Incorporation of Dexamethasone Delivery within Engineered Cartilage

项目总结 对于成熟的透明关节，修复较大的缺损区(2平方厘米至半髁)的能力 在软骨和解决潜在骨缺损的单一程序中使同种异体骨软骨移植 移植是一个有吸引力的选择。适当的大小和表面轮廓可以匹配时，移植物 从适当选择的器官捐赠者那里获得。成熟的软骨细胞可以在移植后存活多年 未经免疫抑制治疗的移植。由于没有足够的合适的软骨移植来 满足临床需求的组织工程化骨软骨移植的发展和策略 促进其在关节中的成功应用，将对局部的治疗产生重大的临床影响。 软骨损伤(本提案中的焦点)和整个关节表面(未来将解决)。 来自动物研究和早期临床试验的数据表明，关节内早期抑制 膝关节创伤后的炎症反应(如4周)可能会改善临床结果。 我们团队的研究描绘了地塞米松(Dex)，一种合成的糖皮质激素，具有促合成代谢和 软骨组织工程体系中的抗分解作用--软骨培养的关键要素 具有天然特性的组织，以及对炎性细胞因子提供软骨保护。就像这些 可能影响软骨组织工程策略临床成功的因素，Dex是FDA- 我们被批准并在临床上用于减轻疼痛和炎症，我们试图开发一种策略来使这些 组织培养结果更具有临床相关性。从我们的角度来看，理想的方法将保留这些好处 地塞米松对工程软骨的作用而不需要其外源性补充，如临床注射 关节中大量的类固醇激素与负面副作用有关。 在这项新的R01拨款中，我们建议加入地塞米松补充的聚丙交酯-乙交酯 (PLGA)微球进入细胞种子水凝胶构建物作为一种从工程体内传递地塞米松的方法 软骨。我们提供的初步数据表明，地塞米松从PLGA微球体内释放 加入软骨细胞种子水凝胶构建物促进机械功能软骨的生长 组织和给予细胞因子保护的方式类似于在外部补充的地塞米松 文化媒体。我们的团队证实了地塞米松微球对脂肪组织的体内疗效 工程应用。通过本地化的Dex交付，这些好处可以通过使用以下集中实现 比临床注射给药低一个数量级。在这一前景的基础上再接再厉 发现并进一步实现这一基于细胞的软骨修复策略的临床翻译潜力， 我们提出了以下全球假设：加入从内部释放地塞米松的聚合物微球 细胞种子水凝胶构建物将保护构建物免受细胞因子暴露和 在炎症环境中改善软骨修复。

PROJECT SUMMARY The ability to resurface larger defects (>2cm2 up to a hemicondyle) with mature hyaline articular cartilage and address the underlying bone deficit in a single procedure makes osteochondral allograft transplantation an attractive option. The appropriate size and surface contour can be matched when the graft is obtained from an appropriately selected organ donor. Mature chondrocytes can survive for many years post- transplantation without immunosuppressive therapy. As there is insufficient supply of suitable cartilage grafts to meet the clinical demand, the development of tissue engineered osteochondral grafts and strategies to promote their successful application in the joint would have significant clinical impact for treatment of localized cartilage lesions (of focus in this proposal) and whole joint surfaces (to be addressed in the future). Data from animal studies and early clinical trials suggest that early inhibition of the intra-articular inflammatory response (e.g., 4 weeks) posttraumatic injury of the knee may improve clinical outcomes. Research from our team portrays dexamethasone (dex), a synthetic glucocorticoid that has pro-anabolic and anti-catabolic effects in cartilage tissue engineering systems, as a critical element for cultivating cartilage tissues with native properties, as well as for providing chondroprotection to inflammatory cytokines. As these factors are likely to impact the clinical success of cartilage tissue engineering strategies, and dex is FDA- approved and used clinically to reduce pain and inflammation, we sought to develop a strategy to make these tissue culture findings more clinically relevant. From our perspective, an ideal method would retain the benefits of dex on engineered cartilage without the requirement for its exogenous supplementation, as clinical injections of steroids in the joint have been associated with negative side effects. In this new R01 grant, we propose the incorporation of dex-supplemented, poly(lactide-co-glycolide) (PLGA) microspheres into cell-seeded hydrogel constructs as a means for dex delivery from within engineered cartilage. We present preliminary data demonstrating that dex release internally from PLGA microspheres incorporated in chondrocyte-seeded hydrogel constructs promotes growth of mechanically functional cartilage tissue and confers cytokine protection in a manner akin to that observed with dex externally supplemented in culture media. In vivo efficacy of dex-microspheres has been confirmed by our team for adipose tissue engineering applications. With localized dex delivery, these benefits were achievable using concentrations that are orders of magnitude lower than adopted for clinical administration by injection. To build on this promising finding and to further realize the potential for clinical translation of this strategy for cell-based cartilage repair, we pose the following global hypothesis: Incorporation of polymer microspheres that release dex from within cell-seeded hydrogel constructs will protect constructs from the deleterious effects of cytokine exposure and improve cartilage repair in an inflammatory environment.