Aghyarian Shant, Bentley Elizabeth, Hoang Thao N, Gindri Izabelle M, Kosmopoulos Victor, Kim Harry K W, C Rodrigues Danieli
Biomaterials for Osseointegration and Novel Engineering Laboratory (BONE Lab), Department of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States.
Department of Orthopaedic Surgery, University of North Texas Health Science Center (UNTHSC), Fort Worth, Texas 76107, United States.
ACS Biomater Sci Eng. 2017 Oct 9;3(10):2267-2277. doi: 10.1021/acsbiomaterials.7b00276. Epub 2017 Aug 8.
Acrylic bone cements, although successful in the field of orthopedics, suffer from a lack of bioactivity, not truly integrating with surrounding bone. Bioactive fixation is expected to enhance cement performance because of the natural interlocking and bonding with bone, which can improve the augmentative potential of the material in applications such as vertebroplasty (VP). In a recent study, two composite cements (PMMA-hydroxyapatite and PMMA-brushite) showed promising results demonstrating no deterioration in rheological and mechanical properties after CaP filler addition. In this study, the dynamic properties of the cements were investigated in vitro and in vivo. The hypothesis was that these composite cements will provide osseointegration around the implanted cement and increase new bone formation, thus decreasing the risk of bone structural failure. The effects of CaP elution were thus analyzed in vitro using these cements. Mass-loss, pore formation, and mechanical changes were tracked after cement immersion in Hank's salt solution. PMMA-brushite was the only cement with a significant mass loss; however it showed low bulk porosity. Surface porosity increases were observed in both composite cements. Mechanical properties were maintained after cement immersion. In vitro culture studies tested preosteoblast cell viability and differentiation on the cement surface. Cell viability was demonstrated with MTT assay and confirmed on the cement surface. ALP assays showed no inhibition of osteoblast differentiation on the cement surface. In vivo experiments were performed using a rat tibiae model to demonstrate bone ingrowth around the implanted cements. Critical size defects were created and then filled with the cements. The animal studies showed no loss in mechanical strength after implantation and increased bone ingrowth around the composite cements. In summary, the composite cements provided bioactivity without sacrificing mechanical strength.
丙烯酸骨水泥虽然在骨科领域取得了成功，但缺乏生物活性，无法与周围骨骼真正融合。生物活性固定有望提高骨水泥性能，因为它能与骨骼自然嵌合和结合，这可以提高材料在椎体成形术（VP）等应用中的增强潜力。在最近的一项研究中，两种复合骨水泥（聚甲基丙烯酸甲酯-羟基磷灰石和聚甲基丙烯酸甲酯-透钙磷石）显示出了令人鼓舞的结果，表明添加磷酸钙填料后其流变学和力学性能没有恶化。在本研究中，对这些骨水泥的动态性能进行了体外和体内研究。假设是这些复合骨水泥将在植入的骨水泥周围实现骨整合并增加新骨形成，从而降低骨结构失效的风险。因此，使用这些骨水泥在体外分析了磷酸钙洗脱的影响。将骨水泥浸泡在汉克斯盐溶液中后，跟踪质量损失、孔隙形成和力学变化。聚甲基丙烯酸甲酯-透钙磷石是唯一一种有显著质量损失的骨水泥；然而，它的总体孔隙率较低。两种复合骨水泥的表面孔隙率均增加。骨水泥浸泡后力学性能得以保持。体外培养研究测试了前成骨细胞在骨水泥表面的活力和分化。通过MTT法证明了细胞活力，并在骨水泥表面得到证实。碱性磷酸酶分析表明骨水泥表面对成骨细胞分化没有抑制作用。使用大鼠胫骨模型进行体内实验，以证明植入骨水泥周围的骨长入情况。制造临界尺寸缺损，然后用骨水泥填充。动物研究表明，植入后力学强度没有损失，复合骨水泥周围的骨长入增加。总之，复合骨水泥在不牺牲力学强度的情况下提供了生物活性。
