An investigation on the correlation between the mechanical property change and the alterations in composition and microstructure of a porcine vascular tissue underwent trypsin-based decellularization treatment

Purpose: The nonlinear pseudoelastic behavior of a native/decellularized vascular tissue is closely related to the detailed composition and microstructure of the extracellular matrix and is important in maintaining the patency of a small-caliber vascular graft. A commonly used enzyme-detergent based decellularization protocol is effective in cell component removal but it also changes the microstructure and composition of the decellularized tissues. Previous studies provide limited information to correlate the mechanical property change with the alterations in composition and microstructure in a decellularization process. In this study, the correlations were studied by implementing a previously established fiber-progressive-engagement model to describe the nonlinear pseudoelastic behavior of a vascular tissue and to evaluate the effects of trypsin concentration and exposure duration on porcine coronary artery decellularization Results: Results showed that tissue length and width increased and thickness and wet weight decreased with the exposure of trypsin. The effects of trypsin exposure times on the four mechanical parameters, i.e. initial strain, turning strain, initial modulus and stiffness modulus, in the longitudinal and circumferential directions were similar, but stronger in the circumferential direction. Major components of the extracellular matrix were vulnerable to the trypsin-based decellularization process. The decreases in initial and turning strain and the increase in initial modulus in circumferential direction were correlated with the significant decrease of collagen and glycosaminoglycans in the media layer. Conclusions: Although trypsin-based decellularization achieved cell component removal and preservation of ultimate tensile stress, the microstructure and composition changed with alterations in the pseudoelastic behavior of the porcine coronary artery. Taken together, the current observations suggested less waviness, early engagement, or re-alignment of insoluble collagen fibers in the media layer, which resulted in turning from anisotropic into isotropic uniaxial mechanical property of porcine vascular tissue. Selecting the proper trypsin concentration (< 0.03–0.5%) and duration (< 12 h) of trypsin exposure in combination with other methods will achieve optimal porcine coronary artery decellularization.