Data from: Simulated blast overpressure induces specific astrocyte injury in an ex vivo brain slice model

Exposure to explosive blasts can produce functional debilitation in the absence of brain pathology detectable at the scale of current diagnostic imaging. Transient (ms) overpressure components of the primary blast wave are considered to be potentially damaging to the brain. Astrocytes participate in neuronal metabolic maintenance, blood–brain barrier, regulation of homeostatic environment, and tissue remodeling. Damage to astrocytes via direct physical forces has the potential to disrupt local and global functioning of neuronal tissue. Using an ex vivo brain slice model, we tested the hypothesis that viable astrocytes within the slice could be injured simply by transit of a single blast wave consisting of overpressure alone. A polymer split Hopkinson pressure bar (PSHPB) system was adapted to impart a single positive pressure transient with a comparable magnitude to those that might be present inside the head. A custom built test chamber housing the brain tissue slice incorporated revised design elements to reduce fluid space and promote transit of a uniform planar waveform. Confocal microscopy, stereology, and morphometry of glial fibrillary acidic protein (GFAP) immunoreactivity revealed that two distinct astrocyte injury profiles were identified across a 4 hr post-test survival interval: (a) presumed conventional astrogliosis characterized by enhanced GFAP immunofluorescence intensity without significant change in tissue area fraction and (b) a process comparable to clasmatodendrosis, an autophagic degradation of distal processes that has not been previously associated with blast induced neurotrauma. Analysis of astrocyte branching revealed early, sustained, and progressive differences distinct from the effects of slice incubation absent overpressure testing. Astrocyte vulnerability to overpressure transients indicates a potential for significant involvement in brain blast pathology and emergent dysfunction. The testing platform can isolate overpressure injury phenomena to provide novel insight on physical and biological mechanisms.

暴露于爆炸冲击波可在当前诊断成像尺度下无法检测到脑病理的情况下，引发大脑功能减退。初级爆炸波的毫秒级瞬态超压成分被认为可能对大脑造成损伤。星形胶质细胞（Astrocytes）参与神经元代谢维持、血脑屏障（blood–brain barrier）稳态环境调控以及组织重塑。通过直接物理作用力造成的星形胶质细胞损伤，有可能破坏神经元组织的局部与整体功能。本研究采用离体脑片模型（ex vivo brain slice model），验证了如下假说：仅由超压构成的单次冲击波传递即可损伤脑片内存活的星形胶质细胞。本研究改装了聚合物分离式霍普金森压杆（polymer split Hopkinson pressure bar, PSHPB）系统，以施加单次正压瞬态信号，其幅值与颅内可能存在的超压幅值相当。本研究搭建的搭载脑片的定制测试舱经过设计优化，以减少流体空间并促进均匀平面波形的传递。通过对胶质纤维酸性蛋白（glial fibrillary acidic protein, GFAP）免疫反应性开展共聚焦显微镜、体视学及形态计量学分析，本研究在测试后4小时的存活周期内观察到两种截然不同的星形胶质细胞损伤表型：(a) 疑似典型星形胶质细胞增生，表现为GFAP免疫荧光强度增强，但组织面积分数无显著变化；(b) 一种与碎裂性星形胶质细胞病（clasmatodendrosis）相似的过程——即远端突起的自噬降解，此前该过程未被报道与爆炸诱导的神经创伤相关。对星形胶质细胞突起分支的分析显示，与未施加超压测试的脑片孵育对照组相比，测试组出现了早期、持续且进行性的形态差异。星形胶质细胞对超压瞬态的易感性表明，其可能在脑爆炸病理及新发功能障碍中发挥重要作用。该测试平台可分离超压损伤现象，为揭示相关物理与生物学机制提供全新视角。