Role of Angiogenesis in Distraction Osteogenesis

血管生成在牵张成骨中的作用

• 批准号: 8721340
• 负责人: Louis Charles Gerstenfeld
• 金额: $ 36.1万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8721340
• 关键词: Ablation; Address; Antibodies; BMP2 gene; Back; Belief; Blood Vessels; Bone Regeneration; Bone Tissue; Cartilage; Cell Differentiation process; Cell Line; Cells; Clinical; Coculture Techniques; Commit; Congenital Abnormality; Data; Development; Distraction Osteogenesis; Endothelial Cells; Endothelium; Excision; Extracellular Matrix; Feedback; Fracture; Galactosidase; Gene Targeting; Genes; Genetic Recombination; Growth Factor; Healed; Impaired wound healing; Injury; Laboratories; Lead; Malignant Neoplasms; Mediating; Mesenchymal Stem Cells; Modeling; Molecular; Morbidity - disease rate; Morphogenesis; Mus; Natural regeneration; Operative Surgical Procedures; Orthopedics; Osteoblasts; Osteogenesis; Osteotomy; Phase; Play; Population; Procedures; Process; Production; Proteins; Recruitment Activity; Relative (related person); Role; Site; Source; Testing; Tissues; Transgenes; Transgenic Mice; Trauma; Vascular Endothelial Growth Factor Receptor; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factor Receptor-2; Vascular Endothelial Growth Factors; Vascular Endothelium; Vascular blood supply; Work; angiogenesis; bone; bone healing; bone morphogenetic protein 2; cell growth; distraction; functional status; healing; innovation; osteogenic; paracrine; receptor-mediated signaling; regenerative; repaired; research study; selective expression; skeletal; skeletal injury; small hairpin RNA; vasculogenesis

DESCRIPTION (provided by applicant): Compromised healing of skeletal injuries is associated with increased morbidity and decreased functional status, and each year surgical orthopedic treatments are performed on over 800,000 fractures with impaired healing. Inadequate blood supply is a major cause of impaired healing in all types of orthopedic treatments. Bone morphogenetic protein 2 (BMP2) plays an essential role in promoting mesenchymal stem cell (MSC) osteogenic differentiation; while vascular endothelia growth factors (VEGFs) play crucial roles in the recruitment and differentiation of vascular endothelia cells (ECs). Currently, it is commonly accepted that BMP2 is either produced by MSCs and osteogenic cells or is proteolytically released from sequestered stores in the extracellular matrix. Our preliminary studies with transgenic mice have shown that ECs that line vessels adjacent to both fracture and osteotomy sites, and within bone repair tissues, are the main source of BMP2 at the repair site. VEGFs have also been shown to function in bone healing however, whether they act in a direct manner via receptor-mediated signaling in osteogenic cells is highly debated. Other preliminary work from our laboratory has shown that while differentiated osteoblasts abundantly express VEGF(s), exogenously added VEGF(s) neither promote MSC osteogenic differentiation nor enhance differentiated osteoblast function. Collectively, these data lead us to the following hypothesis: The development of vascular and bone tissues during post natal bone repair and regeneration is regulated through a positive paracrine feedback loop, which is established through the expression of BMP2 by ECs and VEGF expression by osteogenic cells. This hypothesis is a paradigm shift from prior general beliefs about the cell sources and functions of BMP2 and VEGF during bone repair. A murine model of distraction osteogenesis (DO) will be used to address this hypothesis. DO has three advantages for the proposed studies: a) new bone formation occurs primarily through an intramembranous process devoid of extensive cartilage; b) it is an extremely robust regenerative model capable of inducing immense amounts of highly vascularized bone tissues; c) it is successfully used in the clinical setting to treat some forms of nonunions in the absence of BMP2 treatment. Aim 1 will define the functional relationship between vessel morphogenesis and the induction of BMP2 in endothelial cells by altering vascular morphogenesis through blocking VEGFR 1 and 2 activities. Using transgenic mice containing a conditionally inducible Cre gene that is selectively expressed in endothelial cells, the development of nascent endothelial cells will be tracked within new vessels and co-localized to the cell populations that are expressing BMP2. Aim 2 will use these same transgenic mice to assess the functional role of BMP2 expression by endothelial cells in the formation of bone and vascular tissues by BMP2 gene ablation in ECs during the different phases of DO. The completion of Aims 1 and 2 will determine if ECs are a primary cell source of BMP2 in regulating skeletal healing after surgery or injury and if BMP2 has a functional role in vasculogenesis.

描述（由申请人提供）：骨骼损伤的愈合损害与发病率增加和功能状况降低有关，每年对超过800,000个骨折进行愈合受损的骨折进行了手术骨科处理。血液供应不足是所有类型的骨科治疗中愈合受损的主要原因。骨形态发生蛋白2（BMP2）在促进间充质干细胞（MSC）成骨分化方面起着至关重要的作用。而血管内皮生长因子（VEGFS）在血管内皮细胞（EC）的募集和分化中起着至关重要的作用。目前，通常认为BMP2是由MSC和成骨细胞产生的，或者是从细胞外基质中的隔离商店中蛋白水解释放的。我们对转基因小鼠的初步研究表明，与骨折和截骨切开术相邻的EC以及骨修复组织中的EC是维修部位的BMP2的主要来源。但是，VEGF还显示出在骨骼愈合中的作用，但是它们是否通过成骨细胞中受体介导的信号直接作用。我们实验室的其他初步工作表明，虽然分化成骨细胞大量表达VEGF（S），但外源添加的VEGF（s）既不促进MSC的成骨分化，也没有增强分化的成骨细胞功能。总的来说，这些数据使我们提出了以下假设：在出生后骨修复和再生过程中血管和骨骼组织的发展通过阳性旁分泌反馈回路调节，这是通过ECS和VEGF表达的表达来确定的。该假设是从先前对骨修复过程中BMP2和VEGF的细胞来源和功能的一般信念的范式转变。分散注意力的鼠模型（DO）将用于解决这一假设。 DO在提出的研究中具有三个优点：a）新骨形成主要是通过没有广泛软骨的膜内过程发生的； b）这是一个极强的再生模型，能够诱导大量高度血管化的骨组织； c）在没有BMP2治疗的情况下，在临床环境中成功使用了某些形式的骨不连。 AIM 1将通过阻断VEGFR 1和2活性来改变血管形态发生之间的血管形态发生与BMP2诱导之间的功能关系。使用在内皮细胞中选择性表达有条件诱导的CRE基因的转基因小鼠，将在新容器中跟踪新生内皮细胞的发育，并共定位于表达BMP2的细胞群体。 AIM 2将使用这些相同的转基因小鼠来评估内皮细胞在DO的不同阶段中通过ECS中BMP2基因消融在骨骼和血管组织形成BMP2表达的功能作用。目标1和2的完成将确定EC在调节手术或损伤后调节骨骼愈合以及BMP2是否在血管生成中具有功能作用时，EC是否是BMP2的主要细胞来源。