FUNCTIONAL TISSUE ENGINEERING FOR TENDON REPAIR

我们的总体假设是，含有间充质干细胞的“功能性”组织工程构建物可用于肌腱损伤模型，以改善修复生物力学，结构和生物化学。 植入物将在体外设计为具有适当的收缩特征和初始生物力学，以改善肌腱修复。 功能性组织工程或FTE将用于在培养物中机械刺激组织工程（TE）植入物，并确定植入物在手术后预期传递的体内力的阈值。 我们将讨论四个研究问题。 首先，我们是否可以通过改变体外培养条件来显著改善修复结果？ 第二，正常肌腱传递的体内力的阈值是多少，以及植入手术后这些力如何分布在修复部位？ 第三，改变施加到体外结构的机械信号是否会增强手术后的修复生物力学？ 最后，是否存在与体内结果（短期和长期）相关的体外标记物？ 在一系列体外和体内研究中，将检查以下特定目的：1.使用选定的细胞接种密度、胶原蛋白浓度和胶原蛋白编织物的组合作为缝线替代物，在培养中创建MSC构建体长达6周。评价体外收缩特性、初始生物力学特性、细胞形态、胶原合成以及碱性磷酸酶和骨钙素的表达。 2.在正常跟腱和髌腱上建立各种活动的体内加载方案。 3.使用有限元建模估计不同植入条件组合下修复组织中的载荷分布。 4.根据源自SA 2和SA 3的设计标准，对来自SA 1的选定组合进行体内评价，以确定植入物在替换受损组织方面的成功率。 5.评估连续和间歇循环应变对结构收缩、初始生物力学性能、细胞形态和体外生物化学的潜在受益。 6.根据先前的目标，在体内评价来自SA 5的最有希望的组合，以确定体外机械刺激对术后修复生物力学、组织学和生物化学的潜在益处。 7.通过将体外生物力学、组织学和生化结果与早期和长期体内结果相关联，确定体内结果的可能预测因素。

Our global hypothesis is that "functional" tissue-engineered constructs containing mesenchymal stem cells can be used in models of tendon injury to improve repair biomechanics, structure, and biochemistry. Implants will be designed in vitro with appropriate contraction characteristics and initial biomechanics to improve tendon repair. Functional tissue engineering or FTE will be used to mechanically stimulate the tissue engineered (TE) implants in culture and to establish thresholds of in vivo forces that the implants will be expected to transmit after surgery. We will address four research questions. First, can we significantly improve repair outcome by varying the in vitro culture conditions? Second, what are the thresholds of in vivo force transmitted by normal tendons and how are these forces distributed through the repair site after implant surgery? Third, would altering the mechanical signals applied to the constructs in vitro enhance repair biomechanics after surgery? Finally, do in vitro markers exist that correlate with in vivo outcome, both short and long term? In a series of in vitro and in vivo studies, the following Specific Aims will be examined: 1. Create MSC constructs for up to 6 weeks in culture using selected combinations of cell-seeding density, collagen concentration, and collagen braids as suture replacements. Evaluate in vitro contraction characteristics, initial biomechanical properties, cell morphology, collagen synthesis, and expression of alkaline phosphatase and osteocalcin. 2. Establish in vivo loading regimens on normal Achilles and patellar tendons for various activities. 3. Estimate load distributions in the repair tissues for different combinations of implant conditions using finite element modeling. 4. Evaluate in vivo selected combinations from SA1 in light of design criteria derived from SA2 and SA3 to determine the success of the implant in replacing the injured tissue. 5. Assess the potential benefits of continuous and intermittent cyclic strain on construct contraction, initial biomechanical properties, cell morphology, and biochemistry in vitro. 6. Evaluate in vivo the most promising combinations from SA5 in light of the previous aims to determine the potential benefits of in vitro mechanical stimulation on repair biomechanics, histology, and biochemistry after surgery. 7. Identify possible predictors of in vivo outcome by correlating in vitro biomechanical, histological, and biochemical results with early and long-term in vivo outcomes.