骨髓间充质干细胞移植对百草枯中毒导致肺纤维化的影响

目的 观察外源性骨髓间充质干细胞(BMSCs)移植对大鼠急性PQ中毒导致的肺纤维化是否产生治疗作用及其可能的机制.方法 取54只SD雄性大鼠,随机(随机数字法)分成3组:A组为空白对照组,B组为PQ+ PBS组,C组为PQ+BMSCs组.其中B组、C组均以120mg/kg的PQ溶液予以一次性灌胃染毒,染毒后6hC组大鼠予以尾静脉注入BMSCs 1×106个/mL,而B组大鼠则予以注入相应剂量的PBS.观察各组大鼠的一般情况,于染毒后7d、14 d、28 d处死未死亡的大鼠,取左下肺组织,行HE和Masson染色观察各组肺组织的病理改变情况,根据Szapiel肺泡炎和肺纤维化的分级法进行肺纤维化评分,并行免疫组织化学检测肺组织中TGF-β1及HGF的表达情况;取右下肺,检测HYP对比各组肺组织中的HYP含量的变化情况.结果 肺组织病理改变:染毒7d后可见B组肺泡炎性改变明显,肺泡腔内可见大量渗出液;C组的肺泡炎性渗出相对B组为轻.14 d可见B组肺泡间质水肿及渗出减轻,但肺间质胶原纤维增多;C组间质纤维化沉积程度相对B组较轻.28 d时B组肺间隔增厚普遍可见胶原纤维沉积,肺泡扩张明显,肺泡间隔断裂,肺泡结构紊乱;C组间隔中的胶原纤维化较B组轻,肺泡基本结构仍可见.HYP含量:B组大鼠肺组织HYP含量随着染毒时间的延长呈进行性增加,28 d时达最高峰,各时间点与A组比较均增高(P＜0.01);C组HYP的含量随时间的延长呈进行性增加,28 d达到最高峰,各时间点均较B组减少(P＜0.01).肺组织TGF-β1及HGF的表达:B组大鼠肺组织TGF-β1表达含量增多且分布范围较A组广,TGF-β1的表达在7d为最高峰,此后逐渐减少,但各时间点均高于A组(P＜0.05);C组大鼠肺组织各时间点TGF-β1表达含量均较B组少(P＜0.05).B组肺组织HGF的表达随着时间点延长逐渐增多,但各时间点比较差异无统计学意义(P＞0.05);B组与A组比较略有增多,但差异无统计学意义(P＞0.05);C组肺组织HGF表达含量随着时间的延长逐渐增多,各时间点比较差异有统计学意义(P＜0.05),各时间点与A组及B组比较差异均有统计学意义(P＜0.05).结论 外源性BMSCs移植对PQ诱导的肺纤维化程度有一定的抑制作用,可能与其上调HGF表达、下调TGF-β1的表达有关.

The protective effect of exogenous bone marrow mesenchymal stem cells on pulmonary fibrosis induced by paraquat

Objective To explore the protective effect and possible mechanism of bone marrow mesenchymal stem cells (BMSCs) on pulmonary fibrosis induced by paraquat (PQ) in rats.Methods A total of 54 male SD rats were randomly (random number) divided into 3 groups (n =18 in each).Group A (normal control group),group B [PQ + phosphate buffer solution (PBS)],group C (PQ + BMSCs group).Rats in group B and C were induced to get pulmonary fibrosis by intragastric administration of PQ in a dosage of 120 mg/kg.In addition,BMSCs was given to rats in group C by injection in a dose of 1 × 106/mL via the vena caudalis,whereas an equal volume of PBS (1 mL) was given to rats in group B by injection instead.The survival rats in each groups were sacrificed separately at 7 days,14 days and 28 days after administration of PQ.The lower lobe of left lung were taken to observe histopathological changes with HE staining and Masson staining,and the pulmonary fibrosis was scored by using the Szapiel classification of alveolitis.At the same time,the lower lobe of right lung was harvested to detect the hydroxyproline (HYP),TGF-β1 and HGF in lung tissue by using immunohistochemistry.Results The pathological changes in lung tissue of rats were inflammatory change in alveoli space filled with massive amount of exudate obviously in group B at 7 days after exposure to PQ,but in group C,the inflammatory changes were much milder than those in group B.The exudation and edema in lunge alveoli were mitigated in group B at 14 days after exposure to PQ,but pulmonary interstitial fibers were increased.The degree of pulmonary interstitial fibrosis in group C was milder than that in group B.In group B,there were obvious pathological changes including destroyed alveoli septum,enlarged alveoli,thickened alveoli septum and the deposition of collagen fibers,disarranged alveolar structure at 28 days after exposure to PQ.The deposition off collagen fiber was slighter with well observed basic alveolar structure in group C than that in group B.The levels of HYP in lung tissue at different intervals in B group were escalating with time after exposure to PQ,and reached a peak at 28 day,which were significantly higher than those in group A (P ＜ 0.01).The levels of HYP in lung tissue at different intervals in C group were increasing with time after exposure to PQ,and reached a peak at 28 day,which were significantly lower than those in group B (P ＜ 0.01).The levels of TGF-β1 from different intervals in B group were increased greatly with wider distribution over large portion of lung structure than those in group A,and reached a peak at 7 days,then declined with time,which were significantly higher than those in group A (P ＜ 0.05).The levels of TGF-β1 at different intervals in group C were significantly lower than those in group B (P ＜ 0.05).The levels of HGF at different intervals in B group increased with time,but there was no significant difference among those at different intervals (P ＞0.05).The levels of HGF at different intervals in group B were little bit higher than those in group A,but there was no significant difference between them (P ＞ 0.05).The levels of HGF at different intervals in group C increased with time with significant differences among different intervals (P ＜ 0.05).The levels of HGF at 3 intervals in group C were significantly different from those of group A and group B group (P ＜0.05).Conclusions BMSCs can alleviate pulmonary fibrosis induced by PQ,and increase the survival rate,which may be attributed to decreasing the level of TGF-β1 and increasing the level of HGF.