Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University , No. 17 Changle Xi Road, Xi'an, Shaanxi province 710032, P.R. China.
School of Materials Science and Engineering, Xi'an University of Technology , No. 5 Jinhua South Road, Xi'an, Shaanxi province 710048, P.R. China.
ACS Appl Mater Interfaces. 2017 Nov 22;9(46):40846-40856. doi: 10.1021/acsami.7b12983. Epub 2017 Nov 10.
Poly(methyl methacrylate) (PMMA), the most common bone cement, has been used as a graft substitute in orthopedic surgeries such as vertebroplasty. However, an undesirable minor crack in the bone-cement interface provoked by shrinkage during polymerization and high elastic modulus of conventional PMMA bone cement dramatically increases the risk of vertebral body refracture postsurgery. Thus, herein, a hydrophilous expandable bone cement was synthesized based on a PMMA commercial cement (Mendec Spine Resin), acrylic acid (AA), and styrene (St). The two synthesized cements (PMMA-PAA, PMMA-PAA-PSt) showed excellent volumetric swelling in vitro and cohesive bone-cement contact in rabbit femur cavity defect. The elastic modulus and compressive strength of the new cements were lower than PMMA. Furthermore, the in vitro analysis indicated that the new cements had lower cytotoxicity than PMMA, including superior proliferation and lower apoptotic rates of Sprague-Dawly rat-derived osteoblasts. Western blotting for protein expression and RT-PCR analysis of osteogenesis-specific genes were conducted on SD rat-derived osteoblasts from both PMMA and new cements films; the results showed that new cements enhanced the expression of osteogenesis-specific genes. Scanning electron microscopy demonstrated improved morphology and attachment of osteoblast on new cement discs compared to the PMMA discs. Additionally, the histological morphologies of the bone-cement interface from the rabbit medial femoral condyle cavity defect model revealed direct and cohesive contact with the bone in the new cement groups in contrast to a minor crack in the PMMA cement group. The sign of a new bone growing into the cement has been found in the new cements after 12 weeks, thereby indicating the osteogenic capacity in vivo. In conclusion, the synthesized hydrophilous expandable bone cements based on PMMA and poly(acrylic acid) (PAA) are promising candidates for vertebroplasty.
聚甲基丙烯酸甲酯（PMMA）是最常见的骨水泥，已被用作骨科手术中的移植物替代物，如椎体成形术。然而，聚合过程中收缩和传统 PMMA 骨水泥的高弹性模量引起的骨水泥界面不理想的小裂纹极大地增加了手术后椎体再骨折的风险。因此，本文基于 PMMA 商业水泥（Mendec Spine Resin）、丙烯酸（AA）和苯乙烯（St）合成了一种亲水可膨胀骨水泥。两种合成的水泥（PMMA-PAA、PMMA-PAA-PSt）在体外表现出优异的体积膨胀和兔股骨腔缺损中的骨水泥接触性。新水泥的弹性模量和抗压强度低于 PMMA。此外，体外分析表明，新水泥的细胞毒性低于 PMMA，包括对 Sprague-Dawly 大鼠源性成骨细胞的增殖更好和凋亡率更低。对 PMMA 和新水泥膜中 SD 大鼠源性成骨细胞进行蛋白质表达的 Western blot 和成骨特异性基因的 RT-PCR 分析，结果表明新水泥增强了成骨特异性基因的表达。扫描电子显微镜显示，与 PMMA 盘相比，新水泥盘上成骨细胞的形态和附着得到改善。此外，从兔内侧股骨髁腔缺损模型的骨水泥界面的组织形态学揭示，新水泥组与骨直接且具有粘合力接触，而 PMMA 水泥组则存在小裂纹。在新水泥组中发现了 12 周后有新骨长入水泥的迹象，表明其具有体内成骨能力。总之，基于 PMMA 和聚（丙烯酸）（PAA）合成的亲水可膨胀骨水泥是椎体成形术的有前途的候选物。
