探索骨髓间充质干细胞（MSCs）对放射性肠炎（RE）肠黏膜修复的途径。

体外分离、培养大鼠骨髓MSCs。将RE模型的大鼠采用随机数字表法分为治疗组[经尾静脉注射干细胞悬液1 mL（细胞浓度为1×10⁶个/mL）]和对照组（注射等量生理盐水，每日1次，连续3 d），每组10只。每日观察两组大鼠的活动量、进食和进水量、体质量变化等。1周后处死大鼠获取小肠标本，HE染色观察肠黏膜的修复情况，电镜观察上皮细胞的超微结构，免疫组化染色观察小肠隐窝Bmi-1阳性干细胞增殖情况，采用Image-Pro Plus 6.0软件对Bmi-1阳性细胞数量进行分析。组间差异的比较采用t检验。

成功分离得到大鼠骨髓MSCs，流式细胞仪鉴定：CD29、CD90、CD34、CD45阳性细胞比例分别为98.6﹪、99.6﹪、0.56﹪、0.89﹪。与对照组相比，治疗组大鼠移植1周后，体质量增加（190.30 g ± 13.23 g比235.00 g±14.30 g）；大鼠小肠黏膜上皮得到修复，绒毛高度增高（627.50 μm ± 40.55 μm比984.33 μm ± 61.80 μm）；上皮细胞超微结构较完整、清晰，隐窝Bmi-1阳性干细胞增殖数量增多[（60.67±9.63）个/mm²比（87.33 ±5.47）个/mm²]，差异具有统计学意义（P < 0.05）。

骨髓MSCs能促进RE模型的大鼠肠黏膜的修复，这一作用可能是通过促进小肠隐窝干细胞的增殖发挥。

To detective the effects of bone marrow-derived mesenchymal stem cells (MSCs) on repairing intestinal mucosa of radiation enteritis (RE) .

Bone marrow-derived MSCs of rats were separated and cultured in vitro. The RE rats were randomly divided into a treatment group and a control group according to the random number table (n = 10 per group) . The rats in the treatment group were injected through tail vein with MSCs at a density of 1×10⁶ cells/mL and the control were injected with equal amounts of saline once a day for 3 days. The activity, food and water intake as well as body weight of rats were observed every day. The rats were killed one week later to obtain samples of small intestine. The extent of reparation of intestinal mucosa and the ultrastructure of epithelial cells were observed by HE staining and electron microscope, respectively, and the proliferation of Bmi-1 positive cells in intestinal crypt was detected by immunohistochemical staining and analyzed by Image-Pro Plus 6.0. A comparison between the two groups was made by t test.

Bone marrow-derived MSCs were isolated successfully and identified by flow cytometry. The proportion of CD29, CD90, CD34 and CD45 positive cells were 98.6﹪, 99.6﹪, 0.56﹪ and 0.89﹪, respectively. One week after transplantation, body weight of the rats in the treatment group increased compared with the control group (190.30 g ± 13.23 g vs 235.00 g ± 14.30 g) . The intestinal epithelium of the treatment group rats was repaired and the villus height increased (627.50 μm ± 40.55 μm vs 984.33 μm ± 61.80 μm) ; the ultrastructure of epithelial cells was more complete and clear, and the Bmi-1 positive cells in the crypt were significantly increased [ (60.67±9.63) /mm² vs (87.33 ±5.47) /mm², P < 0.05].

Bone marrow-derived MSCs could promote the reparation of intestinal mucosa in RE model rats by playing a role in promoting the proliferation of small intestinal crypt stem cells (ISC) .