Preparation And Performance Study Of Composite Decellularized Valve Scaffold

The function of the heart valve is to block the return of blood and make the blood flow in a directional flow.Once the heart valve is diseased,the human body will face life-threatening.At present,the most commonly used replacement valves for valve replacement are mechanical valves and biological valves,but these two valves have the problem that they cannot grow in the human body.Patients with mechanical valves need to take anticoagulant drugs for a long time,while biological valves have the disadvantages of easy calcification and short service life.In response to these problems,this paper uses a combination of porcine aortic decellularized valve and polylactic acid material with excellent biocompatibility to prepare a tissue engineered valve with high mechanical strength,good flexibility and good biocompatibility.First of all,in order to solve the problem that decellularized valves are not easy to process,this topic will use polyvinyl alcohol(PVA)and decellularized valves to composite,using PVA and decellularized valves to form a PVA/decellularized valve composite membrane so that it can be processed.The effect of PVA concentration on the microscopic morphology,softness,mechanical properties and biocompatibility of decellularized valves was studied.SEM and FTIR analysis showed that the surface microstructure of the decellularized valve treated with 10% and 12% PVA did not change,while the surface of the decellularized valve treated with 14% and 16% PVA showed uneven structure.Through the test results of softness,mechanical properties and biocompatibility,it is found that PVA solution treatment will not affect the softness,mechanical properties,and biocompatibility of the valve.Therefore,in subsequent experiments,a 12% PVA solution was used to pre-treat the decellularized valve.Secondly,in view of the problem of the mechanical properties of the valve being reduced after decellularization,on the basis of PVA curing the decellularized valve,polylactic acid(PLA)yarn is used to strengthen the decellularized valve.Polylactic acid yarns of different fineness are used to suture and strengthen the decellularized valve.A yarn with a fineness of 28 tex was selected based on the results of microscopic morphology and mechanical properties,and then the yarn spacing was changed.The greater the yarn spacing,the greater the softness of the valve,and the closer it is to the softness of the untreated decellularized valve.The results of the cytocompatibility test show that the decellularized valves sutured with different PLA yarn spacing can promote cell adhesion and proliferation to a certain extent,and the cell adhesion morphology is good.As the culture time increases,the number of cells on the surface of the valve gradually increases,and the adhesion is firm,with good biocompatibility.The mechanical performance test results show that the PLA yarns with different spacing have no obvious enhancement effect on the mechanical performance of the valve.Finally,since the improvement of the mechanical properties of the polylactic acid yarn is not obvious,in order to further improve the mechanical properties,the electrospinning and non-woven processing methods are combined to prepare the PLA/decellularized valve nanofiber-reinforced sandwich structure electrospun scaffold.SEM,FTIR and contact angle meter were used to analyze the surface fiber morphology and structure of the sandwich structure electrospun scaffold.The results show that: the change of electrospinning time will not cause too much influence on the fiber arrangement,fineness and hydrophobicity of the surface of the decellularized valve;The thickness of the electrospinning stent can be adjusted by adjusting the electrospinning time to achieve the purpose of quantitative analysis.The longer the electrospinning time,the thicker the electrospinning stent.Through the mechanical performance test,the result is that the mechanical properties of the decellularized flap can be adjusted by adjusting the electrospinning time.The longer the electrospinning time,the greater the strength and tensile strain.However,as the electrospinning time increases,the hardness of the valve will also increase significantly.Through the biocompatibility test,the result is that the electrospun scaffold has a certain promotion effect on cell adhesion and proliferation,and the cell adhesion form is good.As the culture time increases,the number of cells on the surface of the scaffold gradually increases.The adhesion is firm,but when the electrospinning time is too long,the electrospinning scaffold will be stratified and the cell compatibility will be weakened.