Effect of Mechanical Stresses on Bone Remodeling

研究了生物力学力对小鼠成骨细胞MC3T3-E1单层培养骨组织生长的影响，该细胞在co2培养箱中以320 g离心15 min ~ 72 h。细胞在低浓度（0.3%或1%）胎牛血清（FBS）中离心30分钟，在开始离心20小时后，[^3H]胸腺嘧啶掺入量增加了两倍。然而，在10% FBS下离心，没有引起[^3H]胸苷并入DNA的增加。在0.3% FBS条件下，[^3H]胸苷掺入随离心时间的增加而增加，并在细胞离心3小时时达到最大值。在h -7（一种蛋白激酶c的抑制剂）的存在下，离心对DNA合成的刺激被消除。此外，从离心培养中收集的条件培养基添加到MC3T3-E1细胞的静止培养中，[^3H]胸苷掺入比基础培养基增加了两倍。这些结果表明，离心力通过自分泌一些可扩散的促生长活性刺激成骨细胞的生长。另一方面，体外离心抑制FBS诱导的碱性磷酸酶活性和钙摄取，这是成骨细胞分化表型的两个指标。

The effect of biomechanical force on growth of skeletal tissue was studied in monolayer cultures of mouse osteoblastic MC3T3-E1 cells which were centrifuged at 320 g for 15 min to 72 h in a CO_2 incubator.Centrifugation of the cells for 30 min in low concentrations (0.3 or 1%) of fetal bovine serum (FBS) caused a two-fold increase of [^3H]thymidine incorporation at 20 h from commencing the centrifugation. However, centrifugation under 10% FBS caused no increase in [^3H]thymidine incorporation into DNA. Under 0.3% FBS,[^3H]thymidine incorporation increased in a manner dependent on the period of centrifugation and reached a maximum when the cells were centrifuged for 3 h. Stimulation of DNA synthesis by centrifugation was abolished in the presence of H-7, an inhibitor of protein kinase C. Moreover, conditioned medium collected from the centrifuged cultures increased [^3H]thymidine incorporation by two-fold over the basal when added to a quiescent culture of MC3T3-E1 cells. These results suggest that centrifugal force stimulates growth of osteoblastic cells through autocrine secretion of some diffusible growth-promoting activity.On the other hand, centrifugation of the cells inhibited induction by FBS of alkaline phosphatase activity and calcium-uptake, two indices of the differentiated phenotype of osteoblasts.