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的修复，以恢复受累关节的活动范围。自体移植物是首选；然而，供体部位的发病率和供应的限制是重要的问题。同种异体移植物/异种移植物可引起免疫反应。异物对合成聚合物的反应是一个显著的缺点。再生解决方案加速肌腱修复，使早期活动和降低故障率将通过降低治疗成本具有重要意义。由于缺乏生物支架，肌腱重建面临着诸多挑战，这种生物支架既能将机械稳健性、张力感和能够通过手术整合到修复部位的形式统一起来。在R21项目的部分支持下，我们开发了一种制造电化学排列胶原蛋白（ELAC）线的新方法，其织物方向、填充密度和机械性能与天然肌腱相匹配。ELAC在地形上诱导间充质干细胞（MSC）的成肌腱分化，而编织支架中的MSC合成了一种胶原I和肌腱特异性tenomodulin分子阳性的基质。ELAC在体内具有生物相容性，并分解成肌腱样纤维组织。ELAC的降解速度与肌腱的缓慢修复速度相匹配。因此，ELAC是一种独特的生物活性和机械能力强的平台，具有修复肌腱的潜力，无需添加生长因子。提出的研究将验证基于elac的再生策略修复肌腱间隙缺陷的生物力学将达到或超过自体移植物所达到的假设。第一个目标是优化ELAC的形貌和体外调节过程，以最大限度地提高编织ELAC支架中MSCs的肌腱生成。具体而言，Sub-Aim 1.1将研究基材压实、对准和刚度在引起所观察到的结果中的作用

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.