| Endovascular graft exclusion is an effective therapy for the treatment of vascular disease,which is concerned because of its advantages of micro-trauma and quick recovery.Endovascular prosthesis plays a vital role in the endovascular graft exclusion,as its performance would directly determine the treatment effect.In fact,because of some necrotic human blood vessels with bifurcation structure,it is necessary and important to develop bifurcated endovascular prosthesis to meet the needs of transplant.In order to develop better-performance endovascular prosthesis,nine bifurcated woven endovascular prosthesis(BWEP)with different parameters were designed via orthogonal test and prepared by a modified loom in this study.After this,the BWEP was treated with the process of cleaning,degumming and finalizing the design,and then the final BWEP can be got.The surface topography,thickness,water permeability,surface hydrophilicity,diameter tensile strength and bursting strength of final BWEPs were characterized according to standard protocols,and the results were analyzed using range analysis.The pure silk-based BWEP with a better performance was modified by layer-by-layer heparin coating and mixed solution of silk fibroin and heparin coating,respectively.After coating,the physical performance and blood anticoagulant activity of modified BWEP was compared to those of untreated BWEP.In addition,human vascular smooth muscle cells were cultured in cell culture medium with different liquids of modified BWEP.The range analysis showed that the thickness,diameter tensile strength,burst strength,contact angle,and water permeability of BWEP were influenced most by factor B,C,C,A and C,respectively(A: weft density,B: fabric weave,C: warp×weft materials),so that the preparation process was optimized.The silk-based BWEP with plain weave,fabric density of 1100/10 cm×2000/10 cm with a very good performance in terms of thickness(0.085 mm)and water permeability(5.19 m L/(cm2×min)),which can meet the requirement of transplantation.With layer-by-layer heparin coating,the water permeability of the BWEP was changed from 5.19 m L/(cm2×min)to 4.56 m L/(cm2×min),the surface contact angle was changed from 52.64° to 45.21°,but the thickness,mechanical properties,crystal structure and secondary structure of it was not significantly changed.The anticoagulation experiment in vitro and cell experiment showed that the BWEP with layer-by-layer heparin coating had the functions of anticoagulation and inhibiting the growth of human vascular smooth muscle cells,which was with great potential to avoid congestion of BWEP.By contrast,with mixed solution of silk fibroin and heparin coating,the water permeability of BWEP was changed from 5.19 m L/(cm2×min)to 1.56 and 1.15 m L/(cm2×min),while the thickness and mechanical properties were not significantly changed.Theheparin was just released 60% after 144 h for mixed solution coated BWEP with steam treatment,while it was completely released after 72 h for mixed solution coated BWEP with air drying.The analysis of crystal structure and secondary structure showed that steam treatment can promote the coatings from silk I to silk II,so that affected the release of heparin.In addition,the cell experiment showed that the modified BWEP with steam treatment can still inhibit the growth of human vascular smooth muscle cells after 144 h release,which can avoid congestion resulted from hypertrophy of human vascular smooth muscle cells in certain term.In conclusion,a novel seam Less BWEP was developed with potential applications in transplantation of branched blood vessels.From a series of characterizations and analysis,a better performance BWEP was modified with heparin by different methods.Coagulation experiment in vitro and cell experiment illustrated the modified BWEP was potential for the treatment of vascular disease.Further studies would focus on more cell experiment and animal experiment. |
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