Evaluating the role of immunomodulation in synergizing BMP-induced bone repair

项目摘要 骨形态发生蛋白(BMPs)的使用显示出改善骨修复的治疗前景； 然而，需要较高的超生理浓度才能达到预期的骨诱导效果、成本和 患者的多样性阻碍了以骨形态发生蛋白为基础的疗法的全部优势的实现。因此， 临床上有必要开发新的骨组织工程方法，以促进在 降低BMP剂量，防止不良副作用。健康的骨骼形成和重塑需要精致的 骨骼(如成骨细胞)和免疫(如破骨细胞、巨噬细胞等)之间的平衡单元格，即 在开发新的骨再生疗法时经常被忽视。为了解决这些限制，我们 建议使用免疫调节微粒促进骨形态发生蛋白诱导的骨修复。在蛋白质分解方面- 可降解的透明质酸水凝胶将用于共同传递BMP2和免疫调节微粒 通过细胞介导的水凝胶降解。对于免疫调节微粒，我们设计了新颖的 聚(α-酮戊二酸)微粒(paKG-MPS)，可持续释放α-酮戊二酸(AKG) 在水解性降解时。已知AKG同时调节成骨细胞和破骨细胞的行为。此外， PAKG MPS是高度可调的，能够精确控制AKG的释放动力学。在这个项目中，能够 PAKG MPS促进BMP诱导的成骨作用将在体外和体内进行研究。我们假设 持续的AKG传递将能够控制成骨细胞和破骨细胞信号之间的平衡， 从而增加成骨和骨形成。拟议的工作将通过 目的：(1)研制复合缓释BMP2和AKG的透明质酸水凝胶； (2)评价AKG对a)体外细胞行为和b)体内骨修复的影响。一系列 将测试微粒浓度，以优化AKG的输送。在体外，细胞的行为将通过 活性、增殖、代谢组学、分化(即成骨细胞和破骨细胞标记物)和矿物质 形成和吸收。活体骨修复将使用临界大小的颅骨缺损大鼠模型进行评估。

Project Summary The use of bone morphogenetic proteins (BMPs) shows promise as therapeutics for improving bone repair; however, high supraphysiological concentrations required for the desired osteoinductive effect, costs, and patient variability have prevented the full advantages of BMP-based therapeutics from being realized. Thus, there is a clinical need to develop new bone tissue engineering approaches that promote osteogenesis at lower BMP doses and prevent adverse side effects. Healthy bone formation and remodeling requires a delicate balance between skeletal (e.g. osteoblasts) and immune (e.g. osteoclasts, macrophages, etc.) cells, which is often overlooked when developing new bone regeneration therapeutics. To address these limitations, we propose the use of immunomodulatory microparticles to enhance BMP-induced bone repair. Proteolytically- degradable hyaluronic acid hydrogels will be used to co-deliver BMP2 and immunomodulatory microparticles via cell-mediated hydrogel degradation. For the immunomodulatory microparticles, we have designed novel poly(alpha-ketoglutarate) microparticles (paKG MPs), which sustainably release alpha-ketoglutarate (aKG) upon hydrolytic degradation. aKG is known to regulate both osteoblast and osteoclast behavior. Furthermore, paKG MPs are highly tunable, enabling precise control over aKG release kinetics. In this project, the ability of paKG MPs to enhance BMP-induced osteogenesis will be investigated in vitro and in vivo. We hypothesize sustained aKG delivery will enable control over the balance between osteoblast and osteoclast signaling, leading to increased osteogenesis and bone formation. The proposed work will be accomplished through the following aims: (1) Develop hyaluronic acid hydrogels with combined, sustained delivery of BMP2 and aKG; and (2) Evaluate the effect of aKG on a) in vitro cell behavior and b) in vivo bone repair. A range of microparticle concentrations will be tested to optimize aKG delivery. In vitro cell behavior will be evaluated via viability, proliferation, metabolomics, differentiation (i.e. osteoblast and osteoclast markers), and mineral formation and resorption. In vivo bone repair will be assessed using a critical-sized cranial defect rat model.