关节软骨胶原纤维取向与力学环境的关系研究

Articular cartilage is bearing tissue with different layers of collagen fiber orientation, the specific structure is adapted to its mechanical environment. Although from embryonic development under immobilised condition to postnatal growth study showed that cartilage structure is a self-assembled process under regulation of mechanical condition, but how different load patterns form collagen orientations is not clear. The project using cartilage constructing in vitro model carries out cartilage mechanobiology study with new born in vitro cartilage model, cartilage cells or stem cells seeded gel scaffold models coupled growth factor. Under different load, research on the relationship between collagen fiber orientation and mechanical environment of articular cartilage. Further by using static and dynamic compression, one-way rolling, reciprocating rolling, one-waysliding load, reciprocating sliding load or combination loading method, the mechanical effect of complex fiber orientation will be researched under the multi-scale, including cell proliferation and differentiation effect, collagen and aggrecan gene expression, content changes, and regularities of distribution and mechanical properties of complex change processes. We will establish the model of the relationship between the mechanical effects, and obtain the mechanism of the mechanical environment to regulate the orientation of collagen fibers, and predict the mechanical properties of the cartilage construction. It is of great significance to understand and reveal the structure of cartilage morphology to adapt to the mechanical environment, development of articular cartilage, cartilage repair mechanism and treatment, to promote the development of related research and progress of cartilage tissue engineering.

关节软骨作为承力组织，其分层结构与不同层区胶原纤维取向是适应力学环境的结果。尽管从胚胎发育到后天成长的研究表明软骨结构特征是力学介导下软骨自组织发育过程，但胶原纤维取向如何适应载荷模式的机理仍不明确。课题拟体外软骨构建模型开展软骨力学生物学研究，分别用新出生离体软骨、软骨细胞或干细胞接种凝胶支架复合体，耦合生长因子进行培养，施加不同载荷，研究培养物胶原纤维取向的形成和变化规律。载荷分别采用静态、动态压缩，单向、往复滚压，单向、往复滑动载荷或组合加载方式，多尺度研究培养物纤维取向的力学效应，如细胞增殖和分化效应，胶原、蛋白聚糖基因表达、含量变化和分布规律，培养物力学性能改变过程。建立这些力学效应量关系的模型，获取力学环境调控胶原纤维取向的机理，预测软骨的力学性能。课题对认识和揭示软骨结构形态适应力学环境、关节软骨发育、软骨修复和治疗的机理，促进软骨相关研究的进步以及组织工程的发展有重要意义。

软骨中胶原纤维取向形成是一个渐进式的过程，力学环境则是引导其取向生成的主要因素之一。随着组织发育生长至不同阶段，胶原纤维所处力学环境变化多样，从早期细胞收缩产生的拉力，到组织间小幅值的力学加载、再至组织结构成型阶段高幅值、频率的载荷。在力学环境不断变化中，纤维从初始简单取向排布变化成具有组织结构形态特点的规律排布，再至因载荷破坏而自我修复生长为粗壮、长尺寸的胶原纤维。力学环境促成了纤维取向的多样性，造成了组织形态的特异性，软骨纤维变化就是这样过程，纤维取向变化是力学适应的结果。.研制用于贴壁细胞拉/压加载仪，仪器培养小室改造后可以为离体软骨组织加载培养。研究了拉伸下纤维取向的形成规律，制备出具有高取向度的胶原纤维，且发现拉伸作用下纤维能聚集成束，形成较大直径的粗壮纤维；研究、分析了多个影响因素（浓度、速度、间隙高度等）对纤维取向的影响机制，纤维取向形成存在取向不均的现象，此反映组织中纤维取向的力学效应。.基于现有取向纤维理论提出取向纤维生成模型；阐述软骨、椎间盘纤维取向形成过程。剪切、扭转等力学作用在（软骨、椎间盘）纤维取向中的作用，从微观至细观再至宏观的角度上解释了体内纤维取向多样性生成的机制，给出了体内纤维取向多样性生成过程的概括性机制；同时对胶原分子动力学进行模拟研究，反映软骨中胶原分子的力学行为。.采用丝素蛋白和II型胶原支架构建软骨的研究，压缩应变下细胞增殖和功能有明显的促进作用；对于体外未成熟软骨和成年软骨缺损的滚动载荷效应研究，对比无缺损软骨获得了幼年软骨和成年软骨修复的极限缺损尺寸，且缺损扩展行为受胶原纤维取向影响。.建立了带有纤维增强型软骨损伤模型，研究纤维不同条件下损伤演化的规律，软骨损伤是从矩形底侧两脚开始，逐渐向深层和两侧扩展，表层向两边进行损伤。软骨中层没有直接受到载荷作用，受到的应力较小且损伤速度较慢。基质损伤最后会呈现“W”形,而软骨内部会形成一个“孤岛”。软骨在损伤演化扩展方向和速度有一定规律，与纤维的破坏有着密切关系。