PRECLINICAL EVALUATION OF NANOPARTICULATE MINERALIZED COLLAGEN GLYCOSAMINOGLYCAN MATERIALS IN CALVARIAL REGENERATION

项目总结/摘要 颅骨骼的缺陷经常发生在创伤、中风、癌症和先天性异常中， 严重的神经、心理、社会和职业负担。当前临床选择的局限性 对于颅骨缺损重建，例如自体骨中的组织可用性和供体部位发病率， 挤压、感染和成本等因素，为开发专门 靶向颅骨再生。尽管经过几十年的研究，当代的再生策略 由扩增的干细胞和由支架材料递送的生长因子混合物组成， 获得临床翻译，其次是手术不切实际、成本、耗时的缺点， 超生理剂量生长因子的不良反应。随着人们对 细胞外基质的指导能力，我们以前证明了细胞外基质的功效， 由纳米颗粒矿化胶原糖胺聚糖（MC-GAG）组成的基质启发材料， 无体外祖细胞扩增或外源性生长因子的大面积颅骨缺损的再生 补充。我们进一步表明，MC-GAG诱导成骨分化的机制基础， 是由于骨形态发生蛋白受体（BMPR）信号通路的自体激活。 我们以前的工作建立了MC-GAG的概念，作为一种仅材料的再生策略。然而，在这方面， 有三个问题需要进一步研究。首先，MC-GAG的哪些特性诱导 骨生成和它们可以被提炼吗？第二，使用MC是否有任何不良副作用- GAG？第三，由于脑保护在临床相关缺陷中至关重要，再生不能提供 保护，直到愈合完成，将MC-GAG表现出相同的再生量作为一个 与临床可用的可吸收材料复合用于脑保护？在目标1中，我们将确定 钙和磷酸盐诱导的信号传导和机械刚度在MC-GAG介导的 人骨髓间充质干细胞的成骨作用我们假设钙和磷酸离子信号 可能是MC-GAG上成骨分化的主要触发因素，桥接了MC-GAG与成骨细胞之间的联系。 材料、自体BMPR信号传导、基质矿化和骨愈合。在目标2中，我们将评估 MC-GAG与聚-D，L-丙交酯（PDLLA）补片的复合材料，一种临床可用的可吸收颅骨成形术 材料，在兔颅骨缺损模型中进行生物力学性能、血管分布、炎症、骨 愈合以及局部和全身安全性。我们假设MC-GAG/PDLLA复合材料将导致骨 与单独的MC-GAG相当，并且在再生过程中增加了脑保护的维度。 我们提出的研究是统一的颅骨再生技术的发展目标。当前 该提案将使我们能够了解MC-GAG和祖细胞之间的机制相互作用，以进一步 完善材料，并生成临床前安全性和性能数据，以便向FDA提交IDE申请。

PROJECT SUMMARY/ABSTRACT Defects of the cranial skeleton occur frequently in trauma, stroke, cancer, and congenital anomalies resulting in significant neurological, psychological, social, and vocational burdens. The limitations of current clinical options for cranial defect reconstruction, such as tissue availability and donor site morbidity in autologous bone and extrusion, infection, and cost in alloplastic materials, provide an impetus to develop methods that specifically target calvarial bone regeneration. Despite decades of research, contemporary regenerative strategies consisting of expanded stem cells and growth factor cocktails delivered by scaffolding materials have not attained clinical translation secondary to the drawbacks of surgical impracticality, cost, time consumption, and the untoward effects of supraphysiologic dosages of growth factors. With the increasing knowledge of the instructive capabilities of the extracellular matrix, we previously demonstrated the efficacy of an extracellular matrix-inspired material composed of nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) for regeneration of massive calvarial defects without ex vivo progenitor cell expansion or exogenous growth factor supplementation. We further showed that the mechanistic basis for MC-GAG induced osteogenic differentiation was due to an autogenous activation of the bone morphogenetic protein receptor (BMPR) signaling pathway. Our previous work established the concept of MC-GAG as a materials-only regenerative strategy. However, three questions require further investigation. First, what are the properties of MC-GAG that induce osteogenesis and can they be refined? Second, are there any untoward side effects with the usage of MC- GAG? Third, as cerebral protection is paramount in clinically relevant defects and regeneration offers no protection until healing is complete, would MC-GAG demonstrate the same amount of regeneration as a composite with a clinically available resorbable material for cerebral protection? In Aim 1, we will determine the contributions of calcium and phosphate-induced signaling and mechanical stiffness in MC-GAG-mediated osteogenesis in human mesenchymal stem cells. We hypothesize that calcium and phosphate ion signaling may be the primary triggers for osteogenic differentiation on MC-GAG, bridging the connection between the material, autogenous BMPR signaling, matrix mineralization, and bone healing. In Aim 2, we will evaluate a composite of MC-GAG with poly-D,L-lactide (PDLLA) mesh, a clinically available resorbable cranioplasty material, in a rabbit calvarial defect model for biomechanical properties, vascularity, inflammation, bone healing, and local and systemic safety. We hypothesize that MC-GAG/PDLLA composites would result in bone regeneration equivalent to MC-GAG alone and add the dimension of cerebral protection during regeneration. Our proposed studies are unified in the goal of calvarial regenerative technology development. The current proposal will allow us to understand mechanistic interactions between MC-GAG and progenitor cells to further refine the material and to generate preclinical safety and performance data for an IDE application to the FDA.