PDF(Pubmed)
Abstract：
It is not clear as to whether weight bearing and ambulation may affect bone growth. Our goal was to study the role of mechanical loading (one of the components of ambulation) on endochondral ossification and longitudinal bone growth. Thus, we applied cyclical, biologically relevant strains for a prolonged time period (4 weeks) to one tibia of juvenile mice, while using the contralateral one as an internal control. By the end of the 4-week loading period, the mean tibial growth of the loaded tibiae was significantly greater than that of the unloaded tibiae. The mean height and the mean area of the loaded tibial growth plates were greater than those of the unloaded tibiae. In addition, in female mice we found a greater expression of PTHrP in the loaded tibial growth plates than in the unloaded ones. Lastly, microCT analysis revealed no difference between loaded and unloaded tibiae with respect to the fraction of bone volume relative to the total volume of the region of interest or the tibial trabecular bone volume. Thus, our findings suggest that intermittent compressive forces applied on tibiae at mild-moderate strain magnitude induce a significant and persistent longitudinal bone growth. PTHrP expressed in the growth plate appears to be one growth factor responsible for stimulating endochondral ossification and bone growth in female mice.
摘要：
尚不清楚负重和步行是否会影响骨骼生长。我们的目标是研究机械负荷（步行的组成部分之一）对软骨内骨化和纵向骨生长的作用。因此，我们应用了周期性的，生物学相关的菌株延长的时间段（4周）到一个胫骨的幼鼠，同时使用对侧作为内部控制。到4周装货期结束时，负载胫骨的平均胫骨生长明显大于未负载胫骨。加载的胫骨生长板的平均高度和平均面积大于未加载的胫骨。此外,在雌性小鼠中，我们发现有负载的胫骨生长板中的PTHrP表达高于无负载的胫骨生长板中的PTHrP表达。最后,microCT分析显示，相对于感兴趣区域总体积或胫骨骨小梁体积的骨体积分数，加载和卸载胫骨之间没有差异。因此，我们的发现表明，在轻度-中度应变幅度下施加在胫骨上的间歇性压缩力会引起显着且持续的纵向骨生长。在生长板中表达的PTHrP似乎是一种负责刺激雌性小鼠软骨内骨化和骨生长的生长因子。
