Biocompatibility Research Of Poly-(Para-dioxanone) Applied To Intravascular Stent

Background and objective:Congenital vascular stenosis is an important part in the congenital heart disease,if the metal stents,which were used in the adult vascular stenosis,were applied to the children,it may cause fixed stenosis;if congenital vascular stenosis was treated with balloon dilatation,the vascular may retract acutely.In the treatment of children congenital vascular stenosis,biodegradable stents are credited with huge potential.Biodegradable stents are usually made of polymers,which can be degraded to water and carbon dioxide in vivo and considered no toxic or side effects.PPDO,a kind of biodegradable polymer material,is approved by FDA that can be implanted in the body.Interesting,the in vitro degradation time of PPDO is about 3 ～ 4 months,which is coincide with the support time of orifice stents,so it is regarded as one of the ideal material in making vascular stents.This study selects the poly lactic acid(PLA),which is the most common biodegradable stents materials in clinical as a comparison,simulates the environment of the stent in vascular and then studys the biocompatibility of PPDO;PPDO and iohexol were blended and then were pressed into a radiopaque film,study the biocompatibility of the new polymer blends;at last,we research the particles degraded from PPDO and PLA,which can influence the vascular smooth muscle cells,endothelial cells,macrophages and their regulation between each other.Method:1.The biocompatibility of the PPDO.The PPDO and PLA were pressed by plate vulcanization machine and then turned to films.Blend the film with blood,biocompatibility of the polymers were evaluated through dynamic clotting time test,partial thromboplastin time test,platelet adhesion test and hemolysis test.In addition,the extract of PPDO and PLA wre used to cultivate smooth muscle cells and endothelial cells,the cytocompatibility of the polymers were evaluated through detecting the relative growth rate of the cells.2.The biocompatibility of the PPDO-iohexol mixture.PPDO,mixed with iohexol by 4:1,was pressed into films and then detect the radiopacity of the films.Further study of the biocompatibility of the blend was done as some as the previous method.3.The cells and their microenvironment affected by PPDO.Cultivate vascular smooth muscle cells,endothelial cells and macrophages with PPDO and PLA particles,then detect the phagocytic activity,cytotoxicity and the cell factor(TNF-α、NO、PDGF 和 VEGF)secreted by the cells.At last,co-cultivate smooth muscle cells and endothelial cells,arfer they were stimulated by particles,test the percentage of the two kinds of cells.Rsults:1.PPDO and PLA has similar biological compatibility.2.The mixture of PPDO and iohexol has visuality under x-ray and good biological compatibility3.The PPDO and PLA particles can induce the secretion of PDGF and VEGF came from smooth muscle cells,they can promote the proliferation of smooth muscle cell mildly.Conclusion:PPDO has good biological compatibility,and they can be made biodegradable stents.