Preparation And Performance Study Of PU-CL/PU Membrane/decellularized Scaffold Vascular Patch

The incidence of vascular disease has tended to increase year by year.The vascular graft surgery is still one of the most commonly used methods in clinical means of treating such diseases.Currently,the commonly used clinical prosthetic vascular graft materials are Dacron and expanded polytetrafluoroethylene(e-PTFE).However,when applied to small-diameter(<6mm)vascular revascularization,prosthetic vascular graft materials have a low patency rate by reasons of poor compliance,chronic intimal hyperplasia of vascular surface,easy to cause thrombosis,etc.Thus,this is a difficult problem remaining to be solved in fields of vascular surgery.In recent years,researches on tissue engineered blood vessels have provided new ways to solve these problems.The scaffold material used in tissue engineering is used to support,repair biological and mechanical properties of the tissue,it can served as a carrier of the transplanted cells,which can provide structural support for endogenous cells.Scaffold materials including synthetic materials,natural materials,and a combination of the two materials.The ideal scaffold materials have a good biocompatibility and non-toxic,in addition,it can also induce the growth direction of new tissue,provide the appropriate surroundings,and restore the structure and the function of tissues,introduce biological activity factors,and so on.With the development of decellularized technology,decellularized scaffolds as a foundation for the construction of tissue engineering scaffold materials,and has an incomparable advantage and potentiality among synthetic materials.Therefore,decellularized scaffolds,a kind of ideal tissue engineering scaffold materials,has obtained more attention and application.And after the ordinary decellularized scaffold is implanted into receptor,which can cause immune reaction in the body,and induce the formation of blood clots,so people began to study the surface modification of decellularized scaffolds to improve its blood compatibility,reduce its toxicity,and reduce immunological rejection and platelet adhesion of receptors for allogeneic tissue materials.Polyurethane served as a kind of block copolymer,has good strength,flexibility and a better compliance,the micro phase separation structure let itself posses a good blood compatibility.Polyurethane can meet the designated requirement by the design of physical and chemical properties of molecular structure.Currently,the study of polyurethane is seemed as one of the most widely biomedical materials for anticoagulant.But when contacting the blood,the blood compatibility of polyurethane is not as enough as ideal,it still can form thrombus and similar adverse biological reactions.Consequently,it is very necessary and significant to obtain better polyurethane materials of biocompatibility by modification.Cardiolipin is an important compound to myocardia.Its blood compatibility and cell compatibility is superior to phosphoric acid or poly phosphate.Cardiolipin has two phosphates and can be reacted with different amino groups and other reactive groups,so that the modified material has better chemical stability.Therefore,it can be widely used in the surface modification of biomedical materials to improve the biocompatibility of biomedical polymer materials.In this paper,we firstly use MDI,PTMG and DMPA to synthetize polyurethane(PU),and then use CL and PU to synthetize PU-CL nanoparticles.The structural characterization,the blood compatibility and cell compatibility of synthesized nanoparticles were studied by transmission electron microscopy(TEM),scanning electron microscopy(SEM),particle size analysis(LDS),nuclear magnetic resonance(NMR),X-ray photoelectron spectroscopy(EDS),the hemolysis test,the recalcification experiments,clotting time in vitro test and cell cytotoxicity experiments.The results showed that PU-CL nanoparticles had good blood compatibility and cell compatibility.The prepared PU-CL nanoparticles and PU molecular are dissolved in ethanol,using co-precipitation method to modify the surface of the polyurethane,and the PU-CL/PU nanocomposite was obtained.The morphology and structure of prepared PU-CL/PU nanocomposite were characterized by scanning electron microscopy(SEM),thermal gravimetric analysis(TGA),tensile test,static contact angle(SCA),X-ray photoelectron energy spectrum(XPS)and other means.The blood compatibility and cell compatibility of PU-CL/PU nanocomposite were studied by hemolysis test,recalcification experiments,clotting time in vitro test,dynamic coagulation test,erythrocyte morphology experiments,platelet adhesion experiment,cell toxicity experiments and endothelial progenitor cell adhesion growth experiments.Experimental results show that surface modification of polyurethane by PU-CL nanoparticles,the blood compatibility and cell compatibility of polyurethane were improved,without affecting the structure and performance of the material at the same time,and polyurethane nanocomposites with good anticoagulant properties were obtained.Finally,the PU is coated on the surface of self-made decellularized scaffold,and then the PU-CL nanoparticles were modified to the surface of PU/decellularized scaffold by co-precipitation method to prepare the PU-CL/PU film/decellularized scaffold artificial vascular patch.Then animal transplantation experiment was carried out on the vascular patch in vivo.The B ultrasound results show that,blood in the patch implantation site flow unobstructedly,without using any anticoagulant drugs.30 days after surgery,we remove vascular patch of the implantation in vivo for immunohistochemical staining,results show,vascular patch surface has formed a continuous endothelial cell layer,and the endothelial process of PU-CL/PU film/decellularized scaffold vascular patch still can be successfully completed,without using any drug of promoting cells growth.