力学应变对大鼠骨髓间充质干细胞增殖和成骨分化能力的影响

探讨周期性双轴力学应变对大鼠骨髓间充质干细胞(M esenchym a l stem ce lls,M SC s)增殖和成骨分化能力的影响。选用9月龄健康SD雌性大鼠,分离股骨、胫骨提取骨髓,采用密度梯度离心法分离M SC s。体外培养M SC s传至第3代,以1×105细胞浓度接种于双轴力学应变系统,选取4 000μstra in,频率为1hz的力学应变对M SC s加载。每天加载3次,每次2 h,间隔2 h。观察力学应变作用后1 d、3 d,M SC s增殖和成骨分化能力的变化,并与相应未加力学应变对照组比较。结果表明:(1)力学应变可增高M SC s的碱性磷酸酶(ALP)和骨桥蛋白(OPN)表达量;力学应变作用3 d后M SC s的ALP和OPN表达量明显高于力学应变作用1 d。I型胶原(COL I)仅在力学应变作用3 d增高;骨钙素(OCN)在各组无明显变化。(2)力学应变可促进M SC s增殖,但力学应变作用1 d和3 d对M SC s增殖的作用无明显差异。上述结果提示:力学应变可以促进M SC s的增殖和成骨分化能力。

The Effect of Mechanical Strain on Proliferation and Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells from Rats

In order to investigate the effects of cyclic biaxial mechanical strain on proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs)from rats. The MSCs were isolated from bone marrow in the 9-month-old female Sprague-Dawley rats by a density gradient method. After the third passage,1 x 10(5) cells were seeded on the flexible silicone membrane in the cyclic biaxial mechanical strain unit. The amplitude of mechanical strain applied to the cells were 4000 microstrain, at a frequency of one hertz (1 Hz), for periods of 3 repetitions of 2 hours' mechanical strain and a break of 2 hours. The osteoblastic marker such as osteopontin (OPN),alkaline phosphatease (ALP), osteocalcin (OCN), type I collagen (Col I) were detected by RT-PCR. The proliferation of all cells were studied with Flow Cytometry (FCM). ALP and OPN levels significantly increased in the mechanical strained groups and reached the top at 3th day after mechanical strain. COL I level was increase only at 3th day after mechanical strain, and the change of OCN was not obvious in every group. The proliferation index of the medchanical strained groups was increased, compared with the control. These results showed that mechanical strain can improve MSCs proliferation and make MSCs differentiate to osteoblast.