Tissue compliance characterization for human umbilical arteries after decellularization.

Human umbilical arteries (HUAs) are promising candidates for small-diameter vascular grafts due to their ability to closely replicate the mechanical behavior and structural integrity of native arteries. To minimize immunogenic responses and promote integration with host tissue following implantation, decellularization is required to remove cellular components from HUAs. A thorough understanding of the mechanical properties of decellularized HUAs (Dec-HUAs) is critical for predicting their mechanical compatibility and adaptability within the host circulation. This study aims to characterize the mechanical alterations induced by decellularization using a hyperelastic constitutive model that incorporates both isotropic and anisotropic damage parameters. Five HUA samples are subjected to mechanical characterization following removal of the abluminal layer and subsequent decellularization. The mechanical response is modeled within a modified hyperelastic damage framework, and model parameters are estimated using an improved fitting approach. Statistical analyses are then performed to evaluate the mean, standard deviation, and significance of changes in mechanical properties. The mechanical analysis of stress-strain behavior under large transmural pressure differences shows that Dec-HUAs exhibit reduced compliance compared with native HUAs. The results reveal a notable increase in compliance (C) following abluminal layer removal, whereas decellularization causes a mild decrease in compliance. Both stored strain energy (W) and compliance (C) serve as indices of vessel compliance, but statistical comparisons indicate that W more effectively captures alterations in compliance during the graft preparation process than C. Overall, these findings highlight the key mechanical changes introduced by decellularization and establish a robust parameter-estimation framework for assessing vessel mechanics. This framework can support future studies on mechanical adaptation of Dec-HUAs and ultimately aid in the development of mechanically compatible and durable vascular grafts.