Abstract
Several nonsurgical approaches to the treatment of postradiation proctitis have been described, but no effective conservative treatment has yet been established. In order to establish whether extra-colonic cells contribute to the repair of colonic tissues, this study examined colons of 1) female rats that had received a male bone marrow transplant and 2) male rats that had received a Green Fluorescent Protein (GFP) transgenic bone marrow transplant. Colitis was induced by focal irradiation of 22.5 Gy X ray. By using in situ hybridization to detect Y-chromosomes and immunohistochemistry to detect GFP protein it could be demonstrated that circulating stem cells frequently engraft into the colon and differentiate into colonic epithelial cells. Female rat recipients of male bone marrow grafts showed localization of Y-chromosome. Y-chromozome-containing cells and GFP positive cells were observed within regenerative epithelium, with morphology and location appropriate for colonocytes. By using western blotting method GFP expression in the colon of irradiated area was higher than that in the colon of non-irradiated area. These data indicated that bone marrow cells contribute to regeneration of colonic epithelia after damage, and it is suggested that this could be exploited therapeutically.
