Tendon Tissue Engineering by Electrochemically Aligned Collagen Bioscaffolds

描述（由申请人提供）：仅在美国，每年就有数万例大面积肌腱缺损修复，以恢复相关关节的活动范围。自体移植是首选;然而，供区发病率和供应限制是重要问题。同种异体/异种移植物可引起免疫应答。对合成聚合物的异物反应是一个显著的缺点。再生解决方案加快肌腱修复，使早期动员和减少失败率将是非常重要的，通过降低治疗成本。肌腱重建面临着多重挑战，由于缺乏一个生物支架，统一的机械鲁棒性，tenocinductivity和形式，使修复部位手术整合。在R21项目的部分支持下，我们开发了一种新的方法来制造电化学排列的胶原蛋白（ELAC）线，其织物方向，堆积密度和机械性能与天然肌腱相匹配。ELAC诱导间充质干细胞（MSC）的tenogenic分化的地形和编织支架中的MSC合成的基质是阳性的胶原蛋白I和肌腱特异性tenomodulin分子。ELAC在体内具有生物相容性，并分解为肌腱样纤维组织。ELAC的降解速率与肌腱的缓慢修复速率相匹配。因此，ELAC是一种独特的生物活性和机械性能平台，具有修复肌腱的潜力，而无需添加生长因子。拟议的研究将测试的假设，即ELAC为基础的再生策略修复的肌腱间隙缺损的生物力学将匹配或超过自体移植。第一个目标是优化ELAC拓扑结构和体外调节过程，以最大限度地提高编织ELAC支架中MSC的肌腱生成。具体而言，子目标1.1将研究基底压实、对齐和刚度在引起观察到的 腱原反应将骨髓来源的MSC接种在随机与对齐、电压实与凝胶形式的纹理上，并且基质刚度值调节超过六个数量级（1 kPa至1000 MPa），这是ELAC特有的范围覆盖。子目标1.2研究将优化细胞接种密度并调用机械刺激，以评估应变幅度和应变率对进一步增强体外肌腱形成的影响。第二个目标是通过使用编织的ELAC支架来改善关键尺寸肌腱缺损的修复结果。将采用兔冈下肌腱缺损模型。处理组将包括自体移植修复、ELAC支架（含和不含细胞）和作为阴性对照的缺口缺陷。结果测量将包括修复生物力学、从头基质分子的类型、炎症反应和愈合形态。阐明肌腱形成中基于材料和基于体外调节的线索，并使用兔模型对其优点进行深入验证，将为在大型动物模型中对这种新型生物材料进行临床前评估铺平道路。如果ELAC表现至少与自体移植物一样好，则与自体移植物相关的成本和发病率将被消除。ELAC将通过恢复关节活动范围和 消除了翻修手术。

DESCRIPTION (provided by applicant): Repair of massive tendon defects occur in tens of thousands annually in the U.S. alone to restore the range of motion of involved joints. Autografts are the primary choice; however, donor site morbidity and limits in supply are significant issues. Allografts/xenografts may elicit immune response. Foreign body reaction to synthetic polymers is a significant drawback. Regenerative solutions expediting tendon repair, enabling earlier mobilization and reducing failure rates would be highly significant by reducing treatment costs. Tendon reconstruction faces multiple challenges due to the absence of a bioscaffold which unifies mechanical robustness, tenoinductivity and a form that enables integration to the repair site surgically. Supported in part by a R21 project, we developed a novel method to fabricate electrochemically aligned collagen (ELAC) threads whose fabric orientation, packing density and mechanical properties match those of the native tendon. ELAC induces tenogenic differentiation of mesenchymal stem cell (MSC) topographically and MSCs in woven scaffolds synthesize a matrix that is positive of collagen I and the tendon-specific tenomodulin molecule. ELAC is biocompatible in vivo and resolves into a tendon-like fibrous tissue. The degradation rate of ELAC matches the slow repair-rate of tendon. Therefore, ELAC is a unique bioactive and mechanically competent platform with the potential to repair tendon without the addition of growth factors. The proposed studies will test the hypothesis that the biomechanics of the tendon gap defects repaired by ELAC-based regenerative strategies will match or exceed that is attained by autografts. The first aim will optimize ELAC topography and in vitro conditioning processes to maximize tenogenesis of MSCs in woven ELAC scaffolds. Specifically, Sub-Aim 1.1 will study the roles of substrate compaction, alignment and stiffness in eliciting the observed tenogenic response. Marrow- derived MSCs will be seeded on textures of random vs. aligned, electrocompacted vs. gel form, and matrix stiffness values modulated over six orders of magnitude (1 kPa to 1000 MPa), a range coverage that is unique to ELAC. Sub Aim 1.2 studies will optimize cell seeding density and invoke mechanostimulation to assess effects of strain amplitude and strain rate towards further enhancement of tenogenesis in vitro. The second aim will improve the repair outcome on critical sized tendon defects by using woven ELAC scaffolds. A rabbit infraspinatus tendon defect model will be employed. The treatment groups will include autograft repair, ELAC scaffolds (with and without cells) and gap-defect as the negative control. Outcome measures will include repair biomechanics, types of de novo matrix molecules, inflammatory response and healing morphology. Elucidation of material-based and in vitro conditioning based cues in tenogenesis and in depth validation of its merits using the rabbit model will pave the way for a preclinical assessment of this novel biomaterial in large animal models. If ELAC performs at least as good as autografts the costs and morbidity associated with autografts will be eliminated. ELAC will benefit patients by restoring joint range of motion and by eliminating revision surgeries.