TGF-β/Smad信号通路在大鼠间充质干细胞机械牵张中的表达

Expression of TGF-β/Smad Signal Pathway in the Stretched Rat MSCs

目的:了解TGF-β/Smad信号通路在大鼠骨髓间充质干细胞(MSCs)加载牵张中的作用。方法:分离培养大鼠骨髓MSCs,应用四点弯曲加力系统对细胞施加单一周期的机械张应力刺激(2000με,60min)。用实时荧光定量RT-PCR与western blot检测TGF-β、Smad4的表达,同时检测MSCs细胞增殖及骨向分化标志物ALP的变化情况。结果:在张应力的作用下,TGF-β,Smad4的表达显著增强(P<0.01)。MSCs的增殖、ALP活性也在加力后增强(P<0.01)。结论:TGF-β/Smad信号通路的激活与细胞受张应力刺激密切相关,并与MSCs增殖与骨向分化趋势一致。表明TGF-β/Smad通路参与了细胞力学信号向生物化学信号的转化。

Objective： To observe the role of TGF-β/Smad signal pathway in the stretched rat mesenchymal stem cells （MSCs）. Methods： Bone marrow MSCs were isolated from SD rats and cultured in vitro. A four--point ben- ding apparatus were used to perform a single period of mechanical stretch （20001με, 60min） on MSCs. mRNA and protein expression of TGF-β and Smad4 were detected by RT--PCR and western blot analysis. Cellular prolifera- tion and ALP activity of MSCs were also examined. Results： Under the mechanical stimulation, cell proliferation, ALP activity and expression of TGF-β and Smad4 were all significantly up-- regulated in stretched MSCs when compared with their controls （P〈0.01）. Conclusion： The activation of TGF-β/ Smad signal pathway is related to the mechanical stimulation on MSCs. The mechanical stretch can promote MSCs proliferation, up-- regulate its ALP activity and induce a time--dependent expression of TGF-β/ Smad which in turn result in osteogenic differen- tiation of MSCs.