Identification of Muscle-Derived Soluble and Mechanical Cues to Direct Differenti

描述(申请人提供)：肌腱愈合能力差，断裂时需要手术修复。移植物充满了从失败到供体部位发病率等一系列问题，这促使基于干细胞的组织工程策略用于组织替换。然而，细胞向肌腱谱系(肌腱发生)的分化一直是具有挑战性的，部分原因是对肌腱的发育缺乏了解。发育生物学研究表明，肌肉在肌腱胚胎发生中起着重要作用，但其作用机制尚不清楚，因为在复杂的活体环境中很难研究肌肉组织各自的物理(机械)和可溶性信号因子的影响。我们的目标是识别和表征肌肉细胞产生的可溶的和机械的张力发生线索，以指导肌腱发生。我们假设，肌肉细胞分泌的可溶性因子，作为其发育阶段的函数，将在体外调节TPC的肌腱形成，并且这一过程将通过动态机械刺激而增强。使用一个独特的体外共培养系统，我们将表征肌肉细胞分泌的可能的可溶性因子及其潜在的张力形成作用(目标1)，并通过研究TGF22作为模型可溶性因子来研究机械负荷增强化学调节的可能性(目标2)。这项研究的结果随后将被转化为未来的研究，通过受控应用这些影响来开发基于间充质干细胞的再生策略。我们的长期目标是利用发育生物学作为动力和指导，开发基于间充质干细胞的新策略，以再生新组织来取代受伤或患病的肌腱和韧带。这一研究成果将极大地促进对肌腱发育生物学的了解，有助于确定合理的可溶性因子剂量和祖细胞分化的机械载荷参数，并导致利用间充质干细胞工程肌腱的先进策略。

DESCRIPTION (provided by applicant): Tendons have poor healing ability and require surgical repair with grafts when ruptured. The grafts are fraught with problems ranging from failure to donor site morbidity, motivating stem cell-based tissue engineering strategies for tissue replacement. However, differentiation of cells toward the tendon lineage (tenogenesis) has been challenging due in part to a poor understanding of tendon development. Developmental biology studies have demonstrated that muscle plays a significant role in tendon embryogenesis, though the mechanisms of its contributions are not well understood because the respective physical (mechanical) and soluble signaling factor influences of muscle tissue have been difficult to study in a complex in vivo environment. Our objective is to identify and characterize muscle cell-produced soluble and mechanical tenogenic cues to direct tenogenesis. We hypothesize that soluble factors secreted by muscle cells, as a function of their developmental stage, will regulate tenogenesis of TPCs in vitro and that this process will be enhanced by dynamic mechanical stimulation. Using a unique in vitro co-culture system we will characterize muscle cell secretion of putative soluble factors and their potential tenogenic roles (Aim 1), and investigate the potential for mechanical loading to enhance chemoregulation by studying TGF22 as a model soluble factor (Aim 2). The outcomes of this study will subsequently be translated in a future study to develop a mesenchymal stem cell-based regeneration strategy through controlled application of these influences. Our long-range goal is to use developmental biology as motivation and a guide in developing novel mesenchymal stem cell-based strategies in regenerating new tissue to replace injured or diseased tendons and ligaments. The outcome of this research effort would significantly advance knowledge of tendon developmental biology, help define rational soluble factor dosing and mechanical loading parameters for progenitor cell differentiation, and lead to advanced strategies to engineer tendons with mesenchymal stem cells.