Modulating the development of renal tubules growing in serum-free culture medium at an artificial interstitium.

Little information on the structural growth of renal tubules is available. A major problem is the technical limitation of culturing intact differentiated tubules over prolonged periods of time. Consequently, we developed an advanced culture method to follow tubule development. Isolated tissue containing renal progenitor cells was placed in a perfusion culture container at the interphase of an artificial polyester interstitium. Iscove's modified Dulbecco's medium without serum or protein supplementation was used for culture, and the culture period was 13 days. Tissue growth was not supported by addition of extracellular matrix proteins. The development of tubules was registered on cryosections labeled with soybean agglutinin (SBA) and tissue-specific antibodies. Multiple SBA-labeled tubules were found when aldosterone was added to the culture medium. In contrast, culture without aldosterone supplementation displayed completely disintegrated tissue. The development of tubules depended on the applied aldosterone concentration. The use of 1 x 10(-6) M and 1 x 10(-7) M aldosterone produced numerous tubules, while application of 1 x 10(-8) M to 1 x 10(-10) M led to a continuous decrease and finally a loss of tubule formation. The development of labeled tubules in aldosterone-treated specimens took an unexpectedly long period of at least 8 days. The morphogenic effect of aldosterone appeared to be mineralocorticoid hormone-specific since spironolactone and canrenoate abolished the development. Finally, dexamethasone induced widely distributed cell clusters instead of tubules.