Georgia Institute of Technology, Atlanta, GA 30332, USA.
J Bone Miner Res. 2012 Aug;27(8):1773-83. doi: 10.1002/jbmr.1628.
The surface properties of materials contribute to host cellular response and play a significant role in determining the overall success or failure of an implanted biomaterial. Rough titanium (Ti) surface microtopography and high surface free energy have been shown to enhance osteoblast maturation in vitro and increase bone formation in vivo. Whereas the surface properties of Ti are known to affect osteoblast response, host bone quality also plays a significant role in determining successful osseointegration. One factor affecting host bone quality is patient age. We examined both in vitro and in vivo whether response to Ti surface features was affected by animal age. Calvarial osteoblasts isolated from 1-, 3-, and 11-month-old rats all displayed a reduction in cell number and increases in alkaline phosphatase-specific activity and osteocalcin in response to increasing Ti surface microtopography and surface energy. Further, osteoblasts from the three ages examined displayed increased production of osteocalcin and local factors osteoprotegerin, vascular endothelial growth factor (VEGF)-A, and active transforming growth factor (TGF)-β1 in response to increasing Ti surface roughness and surface energy. Latent TGF-β1 only increased in cultures of osteoblasts from 1- and 3-month-old rats. Treatment with the systemic osteotropic hormone 1α,25(OH)(2)D(3) further enhanced the response of osteoblasts to Ti surface features for all three age groups. However, osteoblasts derived from 11-month-old animals had a reduced response to 1α,25(OH)(2)D(3) compared to osteoblasts derived from 1- or 3-month-old animals. These results were confirmed in vivo. Ti implants placed in the femoral intramedullary canal of old (9-month-old) mice yielded lower bone-to-implant contact and neovascularization in response to Ti surface roughness and energy compared to younger (2-month-old) mice. These results show that rodent osteoblast maturation in vitro as well as new bone formation in vivo is reduced with age. Whether comparable age differences exist in humans needs to be determined.
材料的表面特性有助于宿主细胞的反应，并在很大程度上决定植入生物材料的整体成败。已经表明，粗糙的钛（Ti）表面微形貌和高表面自由能可以增强体外成骨细胞的成熟，并增加体内骨形成。虽然 Ti 的表面特性已知会影响成骨细胞的反应，但宿主骨质量也在很大程度上决定了成功的骨整合。影响宿主骨质量的一个因素是患者年龄。我们分别在体外和体内检查了 Ti 表面特征的反应是否受动物年龄的影响。从 1 个月、3 个月和 11 个月大的大鼠分离的颅骨成骨细胞对 Ti 表面微形貌和表面能的增加均表现出细胞数量减少，碱性磷酸酶特异性活性和骨钙素增加。此外，来自三种年龄检查的成骨细胞显示出增加的骨钙素和局部因子骨保护素、血管内皮生长因子（VEGF）-A 和活性转化生长因子（TGF）-β1 的产生，以响应增加的 Ti 表面粗糙度和表面能。潜伏 TGF-β1 仅在来自 1 个月和 3 个月龄大鼠的成骨细胞培养物中增加。用全身性骨形成激素 1α，25（OH）（2）D（3）处理进一步增强了所有三个年龄组成骨细胞对 Ti 表面特征的反应。然而，与来自 1 个月或 3 个月龄动物的成骨细胞相比，来自 11 个月龄动物的成骨细胞对 1α，25（OH）（2）D（3）的反应降低。这些结果在体内得到证实。与年轻（2 个月龄）小鼠相比，放置在老年（9 个月龄）小鼠股骨骨髓腔内的 Ti 植入物对 Ti 表面粗糙度和能量的骨与植入物接触和新生血管化反应较低。这些结果表明，体外啮齿动物成骨细胞成熟以及体内新骨形成随着年龄的增长而减少。在人类中是否存在类似的年龄差异仍有待确定。
