磷酰胆碱表面改性增强聚四氟乙烯心脏瓣膜材料的生物相容性

Phosphorylcholine coating enhances biocompatibility of expanded polytetrafluoroethylene used in polymeric prosthetic heart valves

背景:前期研究发现将膨体聚四氟乙烯单瓣同时植入绵羊降主动脉和左肺动脉20周,无明显血栓、钙化或降解,验证了其优良的特性,但在左肺动脉处有明显的新生内膜增生。目的:观察磷酰胆碱表面改性超微孔膨体聚四氟乙烯的生物相容性变化。方法:以磷酰胆碱对膨体聚四氟乙烯进行表面改性,观察改性前后膨体聚四氟乙烯表面形状、接触角、屈服点拉伸应力及弹性模量、蛋白吸附能力的变化。1溶血实验:在稀释人血中分别加入改性膨体聚四氟乙烯浸提液、膨体聚四氟乙烯浸提液、生理盐水及蒸馏水。2血小板计数实验:在健康人全血中分别加入改性膨体聚四氟乙烯、膨体聚四氟乙烯、高密度聚乙烯及酵母聚糖A。3血小板激活实验:在健康人全血中分别加入改性膨体聚四氟乙烯、膨体聚四氟乙烯、γ-球蛋白及酵母聚糖A。结果与结论:与改性前比较,改性后膨体聚四氟乙烯的微孔面积显著减小(P<0.001),亲水性及抑制蛋白吸附能力显著增强(P<0.001),生物力学性能及溶血性能无明显变化。体外血小板计数和血小板激活实验显示,改性后膨体聚四氟乙烯的抗血栓性能显著增强。说明磷酰胆碱表面改性可以增强超微孔膨体聚四氟乙烯的抗血栓性和抗蛋白吸附能力,改善其生物相容性。

BACKGROUND：Our preliminary study found that the monocusp valves made of ultramicropore expanded polytetrafluoroethylene （ePTFE） revealed no significant thrombus, calcification, or degradation 20 weeks after implanted into the descending aorta and the left pulmonary artery in sheep, which verified the good property of ePTFE. However, the surface of ePTFE in the left pulmonary artery was covered with obvious neointima. OBJECTIVE： To assess the biocompatibility of phosphorylcholine-coated ePTFE. METHODS：ePTFE surface was modified by phosphorylcholine derivative. Then the changes of surface shape, tensile stress at yield and elasticity modulus, water contact angle, and protein absorption capacity of ePTFE after surface modification were observed. （1） Hemolytic test： the leaching solution of phosphorylcholine-coated ePTFE, leaching solution of uncoated ePTFE, normal saline, and distiled water were added to the diluted human blood, respectively. （2） Platelet count test： the phosphorylcholine-coated ePTFE, uncoated ePTFE, high density polyethylene, and Zymosan A were added to the whole blood samples from healthy volunteers, respectively. （3） Platelet activation test： the phosphorylcholine-coated ePTFE, uncoated ePTFE, γ-Globulins, and Zymosan A were added to the whole blood samples from healthy volunteers, respectively. RESULTS AND CONCLUSION： The mean micropore diameter of ePTFE was significantly decreased after phosphorylcholine coating （P 〈 0.001）. The hydrophilicity and the ability of suppressing protein adsorption were significantly strengthened after phosphorylcholine coating （P 〈 0.001）. Phosphorylcholine coating did not influence ePTFE in biomechanical properties and hemolytic test. The platelet count test and platelet activation test demonstrated that phosphorylcholine coating significantly improved anti-thrombus function of ePTFE. So, phosphorylcholine coating can enhance anti-thrombus function, suppress protein adsorption, and improve biocompatibility of ePTFE.