Osteoclast modulatory biomaterials for skull regeneration

项目概要/摘要 颅骨缺陷继发于创伤、中风、癌症和先天性异常， 神经、心理、社会和职业负担。颅骨成形术或颅骨成形术的当前临床选择 自体骨移植的可用性和发病率以及并发症和成本限制了重建， 异质材料这些缺点提供了一个机会，以开发方法，具体目标 颅骨再生尽管经过几十年的研究，当代再生策略包括 通过支架材料递送的扩增的干细胞和生长因子混合物尚未达到临床应用。 由于手术的不切实际性、成本、时间消耗和安全性问题，日益 细胞外基质（ECM）在细胞命运决定中的指导能力的知识提供了一个 再生的替代范例。我们证明了一种受ECM启发的材料， 纳米颗粒矿化胶原糖胺聚糖（MC-GAG）再生高达60%的矿化 没有离体祖细胞加载或外源性生长的天然颅骨的生物力学性质 因子补充。同时，MC-GAG抑制破骨细胞活化和再吸收，而不影响 破骨细胞通过直接材料与细胞相互作用提供的旁分泌骨诱导特性以及 间接诱导骨祖细胞分泌骨保护素（OPG），一种内源性抑制剂， 破骨细胞活化随着外源性OPG的加入， 破骨细胞生成增强。综合起来，这些数据提供了一个原理证明， 以时空限制方式递送的MC-GAG和OPG（MCGO）材料可能是一种潜在的 颅骨再生的材料。为了开发用于临床翻译的MCGO材料， 必须回答的问题：1。在破骨细胞中，通过与 MC-GAG？2.由于破骨细胞的吸收能力是骨的重塑和成熟所必需的， OPG应该在系统中存在多久？3. OPG应该洗脱还是锚定在材料上？回答 针对这些问题，我们通过非共价和共价结合OPG的方法制备了两种MCGO材料 产生高浓度、快速释放和低浓度、延长释放的MCGO材料， 分别在目的1中，我们将阐明MC-GAG诱导的抗破骨细胞生成机制， MCGO材料。我们假设MC-GAG和两种MCGO材料对hOC的影响不同 活化和再吸收。在目标2中，我们将在家兔中评价两种MCGO材料与MC-GAG的比较 颅骨再生，以生成MCGO材料的临床前有效性、安全性和性能数据 与MC-GAG相比。我们提出的研究是统一的目标颅骨再生技术 发展在拟议的研究结束时，我们预计将积累大量的临床前研究， 支持MCGO材料向FDA提交IDE申请的数据。

PROJECT SUMMARY/ABSTRACT Skull defects occur secondary to trauma, stroke, cancer, and congenital anomalies resulting in significant neurological, psychological, social, and vocational burdens. Current clinical options for cranioplasty, or calvarial reconstruction, are limited by availability and morbidity in autologous bone grafts and complications and cost in alloplastic materials. Such drawbacks provide an opportunity 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 due to surgical impracticality, cost, time consumption, and safety concerns. The increasing knowledge of instructive capabilities of the extracellular matrix (ECM) in cell fate determination has provided an alternative paradigm for regeneration. We demonstrated that an ECM-inspired material composed of nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) regenerates up to 60% the mineralization and biomechanical properties of native calvarium without ex vivo progenitor cell loading or exogenous growth factor supplementation. Simultaneously, MC-GAG inhibits osteoclast activation and resorption without affecting the paracrine osteoinductive properties offered by osteoclasts via direct material to cell interactions as well as indirectly by inducing osteoprogenitors to secrete osteoprotegerin (OPG), an endogenous inhibitor for osteoclast activation. With the addition of exogenous OPG, this uncoupling of osteogenesis from osteoclastogenesis is augmented. In combination, these data provided a proof of principle that a composite material of MC-GAG and OPG (MCGO) delivered in a temporospatially-limited manner may be a potential material for calvarial regeneration. In order to develop the MCGO material for clinical translation, three questions must be answered: 1. What are the mechanisms activated in osteoclasts by direct interactions with MC-GAG? 2. As the resorptive abilities of osteoclasts are necessary for remodeling and maturation of bone, how long should OPG exist in the system? 3. Should OPG be eluted or anchored to the material? To answer these questions, we have developed two MCGO materials via non-covalent and covalent incorporation of OPG resulting in a high concentration, fast release and a low concentration, extended release MCGO material, respectively. In Aim 1, we will elucidate the anti-osteoclastogenic mechanisms induced by MC-GAG and MCGO materials. We hypothesize that MC-GAG and the two MCGO materials will differentially affect hOC activation and resorption. In Aim 2, we will evaluate the two MCGO materials compared to MC-GAG in rabbit calvarial regeneration to generate preclinical efficacy, safety, and performance data for MCGO materials compared to MC-GAG. Our proposed studies are unified in the goal of calvarial regenerative technology development. At the conclusion of the proposed studies, we expect to have amassed significant preclinical data to support an IDE application for MCGO materials to the FDA.