脐带间充质干细胞移植缓解肺泡细胞衰老的作用探讨

Role of umbilical cord mesenchymal stem cell transplantation in alleviating alveolar cell senescence

目的探讨脐带间充质干细胞(UC-MSCs)移植对放射性肺纤维化(RIPF)、RIPF小鼠的肺内衰老细胞的作用。方法C57BL/6小鼠单侧右肺接受17 Gy照射构建RIPF模型,照射后3个月尾静脉注射UC-MSCs,照后6个月取材,记录小鼠生存率、统计肺脏器比,苏木素-伊红(H&E)染色、Masson染色观察肺部结构及胶原沉积;qRT-PCR检测衰老分泌相关表型(SASP)表达情况;β-Gal免疫组化评估肺内细胞衰老;WB检测P53-P21、P16通路关键蛋白表达水平;组织免疫荧光检测肺内P21表达情况。结果经UC-MSCs治疗的RIPF小鼠生存率较未治疗组升高,胶原蛋白沉积减少,塌陷增厚的肺泡结构改善;RIPF小鼠肺内增多的β-Gal阳性衰老细胞和高表达的SASP(IL-6、IL-8、IL-1β)在UC-MSCs治疗后均下降;UC-MSCs治疗降低了RIPF小鼠体内异常增高的P53、p-P53、P21、P16蛋白水平。结论UC-MSCs可能通过抑制P53-P21及P16通路减轻纤维化肺内细胞的衰老,缓解放射性肺纤维化,有望用于放射性肺损伤的治疗。

Objective To investigate whether the transplantation of umbilical cord mesenchymal stem cells(UC-MSCs)can alleviate radiation-induced pulmonary fibrosis(RIPF)and attenuate intrapulmonary cellular senescence in mice with RIPF.Methods The C57BL/6 mice were unilaterally irradiated with 17 Gy in the right lung to construct RIPF models.UC-MSCs were injected into the caudal vein at 3 months after radiation,and samples were taken at 6 months.The survival rate of mice was recorded,and the lung organ ratio was calculated.Lung structure and collagen deposition were observed by hem-atoxylin-eosin staining and Masson staining.The expression of senescence secretion-associated phenotype(SASP)was measured by quantitative real-time polymerase chain reaction.Intrapulmonary cellular senescence was assessed byβ-Gal im-munohistochemistry.The expression of key proteins in the P53-P21 and P16 pathways was measured by Western blot.P21 expression in the lung was measured by tissue immunofluorescence.Results Compared with the untreated group,RIPF mice treated with UC-MSCs showed an improved survivalrate,reduced collagen deposition,and an improvement incollapse and thickening of alveolar structure.Increasedβ-Gal-positive senescent cells and high expression of SASP(IL-6,IL-8,IL-1β)in the lung of RIPF mice were all reduced after UC-MSC treatment.The abnormally increased levels of P53,p-P53,P21 and P16 proteins in RIPF mice were reduced by UC-MSC treatment.Conclusion UC-MSCs may reduce cellular senes-cence in fibrotic lungs and alleviate RIPF by inhibiting P53-P21 and P16 pathways,which is expected to be used for the treatment of radiation-induced lung injury.