MECHANISMS & ENHANCEMENT OF INTEGRATIVE CARTILAGE REPAIR

用于关节软骨修复或再生的组织工程疗法通常涉及单独移植细胞、将细胞移植到工程支架内或含有细胞的组织。一个主要的未解决的问题是植入物和宿主关节软骨之间的不一致的整合。该项目的长期目标是发展对导致综合软骨修复的细胞和分子过程的定量理解，并将此信息应用于改善医疗，手术和物理疗法，以刺激成功的软骨愈合。我们的工作一般假设是：功能性整合修复可以由软骨表面的局部事件序列引起，包括：（a）胶原纤维的分子组分和调节纤维形成的分子的细胞生物合成，（B）这些分子的协调细胞外沉积和纤维胶原网络的相关重塑。这个假设的一个推论是：移植的软骨细胞可以介导和加速这一过程，如果这些细胞保持粘附在缺损部位，并提供适当的分子产物。我们最近的研究（i）涉及内源性软骨细胞的胶原蛋白生物合成，以及随后的胶原蛋白沉积和交联，作为体外牛软骨的并置表面之间发生的适度生物力学整合的关键因素，（2）开发了一种将软骨细胞定量移植到软骨表面上的方法，从而在软骨-软骨界面处提供代谢活性细胞，以及（3）开发了一种表征软骨细胞向关节软骨的粘附的系统（例如，周围的宿主组织）。我们现在要检验两个具体的假设。(i)移植的软骨细胞粘附于关节软骨的能力取决于软骨基质基质与移植细胞的表面受体或预形成的细胞周基质之间的相互作用程度。(2)内源性和移植的软骨细胞在体外促进关节软骨整合修复的能力取决于它们局部存款分子的能力，这些分子有助于胶原网络的重塑。提出的方法包括：（a）将生物力学功能与特定分子的代谢联系起来，（B）进行定量测量以表征胶原蛋白的合成、扩散和交联，以及（c）研究具有潜在临床实用性的操作并提供对潜在分子机制的深入了解。

Tissue engineering therapies for repair or regeneration of articular cartilage typically involve grafting cells alone, cells within engineered scaffolds, or tissues containing cells. A major unresolved problem is the inconsistent integration between the implant and the host articular cartilage. The long- term goal of this project is to develop a quantitative understanding of cellular and molecular processes leading to integrative cartilage repair and to apply this information to improve medical, surgical, and physical therapies for stimulating successful cartilage healing. Our working general hypothesis is: functional integrative repair can result from a local sequence of events at a cartilage surface that includes: (a) cellular biosynthesis of molecular components of collagen fibrils and molecules that regulate fibrillogenesis, (b) coordinated extracellular deposition of these molecules and associated remodeling of the fibrillar collagen meshwork. A corollary of this hypothesis is: transplanted chondrocytes can mediate and accelerate this process if these cells remain adherent at the defect site and contribute appropriate molecular products. Our recent studies (i) implicated collagen biosynthesis by endogenous chondrocytes, and subsequent deposition and crosslinking of collagen, as critical factors for the modest biomechanical integration that occurs between apposing surfaces of bovine cartilage in vitro, (2) developed a method to transplant chondrocytes quantitatively onto a cartilage surface and thereby provide metabolically active cells at a cartilage-cartilage interface, and (3) developed a system to characterize adhesiveness of chondrocytes to articular cartilage (e.g., the surrounding host tissue). We now propose to test two specific hypotheses. (i) The ability of transplanted chondrocytes to adhere to articular cartilage depends on the extent of interactions between the cartilage matrix substrate and the surface receptors or pre-formed pericellular matrix of the transplanted cells. (2) The ability of endogenous and transplanted chondrocytes to promote integrative repair of articular cartilage in vitro depends on their ability to locally deposit molecules that contribute to remodeling of the collagen meshwork. The approaches proposed include (a) relating biomechanical function to the metabolism of specific molecules, (b) making quantitative measurements to characterize collagen synthesis, diffusion, and crosslinking, and (c) investigating manipulations that are of potential clinical utility and provide insight into underlying molecular mechanisms.