Tendon Enthesis Development and Regeneration

 描述（由申请人提供）：由于在其界面处出现应力集中，不同材料的连接具有挑战性。肌腱-骨附着位点（“附着点”）使用功能梯度过渡组织解决了该机械问题，所述过渡组织包括结构、细胞外基质组成和细胞表型的空间梯度。这 在分子和生物物理线索的调节下，在胎儿和出生后的时间点形成了强大而坚韧的附着系统。不幸的是，这种独特的结构在手术修复和愈合后不能重建，导致非常高的失败率。因此，我们的目标是了解肌腱附着点的发育，以促进附着点修复的再生策略。我们的总体假设是，时间和空间的生化（TGF β和Ihh）和生物物理（肌肉力量）线索的调节是必要的，以驱动功能性附着点的发展和损伤后的再生。我们的假设是由我们最近的工作，这表明，胚胎肌腱骨附着启动从一个独特的群体的祖细胞和出生后的附着点成熟和矿化是由印度刺猬信号和肌肉负荷驱动。然而，目前尚不清楚这些细胞群在发展中的附件如何调节成熟附着点的形成。因此，目标1将确定组成成熟附着点的细胞的谱系（或谱系），从胚胎时间点开始并通过骨骼成熟进行。目的2将确定附着点细胞表型的分子和机械调节，重点是早期发育事件的TGF β和后期矿化事件的Ihh信号传导。在目标3中，我们将确定附着点细胞谱系和损伤附着点修复和再生的分子信号传导的作用，重点关注负责附着点Ihh信号传导的细胞。这些目标将使我们能够识别和表征填充附着点的细胞，并揭示其分化所需的分子和生物物理事件序列。结果将直接影响 未来基于细胞和生长因子的肌腱-骨修复再生策略。

 DESCRIPTION (provided by applicant): Attachment of dissimilar materials is challenging due to stress concentrations that arise at their interface. The tendon-to-bone attachment site ("enthesis") solves this mechanical problem using a functionally graded transitional tissue that includes spatial gradients in structure, extracellular matrix composition, and cell phenotype. This strong and tough attachment system is formed during fetal and postnatal timepoints under the regulation of molecular and biophysical cues. Unfortunately, this unique structure is not recreated after surgical repair and healing, leading to remarkably high failure rates. Therefore, our goal is to gain an understanding of tendon enthesis development in order to motivate regenerative strategies for enthesis repair. Our overall hypothesis is that temporal and spatial regulation of biochemical (TGFß and Ihh) and biophysical (muscle force) cues are necessary to drive the development of a functional enthesis and for regeneration after injury. Our hypothesis is motivated by our recent work, which showed that embryonic tendon-to-bone attachment initiates from a distinct population of progenitor cells and postnatal enthesis maturation and mineralization is driven by Indian hedgehog signaling and muscle loading. It remains unclear, however, how these cell populations at the developing attachment regulate the formation of a mature enthesis. Therefore, Aim 1 will determine the lineage (or lineages) of the cells that compose the mature enthesis, starting at embryonic timepoints and progressing through skeletal maturity. Aim 2 will determine the molecular and mechanical regulation of the enthesis cell phenotype(s), focusing on TGFß for early developmental events and Ihh signaling for later mineralization events. In Aim 3, we will determine the role of enthesis cell lineages and molecular signaling for repair and regeneration of the injured enthesis, focusing on cells responsible for Ihh signaling at the enthesis. These aims will allow us to identify and characterize the cells that populate the enthesis and to uncover the molecular and biophysical sequence of events that is required for their differentiation. Results will have a direct impact on future cell- and growth factor-based regenerative strategies for tendon-to-bone repair.