不同直径的钛颗粒负荷对成骨细胞分化和矿化能力的影响

植入假体磨损碎屑颗粒所引起的无菌性松动是假体周围骨形成与骨吸收过程失衡的结果 ,成骨细胞所参与的骨形成代谢受阻在这一病理生理过程中起着重要作用 ,而且不同大小的磨屑颗粒对骨形成影响的机制应该有所不同。为了探讨磨屑颗粒对成骨细胞骨形成能力的影响机制 ,本研究分析了 3种不同直径的钛颗粒负荷对成骨细胞分化成熟和矿化能力的影响。结果显示 ,未经钛颗粒负荷的成骨细胞表现出良好的分化和矿化能力 ;Φ6 .9μm钛颗粒负荷对成骨细胞分化和矿化能力的抑制作用并不显著 ,而 Φ2 .7μm和 Φ0 .9μm钛颗粒负荷 ,尤其是Φ 0 .9μm的抑制作用非常明显 ,且具有一定的时间依赖性。透射电镜观察显示 ,颗粒负荷后成骨细胞的骨形成功能异常与其超微结构改变有关。结合我们以前的工作 ,提示磨屑颗粒直径对骨形成的影响在无菌性松动中发挥至关重要的作用 ,亚微米级颗粒与骨形成受抑有明显的相关性 ,而大直径颗粒可促进骨吸收 ,有关不同颗粒直径对骨形成影响本质的更深入研究必将促进无菌性松动机制的早日阐明。

Influence of Different-sized Titanium Particles Loading on Osteobalstic Differentiation and Mineralization

Studies have recently suggested that the coupling mechanism of bone formation and bone resorption are affected by particulate wear debris inducing aseptic loosening around the bone-prosthesis microenviroment. There may be direct impacts on osteoblasts, resulting in net decrease in bone formation. In addition, the influences of particulate wear debris in different size on the osteogenesis should be various. In order to investigate the hypothesis that particulate wear debris derived from prosthetic biomaterials affects the osteogenesis of osteblasts, we studied the influence of different-sized titanium particles loading on the osteoblastic differentiation by assaying the secretion of alkaline phosphatase (ALP), osteocalcin (OCN), N-terminal type I procollagen (PINP), and on the osteoblastic mineralization with the use of calcified node number, calcified node area and Alizarin Red S (ARS) concentration. Upon in vitro culture in the absence of titanium particles, we observed that cultures of osteoblasts isolated from newborn Japanese rabbits' cranium were excellently capable of differentiation and mineralization. Phi6.9 microm titanium particles did not evidently alter osteoblastic differentiation and mineralization. In comparison, phi2.7 microm and phi0.9 microm titanium particles, especially phi0.9 microm (submicron), significantly suppressed ALP expression, reduced PINP production, decreased OCN secretion and inhibited matrix mineralization. Results of transmission electron microscopy (TEM) of titanium particles-loaded osteoblastic cultures revealed that osteoblasts phagocytized titanium particles and exhibited ultrastructional changes consistent with cellular dysfuction. Combined with our previous studies in vitro findings, these results suggest that particles size play a key role in the process of aseptic loosening, which submicron particles are closely associated with inhibition of bone formation while bigger particles with enhancement of bone resorption. Further understanding the nature of osteoblastic bioreactivity to different-size wear particles should provide additional insights into mechanisms underlying aseptic loosening.