Study On Polyelectrolyte/polyvinyl Alcohol/decellularized Stent Vascular Patch

Vascular disease,as one of the diseases with the highest incidence in the world,seriously affects people’s lives and health.In recent years,with the improvement of people’s living standards,vascular diseases show a marked increase.Thrombosis,stenosis,and cirrhosis caused by vascular disease can seriously affect normal blood supply and resulting in death.The ideal treatment for vascular diseases is to replace or repair blood vessels and regenerate new blood vessels with normal functions.The required material not only should be similar to normal blood vessels in mechanical properties,but also to have good blood compatibility.Therefore,it is very urgent to find suitable materials for small-caliber blood vessels.The decellularized scaffold is biological scaffold which remove cellular components and retain collagen fibers and elastic fibers.The scaffold material after decellularization can not only guarantee its mechanical properties similar to normal human blood vessels,but also reduce its immunogenicity.Therefore,the scaffold material after decellularization can only be used as a support material,and cannot be directly used as a blood vessel replacement material,and it needs to be subjected to a coating treatment.Polyvinyl alcohol is a new type of functional polymer material.Hydrogels prepared by chemical cross-linking method have excellent mechanical properties and superior biocompatibility.They are widely used in the field of biological tissue engineering.The polyvinyl alcohol hydrogel film as a decellularized scaffold not only has good biocompatibility,but also can avoid the influence of common polymer materials mechanical properties of decellularized scaffolds in bionics features.Heparin is a natural anionic polysaccharide which not only has anticoagulant,antithrombotic,and lipid-regulating effects,but also has anti-inflammatory,anti-allergic,anti-viral and anti-cancer effects.Chitosan is a natural cationic weakly basic polysaccharide in nature which contains a large amount of active amino and hydroxyl groups.It is widely exists in the nature.It is not only of stable source and low price,but also has no biological toxicity,good biocompatibility,and biological properties.It has the advantages of degradable and antibacterial properties,but it will react with blood and coagulate;heparin and chitosan can form polyelectrolyte complexes by electrostatic interactions to increase the blood compatibility and anticoagulant capabilities of the substrate material.In this study,decellularized scaffolds were prepared from allogeneic blood vessels by decellularization.The acetalized PVA hydrogels were coated onto the surface of decellularized scaffolds using a coating method.And then,through covalently bonded heparin,using the adsorption of opposite charges to sink chitosan onto the surface of the material.Afterwards,the heparin-chitosan polyelectrolyte is modified on the surface of the polymer material by a layer-by-layer self-assembly technique.By scanning electron microscopy,X-ray photoelectron spectroscopy testing,the surface of the amino content Assays and other results demonstrate that the heparin-chitosan polyelectrolyte has been successfully modified onto the polyurethane/acellular scaffold surface.The mechanical properties,blood compatibility,and cell compatibility of the polyelectrolyte/polyurethane/acellular stent grafts prepared for different layers were tested.The experimental results show that the prepared vascular patch material has greatly improved blood compatibility and cytotoxicity without affecting the bionic properties of the mechanical properties,and the ability to adhere to and grow endothelial progenitor cells is also improved.At the end of this topic,the synthetic vascular patch was transplanted into animals.The results of B-mode ultrasonography and Doppler experiments showed that without the use of anticoagulant agents,blood flowed smoothly at the site of vascular patch implantation and eventually achieved endothelialization.Satisfactory results from animal experiments are obtained,demonstrating that the prepared heparin-chitosan-heparin/polyvinyl alcohol/decellularized scaffold vascular patch can serve as a normal blood vessel substitute.