Muscle-based Tissue Engineering to Improve Bone Healing

描述（由申请人提供）：颅面骨骼中骨缺损的不完全愈合很常见。成骨蛋白，包括骨形态发生蛋白2和4（BMP 2，-4），促进骨缺损的愈合，但是蛋白质的短半衰期和通过血流的快速清除限制了它们的效用。我们最初的R 01项目的主要目标是开发基于肌源性干细胞（MDSC）的组织工程方法，以有效地提供成骨蛋白并改善颅面骨愈合。我们要感谢NIDCR在最初资助期间的支持。我们达到并超过了原始R 01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，经基因工程改造表达BMP 2和BMP 4的MDSC向成骨谱系分化，可以改善颅骨和长骨缺损的骨愈合。我们还发现，同时表达血管内皮生长因子（VEGF）可改善植入表达BMP 2和BMP 4的MDSC后观察到的骨愈合。该DE 013420竞争性更新申请概述了旨在扩展我们的初步发现并促进MDSC临床应用开发以改善骨愈合的实验。首先，我们将研究供体小鼠的性别和年龄对MDSC的数量和成骨潜力的影响。然后，我们将确定肌肉活检的大小和来源，培养时间，激素刺激或离体循环机械应变是否会影响MDSC的数量或成骨潜力，并可能使我们能够平衡MDSC表现出的性别相关差异。这项研究对于MDSC用于自体骨组织工程应用的临床适用性是不可或缺的，这将需要从不同性别和年龄的患者中分离高度成骨细胞。接下来，我们将研究通过使用基于MDSC的组织工程技术优化骨形成和愈合的方法，包括遗传操作和可注射支架。最后，我们将使用前2个目标的结果来分离和表征具有最高成骨潜力的小鼠MDSC的人类等同物，并优化其用于骨再生和修复的用途。这项拟议的研究将提供有关MDSC的基本生物学及其用于骨愈合的重要信息，并应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.