LAUSR

The urinary bladder is a highly dynamic organ, that undergoes large deformations several times a day. Mechanical characteristics of the tissue are crucial in determining the function, and dysfunction, of the organ. Yet, literature reporting on the mechanical properties of human bladder tissue is scarce and, at times, contradictory. In this study, we focused on mechanically testing tissue from both human and pig bladders using identical protocols, to validate the use of pigs as a model for the human bladder. Furthermore, we tested the effect on tissue mechanical properties of two treatments, elastase to digest elastin fibers and oxybutynin to reduce smooth muscle cells spasticity, as well as of the anatomical direction of testing. We also implemented two different material models to aid in the interpretation of the experimental results. We found that human tissue behaves similarly to pig tissue at high deformations (collagen-dominated behavior) while we detected differences between the species at low deformations (amorphous matrix-dominated behavior). Our results also suggest that elastin could play a role in determining the behavior of the collagen fibers network. Finally, we confirmed the anisotropy of the tissue which reached higher stresses in the transverse when compared to the longitudinal direction.