Preparation Of Biomimetic Poly(Vinyl Alcohol)based Scaffold For Cartilage Tissue Engineering

The design of tissue engineering scaffold maximally simulate the composition,structure and function of extracellular matrix in target tissues or organs by the principle of bionics,so as to repair the damage and restore function.In this study,correlating the effective properties of composite materials with their microstructures and biological activity is the basis for optimization design of composite materials.The unique structure in natural articular cartilage is closely related to the mechanical and physiologic properties of the tissue.The design of scaffolds with these intricate architectural characteristics would be an important target for the research of tissue engineering.The details are as follows: 1.Poly(vinyl alcohol)(PVA)hydrogel with porous structure and mechanical properties is very suitable for the repair of articular cartilage.The pure PVA hydrogel after lyophilization will be accompanied by the shrinkage of the polymer network and the collapse of the pores,leading to the inhomogeneous performance of the material even in the state of re-swelling.With the addition of natural polysaccharide carrageenan(CAR)components,the pore structure stability of PVA-CAR composite hydrogel was improved significantly during the process of lyophilization.At the same time,due to the impact on PVA crystalline,the internal structure of composite material is relatively loose,which has significantly improved the pore size of pure PVA hydrogel;2.In the biological assessment,the cells in vitro experimental results show that the addition of the CAR can significantly increase the biological activity of PVA hydrogel,promote cell adhesion and proliferation on material,and possess the ability to maintain cell phenotype.The hemolysis test and macrophage activation experiments show that PVA-CAR composite materials does not cause hemolysis and have low rate of macrophage activation,which indicated the potential applications in vivo.3.Based on the previous research results,a biomimetic scaffold was successfully constructed by using a unidirectional freeze-thaw approach.This scaffold had axially aligned pore structure and maintained good mechanical property.Noticeably,this scaffold imitated the structure feature of nature cartilage,which operated as a template for cells growth along the oriented pore structure.Furthermore,such oriented scaffold could not only efficiently enhance uniformity distribution of cells in vitro,but also promote the regularity of the infiltration tissue within the scaffold in vivo.Additionally,tissue responses towards the scaffolds in vivo were benign,indicating their suitability for implantation purposes.Based on simple preparation method and the potential to be used as cell-free scaffold,this oriented scaffold could be promising tool for application in tissue engineering.4.Inorganic component of hydroxyapatite(HA)was used to combine with PVA and CAR in order to prepare the composite scaffolds for bone tissue engineering.Optimizing the scaffolds for cell culture in vitro,the results show that composite scaffolds can promote the growth of cells.After implantation in vivo,this material has good histocompatibility and promotes the growth of the organization to a certain extent.Then on this basis,a double composite scaffold was prepared by infiltration and directional freeze-thaw method.The double composite scaffold has oriented structure in top and porous structure in bottom,which simulated the characteristics of articular cartilage and subchondral bone.The interface bonding strength was increase with prolonged infiltration time.There is no clear interface in the composite scaffold,which can effectively prevent separation caused by the obvious natural interface.