Visceral Pleura Mechanics: Characterization of Human, Pig, and Rat Lung Material Properties

This study presents the first comprehensive biaxial mechanical characterization of human, porcine, and rat visceral pleura to inform lung sealant and tissue model development. Human pleura demonstrated limited extensibility (~40% strain) and high final stiffness (~13 MPa), while pig and rat pleura were more extensible (~60% strain) with lower stiffness (~2 MPa and ~1 MPa, respectively). Pig pleura most closely mirrored human mechanical behavior, exhibiting similar bilinear stress–strain responses and anisotropy between lobes. Smoker human lungs displayed increased stress relaxation (≈19%) compared to healthy donor tissue (≈16%), consistent with extracellular matrix degradation and glycosaminoglycan loss. Confocal microscopy revealed tighter collagen bundling in human pleura and wavier collagen networks in pig and rat, explaining interspecies differences. These results establish cross-species pleural mechanics as a foundation for biomimetic surgical adhesive design and pulmonary biomechanics modeling.