Chemically defined medium environment for the development of renal stem cells into tubules.

The use of stem cells is a valuable therapeutical option for the regeneration of diseased tissues and organs. However, the involved cellular processes are hardly known. To gain detailed information about their development, a new culture technology was developed. Embryonic renal tissue containing stem/progenitor cells was mounted within a perfusion culture container at the interface of an artificial interstitium made of polyester. Using this innovative approach we show that renal tubules develop in chemically defined Iscove's modified Dulbecco's medium without serum addition and without coating by extracellular matrix proteins. The development of tubules depends on the administration of aldosterone, and can be visualized by immunohistochemical labeling. The presented technology makes the exact analysis of developmental steps now possible, and provides a new powerful tool to optimize growth and differentiation of renal stem cells. It may also enable many other kinds of stem cells to steer their development into functional tissues under clearly defined in vitro conditions.