Braun G, Kohavi D, Amir D, Luna M, Caloss R, Sela J, Dean D D, Boyan B D, Schwartz Z
Willford Hall Medical Center, Lackland Air Force Base, Texas, USA.
Clin Oral Implants Res. 1995 Mar;6(1):1-13. doi: 10.1034/j.1600-0501.1995.060101.x.
Critical events in the adaptation of osseous tissues to implant materials involve initial calcification of the newly synthesized bone. Previous studies indicated that bone-bonding but not nonbonding glass ceramics increase the matrix vesicle number, thereby compensating for delayed maturation of the extracellular organelles. The present study assessed whether this was also true for metal implants commonly used in orthopaedics and oral medicine. Bone-bonding titanium (Ti) or nonbonding stainless steel (SS) implants were placed in the right tibias of Sabra rats following ablation of the marrow. At 3, 6, 14, and 21 days postinjury, newly formed endosteal bone in the treated and contralateral limbs was removed and matrix vesicle-enriched membranes isolated. Alkaline phosphatase and phospholipase A2 specific activities and phosphatidylserine (PS) content were determined and compared with those of a nonsurgical control group. Results show that matrix vesicle alkaline phosphatase and phospholipase A2 activity and PS content was increased in the Ti-implanted limbs at 6 (peak), 14, and 21 days, although at levels less than observed in normal healing. Alkaline phosphatase activity remained elevated throughout the healing period. In contrast, these parameters were markedly inhibited in the SS-implanted limbs with respect to Ti or to normal healing. Both implants altered the systemic response associated with marrow ablation, but in an implant-specific manner. The results support the hypothesis that cells adjacent to bone-bonding materials can compensate for negative effects on primary mineralization during osteogenesis, whereas cells adjacent to nonbonding materials either do not compensate or are further depressed. The data support the use of the rat marrow ablation model as a tool for rapid, initial assessment of biomaterials in bone.
骨组织适应植入材料的关键事件涉及新合成骨的初始钙化。先前的研究表明，具有骨结合能力的而非无骨结合能力的玻璃陶瓷会增加基质小泡的数量，从而弥补细胞外细胞器成熟延迟的问题。本研究评估了这一情况对于骨科和口腔医学中常用的金属植入物是否同样适用。在去除骨髓后，将具有骨结合能力的钛（Ti）植入物或无骨结合能力的不锈钢（SS）植入物置于Sabra大鼠的右胫骨中。在损伤后3、6、14和21天，取出治疗侧和对侧肢体新形成的骨内膜骨，并分离富含基质小泡的膜。测定碱性磷酸酶和磷脂酶A2的比活性以及磷脂酰丝氨酸（PS）含量，并与非手术对照组进行比较。结果显示，在植入钛的肢体中，基质小泡碱性磷酸酶和磷脂酶A2活性以及PS含量在第6天（峰值）、14天和21天时增加，尽管其水平低于正常愈合时观察到的水平。碱性磷酸酶活性在整个愈合期都保持升高。相比之下，在植入不锈钢的肢体中，这些参数相对于钛植入肢体或正常愈合明显受到抑制。两种植入物都改变了与骨髓消融相关的全身反应，但方式具有植入物特异性。这些结果支持了这样的假设，即与具有骨结合能力的材料相邻的细胞可以补偿成骨过程中对初级矿化的负面影响，而与无骨结合能力的材料相邻的细胞要么不进行补偿，要么进一步受到抑制。这些数据支持将大鼠骨髓消融模型用作快速初步评估骨生物材料的工具。
