Laboratory of Immune Regulation and Tissue Engineering, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90089, USA.
Tissue Eng Part A. 2011 Dec;17(23-24):2911-8. doi: 10.1089/ten.tea.2010.0584. Epub 2011 Aug 26.
Bone regeneration often requires harvesting of autologous bone with significant potential morbidity and cost. Recombinant human bone morphogenetic protein (rhBMP)-2 has been approved by the U.S. Food and Drug Administration for specific regenerative indications. However, administration of exogenous growth factors has many drawbacks. The objective of the present proof-of-concept study was to determine whether immobilized anti-BMP-2 antibodies (Abs) could capture endogenous BMP-2 in local sites to mediate osteogenesis, a strategy we refer to as antibody-mediated osseous regeneration (AMOR). We have generated a murine anti-BMP-2 monoclonal antibody library, which was tested along with commercially available Abs in vitro and in vivo for their ability to mediate AMOR. In vitro studies demonstrated that only some anti-BMP-2 Abs tested formed immune complexes with BMP-2, which can bind to BMP cellular receptor, whereas other BMP-2/anti-BMP-2 complexes failed to bind. To investigate whether anti-BMP-2 Abs were able to mediate AMOR in vivo, anti-BMP-2 Abs were immobilized on absorbable collagen sponge (ACS) and surgically placed in rat calvarial defects. Microcomputed tomography analysis of live animals at 2, 4, and 6 weeks demonstrated that some anti-BMP-2 Abs immobilized on ACS mediated significant bone regeneration, whereas other clones did not mediate any bone regeneration. In situ BMP-2 and osteocalcin expression was investigated by immunohistochemistry. Results demonstrated higher BMP-2 and osteocalcin expression in sites with increased bone regeneration. Results provide first evidence for the ability of anti-BMP2 Abs to form an immune complex with endogenous BMP-2 and mediate bone regeneration in vivo, suggesting a promising therapeutic method for tissue engineering.
骨再生通常需要采集自体骨，这具有很大的潜在发病率和成本。重组人骨形态发生蛋白（rhBMP-2）已被美国食品和药物管理局批准用于特定的再生适应症。然而，外源性生长因子的给药有许多缺点。本概念验证研究的目的是确定固定化抗 BMP-2 抗体（Abs）是否可以在局部捕获内源性 BMP-2 以介导成骨作用，我们将这种策略称为抗体介导的骨再生（AMOR）。我们已经生成了一个抗 BMP-2 单克隆抗体文库，该文库与市售的 Abs 一起在体外和体内进行了测试，以评估它们介导 AMOR 的能力。体外研究表明，只有一些测试的抗 BMP-2 Abs 与 BMP-2 形成免疫复合物，该复合物可以与 BMP 细胞受体结合，而其他 BMP-2/抗 BMP-2 复合物则不能结合。为了研究抗 BMP-2 Abs 是否能够在体内介导 AMOR，将抗 BMP-2 Abs 固定在可吸收胶原海绵（ACS）上，并通过手术植入大鼠颅骨缺损中。在 2、4 和 6 周时对活体动物进行微计算机断层扫描分析表明，一些固定在 ACS 上的抗 BMP-2 Abs 介导了显著的骨再生，而其他克隆则没有介导任何骨再生。通过免疫组织化学研究了原位 BMP-2 和骨钙素的表达。结果表明，在骨再生增加的部位，BMP-2 和骨钙素的表达更高。结果首次提供了抗 BMP-2 Abs 与内源性 BMP-2 形成免疫复合物并在体内介导骨再生的能力的证据，为组织工程提供了一种有前途的治疗方法。
