RECOMBINANT BMP AND BONE FORMATION

骨形成受全身激素和局部生长因子的调节 其影响骨细胞复制和分化。骨 形态发生蛋白（BMP）是骨诱导蛋白， 最初通过在脱矿骨提取物中的存在来鉴定。 至少有六个相关的家庭成员已被确定， 分子克隆，并被称为BMP-2至BMP-7。这些分子 基于一级氨基酸序列的TGF β超家族的一部分 同源性（罗森和Thies，1992）。骨形成蛋白具有骨诱导性 性质，并能够诱导新软骨的形成， 当异位植入啮齿动物试验系统或与 体内骨折愈合模型。 据推测，成骨细胞是从一个多潜能的基质， 骨髓中的干细胞本研究计划的目的是 为了确定将BMP基因（即BMP-2）引入 骨髓基质细胞将1）将基质细胞转化为 骨祖细胞，2）证明存在自分泌环 通过激活内源性BMP基因来制备BMP。 初步实验 在这项拟议的研究中，将检查BMP对生长的影响， 以及基质细胞和成纤维细胞在体外培养中的分化 系统各种连续的基质细胞系和成纤维细胞系将被 测试.这些细胞系将被含有BMP-2的逆转录病毒感染 vector. 如果培养研究成功，则可进行测试 这些概念在体内啮齿动物骨折模型中。这些差异化 基质和成纤维细胞系，其可以提供持续的局部 在骨折部位产生的BMP将用于愈合骨 缺损这项研究将增加我们对这种关系的理解 TGF-β超家族与骨生长和发育之间的关系， 骨折修复

Bone formation is regulated by systemic hormones and local growth factors which influence bone cell replication and differentiation. The bone morphogenetic proteins (BMP) are osteoinductive proteins which were originally identified by their presence in extracts of demineralized bone. At least six related members of this family have been identified by molecular cloning and are called BMP-2 through BMP-7. These molecules are part of the TGFbeta superfamily based on primary amino acid sequence homology (Rosen and Thies, 1992). The BMPs possess osteoinductive properties and are capable of inducing the formation of new cartilage and bone when implanted ectopically in a rodent assay system or when used with in vivo fracture healing models. It is hypothesized that osteoblasts develop from a multi-potential stromal stem cell in the bone marrow. The objective of this research proposal is to determine if the introduction of the gene for BMP (i.e. BMP-2) into bone marrow stromal cells will 1) transform the stromal cells into osteoprogenitor cells, 2) demonstrate the presence of an autocrine loop for BMP by activation of an endogenous BMP gene. The initial experiments in this proposed study would examine the influence of BMP on the growth and differentiation of stromal and fibroplastin, cells in an vitro culture system. Various continuous stromal cell lines and fibroblast lines will be tested. These cell lines will be infected by a BMP-2 containing retroviral vector. If the culture studies are successful it would then be appropriate to test these concepts in an in vivo rodent fracture model. These differentiated stromal and fibroplastin cell lines which can provide sustained local production of BMP at the fracture site will be employed to heal a bone defect. This research will increase our understanding of the relationship between the TGF-beta superfamily and bone growth and development and fracture repair.