Mechanical Testing And Performance Optimization Of Decellularized Artery

With the number of people suffering from Coronary artery disease(CAD) continuing to rise, the demands for artificial arteries increased year by year. Currently, The large caliber artery have already achieved a good clinical application. But when using the same material obtained in small-caliber artery(diameter <6mm) was prone to thrombosis problem, the reason may be related to the properties of the material of artery. In the option of artificial arteries, the body's own arteries and allograft artery is the best choice, but obtaining body's own arteries have huge hurt to body and the number of which is limited; moreover allograft arteries have rejection and the number of which is limited too. Those reasons lead that a large number of patients can not timely and effective achieve medical treatment. So finding a kind of artery that it is similar with body's and it has rich source is particularly important.Decellularized artery removed xenogeneic cell, which can effectively reduce the rejection, and maintain the extracellular matrix. The extracellular matrix keeps the most mechanical properties of artery, thus decellularized artery retains most of the mechanical properties of the original artery, which has great significant for revascularization, antithrombotic.In this paper, fresh rat carotid artery has been used to make decellularized artery by repeated freezing and thawing + trypsin digestion, and do mechanical testing for decellularzed artery. Outer diameter of decellularized artery is about 0.97 ± 0.03 mm, inner diameter of which is about 0.07 ± 0.01 mm, those meet the size of small-caliber arteries; and mechanic testing detected that residual stress of decellularized artery has greatly reduced. while the residual stress in the artery wall can avoid the stress concentration and is important to prevent the disease, etc. This paper explores the different crosslinked methods in order to recover the residual stress in the artery wall.The main research contents and results:(1) Mechanical testing and tissue analysis of decellularized artery. In terms of mechanical testing, we compared with native artery with opening angle, the residual strain of the inner wall, the residual strain of the outer wall, radial residual strain, elastic modulus. Experimental results show that the residual strain of outer wall, radial residual strain and opening angle of decellularized artery reduced compared with the native artery, however the residual strain of the inner wall has little change, and the elastic modulus increases. Tissue analysis of decellularized artery clarify the reasons why mechanical properties decrease and provide a theoretical basis for residual stress recovery. Tissue analysis of decellularized artery mainly compared the changes between decellularized artery and native artery through HE staining and SEM. The results show that the decellularized artery don't have any cells, outer fiber become loose compared to native artery, and the inner wall has little change;(2) The effect of different ways of crosslinking. In this paper, we use the traditional Crosslinking agent, 0.25%glutaraldehyde, and 0.01% methylene blue+2h ultraviolet irradiation, 0.03% methylene blue+4h ultraviolet irradiation, 0.005% methylene blue+1h ultraviolet irradiation, total four ways of crosslinking. The results showed that the best crosslinked manner is 0.01 % methylene blue+2h ultraviolet radiation, opening angle of which is increased and there is a significant difference with the original opening angle;(3) Mechanical testing and tissue analysis of crosslinked artery. We use the best crosslinked artery to next experiment. Mechanical testing, issue analysis and its indexes are same with decellularized artery. The results show that opening angle increases after crosslinked, the residual strain of the outer wall increased, the residual strain of inner wall and radial residual strain has little change. Elastic modulus is still greater than native artery, but smaller than decellularized artery. Outer fiber becomes closer, and little change in the inner fiber;(4) Experiments of blood compatibility and cytotoxicity of crosslinked artery. Experiments of blood compatibility use the blood of rabbit, and the results show that hemolytic rate of crosslinked artery is 2.8%, which does not have hemolysis. Cytotoxicity of crosslinked artery indicated that RGR of first day, third day, fifth day are more than 75%, in line with national medical material.