The Fabrication Of Newsmall-diameter Vascular Grafts

Cardiovascular disease is one of the major diseases which affect human's health. The prevailing treatment is vascular graft surgery. Currently large diameter artificial blood vessels made by polymer materials have been used in clinical. However, artificial blood vessels with diameter? 5mm still can not meet the clinical needs due to thrombus, internal hyperplasia and other problems. The tissue engineering scaffolds prepared by electrospinning have high porosity, high specific surface area and internal void unicom network, which can help cell attachment and penetration, and the mechanical properties can be adjusted by selecting materials. Thus electrospinning vascular graft has become a research hotspot. This study used electrospinning to fabricate small diameter artificial blood vessels by mixing poly-caprolactone (PCL), gelatin (GT) and polyvinyl alcohol(PVA).The research results are summarized as below:PCL/GT fibrous scaffolds and PCL/GT:PVA hybrid fibrous scaffolds were prepared by co-electrospinning. SEM images show that those two fibrous scaffolds are uniform and stable, and no beads or blocking. After immersed in PBS(37?)overnight, the PCL/GT:PVA fiber diameter has higher change rate, which is due to the rapid dissolution of the PVA, cause the average diameter becomes smaller. So PCL/GT: PVA scaffolds would have higher porosity after implantation. The mechanical properties degraded after the PVA addition, but it's still slightly higher than most of the blood vessels, such as porcine coronary artery.Heparinwasbound to gelatin by chemical bonding which was confirmed byspectro scopicanalysis. The anti-coagulation ability of the fibrous scaffold after heparinization was improved significantly by platelet adhesion test, and it was confirmed that adding suitable amount of PVA could improve the anti-coagulant ability of the material. MTT results proved that the two scaffolds have good biocompatibility and the PCL/GT: PVA= 3:1 scaffold had better cell compatibility due to the rapid dissolution of PVA in PCL/GT:PVA= 3:1 scaffold, increasing the porosity of the scaffolds. The biocompatibility of the scaffold was also improved after heparinization.The permeability of the cells was tested by implanting two artificial blood vessels into the experimental mice. There were no inflammation or other adverse reactions occurred in mice after implantation. The two vessels were proved to have good biocompatibility. The artificial vessels were removed at 3and8 weeks, then they were sliced and stained by H&E and DAPI. The result shows that the number of cells that adsorbed onto the two scaffolds is similar at 3 weeks. However the depth of cell penetration has reached300microns in the PCL/GT:PVA=3:1 artificial blood after 8 weeks while the PCL/GT scaffold only penetrated 100 microns. Results demonstrate that after adding suitable amount of PVA can greatly improve the penetration ability of the artificial blood vessel cells.