A method for the isolation and culture of human colonic crypts in collagen gels.

Little is known concerning the biological factors that control the proliferation of the stem cells of the colonic mucosa. In part this is due to a lack of systems suitable for studying the proliferation of this mucosa in vitro. We describe a simple technique for the isolation of single viable intact crypts which are free of stroma and which can then be cultured for periods of at least 16 d using a collagen gel culture method. This method of crypt isolation was efficient with the mean yield of viable intact crypts being 1.4 +/- 1.2 X 10(4) (mean +/- 1 SD) crypts/cm2 of mucosa. In culture, mucosal cells only survived for extended periods when the crypts were cultured in collagen gels over a feeder layer of bovine aortic endothelial cells. Cells containing mucus were present in the cultured crypts at all stages of the culture; however we have not been able to demonstrate alkaline phosphatase activity in these crypts. Studies of DNA synthesis after 7 d in culture, using a 18-h pulse label with bromodeoxyuridine (BUdR) has shown that DNA synthesis, as measured by incorporation of BUdR into nuclei, is still occurring in these cultured crypts.