Stem cells and cancer project
Although the precise identity of the intestinal epithelium stem cells is still controversial and may reveal unexpected complexity, Lgr5-expressing cells in the crypt bottom have all the features expected from stem cells. Some studies carried out during the last decade led to the conclusion that by segregating their chromosomes asymmetrically, intestinal epithelial stem cells are capable of preserving the integrity of their genome during the organism life span. Using a different approach we came to the conclusion that both in a physiological situation and after irradiation intestinal epithelial stem cells segregate their chromosomes randomly (Escobar et al, Nature Comunications 2011). Thus, the «immortal DNA strand hypothesis» does not apply to the Lgr5+ intestinal epithelial stem cells, and other protective mechanisms must be involved to avoid the accumulation of mutations during the enormous number of mitoses that these stem cells undergo during their lifes.
Stem cells, located between Paneth cells at the bottom of intestinal crypts 12 and 52 hours after a single BrdU injection. The dilution of the BrdU staining is well visible after 52 hours. Green: BrdU; red: lysozyme; blue: Dapi.
Additional projects are underway to understand the molecular bases of tumorigenesis. This group is part of the GIStem consortium, involved in the study of stem cells and their behaviour in the healthy and cancer epithelium.
GIStem CONSORTIUM WEB SITE.