Three Dimensional Printing Of Cardiac Aortic Valve Based On Mold Aided And Cell Damage Simulation

As the incidence of heart valve disease is increasing year by year,taking advantage of three dimensional printing technology to manufacture tissue engineered valves with good growth,self-repair and self-reconstruction ability has become a hot topic in artificial heart valve research.It is a great challenge to fabricate tissue engineered valves with modeling of valves,printing of hydrogel materials,process of valve formation and cell damage.In this paper,the research on three dimensional printing and cell damage analysis of cardiac aortic valve has been studied.Firstly,based on the theory of plate and shell and hemodynamics,taking advantage of the computer-aided design method to construct models of aortic valve and put forward the concept of mold-assisted printing,which provides mechanical support for the aortic valve leaflets and maintains the three-dimensional structure of the leaflet surface to prevent the collapse of the leaflet structure effectively.Compared with natural heart aortic valve,the geometrical form and size parameter of models constructed are similar.Secondly,taking into account the influence of the extrusion swell of hydrogel extruded from the micro needle during the three dimensional printing process according to the fluid simulation software and experimental research.Exploring regulation and impact of extrusion swell under different viscosity and external initial extrusion pressure.The results showed that viscosity determines the formation of hydrogel material on the substrate platform,the extrudate swell ratio decreases with the viscosity increases,extrusion pressure affects the molding quality of the hydrogel material and the extrudate swell ratio increases with the pressure increases.Thirdly,according to the process characteristics of mold-assisted printing,analyzing the printing path of the leaflet supporting mold,leaflet and closed ring,adjusting print parameters and print paths through multiple experiments for critical paths.Using 25 mass fraction of pluronic,2 and 6 mass fraction of sodium alginate-gelatin hydrogel to print completed aortic valve.Compared with the process of bath printing,the processing period is shorter,the printing cost is lower and the material impurities is less.Finally,considering bone marrow mesenchymal stem cells loaded for cell damage after cardiac aortic valve printed,based on mathematical model of cell damage,researching the effect of different nozzle lengths and nozzle diameters on cell damage according to simulation analysis under the criteria of the cell loaded duration and maximum internal pressure.The results showed that the maximum internal pressure inside cell increases with the length of the nozzle increases and the growth of cell loaded duration is tending towards stability.The maximum internal pressure inside cell increases sharply with the length of the nozzle decreases and the growth of cell loaded duration decreases initially and increases afterwards.