Study On The Construction And Properties Of Biomimetic Nano-Fiber Artificial Anterior Cruciate Ligament

Objective: The biphasic composite scaffold was firstly prepared with the principle and method of bionics.In order to reproduce the inherent heterogeneity of natural ligaments,scaffold must consisted of two regions with different compositions.Scaffold could match the mechanical properties of ACLs for joint stability after reconstruction and degrade slowly for regenerated tissue grow in.Scaffold had contact guidance on the morphology and differentiation of mesenchymal stem cells.These provided a new idea for scaffold materials of ligament tissue engineering.Methods: The diphasic nanofiber structure with random arrangement at both ends and orientation arrangement in the middle was prepared by the new biphase electrospinning technology,and the morphology of the scaffold observed.The advantages and characteristics of scaffold were confirmed from multiple angles.The morphology of scaffold was observed by scanning electron microscopy,the mechanical properties of scaffold were tested by universal mechanical experimental machine,and the degradation performance was also tested.Mesenchymal stem cells(MSCs)were inoculated on the scaffold and the proliferation,morphology,arrangement and fibroblast differentiation expression related genes of MSCs was tested.To investigated cell-scaffold interactions and explored the relative effects of nanofiber matrix arrangement and mechanical stimulation on the differentiation of MSCs and their interactions.Results: 1、Scaffold had a highly porous structure and smooth surface.The ultimate tensile stress of PLGA/PCL(1:5)was 58.3 ± 7.4,which was comparable to natural ACLs for prevent excessive sliding of tibia after implantation.PLGA/PCL(1:5)retained 91% of their original weight.Bionic scaffolds with random-orientation-random structure were fabricated by a new electrospinning strategy.2、The oriented scaffold and mechanical stimulation promoted the proliferation of MSCs.MSCs showed distinctly preferential orientations no matter whether tension was applied and exhibited slender spindle-shaped morphologies on the aligned phase,which was similar to tendon cells in phenotype.MSCs had no obvious orientation and exhibited paving-stone-like morphologies on the random phase,but the cells exhibited aligned morphologies along the axial direction of the fibers when the scaffolds were placed under tensile stress.MSCs produced collagen type Ⅲ Only on the random phase under tensile force.More importantly,for the aligned phase,nanofibrous membranes with tension showed the highest gene expression levels for type III collagen,fibronectin,tenascin-c,and scleraxis compared with those of the other groups,indicating a much more vigorous process of fibroblast differentiation.Otherwise,there were no significant differences between groups for gene expression of type I collagen.Conclusion: Nanofiber scaffold had similar mechanical properties of natural ACLs and adjusted the degradation rate to match the formation of new tissues.It was the best combination for ACLs tissue engineering and provided theoretical basis for clinical application of scaffold materials.Biphasic electrospinning scaffolds can simulated the structural and chemical changes of natural ligaments,the arrangement of scaffold fibers guided the morphology and distribution of MSCs,and co-stimulated of oriented fibers and mechanical stimulation promoted the differentiation of MSCs.