In Silico Model for Determination of In Vivo Pre-Stretch in Neonatal and Adult Murine Cranial Dura Mater

Cranial dura mater is a dense interwoven vascular connective tissue that protects the brain and helps regulate neurocranial remodeling during head development. In vivo investigations indicate that the tissue mediates cranial suture fusion by responding to strains from the growing brain. Ex vivo experimentation has attempted to characterize the mechanical properties that make the dura an effective mechanoreceptor and mechanotransmitter; however, they fail to capture key characteristics of the dura in vivo, such as the impact of tissue pre-stretch. Residual strain, or pre-stretch, is an important quality of many biological tissues, and when not accurately captured by ex vivo experiments, generally leads to underestimation of mechanical stiffness. Considering the importance and lacking characterization of dural pre-stretch, this study aimed to create a robust in silico model for determination of in vivo pre-stretch in neonatal and adult murine cranial dura mater. Transverse and longitudinal incisions were performed ex vivo in the parietal dura of newborn (day ∼4) and mature (day 60+) mice. In silico models of incised neonatal and adult dura experiencing isotropic stretching in the plane transverse to the model’s surface normal were simulated in Abaqus/Standard. The ex vivo and in silico incision opening ratios (opening width over length) were compared, allowing the in vivo in-plane pre-stretch to be determined. Images of cut openings and estimations of pre-stretch indicate the dural pre-stretch is direction-dependent. Differences in neonatal and adult pre-stretch provided further insight into the age-dependency of murine cranial dura mater pre-stretch.