"In Vitro Mechanical Stimulation to Enhance Tendon Repair"

描述(申请人提供)：拟议的研究将优化应用于间充质干细胞(MSC)结构的机械刺激，以检验在体内提供应变模拟既能加强修复又能缩短愈合时间的全球假设。这项研究解决了三个重要的临床问题：用生物结构填充肌腱缺损以减轻疼痛和僵硬，并为翻修手术提供移植物；修复大的肩袖撕裂和加强韧带重建；修复慢性退行性肌腱损伤。利用功能组织工程学或FTE路线图，结合体外和体内研究，我们将在兔髌腱模型(PT)中建立4种日常生活活动的在体作用力和位移(目标1)。利用一种新的设计策略，6个机械治疗因素将在培养中变化，以优化手术前结构的切线刚度(目标2)。具有明显不同切线刚性值的结构将被植入兔PT缺损处，以检查修复刚度的显著改善(目标3)。因此，我们将检验一系列相关的假设：Hyp 1.兔PT在所有活动中保持非零的组织应变和力。增加步态表面的坡度或倾斜度会增加活体的力和应变参数。暴露于体内应变形状的兔和小鼠结构比暴露于梯形或正弦形状的结构发展出更高的切线刚度。在生理范围内增加应变幅度会增加培养中的切线硬度。Hyp.5.与活体信号具有相似起伏时间和相似周期的应变模式在培养中表现出最大的刚性值。Hyp 6.在培养中具有最大切线刚度的小鼠结构显示出ColI基因表达的最大增加。Hyp 7.增加培养中的结构硬度会增加手术后的修复硬度，并更好地使修复部位的细胞和细胞外基质对齐。我们新颖的体外/体内交互研究应该有助于开发体外预测手术后体内修复结果的指标，该指标也适用于其他组织系统。

DESCRIPTION (provided by applicant): The proposed studies will optimize mechanical stimuli applied to mesenchymal stem cell (MSC) constructs to test the global hypothesis that delivering in vivo strain simulations boths stiffens repairs and shortens healing time. This research addresses 3 important clinical problems: filling tendon defects with biological constructs to reduce pain and stiffness and to provide grafts for revision surgery; repairing large rotator cuff tears and augmenting ligament reconstructions; and repairing chronic degenerative tendon injuries. Using a functional tissue engineering or FTE roadmap with linked in vitro and in vivo studies, we will establish in vivo forces and displacements for 4 activities of daily living in the rabbit patellar tendon model (PT) (Aim 1). Using a novel design strategy, 6 mechanical treatment factors will then be varied in culture to optimize the construct's tangent stiffness before surgery (Aim 2). Constructs with significantly different tangent stiffness values will be implanted in rabbit PT defects to examine significant improvements in repair stiffness (Aim 3). We will thus test a series of related hypotheses: Hyp 1. The rabbit PT maintains non-zero tissue strain and force for all activities. Hyp 2. Increasing the grade or inclination of the gait surface increases in vivo force and strain parameters. Hyp 3. Rabbit and mouse constructs exposed to in vivo strain shapes develop higher tangent stiffness than constructs exposed to trapezoidal or sinusoidal profiles. Hyp 4. Increasing strain amplitude, within physiological limits, increases tangent stiffness in culture. Hyp. 5. Strain patterns with similar times to rise and fall and similar periods as in vivo signals exhibit the largest stiffness values in culture. Hyp 6. Mouse constructs having the largest tangent stiffness in culture exhibit the greatest increases in col I gene expression. Hyp 7. Increasing construct stiffness in culture increases repair stiffness after surgery and better aligns cells and extracellular matrix in the repair site. Our novel, interactive in vitro / in vivo study should help to develop in vitro predictors of in vivo repair outcome after surgery that also apply to other tissue systems.