脐带间充质干细胞源外泌小体减轻糖尿病模型小鼠心肌纤维化

Human umbilical mesenchymal stem cell-derived exosome attenuates cardiac fibrosis in diabetic mice

目的:探讨脐带间充质干细胞外泌小体对糖尿病模型小鼠心肌纤维化的保护作用。方法:6~8周C57BL/6雄性小鼠随机分为3组:对照组、糖尿病模型组和糖尿病+外泌小体组。采用高脂饮食连续喂养5周后,联合小剂量多次(45 mg/kg,每周1次,连续5周)腹腔注射链脲佐菌素的方法诱导糖尿病(血糖≥16.7 mmol/L)模型。糖尿病+外泌小体组在糖尿病造模后,经尾静脉每周注射1次外泌小体,连续注射4周;对照组和糖尿病组予等体积的生理盐水连续注射4周。利用小动物彩色多普勒超声诊断仪检测小鼠心功能指标;然后取腹主动脉血,用生化比色法检测葡萄糖和游离脂肪酸的含量;同时取心脏组织,HE染色观察心肌纤维的结构变化;Masson染色观察心肌纤维化水平。结果:超声心动图结果显示,与对照组相比,糖尿病组较对照组的左心室舒张末期内径和左心室收缩末期内径增大(分别P<0.05和P<0.01),射血分数和室壁缩短率下降(P<0.01);糖尿病+外泌小体组较糖尿病组的左心室收缩末期内径减小,心室扩张减小,射血分数和室壁缩短率提高(P<0.01)。生化比色法检测血糖及血浆游离脂肪酸结果显示,与对照组相比,糖尿病组血糖及血浆游离脂肪酸水平显著增高,差异有统计学意义(P<0.01);糖尿病+外泌小体组可显著降低血糖及游离脂肪酸水平,差异有统计学意义(P<0.01)。HE染色结果显示,对照组心肌细胞完整,排列整齐;糖尿病组心肌细胞出现肥大、断裂;糖尿病+外泌小体组心肌细胞较完整,排列较整齐。Masson染色结果显示,与对照组相比,糖尿病组纤维化面积显著增大,差异有统计学意义(P<0.01);与糖尿病组比较,糖尿病+外泌小体组纤维化面积减小,差异有统计学意义(P<0.01)。结论:局部注射人脐带间充质干细胞外泌小体可以减轻糖尿病小鼠心肌纤维化,并改善心脏功能。

AIM:To explore the protective effects of exosome secreted by human umbilical mesenchymal stem cells on cardiac fibrosis in diabetic mouse model.METHODS:Male C57BL/6mice at6~8weeks of age were divided into3groups randomly:control group,diabetes mellitus(DM)group and DM+exosome group.To develop mouse DM mo-del,the mice were fed with high-fat diet for5weeks,followed by intraperitoneal injection of45mg/kg streptozocin once a week for5weeks.It was considered as a successful DM model that the blood glucose of the mice was≥16.7mmol/L.The mice in DM+exosome group were injected with exosome via tail vein.The mice in other2groups were injected with saline at the same volume.The heart function was evaluated by color Doppler echocardiography for small animals.The blood samples were collected from abdominal aortas.The blood glucose and non-esterified fatty acids were measured by biochemical colorimetric assay.HE staining was performed to observe the structural changes of myocardial fibers,and Masson staining was used to observe the cardiac fibrosis.RESULTS:The results of echocardiography showed that left ventricular end-diastolic dimension(LVIDd)and left ventricular end-systolic dimension(LVIDs)of diabetic mice were larger than those in control mice(P<0.05and P<0.01,respectively).The ejection fraction(EF)and fractional shortening(FS)decreased in the diabetic mice(P<0.01).Exosome treatment significant decreased the LVIDs(P<0.01),but increased the EF and FS(P<0.01).The blood glucose and non-esterified fatty acids were significantly increased in the diabetic mice.The injection of the stem cell exosome significantly decreased the blood glucose and non-esterified fatty acids(P<0.01).HE staining observation showed that cardiomyocyte hypertrophy and fragmentation of cardiomyocyte in DM group were more se-rious than those in control group.Masson staining showed that the area of fibrosis in DM group was larger than that in control group(P<0.01),but that in DM+exosome group was reduced(P<0.01).CONCLUSION:Exosome secreted by human umbilical mesenchymal stem cells protects the DM model mice from cardiac fibrosis.