Department of Anatomy and Medical Imaging, School of Medical Sciences, Faculty of Medical and Health Sciences and The Centre for Brain Research, University of Auckland, New Zealand.
School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, New Zealand.
J Neurosci Methods. 2021 Oct 1;362:109302. doi: 10.1016/j.jneumeth.2021.109302. Epub 2021 Jul 31.
Axonal injury is a major component of traumatic spinal cord injury (SCI), associated with rapid deformation of spinal tissue and axonal projections. In vitro models enable us to examine these effects and screen potential therapies in a controlled, reproducible manner.
A customized, stretchable microchannel system was developed using polydimethylsiloxane microchannels. Cortical and spinal embryonic rat neurons were cultured within the microchannel structures, allowing a uniaxial strain to be applied to isolated axonal processes. Global strains of up to 52% were applied to the stretchable microchannel-on-a-chip platform leading to local strains of up to 12% being experienced by axons isolated in the microchannels.
Individual axons exposed to local strains between 3.2% and 8.7% developed beading within 30-minutes of injury. At higher local strains of 9.8% and 12% individual axons ruptured within 30-minutes of injury. Axon bundles, or fascicles, were more resistant to rupture at each strain level, compared to individual axons. At lower local strain of 3.2%, axon bundles inside microchannels and neuronal cells near entrances of them progressively swelled and degenerated over a period of 7 days after injury.
COMPARISON WITH EXISTING METHOD(S): This method is simple, reliable and reproducible with good control and measurement of injury tolerance and morphological deformations using standard laboratory equipment. By measuring local strains, we observed that axonal injuries occur at a lower strain magnitude and a lower strain rate than previous methods reporting global strains, which may not accurately reflect the true axonal strain.
We describe a novel stretchable microchannel-on-a-chip platform to study the effect of varying local strain on morphological characteristics of neuronal injury.
轴突损伤是外伤性脊髓损伤（SCI）的主要组成部分，与脊柱组织和轴突投射的快速变形有关。体外模型使我们能够以可控、可重复的方式检查这些影响并筛选潜在的治疗方法。
使用聚二甲基硅氧烷微通道开发了定制的、可拉伸的微通道系统。皮质和脊髓胚胎大鼠神经元在微通道结构内培养，允许对分离的轴突过程施加单轴应变。可拉伸微通道片上平台的全局应变高达 52%，导致微通道内分离的轴突经历高达 12%的局部应变。
暴露于 3.2%至 8.7%局部应变的单个轴突在损伤后 30 分钟内形成珠状。在更高的局部应变 9.8%和 12%下，单个轴突在损伤后 30 分钟内断裂。与单个轴突相比，轴突束或束更能抵抗每个应变水平的断裂。在较低的局部应变 3.2%下，微通道内的轴突束和它们入口附近的神经元细胞在损伤后 7 天内逐渐肿胀和退化。
该方法简单、可靠且可重复，使用标准实验室设备可良好地控制和测量损伤耐受性和形态变形。通过测量局部应变，我们观察到轴突损伤发生在比报告全局应变的先前方法更低的应变幅度和应变率下，这可能不能准确反映真实的轴突应变。
我们描述了一种新颖的可拉伸微通道片上平台，用于研究局部应变变化对神经元损伤形态特征的影响。
