Protective effect of bone marrow mesenchymal stem cells in intestinal barrier permeability after heterotopic intestinal transplantation

AIM: To explore the protective effect of bone marrow mesenchymal stem cells (BM MSCs) in the small intestinal mucosal barrier following heterotopic intestinal transplantation (HIT) in a rat model. METHODS: BM MSCs were isolated from male Lewis rats by density gradient centrifugation, cultured, and analyzed by flow cytometry. The HIT models were divided into a non-rejection group, saline-treated rejection group (via penile vein), and BM MSC-treated group (via penile vein). Intestinal mucosal barrier injury was estimated by diamine oxidase (DAO) and D-lactic acid (D-LA) expression levels. Tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (INF-gamma), interleukin-10 (IL-10), and transforming growth factor-beta (TGF-beta) were detected by enzyme-linked immunosorbent assay. Ultrastructural change of tight junctions (TJs) was observed under transmission electron microscope. Expression levels of the TJ proteins occludin and zona occludens (ZO)-1, affected by the inflammatory factors, were measured using real-time polymerase chain reaction and Western blotting. RESULTS: The pathological score at each time point after surgery indicated significantly less serious injury in the BM MSCs-treated group than in the rejection group (P < 0.05). In the former, graft levels of DAO and D -LA were reduced, and TNF-alpha and INF-gamma production was inhibited (at day 7: 10.6473 +/- 0.0710 vs 17.2128 +/- 0.4991, P < 0.05; 545.1506 +/- 31.9416 vs 810.2637 +/- 25.1175, P < 0.05). IL-10 and TGF-beta production was increased greatly (at day 7: 125.7773 +/- 4.7719 vs 80.3756 +/- 2.5866, P < 0.05; 234.5273 +/- 9.3980 vs 545.1506 +/- 31.9416, P < 0.05). There was increased expression of occludin and ZO-1 protein (at day 7: 0.2674 +/- 0.0128 vs 0.1352 +/- 0.0142, P < 0.05; at day 5: 0.7189 +/- 0.0289 vs 0.4556 +/- 0.0242, P < 0.05) and mRNA (at day 7: 0.3860 +/- 0.0254 vs 0.1673 +/- 0.0369, P < 0.05; at day 5: 0.5727 +/- 0.0419 vs 0.3598 +/- 0.0242, P < 0.05). CONCLUSION: BM MSCs can improve intestinal barrier permeability, repair TJs, and increase occludin and ZO-1 protein expression. With altered cytokine levels, they can protect the intestinal mucosa after transplantation. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.