and redifferentiation are regulated by local growth factors. Renal stem cells can also participate in this process. Mesenchymal stem cells play a pivotal role in renal regeneration and if these are still present in the adult kidney, they could be the source material for repair and regeneration following injury. The exact location and role of resident mesenchymal stem cells which have been demonstrated in the kidneys is still unclear. New surface markers and a better characterisation of the many cell populations possibly participating in the regeneration process are necessary in order to clarify their complex interaction. It is also unclear whether mesenchymal stem cells from bone marrow or other organs are also involved. In addition to structural regeneration, the stem cells also play a role in the functional recovery following acute renal failure. Artificial regeneration of human kidneys is difficult due to their functional and spatial complexity. By the additional use of cells in dialysis machines it may be possible to improve the quality of filtration and also replace other renal functions. Initial results using this new technique in clinical phase I/II studies on patients with acute renal failure are promising.