Muscle-based Tissue Engineering to Improve Bone Healing

描述(由申请人提供)：颅面骨骼骨缺损的不完全愈合是常见的。成骨蛋白，包括骨形态发生蛋白2和4(BMP2，-4)，可促进骨缺损的愈合，但其短暂的半衰期和血流的快速清除限制了它们的应用。我们最初的R01项目的主要目标是开发基于肌肉来源干细胞(MDSCs)的组织工程方法，以有效地运送成骨蛋白并改善颅面骨愈合。我们要感谢NIDCR在最初筹资期间提供的支持。我们达到并超过了最初R01申请中的所有关键目标，我们的结果构成了24篇论文和52篇摘要的基础。我们证明，通过基因工程表达BMP2和BMP4的MDSCs向成骨方向分化，可以促进颅骨和长骨缺损处的骨愈合。我们还发现，同时表达血管内皮生长因子(VEGF)可以改善BMP2和BMP4表达的MDSCs植入后的骨愈合。这份DE013420竞争性更新申请概述了旨在扩大我们的初步发现并促进MDSCs临床应用的开发以改善骨骼愈合的实验。首先，我们将考察供鼠的性别和年龄对MDSCs数量和成骨能力的影响。然后我们将确定肌肉活检的大小和来源、培养时间、激素刺激或体外循环机械应变是否影响MDSCs的数量或成骨潜力，并可能使我们能够抵消MDSCs表现出的性别差异。这项研究对于MDSCs在自体骨组织工程中的临床应用是不可或缺的，这将需要从不同性别和年龄的患者中分离出高度成骨的细胞。下一步/我们将研究通过使用基于MDSC的组织工程技术来优化骨形成和愈合的方法，包括基因操作和可注射支架。最后，我们将使用前两个目标的结果来分离和鉴定具有最高成骨潜力的人类MDSCs，并优化其在骨再生和修复中的使用。这项拟议的研究将提供有关MDSCs的基本生物学及其用于骨愈合的重要信息，并将促进骨缺陷临床治疗的发展。

DESCRIPTION (provided by applicant): Incomplete healing of bone defects in the craniofacial skeleton is common. Osteogenic proteins, including bone morphogenetic protein 2 and 4 (BMP2, -4), promote healing in bone defects, but the proteins' short half-lives and rapid clearance by the bloodstream limit their utility. The main goal of our initial R01 project was the development of tissue engineering approaches, based on muscle-derived stem cells (MDSCs), to efficiently deliver osteogenic proteins and improve craniofacial bone healing. We would like to thank NIDCR for their support during the initial funding period. We met and exceeded all the key objectives in the original R01 application, and our results formed the basis for 24 papers and 52 abstracts. We demonstrated that MDSCs genetically engineered to express BMP2 and BMP4 differentiate toward an osteogenic lineage and can improve bone healing in calvarial and long bone defects. We also found that concomitant expression of vascular endothelial growth factor (VEGF) improves the bone healing observed after implantation of BMP2-and BMP4-expressing MDSCs. This DE013420 competitive renewal application outlines experiments designed to extend our initial findings and facilitate the development of clinical applications of MDSCs to improve bone healing. First, we will examine the effect of the sex and age of donor mice on the number and the osteogenic potential of MDSCs. We will then determine if muscle biopsy size and source, time of culturing, hormonal stimulation, or ex vivo cyclic mechanical strain influence the number or osteogenic potential of MDSCs and might enable us to counterbalance sex-related differences exhibited by MDSCs. This research is integral to the clinical applicability of MDSCs for autologous bone tissue engineering applications, which will necessitate the isolation of highly osteogenic cells from patients of different sexes and ages. Next/we will investigate ways to optimize bone formation and healing by using MDSC-based tissue engineering techniques, including genetic manipulation and injectable scaffolds. Finally, we will use the results from the first 2 aims to isolate and characterize the human equivalents of the mouse MDSCs with the highest osteogenic potential and optimize their use for bone regeneration and repair. The proposed study will provide important information regarding the basic biology of MDSCs and their use for bone healing and should foster the development of clinical treatments for osseous deficiencies.