Heterogeneity in cranial dura mater at the microscale: An In-situ and ex-vivo structural and mechanical investigation of sulcus and gyrus Dura

Abstract

This study examines cranial dura mater's structural and mechanical heterogeneity, focusing on the distinct properties between the sulcus and gyrus regions. Microscale analyses using two-photon microscopy and atomic force microscopy (AFM) revealed significant regional differences in thickness (p < 0.05), with sulcus dura being 1.34 times thicker than gyrus dura. Differences in effective Young's modulus were observed, with values of 6.75 ± 5.12 kPa in the sulcus and 10.48 ± 7.13 kPa in the gyrus. These findings highlight the dura mater's pronounced variability in stiffness and anisotropy, with the periosteal layer being substantially stiffer than the meningeal layer. These results underscore the critical role of collagenous architecture in determining dura's mechanical behavior, particularly in the transfer of loads across the brain. This study provides valuable insights into the functional heterogeneity of the dura mater and emphasizes the importance of these variations in the design of biomimetic dural grafts. The quantitative data generated in this study has significant implications for enhancing the biofidelity of computational models used in brain biomechanics and advancing tissue engineering strategies to develop dural substitutes. STATEMENT OF SIGNIFICANCE: This study presents a comprehensive analysis of the structural and mechanical heterogeneity of cranial dura mater at the nanoscale, focusing on the differences between sulcus and gyrus regions. By employing advanced techniques such as atomic force microscopy (AFM) and two photon microscopies, the findings are crucial for understanding the dura's protective functions and its role in load transfer across the brain. The implications of this study are significant for the development of biomimetic dural grafts, as it offers detailed quantitative data necessary for designing grafts that closely mimic the native dura's structural and mechanical. Additionally, this research could help develop more accurate finite element models (FEM) to study traumatic brain injuries (TBI) and brain dynamics.

Keywords: Atomic force microscopy; Cranial dura mater; Mechanical properties; Microstructure; Nanoindentation; Two-photon confocal microscopy.