Multiscale measurement of brain tissue and cell biomechanics using a mouse model
image: A Shear wave propagation in a mouse brain was recorded along three orthogonal axes using MRE at a frequency of 1.0 kHz, capturing wave images. B The cerebral cortex and hippocampus regions were delineated using the magnitude images acquired by the MRE sequence. Panels C, D and E are maps of the storage modulus (G’) (C), loss modulus (G’’) (D), and shear stiffness (|G*|) (E), respectively
Credit: HIGHER EDUCATON PRESS
The intricate structure of the brain at various scales is linked to its functional and biomechanical properties. Since understanding the biomechanical properties is vital for comprehending brain diseases, development, and injuries, measurements at different scales are necessary. Here we introduce methods to measure the biomechanical properties at both tissue and cellular levels using a mouse model. A specially designed magnetic resonance elastography system is introduced for imaging the mouse brain, enabling in vivo mapping of its shear modulus. Additionally, protocols for isolating and culturing primary neurons and astrocytes from the hippocampus and cerebral cortex of the mouse brain are presented. The nanoindentation technique using atomic force microscopy is employed to measure the biomechanical properties of individual cells. The results indicate that the storage/loss modulus of the mouse cerebral cortex and hippocampus are 8.07 ± 1.28 kPa / 3.20 ± 0.66 kPa and 6.60 ± 0.52 kPa / 2.52 ± 0.33 kPa, respectively. Meanwhile, the Young’s modulus for neurons and astrocytes is 470.88 ± 17.67 Pa and 681.13 ± 14.15 Pa, respectively. These findings demonstrate that the brain exhibits distinct biomechanical properties at different scales. The proposed methods offer general techniques for investigating the multiscale biomechanical properties of the brain.