Study Of Modified Acellular Scaffold With Hydrogel As Outer Layer

Background: In recent years,vascular diseases are increasing year by year.Although self blood vessels are the best choice for transplantation,due to their own limitations,they can not meet the needs of clinical vascular bypass,and there is no good solution for small-diameter artificial blood vessels due to poor patency in the near future.Therefore,the research and development of small-diameter artificial blood vessels with good patency has become a hot spot of current research.If there is a better patency of small-diameter artificial blood vessels,it will greatly improve the current clinical situation of the need for small-diameter bypass.In order to solve the problem that small diameter vessels are easy to be narrowed,we carried out the related research work through the acellular stent covered with membrane,hoping to make a breakthrough and lay a certain foundation for clinical research.The whole process is divided into three parts.Part I Preparation of acellular vascular stentObjective: To prepare the ideal acellular stent by the mixture of 1% Triton X-100 and 0.5% sodium dodecyl sulfate.Methods: Fresh blood vessels were immersed in a mixture of 1% Triton X-100 and 0.5% sodium dodecyl sulfate for 48 hours at room temperature,and then washed and immersed in PBS for 30 days to prepare acellular stent.It was evaluated by electron microscopy,hematoxylin and eosin staining,immunohistochemistry and other detection methods.Results: Only extracellular matrix structure was preserved in 1% Triton X-100 and 0.5% sodium dodecyl sulfate solution.Hematoxylin and eosin staining,immunohistochemistry and other histopathological sections further confirmed the effectiveness of acellular vascular stent.Conclusion: The mixed solution of 1% Triton X-100 and 0.5% sodium dodecyl sulfate has a satisfactory effect on the construction of acellular vascular scaffolds,which can be used as the materials for the study of biological tissue engineering.Part II Modification of acellular vascular scaffolds and coated hydrogelObjective: To explore the feasibility of hydrogel membrane as a tissue engineering vascular graft after modification of acellular vascular scaffold,and to provide a new scheme for further study of vascular graft.Methods: Hydrogel containing 5% glutaraldehyde concentration acetal polyvinyl alcohol was prepared.The acellular blood vessel scaffold modified with ammonium phosphate zwitterion was treated with hydrogel film by co precipitation method.Platelet adhesiveness test,endothelial progenitor cell adhesion test,hemolysis test,calcium complex test,cytotoxicity test and suture tear strength test were used to evaluate the acellular vascular scaffolds modified by ammonium phosphate zwitterion.Results: Hydrogel was made of ammonium phosphate zwitterion modified acellular vascular scaffold,which was more compact and smooth than that of artificial blood vessel.It can inhibit platelet adhesion,has better blood compatibility,is more conducive to cell adhesion and growth,hemolysis rate is less than the required value of biomedical materials,calcium recovery time is prolonged and cytotoxicity is weakened.Conclusion: the acellular vascular stents modified and covered with hydrogel are better in morphology than that in artificial blood vessels,and have better blood compatibility,cytocompatibility,cytotoxicity and low hemolysis rate,so as to meet the medical standards required by biomedical materials.Part III Animal experimentsObjective: Acellular vascular stent modified of ammonium phosphate zwitterion with hydrogel as outer membrane was verified.through animal experimentsMethods: The animals were randomly divided into two groups.The experimental group used patches of acellular vascular scaffold modified modified of ammonium phosphate zwitterion by hydrogel as the outer layer.The control group used artificial vascular patch,and the blood vessels were tested by B ultrasound,CT scanning and CTA three-dimensional reconstruction.Results: The operations of all the animals were successful.In the control group,stenosis was found by B-ultrasound at 6 months after operation.In the control group,CT scan and CTA three-dimensional reconstruction were carried out at 6 months after operation.It was found that the vessels in the experimental group were still unobstructed and the walls of vessels were smooth at 6 months after operation.In the control group,stenosis was found.Conclusion:The patch of ammonium phosphate zwitterion modified acellular vascular scaffold with hydrogel as the outer layer shows good biocompatibility.In terms of vascular patency,it is better than the artificial vascular patch.