Lu Mengmeng, Zhuang Xiaohua, Tang Kaiwei, Wu Peishi, Guo Xiaojing, Yin Linling, Cao Huiliang, Zou Derong
Department of Stomatology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
Department of Stomatology, Gongli Hospital, Second Military Medical University, Shanghai, China.
Cell Physiol Biochem. 2018;51(2):589-609. doi: 10.1159/000495280. Epub 2018 Nov 20.
BACKGROUND/AIMS: Accumulating evidence demonstrates the superior osteoinductivity of tantalum (Ta) to that of titanium (Ti); however, the mechanisms underlying these differences are unclear. Thus, the objective of the present study was to examine the effects of Ta and Ti surfaces on osteogenesis using rat bone mesenchymal stromal cells (rBMSCs) as a model.
Ta and Ti substrates were polished to a mirror finish to minimize the influences of structural factors, and the intrinsic surface effects of the two materials on the integrin α5β1/mitogen-activated protein kinases 3 and 1 (ERK1/2) cascade-mediated osteogenesis of rBMSCs were evaluated. Alkaline phosphatase (ALP) activity, Alizarin Red staining, real-time polymerase chain reaction, and western blot assays of critical osteogenic markers were conducted to evaluate the effects of the two substrates on cell osteogenesis. Moreover, the role of the integrin α5β1/ERK1/2 pathway on the osteoinductive performance of Ta and Ti was assessed by up- and down-regulation of integrin α5 and β1 with RNA interference, as well as through ERK1/2 inhibition with U0126.
Osteogenesis of rBMSCs seeded on the Ta surface was superior to that of cells seeded on the Ti surface in terms of ALP activity, extracellular matrix calcification, and the expression of integrin α5, integrin β1, ERK1/2, Runt-related transcription factor 2, osteocalcin, collagen type I, and ALP at both the mRNA and protein levels. Moreover, down-regulation of integrin α5 or integrin β1, or ERK1/2 inhibition severely impaired the osteoblastic differentiation on the Ta surface. By contrast, over-expression of integrin α5 or integrin β1 improved osteogenesis on the Ti substrates, while subsequent ERK1/2 inhibition abrogated this effect.
The integrin α5β1/ERK1/2 pathway plays a crucial role in regulating rBMSCs osteogenic differentiation; thus, the greater ability of a Ta surface to trigger integrin α5β1/ERK1/2 signaling may explain its better osteoinductivity. The different effects of Ta and Ti surfaces on rBMSC osteogenesis are considered to be related to the conductive behaviors between integrin α5β1 and the oxides spontaneously formed on the two metals. These results should facilitate the development of engineering strategies with Ta and Ti surfaces for improved osteogenesis in endosteal implants.
背景/目的：越来越多的证据表明钽（Ta）的骨诱导性优于钛（Ti）；然而，这些差异背后的机制尚不清楚。因此，本研究的目的是以大鼠骨髓间充质基质细胞（rBMSCs）为模型，研究Ta和Ti表面对成骨的影响。
将Ta和Ti基底抛光至镜面光洁度，以尽量减少结构因素的影响，并评估这两种材料对整合素α5β1/丝裂原活化蛋白激酶3和1（ERK1/2）级联介导的rBMSCs成骨的内在表面效应。进行碱性磷酸酶（ALP）活性、茜素红染色、实时聚合酶链反应以及关键成骨标志物的蛋白质印迹分析，以评估两种基底对细胞成骨的影响。此外，通过RNA干扰上调和下调整合素α5和β1以及用U0126抑制ERK1/2，评估整合素α5β1/ERK1/2途径对Ta和Ti骨诱导性能的作用。
接种在Ta表面的rBMSCs在ALP活性、细胞外基质钙化以及整合素α5、整合素β1、ERK1/2、 runt相关转录因子2、骨钙素、I型胶原和ALP的mRNA和蛋白质水平表达方面，其成骨能力优于接种在Ti表面的细胞。此外，整合素α5或整合素β1的下调或ERK1/2的抑制严重损害了Ta表面的成骨细胞分化。相比之下，整合素α5或整合素β1的过表达改善了Ti基底上的成骨，而随后的ERK1/2抑制消除了这种作用。
整合素α5β1/ERK1/2途径在调节rBMSCs成骨细胞分化中起关键作用；因此，Ta表面触发整合素α5β1/ERK1/2信号的能力更强，这可能解释了其更好的骨诱导性。Ta和Ti表面对rBMSC成骨的不同影响被认为与整合素α5β1与两种金属上自发形成的氧化物之间的传导行为有关。这些结果应有助于开发具有Ta和Ti表面的工程策略，以改善骨内植入物的成骨。
