Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
Biomater Sci. 2021 Sep 7;9(17):5907-5916. doi: 10.1039/d1bm00884f. Epub 2021 Jul 21.
The adaptive response of bones to mechanical loading is essential for musculoskeletal development. Despite the importance of collagen in bone mineralization, little is known about how cyclic strain influences physicochemical responses of collagen, especially at the early stage of mineralization when the levels of strain are higher than those in mature bones. The findings in this study show that, without any cell-mediated activity, cyclic strain increases nucleation rates of calcium phosphate (CaP) nanocrystals in highly-organized collagen matrices. The cyclic strain enhances the transport of mineralization fluids with nucleation precursors into the matrix, thus forming more CaP nanocrystals and increasing the elastic modulus of the collagen matrix. The results also suggest that the multiscale spatial distribution of nanocrystals in the fibrous collagen network determines tissue-level mechanical properties more critically than the total mineral content. By linking nano- and micro-scale observations with tissue-level mechanical properties, we provide new insights into designing better biomaterials.
骨骼对机械加载的适应性反应对于肌肉骨骼的发育至关重要。尽管胶原蛋白在骨矿化中很重要，但对于循环应变如何影响胶原蛋白的理化反应，尤其是在矿化的早期阶段，应变水平高于成熟骨骼时，知之甚少。本研究的结果表明，在没有任何细胞介导的活性的情况下，循环应变会增加高度有序的胶原蛋白基质中钙磷（CaP）纳米晶体的成核速率。循环应变增强了含有成核前体的矿化液的运输进入基质，从而形成更多的 CaP 纳米晶体并增加胶原蛋白基质的弹性模量。结果还表明，纳米纤维状胶原蛋白网络中纳米晶体的多尺度空间分布比总矿物质含量更能决定组织水平的力学性能。通过将纳米和微观尺度的观察与组织水平的力学性能联系起来，我们为设计更好的生物材料提供了新的见解。
