Cellular Contribution to Bone Healing

描述(申请人提供)：我的长期目标是了解在胚胎骨骼形成和成人受损骨骼修复过程中调节骨形成的细胞和分子机制。成人骨骼通过形成与邻近未受伤组织难以区分的新骨，具有显著的愈合潜力。这种成人再生过程的某些方面类似于胎儿时期的骨骼发育。然而，胎儿的发育程序与成人的再生过程存在差异，例如骨骼干细胞的来源。成人骨骼干细胞的起源及其对骨骼组织再生的细胞和分子贡献仍未得到充分认识。这项建议中概述的工作的目标是评估在骨修复过程中，位于骨膜(骨的外表面组织)和骨内膜(骨的内表面的组织)中的骨骼干细胞对膜内和软骨内成骨的不同贡献程度。 目的1通过分析造成骨膜或骨内膜损伤后不同的细胞和分子反应，比较骨膜和骨内膜的骨愈合机制。目的2将开发一种新的谱系分析方法，以确定骨膜内和软骨内成骨在愈合过程中骨膜和骨内膜的细胞贡献。这种方法将基于骨移植实验，这将使我能够在愈合过程中区分骨膜和骨内膜来源的细胞。目的3将评估骨膜和骨内膜的愈合反应在多大程度上是每个组织固有的，或者微环境是否影响细胞分化。为此，含有骨膜或骨内膜干细胞的骨移植将被异位移植，并将分析这些干细胞对骨愈合的贡献。 这些实验对于开发新的方法来阐明成骨和成软骨因子在骨骼内不同干细胞群体中的作用至关重要。这项研究将对组织工程学产生直接影响，组织工程学旨在利用干细胞与骨诱导和骨传导材料的组合来改善延迟骨折愈合和骨骼疾病的治疗。

DESCRIPTION (provided by applicant): My long-term goals are to understand the cellular and molecular mechanisms regulating bone formation during skeletogenesis in the embryo and during repair of injured bone in the adult. The adult skeleton has a remarkable potential to heal by forming new bone that is indistinguishable from adjacent, uninjured tissues. Aspects of this adult regenerative process resemble skeletal development during fetal life. However, differences exist between the fetal developmental program and the adult regenerative process, such as the sources of skeletal stem cells. The origins of adult skeletal stem cells and their cellular and molecular contributions to skeletal tissue regeneration remain under appreciated. The goal of the work outlined in this proposal is to assess the extent to which skeletal stem cells residing in the periosteum (the tissue at the outer surface of bone) and endosteum (the tissue at the inner surface of bone) contribute differently to intramembranous and endochondral ossification during bone repair. Aim 1 will compare the mechanisms of bone healing in the periosteum and endosteum, by analyzing the distinct cellular and molecular responses after creating periosteal or endosteal injuries. Aim 2 will develop a new lineage analysis approach in order to determine the cellular contribution of the periosteum and endosteum during healing via intramembranous and endochondral ossification. This approach will be based on bone grafting experiments, which will allow me to distinguish periosteal- and endosteal-derived cells during healing. Aim 3 will assess the extent to which the healing responses of the periosteum and endosteum are intrinsic to each tissue or whether the microenvironment influences cell differentiation. To do so, bone grafts containing periosteal or endosteal stem cells will be ectopically transplanted and the contribution of these stem cells to bone healing will be analyzed. These experiments will be essential to develop new approaches to elucidate the role of osteogenic and chondrogenic factors on different stem cell populations within the bone. This research will have a direct impact on tissue engineering, which aims to use combinations of stem cells with osteoinductive and osteoconductive materials to improve the treatment of delayed fracture healing and bone diseases.