Repair and regeneration of osteochondral defects in mouse articular joints

1133883在很高比例的患者中，关节软骨面和软骨下骨的损害很容易进展为关节退行性变，特别是骨关节炎，这是美国慢性残疾的主要原因。骨软骨缺损的治疗已经取得了广泛的成果，但目前还没有一种被广泛接受的方法能取得一致满意的结果。再生软骨在形态、生化、生物力学等方面均逊于原始软骨。纤维软骨不是形成关节软骨，而是正常生成，缺乏长期稳定性，不能承受对关节的长期应力。因此，需要一种性能优于当前使用的方法的新方法。在本研究中，我们建议开发一种结构和力学性能与天然软骨相似的梯度支架，将GFP记者鉴定的关节特异性软骨前体细胞负载到支架上，然后将负载细胞的支架植入新的转基因小鼠软骨模型中，以测试骨软骨的修复和再生。本研究的创新之处在于：(1)开发出一种结构、取向、组成和力学性能与天然软骨和软骨下骨相似的分级支架；(2)深入了解软骨细胞分化途径并建立其谱系关系；(3)利用一系列软骨GFP报告鉴定关节特异性软骨前体细胞；(4)开发信息丰富的转基因小鼠软骨模型，以相对较低的成本评估骨软骨修复及其与宿主组织的整合。广泛影响：拟议的项目对各种科学学科具有更广泛的影响。研究结果将有助于我们首次了解细胞-支架相互作用、软骨细胞分化途径以及宿主/供体细胞在关节软骨修复中的作用。在此获得的信息将是开发和解释组织工程策略的重要组成部分，以确定最佳支架设计和祖细胞来源，以及修复过程是由宿主还是捐赠者发起的。根据填充修复区域的单元的组成来区分修复的完整性将是修复策略成功的另一个衡量标准。这项拟议的研究将对组织工程领域产生变革，因为它直接解决了骨软骨软骨修复的现有问题，其方法可能为这些问题提供有效的解决方案。该项目将导致组织工程领域的一名研究生和一些本科生的培训，同时将他们暴露在一个多学科的工作环境中。我们将努力招募女性和少数族裔学生，将我们的研究活动与系、校和大学各级现有的招聘工作结合起来，并参加各种专业协会为代表性不足的少数群体组织的活动。此外，我们将进行K-12推广，让高中生，特别是女性和代表性不足的少数族裔，对工程研究感到兴奋。该项目取得的成果将通过在科学期刊上发表、在会议上发表以及通过网站向公众宣传等方式广泛传播。我们将确保所有数据在获奖结束后至少保存三年或在公开发布后保存三年，以较迟的为准。我们还将向组织工程界提供我们的转基因小鼠，以便更多的研究人员可以使用它们来优化他们的修复策略。

1133883WeiIn a high percentage of patients, damages to the articular cartilage surface and the underlying subchondral bone can easily progress to joint degeneration, especially osteoarthritis which is the main cause of chronic disability in US. Extensive efforts have been made in osteochondral defect treatment, but there is still no widely accepted method which produces consistent satisfactory results. The regenerated cartilage is inferior to the original cartilage morphologically, biochemically, and biomechanically. Instead of forming articular cartilage, fibrocartilage is normally generated, which lacks of the long-term stability and cannot withstand prolonged stress to the joint. Thus, there is a need for a new approach that outperforms currently used methods. In this study, we propose to develop a graded scaffold with structure and mechanical properties mimicking those of natural cartilage, load the scaffold with articular-specific chondroprogenitor cells identified by GFP reporters, and then implant the cell-loaded scaffold into a novel transgenic mouse cartilage model to test for osteochondral repair and regeneration. It is expected that an optimum cell-scaffold construct will be determined which effectively regenerates osteochondral cartilage with excellent functionality and long-term stability.Intellectual merits: The novelty of the current proposal includes: (1) the development of a graded scaffold with structure, orientation, composition and mechanical properties mimicking those of natural cartilage and subchondral bone; (2) the development of an in-depth understanding of chondrocytes differentiation pathways and establishment of their lineage interrelationships; (3) the identification of articular-specific chondroprogenitor cells using a series of cartilage GFP reporters; (4) the development of an informative transgenic murine cartilage model to assess osteochondral repair and its integration with host tissues at a relatively low cost.Broader impact: The proposed project has a broader impact on various scientific disciplines. The results of the proposed research will contribute to our understanding of the cell-scaffold interactions, chondrocyte differentiation pathways, and host/donor cell contribution to the articular cartilage restoration for the first time. The information gained here will be an essential ingredient in developing and interpreting tissue engineering strategies to determine the optimal scaffold design and source of progenitors, and whether a repair process is initiated from the host or donor. Distinguishing the completeness of the repair in terms of the composition of cells that fill the repair region will be another measure of success of a repair strategy. The proposed research will be transformative to the tissue engineering field as it directly addresses the existing problems of the osteochondral cartilage repair and its approach may provide an effect solution to these problems.This project will result in the training of a graduate student and a number of undergraduate students in areas of tissue engineering, while exposing them to a multidisciplinary working environment. Efforts will be made to recruit female and minority students by integrating our research activities with existing recruiting efforts at the Department, the School and the University levels as well as participating in activities organized by various professional societies dedicated to underrepresented minorities. In addition, we will perform K-12 outreach to get high school students, especially female and underrepresented minorities, excited about engineering research. The results obtained from the project will be disseminated broadly via publishing in scientific journals, presenting in conferences and publicizing to general public via a website. We will make sure that all data will be kept for at least three years after conclusion of the award or three years after public release, whichever is later. We will also make our transgenic mice available to the tissue engineering community so that more researchers can use them to optimize their repair strategies.