Exendin-4 通过PI3K/Akt 信号通路促进脂肪干细胞旁分泌细胞因子

目的探讨Exendin-4 促进脂肪来源干细胞（ADSCs）旁分泌细胞因子的机制。方法混合酶消化法提取和培养SD大鼠
腹股沟处的脂肪干细胞，使用流式细胞学检测有或无Exendin-4 处理后的第4 代ADSCs表面标记物，MTT法绘制0、1、5、10、
20 nm/L不同浓度Exendin-4下的ADSCs生长曲线；qPCR法检测不同浓度Exendin-4处理12 h后bFGF、VEGF、HGF、IGF-1的
表达变化。Western blotting和qPCR检测Exendin-4对于Akt通路的作用。同时添加通路阻断剂LY-294002，使用ELISA检测
Akt 通路阻断后Exendin-4 对于旁分泌蛋白的影响。结果分离培养的ADSCs 高表达CD29、CD90、CD105，低表达CD34、
CD45，并且能够多向分化为脂肪细胞、骨细胞，符合间充质干细胞的表型特点。Exendin-4处理后，不仅不会改变ADSCs的表
型，还能以浓度依赖方式促进ADSCs 在体外增殖（P<0.05）。不同浓度Exendin-4 处理ADSCs 12 h 后，旁分泌蛋白bFGF、
VEGF、HGF、IGF-1的表达量逐渐提高，其中10 nm/L Ex-4处理12 h可能为最佳处理浓度（P<0.05）。Western blotting和qPCR
提示Exendin-4 能够显著提高胞内Akt 的磷酸化水平，而给予LY-294002 后，磷酸化Akt 表达减弱，同时ADSCs培养液上清中
bFGF、VEGF、HGF、IGF-1的含量也明显降低（P<0.05）。结论短暂Exendin-4处理不会改变ADSCs表型，但能加强细胞的增殖
能力，且以剂量依赖方式促进干细胞旁分泌细胞因子bFGF、VEGF、HGF、IGF-1。10 nm/L可能为Exendin-4 最适促旁分泌浓
度，其扩大干细胞旁分泌的机制部分是通过激活PI3K/Akt信号通路来介导。

Exendin-4 promotes paracrine action of adipose-derived stem cells through PI3K/Aktsignaling pathways

Objective To investigate the mechanism by which exendin-4 promotes paracrine secretion of cytokines by
adipose-derived stem cells (ADSCs). Methods In vitro cultured SD rat ADSCs (fourth passage) with or without exendin-4
treatment underwent flow cytometry to characterize the surface markers. MTT assay was performed to assess the proliferation
of the cells exposed to different concentrations (0-20 nm/L) of exendin-4, and the paracrine secretion of cytokines (bFGF, VEGF,
HGF, and IGF-1) by the ADSCs was evaluated by qPCR. The changes in the expressions of p-Akt in the cells were analyzed by
Western blotting and qPCR in response to exendin-4 (10 nm/L) with or without exposure to PI3K/Akt inhibitor LY-294002 (50
nm/L); bFGF, VEGF, HGF, and IGF-1 production in the cells were detected using ELISA kits. Results Treatment with exendin-4
for 12 h did not affect the surface marker profile of the ADSCs but promoted the cell proliferation (P<0.05). Exendin-4
significantly increased the mRNA expressions of VEGF, bFGF, HGF, and IGF-1 in a concentration-dependent manner, and 10
nm/L was the optimum concentration (P<0.05). Exendin-4 treatment resulted in significantly increased p-Akt expressions in the
ADSCs, and PI3K/Akt inhibitor not only reversed such effects of exendin-4 on p-Akt but also diminished the exendin-4-
mediated up-regulation of the paracrine cytokines. Conclusion Exendin-4 can concentration-dependently promote the
proliferative and paracrine capacities of ADSCs partially through the PI3K/Akt signaling pathway without affecting the
surface marker profile of the cells.