HucMSC-ex通过Let-7b调控TGF-βR1抑制肝星状细胞胶原合成

目的: 探讨人脐带间质干细胞来源的外泌体(human umbilical cord mesenchymal stem cells derived exosome, HucMSC-ex)对肝星状细胞LX-2胶原合成的影响及作用机制。方法: 提取HucMSC-ex，采用透射电镜分析HucMSC-ex形态，蛋白质印迹法检测特异性标志蛋白CD9和CD63的表达；建立TGF-βR1诱导的人肝星状细胞(hepatic stellate cells，HSC)LX-2细胞株活化模型，分别加入25，50和100 μg/mL HucMSC-ex共培养，另设对照组(常规培养)，qRT-PCR检测4组Col1、Col3、TGF-βR1和Let-7b mRNA表达，免疫印迹法检测对应的蛋白表达；Let-7b过表达转染LX 2细胞株，qRT-PCR和免疫印迹法检测LX-2中TGF-βR1、α-SMA蛋白和mRNA表达。结果： HucMSC-ex是30~100 nm的膜性囊泡，表达外泌体的特异标志CD9和CD63。与对照组相比，HucMSC-ex处理组中Col1、Col3和TGF-βR1表达明显下调(P均<0.001)，而Let-7b表达明显上调(P均<0.001)；Let-7b过表达显著抑制LX-2细胞中TGF-βR1和α-SMA的表达(P均<0.05)。 结论： HucMSC-ex转运Let-7b到肝星状细胞，调控肝星状细胞TGF-βR1表达，抑制肝星状LX-2细胞胶原合成。

HucMSC-ex inhibit collagen synthesis of hepatic stellate cells throughLet-7b mediated TGF-βR1 downregulation

Objective: To study the effect of human umbilical cord mesenchymal stem cells derived exosomes(HucMSC-ex) on collagen synthesis in hepatic stella cell line (LX-2) and its mechanism. Methods: HucMSC-ex was identified by transmission electron microscopy for morphology and western blotting for exosomal markers CD9 and CD63 expression. The mRNA levels of Col1, Col3, TGF-βR1 and Let-7b in LX-2 cells were detected by qRT-PCR. The level of TGF-βR1 protein in LX-2 cells was detected by western blotting. Results: HucMSC-ex are membrane vesicles with a diameter of 30-100 nm and express exosomal markers CD9 and CD63. Compared with the control group, HucMSC-ex significantly reduced Col1, Col3 and TGF-βR1 expression (all P<0.001), promoted Let-7b expression (all P<0.001). Let-7b mimics transfection down regulated TGF-βR1 and α-SMA expression in LX-2 cells (both P<0.05). Conclusion: HucMSC-ex may inhibit LX-2 activation through delivering Let-7b to regulate TGF-βR1 expression in hepatic stellate cells. ［Key words］Let 7b; human umbilical cord mesenchymal stem cells derived exosomes; hepatic stellate cells