Kavukcuoglu N Beril, Denhardt David T, Guzelsu Nejat, Mann Adrian B
Department of Materials Science and Engineering, Rutgers University, New Jersey 08854, USA.
J Biomed Mater Res A. 2007 Oct;83(1):136-44. doi: 10.1002/jbm.a.31081.
Osteoporosis is a bone disease characterized by low bone mass and deterioration of the tissue leading to increased fragility. Osteopontin (OPN), a noncollageneous bone matrix protein, has been shown to play an important role in osteoporosis, bone resorption, and mineralization. However, OPN's role in bone mechanical properties on the submicron scale has not been studied in any detail. In this study, nanoindentation techniques were utilized to investigate how OPN and aging affect bone mechanical properties. Hardness and elastic modulus were calculated and compared between the OPN-deficient mice (OPN(-/-)) and their age and sex-matched wild-type (OPN(+/+)) controls. The results show that the mechanical properties of the young OPN(-/-) bones (age < 12 weeks) are significantly lower than that of the youngest OPN(+/+) bones. This finding was confirmed by additional microindentation testing. Biochemical analysis using micro-Raman spectroscopy indicated more mineral content in young OPN(+/+) bones. Older (age > 12 weeks) bones did not show any significant differences in mechanical properties with genotype. In addition, OPN(+/+) bones show a decrease in mechanical properties between young and older age groups. By contrast, OPN(-/-) bones showed no significant change in mechanical properties with aging.
骨质疏松症是一种以骨量低和组织退化导致脆性增加为特征的骨病。骨桥蛋白（OPN）是一种非胶原蛋白骨基质蛋白，已被证明在骨质疏松症、骨吸收和矿化中起重要作用。然而，OPN在亚微米尺度上对骨力学性能的作用尚未得到详细研究。在本研究中，利用纳米压痕技术研究OPN和衰老如何影响骨力学性能。计算并比较了OPN缺陷小鼠（OPN(-/-)）及其年龄和性别匹配的野生型（OPN(+/+)）对照的硬度和弹性模量。结果表明，年轻的OPN(-/-)骨（年龄<12周）的力学性能明显低于最年轻的OPN(+/+)骨。这一发现通过额外的微压痕测试得到了证实。使用显微拉曼光谱进行的生化分析表明，年轻的OPN(+/+)骨中矿物质含量更高。年龄较大（年龄>12周）的骨在力学性能上未显示出基因型的显著差异。此外，OPN(+/+)骨在年轻和老年组之间力学性能下降。相比之下，OPN(-/-)骨的力学性能随衰老没有显著变化。
