GDF Modulation of Tendon Maintenance and Repair

描述（由申请人提供）：临床上，生长因子如生长/分化因子（GDF）代表了治疗肌腱损伤的独特潜力。为了在临床环境中有效地施用这些药剂，完全理解它们在肌腱维护和修复中的作用机制是必不可少的。我们以前对GDF-5缺陷型短足症小鼠的研究表明，GDF-5缺陷导致肌腱组成、超微结构和力学行为改变，以及跟腱愈合延迟。GDF-6和GDF-7与GDF-5一起形成相关GDF蛋白的亚家族。最近，已经开发了敲除小鼠模型，其中GDF-6和GDF-7的基因已经被修饰。这两种动物模型为研究GDFs在哺乳动物中的作用提供了进一步独特的实验系统。本研究的目的是检查GDF-6和GDF-7对肌腱维护和修复的影响。了解这些蛋白质的体内作用将使该生长因子家族被考虑用于肌腱愈合的治疗用途。在第一组实验中，将检查GDF-6和GDF-7在建立正常肌腱结构和功能中的作用。将从拉伸机械测试获得来自雄性和雌性16周龄GDF-6或GDF-7缺陷型小鼠的跟腱的机械性质，并与野生型对照同窝出生小鼠进行比较。为了解释机械性能的差异，将使用分子生物学、生物化学、光学和透射电子显微镜的标准技术进行组织学、超微结构、成分和分子表征。在第二组实验中，将检查GDF-6和GDF-7在肌腱修复中的作用。将在16周龄小鼠中进行跟腱的中间物质腱切断术。将在3、5、7、9、14、28、42和84天后表征组织学、成分和分子反应。在肌腱切断术后1、2、4、6和12周检查肌腱超微结构和机械完整性。拟议的实验将提供GDF-6和GDF-7缺陷小鼠肌腱特性的必要基线表征，并阐明跟腱损伤的短期和长期愈合反应。这些研究联合收割机增强了我们对GDF在肌腱维护和修复中的作用机制的理解。

DESCRIPTION (provided by applicant): Clinically, growth factors such as the growth/differentiation factors (GDFs) represent a unique potential for the treatment of tendon injuries. To administer these agents effectively in a clinical setting, a complete understanding of their mechanisms of action in tendon maintenance and repair is essential. Our previous work on the GDF-5 deficient brachypodism mouse has demonstrated that GDF-5 deficiency results in altered tendon composition, ultrastructure and mechanical behavior, as well as a delay in Achilles tendon healing. Together with GDF-5, GDF-6 and GDF-7 form a subfamily of related GDF proteins. Recently, knockout mouse models have been developed in which the genes for GDF-6 and GDF-7 have been modified. These two animal models provide further unique experimental systems for examining the role of GDFs in mammals. The goal of this research is to examine the effects of GDF-6 and GDF-7 on tendon maintenance and repair. Understanding the in vivo roles of these proteins will allow this family of growth factors to be considered for therapeutic use in tendon healing. In the first set of experiments, the roles of GDF-6 and GDF-7 in the establishment of normal tendon structure and function will be examined. Mechanical properties of Achilles tendons from male and female 16 week-old GDF-6 or GDF-7 deficient mice will be obtained from tensile mechanical tests and compared to wild-type control littermates. To explain differences in mechanical properties, histological, ultrastructural, compositional, and molecular characterization will be performed using standard techniques of molecular biology, biochemistry, and light and transmission electron microscopy. In the second set of experiments, the roles of GDF-6 and GDF-7 in tendon repair will be examined. Mid-substance tenotomies of the Achilles tendon will be performed in 16-week-old mice. The histologic, compositional, and molecular response will be characterized after 3, 5, 7, 9, 14, 28, 42, and 84 days. Tendon ultrastructure and mechanical integrity will be examined at 1, 2, 4, 6, and 12 weeks after tenotomy. The proposed experiments will provide the necessary baseline characterization of tendon properties in GDF-6 and GDF-7 deficient mice, as well as elucidate the short and long-term healing response to Achilles tendon injury. These studies combine to enhance our understanding of the mechanisms of action of GDFs in tendon maintenance and repair.