Tissue Engineering of the Anterior Cruciate Ligament on Resorbable Embroidered Scaffolds: Design of a Hybrid Scaffold Structure Composed of a Biomechanical Unit , a Bio-Functional Unit and a Vital Unit

通过组织工程方法替代前交叉韧带（ACL）可能是未来取代有限可用性的自体肌腱移植的首选手术实践。应用的基本要求是替代结构具有足够的生物力学阻力。提出的项目重点是设计一种能够用于ACL组织工程的混合支架结构。混合结构由生物力学单元（用于补偿力）、生物功能单元（用于支持增强的生物整合）和重要单元（包括中间物质和末端的组织特异性细胞）组成，以加速组织再生。该方法基于定制的三相支架结构，随后的功能化和在父项目中已经建立的细胞播种策略。为了补充刺绣支架，进一步的功能单元，如细胞屏障或控制结构，需要技术进步，适应和优化刺绣过程以及应用的材料。生物整合可以通过一种新的方法在气相中氟化合成聚合物的表面以及通过将胶原制剂渗透到纺织品结构中来增强。所述胶原蛋白制剂被加工成稳定的泡沫，在纺织结构内部执行相互连接和排列的孔隙系统。这里要解决的一个科学问题是，合成聚合物的氟化表面增强了细胞的粘附性。这种新型的混合结构将以在母项目中已经建立的悬挂滴法制备的小球体为种子。将不同细胞类型播种的杂交结构进行机械刺激，建立一种优化的方案，使ACL终结和中间物质的所有细胞类型受益。与骨原、软骨分化细胞以及韧带细胞进行体外共培养。此外，还将研究细胞屏障在防止细胞迁移和末端形成方面的积极作用。在动态裸鼠模型和原位兔前交叉韧带重建模型中，我们将选择一种优化的程序并对其进行评估。在项目结束时，将确定一个程序，包括生物力学，生物功能和生物集成单元的制造以及细胞播种和培养策略，将直接适用于随后的大型动物试验。

The replacement of the anterior cruciate ligament (ACL) by a tissue engineering approach could be the favored surgical practice in future superseding the transplantation of autologous tendons with limited availability. An essential requirement for the application is a sufficient biomechanical resistance of the surrogate structure. The proposed project focusses on the design of a hybrid scaffold structure capable for ACL tissue engineering. The hybrid structure is composed of a biomechanical unit for the compensation of forces, a bio-functional unit to support an enhanced bio-integration and a vital unit including tissue-specific cells of the mid-substance and enthesis to accelerate tissue regeneration. The approach is based on the tailored triphasic scaffold structure, subsequent functionalization and cell seeding strategies already established in the parent project.To complement the embroidered scaffolds, further functional units such as cell barriers or control structures are included requiring technological advancement, adaption and optimization of the embroidery process along with the applied materials. Bio-integration could be enhanced by a novel method of fluorinating the surface of the synthetic polymer in a gaseous phase as well as by infiltrating collagen preparations into the textile structure. The collagen preparations are processed to stable foams performing an interconnected and aligned pore system inside the textile structure. A scientific question addressed here is the enhanced cell adherence on the fluorinated surfaces of the synthetic polymers. The novel hybrid structures will be seeded with small spheroids prepared by the hanging-drop method already established in the parent project. The hybrid structures seeded with different cell types will be mechanically stimulated and an optimized protocol will be established to the benefit of all cell types of ACL enthesis and mid-substance. Co-cultivation with osteogen and chondrogen differentiated as well as ligament cells will be performed in vitro. Additionally, the positive effect of a cell barrier on the prevention of cell migration and the formation of an enthesis will be studied. An optimized procedure will be chosen and evaluated for ligamentogenesis in a dynamic nude mice model as well as in an orthotopic rabbit ACL reconstruction model.At the end of the project a procedure, comprising the manufacturing of the biomechanical, the bio-functional and the bio-integrative units as well as the cell seeding and cultivation strategies, will be determined directly applicable for a subsequent large animal testing.