有机无机仿生人工骨支架微结构构建过程的工程学

Bone scaffolds are the research focus in passive medical instrument field. The bioactive and bio-function of the passive medical instrument mainly depends on the processing and the composition of the scaffolds. Different engineering and technical treatment methods would result in the significant change of microstructure of the scaffolds, of course, leading to the big difference on the bioactive and bio-function observed in clinical test. The microstructure parameters of the scaffolds, such as porosity, average pore size, pore size distribution, flexibility and connectivity, are more important to the cell adhesion, migration, growth and proliferation. The relationship between the cell migration, growth and proliferation and the microstructure, surface chemical characters and surface topography of the scaffolds, resulted from processing and technological parameters, i.e. thermodynamics and dynamics during the processing, would be studied. The target is to reveal the correlation between the engineering control strategy and the microstructure of the scaffolds, the contribution of multi-scale hole to bone-tissue repair, the orderly and disorderly distribution of pores of scaffolds to the cell adhesion function of the osteoblast and the chondrocyte, the relationship between the distribution, proportion and porosity of the pore and the bioactive, bio-function in tissue engineering repair. This study would give a theoretical guidance and basis on the processing parameters for scaffolds of tissue repair to reach a better clinical application.

1.骨支架是目前国际无源医疗器械产品的研究热点之一，无源医疗器械产品的生物学功效取决于支架材料加工过程和支架材料本身。不同的加工过程导致材料的微结构差异很大，从而引起生物学功效的变化。支架的微结构，如孔隙率、平均孔径、孔径分布、弯曲度及其连通性等对细胞的迁移、生长和增殖非常重要。本研究旨在阐释多孔支架构建过程中工程及工艺参数即过程中的热力学和动力学变化引起的支架的微结构、表面化学特性、表面形貌与细胞粘附、迁移、生长和增殖的关系，解释工程控制策略与支架微结构形成的相关性，阐释支架内多尺度孔对骨修复过程的贡献；孔的有序分布与无序分布与软骨、成骨细胞等粘附作用的关系；充分表征其构建过程中工程参数与支架材料的生物学功效、力学强度、降解行为之间的关系。研究不同尺度孔径和孔径分布、比例及孔隙率在组织工程修复中的作用。为工业化生产过程中创制利于组织修复的可行的操作手段和策略的选择提供理论依据。

基于目前临床上存在的骨移植支架材料或是生物相容性不高，或是机械强度不够，或是降解性能不佳，或是孔径及孔隙率不适于成骨细胞的粘附与攀爬，或是制作工艺繁琐不利用放大化生产等缺点，本课题首先尝试以类人胶原蛋白（HLC）和纳米羟基磷灰石（nHA）为原料，通过冷冻干燥法和交联法相结合的技术构建组织工程软骨支架，并进行了理化性能、体外细胞相容性、生物学评价的研究。经实验测定：. 1. 京尼平交联HLC/nHA人工骨修复支架材料和EDC交联HLC/nHA人工骨修复支架材料均呈三维的多孔状结构，孔隙在100-300μm之间，理化性质良好，均表现出很好的细胞相容性，不仅能促进细胞很好的粘附、生长和增殖，引导细胞向孔隙内生长，并能维持细胞天然的圆形或多角形软骨形态，促进细胞外基质分泌，形成致密的细胞层。两种HLC/nHA支架材料的全身急性毒性、血液相容性和热原检测结果均符合国家标准对植入性器械的要求。京尼平交联的HLC/nHA支架材料植入小鼠皮下周围组织正常，无红肿，无炎症反应，组织相容性良好，其结果优于EDC交联HLC/nHA支架材料，可应用于骨组织工程领域。. 2. BDDE交联HLC/nHA人工骨修复支架材料Sca2、Sca5和Sca8孔隙率差别不大，分别为77.27 ± 2.3%、77.86 ± 2.6%和77.90 ± 2.3%，抗压强度分别为1.52 ± 0.08 Mpa，2.22 ± 0.09 Mpa和2.24 ± 0.07 Mpa，具有较高的力学性能，内毒素及外源DNA的检测与分析已达到相关标准，细胞毒性等级均为1级，可支持成骨细胞MC3T3-E1的粘附、增殖与攀爬。兔皮下植入及H&E染色显示，BDDE交联HLC/nHA人工骨修复支架材料具有良好的生物学相容性，具有潜能作为人工骨替代物进行骨修复移植而应用于骨组织工程领域。