Local Delivery of Neurogenic Factors via Polymeric Microparticles for Enhanced Endochondral Bone Repair in the Mandible

通过聚合物微粒局部递送神经源性因子以增强下颌骨软骨内骨修复

• 批准号: 9895427
• 负责人: Kevin Omar Rivera
• 金额: $ 4.01万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-01 至 2021-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9895427
• 关键词: Accelerated Phase; Accounting; Acute; Address; Adopted; Affinity; Applications Grants; Biocompatible Materials; Biological; Biological Assay; Biological Availability; Biomechanics; Bone Density; Bone Development; Bone Regeneration; Bone callus; Cartilage; Chondrocytes; Clinical; Clinical Trials; Communication; Coupled; Data; Dependence; Development; Drug Delivery Systems; Engineering; Erinaceidae; Esthetics; Fellowship; Food; Fracture; Fracture Healing; Goals; Grant; Harvest; Histology; Image; Impaired healing; In Vitro; Injectable; Injury; Invaded; Kinetics; Life; Ligands; Link; Mandible; Mandibular Fractures; Mastication; Measures; Mediator of activation protein; Methods; Molecular; Mus; NGFR Protein; Natural regeneration; Nerve Growth Factors; Neurotrophic Tyrosine Kinase Receptor Type 1; Operative Surgical Procedures; Osteoblasts; Osteogenesis; Outcome Measure; Painless; Pathway interactions; Patients; Peripheral Nerves; Phenotype; Physiologic Ossification; Polyethylene Glycols; Polymers; Prevalence; Process; Proteins; Publishing; Regulation; Role; Signal Transduction; System; Technology; Testing; Therapeutic; Tissues; Transgenic Mice; Translating; United States; Vascular Endothelial Cell; Western Blotting; Work; aggrecan; angiogenesis; base; beta catenin; bicinchoninic acid; bone; bone strength; cartilaginous; cell type; chondrocyte stimulating factor; clinically relevant; controlled release; cost effective; craniofacial bone; crosslink; density; effective therapy; experimental study; facial disfigurement; functional outcomes; healing; in vivo; maxillofacial; microCT; mineralization; mutant; neurotransmission; neurovascular; new therapeutic target; novel therapeutic intervention; oral communication; premature; prevent; repaired; sample fixation; transdifferentiation; treatment response

Project Summary/Abstract There are approx. 15 million bone fractures annually and the mandible sustains the vast majority of craniofacial bone fractures. Currently clinical approaches, such as maxillofacial fixation, are exceedingly invasive and the prevalence of impaired healing remains. Therefore, the objective of this grant is to address the clinical need for a translational and clinically relevant approach to mandibular fractures. Accomplishing this goal requires cross- disciplinary methods that harness expertise in biomaterials and drug delivery coupled with an understanding of the mechanisms that drive functional bone repair. The mandible primarily heals through endochondral ossification, in which a cartilage intermediate forms and is later replaced by bone. In recent years, many groups, including ours, have published significant evidence to show that chondrocytes transdifferentiate into osteoblasts during bone development and fracture healing. The mechanisms underlying chondrocyte transdifferentiation have thus far not been thoroughly explored. However, my preliminary data, along with previously published work, indicate that β-catenin signaling is a critical mediator of chondrocyte-derived osteoblastogenesis. Activation of β-catenin by NGF/TrkA signaling has been observed in various cell types and interestingly; our preliminary data show an increase in NGF and TrkA expression in fracture calluses. Finally, our preliminary data show that NGF administration onto fractures during the cartilaginous phase accelerates bone repair. During this fellowship I aim to understand the role of NGF in chondrocyte transdifferentiation, and develop a therapeutic delivery system for local and sustained release of a “painless” NGF, NGFR100W. The central hypothesis for this project is that sustained release of NGFR100W via PEGDMA microparticles will accelerate endochondral fracture healing by activating β-catenin signaling in hypertrophic chondrocytes. In the first Aim I will build on our preliminary data of enhanced bone repair in NGF-treated mice by engineering NGFR100W-eluting PEGDMA microparticles to accelerate healing. NGFR100W-loaded PEGDMA microparticles will be injected percutaneously onto fracture calli followed by assessment of tissue composition, biomechanical strength, and rate of healing by using histology, microCT imaging, three-point bending tests, and stereology. In the second Aim, I will determine the mechanism by which NGF stimulates osteogenesis. I will use an ex vivo system of fracture callus-derived cartilage cultured with NGF to measure downstream markers of osteogenesis, angiogenesis, and candidate pathways including β-Catenin, Sox2, and hedgehog by RT-qPCR and western blot. In vivo I will conditionally delete TrkA from chondrocytes by crossing the TrkAfl/fl and aggrecan-CreER transgenic mice to test if NGF is required for chondrocyte transdifferentiation during fracture healing using the same functional outcome measures described in Aim 1.

项目总结/摘要 有大约每年有1500万人骨折，下颌骨支撑着绝大多数的颅面 骨折目前的临床方法，如颌面固定，是非常侵入性的， 愈合受损的普遍性仍然存在。因此，该补助金的目的是解决临床需求， 下颌骨骨折的平移和临床相关方法。要实现这一目标，需要跨... 利用生物材料和药物输送方面的专业知识， 驱动功能性骨修复的机制。下颌骨主要通过软骨内愈合 骨化，其中软骨中间体形成，随后被骨取代。近年来不少 包括我们在内的研究小组已经发表了重要的证据，表明软骨细胞转分化为 成骨细胞在骨发育和骨折愈合过程中的作用。软骨细胞的作用机制 转分化迄今尚未被彻底研究。然而，我的初步数据，沿着 先前发表的工作表明，β-连环蛋白信号是软骨细胞源性 成骨细胞生成已经在各种细胞类型中观察到通过NGF/TrkA信号传导激活β-连环蛋白， 有趣的是，我们的初步数据显示骨折骨痂中NGF和TrkA表达增加。最后， 我们的初步数据显示，在软骨形成阶段， 骨修复在此期间，我的目标是了解神经生长因子在软骨细胞转分化的作用， 开发一种局部和持续释放“无痛”神经生长因子的治疗输送系统，NGFR 100 W。的 该项目的中心假设是通过PEGDMA微粒持续释放NGFR 100 W将 通过激活肥大软骨细胞中的β-catenin信号促进软骨内骨折愈合。 在第一个目标中，我将建立在我们的初步数据上，即通过工程技术增强经NGF治疗的小鼠的骨修复。 NGFR 100 W洗脱PEGDMA微粒加速愈合。NGFR 100 W-负载的PEGDMA微粒将 将其注射到骨折骨痂上，然后评估组织成分、生物力学 通过使用组织学、microCT成像、三点弯曲试验和体视学来评估强度和愈合率。 在第二个目标中，我将确定神经生长因子刺激成骨的机制。我将使用体外 用NGF培养的骨折骨痂衍生软骨系统，以测量 骨生成、血管生成和候选途径，包括β-连环蛋白、Sox 2和hedgehog（通过RT-qPCR） 和western blot在体内，I将通过使TrkAfl/fl和TrkA/fl交叉而从软骨细胞中有条件地缺失TrkA。 聚集蛋白聚糖-CreER转基因小鼠，以测试骨折期间软骨细胞转分化是否需要NGF 使用目标1中描述的相同功能结局指标进行愈合。