目的 探讨年轻 Sca⁃1 骨髓干细胞对年老小鼠心外膜细胞衰老的调控作用及机制。 方法 将年轻和年老小鼠 Sca⁃1 骨髓干细胞分别与年老小鼠心外膜细胞共培养（分为 Y Sca⁃1 细胞组与 O Sca⁃1 细胞组）。通过细胞染色、基因及蛋白检测，探讨 Sca⁃1 骨髓干细胞对年老小鼠心外膜细胞衰老 的影响。结果 与 O Sca⁃1 细胞组相比，Y Sca⁃1 细胞组可明显减少心外膜细胞衰老：P16 免疫荧光染色 阳性细胞比例下降；P27 基因及蛋白表达减少；Sirt 1 基因及蛋白表达增加（P < 0.05）。分子机制研究发 现，与 O Sca⁃1 细胞相比，Y Sca⁃1 细胞可旁分泌更多的 GDNF（P < 0.05）。中和 GDNF 后，使 Y Sca⁃1 细胞 失去减少年老心外膜细胞衰老的作用。结论 年轻 Sca1 骨髓干细胞可通过旁分泌 GDNF 减少年老心 外膜细胞衰老。

Objective To study the regulating effect of young Sca⁃1 bone marrow stem cell on epicardial cell senescence and its mechanism. Methods Young（Y）and old（O）Sca⁃1 bone marrow cell was co⁃cultured with old epicardial cell under hypoxia condition，respectively. The effect of Sca⁃1 bone marrow cell on epicardial cell senescence was detected by immunofluorescent staining，qRT ⁃PCR，and western blot，respectively. Results Compared to O Sca⁃1 bone marrow cell，Y Sca⁃1 cell decreased epicardial cell senescence，with decreased senes⁃ cent cell rate，decreased P27 gene and protein expression，and increased Sirt 1 gene and protein expression（P < 0.05）. More GDNF（Glial cell line⁃Derived Neurotrophic Factor）was found in Y Sca⁃1 cell group when compared to that in O Sca⁃1 cell group（P < 0.05）. The effect of Y Sca⁃1 cell on old epicardial cell senescence was lost when GDNF expression was blocked. Conclusion Young Sca⁃1 bone marrow stem cell decreases old epicardial cell senescence by GDNF.