Abstract: Objective To investigate the potential effect of bone marrow mesenchymal stem cells (MSCs) on repairing the colon epithelial cell,and on treating the the rats with ulcerative colitis (UC).Method Monocytes were purified from bone marrow, amplified and identified as MSCs in vitro.Thirty female Wistar rats were randomly divided into 3 groups, the normal control, model and MSCs groups (10 rats/group).The rats in model and MSCs groups were induced colitis with trinitro-benzene-sulfonic acid;The rats in normal control group and model groups were injected with 1mL saline via tail vein, while those in MSCs group with 1mL MSCs suspension. After two weeks, colon tissue samples were analyzed for histopathology,and the colon tissues were made into serial section for determining the distribution of Y chromosome and CK20 double positive cells,analyzing the mRNA levels of CK20、NF-κB、IL-4 by RT-PCR,and assaying colonic NF-κB protein expression with Westen blot,detecting colon tissues IL-4 content with ELISA. Results Y chromosome and CK20 double positive cells could be seen in MSCs transplanted colon tissues.The expression of CK20 was increased in the colon tissues of UC rats(P <0.01), while in MSCs group was increased compared with model group (P <0.01). The expression of NF-κB was increased in the colon tissues of UC rats (P <0.01), while in MSCs group was decreased compared with model group (P <0.01).The expression of IL-4 was decreased in the colon tissues of UC rats (P <0.01), while in MSCs group it was increased compared with model group (P <0.01). Conclusion MSCs may exert therapeutic efficacy on colitis in rats through differentiating into colon epithelial cells.

Key words: mesenchymal stem cells, ulcerative colitis, repair, epithelial cell, NF-κB, IL-4