The Preparation And Basic Researches Of Blood Vessels With Anticoagulant And Endothelial Functions

There are 3 kinds of blood vessel grafts for the clinical use in the current:autologous blood vessels,allogeneic blood vessels and vascular synthetic materials.Autologous blood vessels are the most suitable because of no immune response,while limited by quantity,sources,and the possibility of damaging to the patients;Allogeneic blood vessels are prone to immune rejection;Polymer synthetic blood vessels are restricted to diameter to the preparation of small blood vessels.The Stent synthetic polymer materials has been successfully applied in the large diameter of blood vessels,but the small blood vessels(diameter 6 mm or less)has not been applied successfully so far.So the construction of small diameter artificial blood vessels,the application of the principle of biology and engineering to build a new type of tissue engineering artificial blood vessels is very important.Extracellular matrix(ECM)that composed of large molecules such as collagen,the collagen glycoprotein and glycosaminoglycans sugar complex is a biological networks structure.Extracellular matrix is a special kind of natural biological derivatives,providing physical support for cell growth and suitable living environment,and regulating the cell adhesion,growth,proliferation and differentiation through the signal transduction,ECM plays an important regulatory role in the growth process of cell differentiation and tissue trauma repairation and regeneration.Natural extracellular matrix has the advantages of synthetic scaffold materials and overcomes its shortcomings,and has low immunogenicity and excellent biological characteristics.Hepatic fibrosis is a wound-healing response that engages a range of cell types and mediators to encapsulate injury.Hepatic fibrosis is characterized by an abnormal deposit of extracellular matrix(ECM)constituents,especially type I collagen.The activated hepatic stellate cell(HSC)is responsible for increased collagen synthesis during liver fibrosis.Type I collagen comes mainly from the activation of hepatic stellate cells.Studies have demonstrated that the damage of hepar can promote the activation of hepatic stellate cells and accelerate protein expression of collagen typeI.These cells are activated by fibrogenic cytokines such as TGF-?1,angiotensin ?.Liver fibrosis is the excessive accumulation of extracellular matrix proteins including collagenthat occurs in most types of chronic liver diseases.Advanced liver fibrosis results in cirrhosis,liver failure,and portal hypertension and often requires liver transplantation.Our knowledge of the cellular and molecular mechanisms of liver fibrosis has greatly advanced.Activated hepatic stellate cells,portal fibroblasts,and myofibroblasts of bone marrow origin have been identified as major collagen-producing cells in the injured liver.TGF-?1 can activate the hepatic stellate cells(HSCs)to enhance the secretion of extracellular matrix(ECM)which plays a key role for the development of liver fibrosis.So in this research,we will employ the ability of activated HSCs to prepare human-derived ECM biological vascular grafts.According to our previous study,the activated HSCs presented a stronger ability in secretion of collagen than fibroblasts,we will prepare PCL-gelatin nanofibers vascular scaffold with electrospinning.We will seed activated HSCs on the PCL-gelatin scaffold.The activated HSCs will secrete ECM such as collagen on the prepared vascular scaffold which will be cultured under self-made vascular bio-reactor.The ECM nanofibers are remodeled under the stress,and crosslink with PCL nanofibers.At intervals,the ECM will be analyzed for an ideal production parameter.The HSCs-ECM-PCL vascular construction will be decellularized and lyophilized,and modified with heparin chitosan hydrogel for anticoagulant ability.The anticoagulant ECM-PCL vascular graft will be implanted for arteriovenous hemodialysis access in animal model.The analysis of the original ECM and PCL degradation,host immune and vascular cells infiltration,different layers of vascular wall formation or regeneration and host ECM regeneration will be carried out to confirm vascular mature duration and characters.