负载重组人骨形态发生蛋白2的纳米羟基磷灰石/丝素蛋白复合材料重建脊柱稳定性

摘要

背景:随着骨修复支架在医学领域的广泛应用,具有良好生物学性能的纳米羟基磷灰石和丝素蛋白成为近年来的研究热点.目的:探讨负载重组人骨形态发生蛋白2的纳米羟基磷灰石/丝素蛋白复合材料重建兔脊柱节段初始稳定性的可行性.方法:将36只雄性新西兰兔随机分为3组,均制备脊柱失稳模型.自体骨组在L4、L5椎间植入自体髂骨,nHA/SF组将纳米羟基磷灰石/丝素蛋白复合材料植入椎间隙进行椎间融合,rhBMP-2/nHA/SF组将负载重组人骨形态发生蛋白2的纳米羟基磷灰石/丝素蛋白复合材料植入椎间隙进行椎间融合.术后12周,X射线观察手术节段的融合情况,然后处死实验动物进行大体观察.使用电于拉力机测试融合节段的稳定性.组织学观察手术部位的植骨融合情况.结果与结论:①术后各组标本融合部位质地均较硬.自体骨组融合迹象明显,rhBMP-2/nHA/SF组次之,nHA/SF组未见融合迹象.②自体骨组椎体与髂骨植骨块分界处有大量骨小梁长入,nHA/SF组分界处有少量骨小梁长入,rhBMP-2/nHA/SF组分界处骨小梁较多.经X射线评估分别有10只、3只和9只符合融合标准.③rhBMP-2/nHA/SF组脊柱活动度与自体骨组间比较差异无显著性意义,rhBMP-2/nHA/SF组脊柱活动度优于nHA/SF组,差异有显著性意义(P<0.05).④自体骨组髂骨周边可见骨性连接,nHA/SF组材料周边可见骨性连接,未见成熟骨组织,rhBMP-2/nHA/SF组周边有大量新生毛细血管,并渗入组织内部.⑤结果表明,负载重组人骨形态发生蛋白2的纳米羟基磷灰石/丝素蛋白复合材料具有良好的生物相容性、力学性能和骨诱导能力,能在较短时间内重建兔脊柱稳定性.%BACKGROUND:With the wide application of bone repair scaffold in the field of medicine, nano-hydroxyapatite (nHA) and silk fibroin (SF) both of which have good biological properties have become research hotspots in recent years.OBJECTIVE:To study the feasibility of nHA/SF composite materials loaded with recombinant human bone morphogenetic protein 2 (rhBMP-2) to restore the initial stability of the spinal segment in rabbits.METHODS: Thirty-six male health New Zealand rabbits were randomly divided into three groups, followed by preparation of spinal instability models. Autogenous iliac bone, nHA/SF composite, and rhBMP-2/nHA/SF composite were implanted into the L4/5 spinal segment in autologous bone group, nHA/SF group and rhBMP-2/nHA/SF group, respectively. X-ray exmaination was performed at 12 weeks postoperatively, and then the animals were killed for gross observation. The stability of the fusion segments was tested through a tensile machine. Histologically, bone graft fusion at the surgical site was observed.RESULTS AND CONCLUSION:(1) Findings from the gross specimen observation showed that the specimens at the fusion site presented with a hard texture. Obvious signs of fusion were visible in the autologous bone group, followed by the rhBMP-2/nHA/SF group, while no signs of fusion were detected in the nHA/SF group. (2) At 12 weeks postoperatively, a large number of trabecular bones grew into the boundary between the vertebral body and the iliac crest graft block in the autologous bone group. A little trabecular bone was found in the boundary in the nHA/SF group, while a lot of trabecular bone tissues were found in the boundary in the rhBMP-2/nHA/SF group. In accordance with the standard of fusion, there were 10, 3, and 9 rats in the autologous bone, nHA/SF and rhBMP-2/nHA/SF groups, respectively. (3) The range of motion of the spine in the rhBMP-2/nHA/SF showed no statistical difference from that in the autologous bone group, but was significantly higher than that in the nHA/SF group (P < 0.05). (4) Osseous connection was found around the bone graft in the autologous bone and nHA/SF groups, but no mature bone tissue was visible in the latter group. In the rhBMP-2/nHA/SF group, a large number of new capillaries was found and permeated into the spinal tissues. In summary, nHA/SF composite materials loaded with rhBMP-2 possess good biocompatibility, mechanical properties and bone induction ability, which can rebuild the initial stability of the spine in a short time.