Effect of sadiron azide on morphology and biomechanics of rite decellular tissue-engineered cardiac valves

Abstract

Objective Heart valves made by tissue engineering procedure may be superior to those by converaitional procedure. Optimal techniques for decellularization farm pretreated heart valves should preserve maximum matrix, which is associated directly withthe mechanical strength and durability of the valves. The study was designed to compare the morphology and biomechanics of the matrix after decellularization procedures with conventional aodium-deoxycholate method and the addition d sodium azide to the fonner method, in order to provide experimental basis for producing ideal tissue-engineered heart valves. Methods Fresh aortic valves from porcine of 6 to 7 month were divided randomly into two groups (60 valve leaflets in each group). Valves in one group were treated with Triton-X100 and sodium deoxycholate, and those in the other group were treated with identical chemicals and sodium azide. Changes of the matrix structure and effects of treatment on the collagen and elastic fibers were observed by microscopy(with hematoxylin and eosin stain, Masson's trichrome stain and Weigert's stain for elastic fiber) and transmission electron microscope. Tissue thickness (60 specimens) and biomechanics properties (50 specimens) were measured. Biomechanics characteristics measured after decellularization weer maximum deflection, elongation rate, max tensile stress and max load. Statistical analysis was performed to compare the thickness and mechanical properties after two decellularization procedures. Results No significant difference in tissue thiekness was found be-tween two methods(P > 0.01), but biomechanics properties-maximum deflection, elongation rate, max tensile stress and max load-were increased significantly in the group with sodium azide (P <0.01). Same results could be obtained through Tensile deflection-Tensile stress and Tensile deflection-Load curve. Although complete decellularization was achieved, matrix structure was comparative integrity in the group treated with sodium azide. Intact, dense collagen fibers and plush-like fibers were seen in the experimental Stoup, while sparse collagen fibers and less velvet-like fibers were present in the control group. Complete and continuous elastic fibers were preserved in the specimens treated with sodium azide while discontinuous, broken and thin fibers were seen in the control group. The pattern d ultrastructure in the sodimn azide group revealed matrix in high density and more fiber bundles in the field. In the com-trol group, the quality of the matrix decreased significantly, and loose fibers with apparent gap were seen. Conclusion Sodium azide can preserve the matrix structure efficiently during the decellurazation procedure and improve the bio-mechanical properties of tissue engineered cardiac valves. Key words: Heart valves; Tissue engineering; Biomechanics