| Arteries have a key role in transporting blood to everywhere in the human body. Once a vascular disease is appeared, it will seriously affect the health of human.Currently cardiovascular and peripheral vascular diseases are increasingly threatening people’s health and life throughout the word. The most effective method to treat vascular diseases is still the vasotransplantation. Due to the special location, small size and so on, small diameter arterial prostheses prone to form angiostenosis which blocked their way to commercialization. How to fabricate small diameter arterial prostheses with excellent performances becomes the focus of current research.Polyester has both excellent mechanical properties and biocompatibility which make it a superb material in medium and large diameter vascular grafts. Fibroin have excellent biocompatibility that can serve cell adhesion and growth in vivo. This superior property make it more and more popular in the field of biomedical materials. There were research group found the proliferation of endothelial cells which has a potential of endothelialization. This make it possible for fibrion to prevent thrombosis after implantation when used in small diameter arterial prostheses.As a result, silk fibroin became a promising material in fabricating small caliber vascular prosthesis.For the above reasons, the polyester multifilament and silk multifilament were selected to weave polyester/silk blended small diameter arterial prostheses. The multifilaments were braided to aviod sizing before weaving. This not only simplified the weaving process, but also avoid the toxicity or inflammatory reaction that may cause by the sizing agent. In addtion, no sizing means no desizing, which aviod the possible pollution. By adjusting the weaving parameters, polyester/silk blended small diameter arterial prostheses with uniform wall structure were obtained. The inner diameters of the arteial prostheses were no more than4mm. By designing, we have obtained the small diameter arterial prostheses which were preclot-free. In this part, we have applied the patent of invention (No. CN102920531A). Meanwhile,100%polyester and100%silk small caliber vascular grafts were fabricated as reference samples. the tubular seamless small diameter artificial blood vessels with uniform wall strucuture were obtained by heat-setting the prototype of small diameter vascular grafts at120℃for10minutes.Sericin contained in the silk yarns may cause inflammation after implantation. We have tried many ways to remove sericin gum in the small diameter arterial prostheses. Samples were scoured to remove the sericingum in sodiumcarbonate(0.05wt%) at87℃for90minutes with mechanical action. The samples were first dyed with a picric acid-camine compound dye liquor which produces a red color with sericin and a yellow color with silk fibroin. The effect of degumming was confirmed gravimetrically by measuring the weight loss. In addition, the cytotoxicity was applied as one of the method to inspect the efficiency of degumming. All showed the result that, after degumming the samples were degummed completely. Compared the yarn counts, thicknesses, diameters of the small diameter arterial prostheses before and after degumming, an increase within5%was found in the change of warp yarn counts while that of the weft yarn counts reached10%. Significant changes were observed in thickness before and after degumming. After degumming, almost all samples have larger inner diameter than before.Degummed small diameter arterial prostheses were evaluated systemly in this paper, including water permeability, mechanical properties and cytocompatibility. The relationship between performances and the construction of the samples were also analyzed. In detail, the in-vitro performances of the small diameter arterial prostheses were evaluated with ISO7198:1998as the reference. The ePTFE commercial graft as well as host arteries were set as control. The small diameter artificial blood vessels in the study have a value of water permeability between0and165mL/(cm2*min), which makes it preclot-free. Yarn types as well as construction of fabric exercise a great influence on water permeability. Woven small diameter arterial prostheses were qualified as the substitution of the host arteries because they show higher probe bursting strength when compared with ePTFE commercial grafts. Among all the woven prostheses, the polyester/silk blended sample with a1/1plain weave has the highest bursting strength which was2times of that of the ePTFE commercial graft. In addition, the suture retention forces of all samples were significantly higher than that of the dog femoral artery, wherein the polyster/silk blended sample with a2/2twill weave has the highest suture retention force, which was4.7times of that of the dog femoral artery and2.5times of that of the commercial ePTFE graft. The radial compliance of the samples was measured on an Enduratec dynamic mechanical simulation system manufactured by the Bose Corporation. It was found that the compliance values of the woven samples lie between the values of the pig’s carotid artery and that of the ePTFE sample, herein indicates that the radial compliance of the woven samples needs to be further improved. Cell viability was determined by the MTT test as well as observation of confocal microscopy. The MTT test showed that the cell proliferation on the Polyester/silk arterial prostheses was significantly superior to the level of that on the ePTFE commercial control.The dynamic fatigue property of the small diameter arterial prosthese was evaluated by EnduraTec(?) accelerated fatigue tester introduced from BOSE Company. The evolution of the structures and performances fo the woven small diameter arterial prostheses after fatigue test were studied. The research shows that yarn types and the constructions make an impact on the performances after fatigue test. In addition, the order of all the woven small diameter arterial prostheses based on the performances were obtainded by using Borda method.In summary, this study has formed the polyester/silk blended small diameter arterial prostheses with a uniform wall structure, excellent mechanical properties and in vitro cell compatibility. In addition, a preliminary discussion of the relationship between the weaving parameters and performances of the arterial prostheses were discussed. It has built a foundation for the further study of the small diameter arterial prostheses. |
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