Stem/progenitor cells are in the focus of research as a therapeutic perspective to cure acute and chronic renal failure. Following this innovative strategy one has to consider that stem/progenitor cells are first kept in the beneficial atmosphere of a CO 2 -dependent culture medium, while after implantation they are exposed to unbalanced interstitial fluid of diseased parenchyma. However, this abrupt transition has consequences, since it limits survival of implanted stem/progenitor cells. To offer a constant environment during isolation, culture, surgical processing and initial seeding within diseased parenchyma, an improved concept is under current work. In present experiments stabilization of fluid environment was investigated by isolating renal stem/progenitor cells in chemically defined and CO 2 -stabilized culture media. Interstitial influences on spatial development of tubules were tested by mounting stem/progenitor cells in a polyester fleece as a substitute for extracellular matrix and by transporting always fresh medium in perfusion culture for 13 days. Finally, morphological quality of raised constructs was analyzed by histochemistry, light and transmission electron microscopy. The present results demonstrate that three different culture media can be short-listed for protecting stem/progenitor cells during the process of implantation. Earlier approved Iscove´s Modified Dulbecco´s Medium buffered by HEPES revealed formation of numerous tubules. Also application of Leibovitz's L-15 Medium and CO 2 Independent Medium demonstrated unexpected promoting effects on the generation of tubules. In all series typical features of transporting tubule cells were registered. Formation of an excess of vacuoles as an indicator for cytotoxicity was not observed. In conclusion, although very different in chemical composition the tested culture media reflect an advantageous microenvironment for isolation, implantation and development of stem/ progenitor cells.
