力学拉伸强度对破骨细胞形成和分化的影响

Effects of mechanical strain magnitude on formation and differentiation of osteoclasts

目的探讨早期力学拉伸强度对破骨细胞形成和分化的影响。方法对采用巨噬细胞集落刺激因子和破骨细胞分化因子诱导的RAW 264．7细胞分别施加0，1000，1 500，2000，2500和5000με的力学拉伸3d。于培养第7天观察各组破骨细胞形态、计数及检测前体细胞增殖，并于培养第4，7天检测各组细胞培养液中抗酒石酸酸性磷酸酶（TRAP）活性。结果2500με组的破骨细胞形成数量明显减少，5000με组的破骨细胞数量显著增加；2000，2500με组前体细胞增殖明显，5000με组前体细胞增殖显著降低；1000，1500με组与静态组在破骨细胞形成数量和前体细胞增殖方面差异无统计学意义。与静态组相比，应变组第4，7天培养液的破骨细胞TRAP活性均降低。结论早期力学因素可直接影响破骨细胞的形成和分化，较高强度的生理载荷可抑制破骨细胞形成，病理过载促进破骨细胞的形成，而低强度载荷几乎不影响破骨细胞形成；早期力学载荷可抑制破骨细胞分化。

Objective To study the effects of early mechanical strain magnitude on formation and differentiation of osteoclasts. Methods RAW 264.7 cells induced by macrophage colony-stimulating factors and osteoclast differentiation factors were subjected to 0, 1 000, 1 500, 2 000, 2 500 and 5 000 με mechanical straining for three days. The morphological changes, number of osteoclasts and proliferation of precursor cells were determined at day 7. The activity of the tartrate-resistant acid phosphatase （TRAP） in the culture medium was detected at days 4 and 7. Results The number of osteoclasts was decreased in 2 500 με group, while it was increased in 5 000 με group. The proliferation of precursor cells was increased in 2 000 and 2 500 με group, while it was decreased significantly in 5 000 με group. There was no significant difference in the number of osteoclasts and proliferation of precursor cells among 1 000 με group, 1 500 με group and 0 με group. The activity of TRAP was decreased in 1 000, 1 500, 2 000, 2500 and 5 000με groups at days 4 and 7 when compared with 0 με group. Conclusions Early mechanical straining plays a direct role in formation and differentiation of osteoclasts. The high strain magnitude within physiological load inhibits osteoclast formation, while high strain magnitude beyond physiological load stimulates osteoclast formation. Low strain magnitude has nearly no impact on formation of osteoclasts. Early mechanical straining may inhibit differentiation of osteoclasts.