Abstract: Objective: Comparing biological characteristics and the roles in repair of intestinal irradiation injury of bone marrow derived Flk-1+ MSCs and small intestinal derived SP cells. Methods: Phenotypes of the two cell population were determined by flow cytometery. Flk-1+ MSCs and intestinal SP cells were infused into irradiated mice respectively, and distribution and differentiation of these cells were determined. Histopathological examination and fibrosis degree was analyzed. Results: The phenotypes of Flk-1+ MSCs and intestinal SP cells were largely different. Both Flk-1+ MSCs and intestinal SP cells could home to injury rapidly, participate intestinal epithelial repair, and alleviate fibrosis and collagen deposition after irradiation. SP cells mostly engrafted into intestinal epithelium, while Flk-1+ MSCs partly engrafted into interstitial region as well as epithelium. Conclusion: Flk-1+ MSCs and intestinal SP cells could alleviate symptoms effectively, though their mechanisms are disparity.

Key words: Mesenchymal stem cell, SP cell, intestinal irradiation injury, stem cell transplantation