期刊
ACTA BIOMATERIALIA
卷 42, 期 -, 页码 265-272出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.actbio.2016.07.040
关键词
Brain; Mechanical testing; Indentation; Soft matter; Stiffness; Myelin
资金
- German National Science Foundation [STE 544/50-1]
- Bavaria California Technology Center grant 'Mechanical Characterization of Brain Development'
- Bio-X IIP seed grant 'Understanding Gyrification Dynamics in the Human Brain'
Brain stiffness plays an important role in neuronal development and disease, but reported stiffness values vary significantly for different species, for different brains, and even for different regions within the same brain. Despite extensive research throughout the past decade, the mechanistic origin of these stiffness variations remains elusive. Here we show that brain tissue stiffness is correlated to the underlying tissue microstructure and directly proportional to the local myelin content. In 116 indentation tests of six freshly harvested bovine brains, we found that the cerebral stiffnesses of 1.33 +/- 0.63 kPa in white matter and 0.68 +/- 0.20 kPa in gray matter were significantly different (p < 0.01). Strikingly, while the inter specimen variation was rather moderate, the minimum and maximum cerebral white matter stiffnesses of 0.59 +/- 0.19 kPa and 2.36 +/- 0.64 kPa in each brain varied by a factor of four on average. To provide a mechanistic interpretation for this variation, we performed a histological characterization of the tested brain regions. We stained the samples with hematoxylin and eosin and luxol fast blue and quantified the local myelin content using image analysis. Interestingly, we found that the cerebral white matter stiffness increased with increasing myelin content, from 0.72 kPa at a myelin content of 64-2.45 kPa at a myelin content of 89%, with a Pearson correlation coefficient of rho = 0.91 (p < 0.01). This direct correlation could have significant neurological implications. During development, our results could help explain why immature, incompletely myelinated brains are softer than mature, myelinated brains and more vulnerable to mechanical insult as evident, for example, in shaken baby syndrome. During demyelinating disease, our findings suggest to use stiffness alterations as clinical markers for demyelination to quantify the onset of disease progression, for example, in multiple sclerosis. Taken together, our study indicates that myelin might play a more important function than previously thought: It not only insulates signal propagation and improves electrical function of single axons, it also provides structural support and mechanical stiffness to the brain as a whole. Statement of Significance Increasing evidence suggests that the mechanical environment of the brain plays an important role in neuronal development and disease. Reported stiffness values vary significantly, but the origin of these variations remains unknown. Here we show that stiffness of our brain is correlated to the underlying tissue microstructure and directly proportional to the local myelin content. Myelin has been discovered in 1854 as an insulating layer around nerve cells to improve electric signal propagation. Our study now shows that it also plays an important mechanical role: Using a combined mechanical characterization and histological characterization, we found that the white matter stiffness increases linearly with increasing myelin content, from 0.5 kPa at a myelin content of 63-2.5 kPa at 92%. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据