Biocompatibility And Efficacy Of Biodegradable Small Diameter Artificial Blood Vessel

Cardiovascular disease and peripheral arteriovenous disease are serious threat tohuman health, and artificial blood vessel replacement is necessary for severe patients.Generally speaking, great saphenous vein and internal mammary artery are the goldstandard of blood vessel replacement for bypass graft or In situ replacement to thevascular lesions. Due to the limitation of the patient’s own body condition, autologousvessels often cannot be applied. The Allogeneic or xenogeneic vascular has thesimilar compliance with the autologous vascular, but the rejection problem cannot beavoided. Therefore, synthetic vascular prosthesis has attracted scientists’ extensiveresearch and achieved good results in the replacement of macro vascular, such asaortic dissection. However, small diameter artificial vascular (inner diameter<6mm),particularly synthetic vascular and tissue-engineered blood vessels, lead to graftfailure easily due to vascular thrombosis and intimal hyperplasia. Consequently,small-caliber artificial vascular with better biocompatibility and enough mechanicalstrength become the focus of study. In this study, the biodegradable small diameterartificial blood vessel (B-SDAV) chose the chitosan fiber, which has betterbiocompatibility, as skeleton, supplemented by gelatin and heparin. When thematerials were cross linked, preparation of the B-SDAV are completed. This papermainly studied the physicochemical properties, mechanical properties, biologicalsafety, metabolism of chitosan, and the efficacy of B-SDAV.The experiment yielded the following results and progress:1. There were more comprehensive evaluation of the physicochemical propertiesand mechanical strength of B-SDAV. This paper mainly determined the ash, loss ondrying, heavy metals, bacterial endotoxin and pyrogen, and so on. The results showedthat: ash was0.4%, loss on drying was13%, heavy metal was less than10μg/g,bacterial endotoxin was0.25EU/mg, pyrogen was lower than1.3℃(3rabbits). Thecompliance, porosity, longitudinal tensile strength, burst pressure and resistance suture strength of the B-SDAV was mainly measured. The results showed that: thecompliance of B-SDAV were lower than the one’s of natural vascular, longitudinaltensile strength of B-SDAV were stronger than the one’s abdominal aorta but belowthe one’s canine femoral artery, the burst pressure of B-SDAV were higher than thenatural vascular and the resistance suture strength of B-SDAV were stronger than theabdominal aorta, the pore rate of B-SDAV was96.24%±3.99%.2. There were comprehensive evaluation of biosafety and biocompatibility ofB-SDAV. Cytotoxicity of extracts of B-SDAV and cell compatibility of lumen ofB-SDAV both meets the requirements. The blood compatibility experiments ofB-SDAV in vitro showed that: no thrombosis, no hemolysis or no platelet adsorption,coagulation display anticoagulant well. After the B-SDAV was implanted into thebody, the inflammation of surrounding tissue was always lower, and the inflammationdisappeared when the B-SDAV completely degraded. Heparin gradually released withthe degradation of B-SDAV, which could meet the requirements of earlyanticoagulation of B-SDAV. B-SDAV was no acute systemic toxicity. In summary,B-SDAV showed good biocompatibility and biosafety.3. The metabolism of chitosan, which was same with “skeleton” material ofB-SDAV. The degradation products of chitosan was detected in the liver, spleen,kidney, heart and brain, and the content of degradation products of chitosan in theliver and kidney were more than other organs, while the content of degradationproducts of chitosan in the spleen, heart and brain were lower. Urine excretion was themain metabolic pathway of chitosan, and the molecular weight of degradationproducts of chitosan was lower than65kDa.4. The canine femoral artery was replaced by B-SDAV. After implantation,specific staining showed that collagen fibers and elastic fibers were detected in theB-SDAV, and there was no significant difference between normal blood vessels andB-SDAV. B-SDAV formed three-cell structure, which were vascular endothelial cells,vascular smooth muscle cells and fibroblasts from the inside to the outside.