骨髓间充质干细胞对肺损伤大鼠转化生长因子β及单核细胞趋化蛋白1的影响

Effects of bone marrow mesenchymal stem cells on transforming growth factor beta and monocyte chemoattractant protein-1 in lung injury rats

背景：转化生长因子β及单核细胞趋化蛋白1是肺纤维化形成过程中的重要细胞因子，已证实骨髓间充质干细胞可降低损伤肺组织中的胶原含量，减轻肺纤维化。目的：观察骨髓间充质干细胞对肺损伤大鼠转化生长因子β及单核细胞趋化蛋白1的影响。设计、时间及地点：随机对照，细胞学体外实验，于2005—05／2006—02在解放军第四军医大学完成。材料：清洁级雌性SD大鼠20只，随机分为正常对照组、细胞对照组、肺损伤组、细胞移植组，5只/组。雄性SD大鼠5只用于骨髓间充质干细胞的采集。方法：肺损伤组、细胞移植组大鼠经气管注入5mg／kg博来霉素0．2～0．3mL诱发建立肺损伤模型。造模后12h，细胞移植组、细胞对照组大鼠经尾静脉注入骨髓间充质干细胞悬液0．5mL，约5×10^6个细胞；肺损伤组、正常对照组大鼠同法注入无血清DMEM-F120．5mL。主要观察指标：苏木精-伊红染色观察肺组织形态学变化。酸解法测定肺组织羟脯氨酸含量。ELISA法检测血清及支气管肺泡灌洗液中转化生长因子β、单核细胞趋化蛋白1的表达。结果：细胞移植2周后，正常对照组及细胞对照组的肺泡腔均匀完整；肺损伤组的肺泡结构破坏，肺泡间隔增厚，间质增生；细胞移植组肺损伤程度明显减轻。与正常对照组比较，肺损伤组、细胞移植组的肺组织羟脯氨酸含量均显著升高（P〈0.01或0．05），细胞移植组升高幅度明显低于肺损伤组（P〈0．01）。各组大鼠血清及支气管肺泡灌洗液中转化生长因子β、单核细胞趋化蛋白1的表达水平与肺组织羟脯氨酸含量基本相似。结论：骨髓间充质干细胞可减少肺损伤大鼠肺组织羟脯氨酸含量，减轻大鼠肺损伤及纤维化程度，可能与降低转化生长因子β、单核细胞趋化蛋白1的表达有关。

BACKGROUND： Transforming growth factor- β （TGF- β ） and monocyte chemoattractant protein-1 （MCP-1） are key cytokines during pulmonary fibrosis. It has been verified that bone marrow mesenchymal stem cells （BMSCs） can decrease collagen content and pulmonary fibrosis in injured pulmonary tissues. OBJECTIVE： To investigate the effect of BMSCs on TGF- β and MCP- 1 in lung injury rats. DESIGN, TIME AND SETTING： The randomized control experiment was performed at the Fourth Military Medical University of Chinese PLA from May 2005 to February 2006. MATERIALS： Twenty clean female Sprague Dawley （SD） rats were randomly divided into normal control group, cell control group, lung injury group and cell transplantation group, with 5 rats in each group. Five male SD rats were used for BMSCs collection. METHODS： Lung injury models were created by intratracbealy injecting bleomycin of 5 mg/kg （0.2-0.3 mL） into rats of the lung injury group and cell transplantation group. Twelve hours later, rats of the cell transplantation group and cell control group were injected with 0.5 mL of BMSCs of 0.5×10^6 per rat into the tail vein. Serum-free DMEM-F12 0.5mL was injected into rats of the normal control group by the same method. MAIN OUTCOME MEASURES： Hematoxylin-eosin staining was used to observe the morphology in lung tissue. Acid hydrolyzation was employed to measure hydroxyproline concentration in lung tissues. Enzyme-labeled immunosorbent assay （ELISA） was used to detect the contents of TGF- β and MCP- 1 in serum and bronchoalveolar lavage fluid （BALF）. RESULTS： Two weeks after transplantation, most of alveolar space was intact in rats of the normal control and cell control groups. The lung structure of rats in the lung injury group was destroyed and the thickness of alveolar wall and lung interstitium were increased. The lung injury degree was significantly reduced in the cell transplantation. Hydroxyproline content in lung interstitium of rats in lung injury group and cell transplantation group were significantly increased compared to the normal control group （P 〈 0.01 or 0.05）. Increased degree in the cell transplantation group was significantly lower compared to the lung injury group （P 〈 0.01）. TGF- β and MCP- 1 expression in serum and BALF were similar to the hydroxyproline content in each group. CONCLUSION： BMSCs can decrease hydroxyproline content, and relieve lung injury and fibrosis in lung tissues of rats, which may be associated with the decreased expression of TGF- β and MCP-1.