本论文研究了天然胶原、重组胶原调制磷酸钙生长的生物矿化过程的机理，并在此基础上仿生制备了矿化重组胶原基骨修复材料，解决了以往动物源性胶原基骨材料的病毒隐患等安全问题。并进一步提高了材料的生物相容性，赋予材料骨诱导性，获得了具有广阔市场前景的新型骨修复材料。 生物矿化机理研究是制备具有优异性能的仿生材料的基础。骨属于胶原-磷酸钙天然复合系统，因此研究生物矿化过程中胶原和磷酸钙的相互作用对于仿生骨材料的制备至关重要。我们的研究指出，在磷酸钙发生非晶/晶体转变及晶体成熟过程中，胶原发生明显的构象变化，以适应晶体的形成和长大。结合以往的研究，进一步对体外胶原矿化全过程进行了阐释，促进了对体内生物矿化的理解。通过对重组胶原调制磷酸钙矿化的研究，我们证明重组胶原上的羰基可与钙离子配位，成为矿物形核位点，调制纳米级磷酸钙形核生长，得到仿生的矿化重组胶原，为制备仿生的矿化重组胶原基骨材料提供了理论根据。 基于以上的理论研究，我们首次用仿生的矿化重组胶原（nHA/RC）代替天然动物源性胶原制备出新型骨修复框架材料nHA/RC/PLA。该材料成分和结构均与天然骨有相似性，通过体外细胞实验和体内动物实验，证明其具有良好的生物相容性和骨传导性，可以达到与动物源性胶原基骨材料相同的效果。而重组胶原避免了动物源性胶原的安全隐患，使新材料具有了更高的安全性能，有望替代天然胶原基骨材料成为骨修复的优选材料。 在材料制备过程加入适量的双亲性卵磷脂可以显著提高材料的亲水性，更有利于细胞在材料上的粘附和增殖。混合材料在生物体内不引起显著的免疫排斥反应，具有更高的生物相容性。 通过复合生长因子有效提高材料的生物活性也是骨修复研究的热点。复合了BMP-2活性多肽的nHA/RC/PLA材料，在大鼠异位成骨实验中可引起肌肉组织内的异位成骨，并存在量效关系。对于大鼠5mm全层颅骨缺损可以有效促进骨再生，在20周时达到愈合，材料基本完全降解。重组胶原基骨材料与动物源性胶原基骨材料效果无显著性差异。
In the present study, the initial stage of collagen and recombinant collagen biomineralization was investigated. Based on this research, mineralized recombinant collagen was obtained to fabricate a new scaffold (nano-hydroxyapatite/recombinant collagen/poly (lactic acid), nHA/RC/PLA) for bone replacement implants. It avoids virus-dangers of animal-sourced collagen. Furthermore, the biocompatibility and osteoinductivity of the scaffold were improved. The scaffold is a promising material for bone repair. The mechanism of biomineralization is the fundamental for fabricating biomimetic material. Collagen and calcium phosphate are the basis of bone, so the study on the interaction between collagen and calcium phosphate is crucial for biomimetic bone scaffolds fabrication. In our work, it was revealed that the marked conformation evolution of collagen occurred during the amorphous/crystalline conversion and crystal ripening. Collagen molecules adopted different conformation to suit the crystal growth as protein template. The model of the collagen mineralization process in vitro was proposed and improved the understanding of biomineralization in vivo. Recombinant collagen (RC) was proved to be able to regulate the deposition of hydroxyapatite nanocrystals through the interaction between calcium ions and carbonyl groups of RC. A biomimetic scaffold based on mineralized RC (nHA/RC/PLA) was fabricated for the first time. The scaffold showed some features of natural bone both in main component and hierarchical microstructure. Cell culture and implantation experiment in rabbit exhibited the good biocompatibility and osteoconduction of the scaffold. The results were very comparable with that of the scaffold based on mineralized animal-sourced collagen. nHA/RC/PLA is safer than scaffolds containing animal-sourced collagen and may be used to substitute them, since RC has no virus-dangers. Hydrophilicity of nHA/RC/PLA was improved by blending lecithin during fabrication. Lecithin has amphiphilic chemical structure and can promote cell adherence and proliferation. The blended scaffold containing proper percent of lecithin doesn’t provoke significant inflammatory response in vivo and has better biocompatibility compared with single nHA/RC/PLA. BMP-2 derived peptide, a kind of growth factor, was combined with nHA/RC/PLA. The active scaffold induced ectopic osteogenesis in back muscles of rats and the peptide has dose-depent effect. It can promote the concrescence of 5mm cranial defects of rat. The defect healed up in 20 weeks and the scaffold degraded almost completely. The effects of nHA/RC/PLA and the scaffold based on mineralized animal-sourced collagen have no significant difference.
