Mammalian intestinal epithelium is one of the most swiftly self-renewing tissues in the body, turning over completely every 3 to 5 days. Because of the absence of reliable stem cell markers, however, researchers have argued for decades about the identity and location of the stem cells that fuel this growth capacity.
In the intestinal epithelium, cells proliferate in glandular pockets termed the crypts of Lieberkühn. In the 1970s, two competing theories emerged for where in the crypt these all-important, self-renewing cells abide. The predominant idea, put forth by Chris Potten at the Paterson Institute for Cancer Research in Manchester, United Kingdom, and a cofounder of Epistem, an epithelial stem cell company, placed the stem cells in a location about halfway up the crypt (termed position +4).1 Lesser known work from the McGill University lab of Charles Philippe Leblond, who died in 2007, proposed that crypt base columnar (CBC) cells, at ...
