Celoptics, Inc., Rockville, Maryland.
National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland.
Biophys J. 2019 Oct 1;117(7):1167-1178. doi: 10.1016/j.bpj.2019.07.052. Epub 2019 Aug 15.
Toward the goal of understanding the pathophysiology of mild blast-induced traumatic brain injury and identifying the physical forces associated with the primary injury phase, we developed a system that couples a pneumatic blast to a microfluidic channel to precisely and reproducibly deliver shear transients to dissociated human central nervous system (CNS) cells, on a timescale comparable to an explosive blast but with minimal pressure transients. Using fluorescent beads, we have characterized the shear transients experienced by the cells and demonstrate that the system is capable of accurately and reproducibly delivering uniform shear transients with minimal pressure across the cell culture volume. This system is compatible with high-resolution, time-lapse optical microscopy. Using this system, we demonstrate that blast-like shear transients produced with minimal pressure transients and submillisecond rise times activate calcium responses in dissociated human CNS cultures. Cells respond with increased cytosolic free calcium to a threshold shear stress between 8 and 21 Pa; the propagation of this calcium response is a result of purinergic signaling. We propose that this system models, in vitro, the fundamental injury wave produced by shear forces consequent to blast shock waves passing through density inhomogeneity in human CNS cells.
为了理解轻度爆炸引起的创伤性脑损伤的病理生理学，并确定与原发性损伤阶段相关的物理力，我们开发了一种系统，该系统将气动爆炸与微流道耦合，以便在类似于爆炸的时间尺度上，但压力瞬变最小，精确且可重复地向分离的人中枢神经系统 (CNS) 细胞传递剪切瞬变。使用荧光珠，我们已经描述了细胞经历的剪切瞬变，并证明该系统能够准确且可重复地传递具有最小细胞培养体积压力的均匀剪切瞬变。该系统与高分辨率、延时光学显微镜兼容。使用该系统，我们证明了用最小的压力瞬变和亚毫秒上升时间产生的类似爆炸的剪切瞬变会激活分离的人中枢神经系统培养物中的钙反应。细胞对 8 至 21 Pa 之间的阈值剪切应力表现出细胞溶质游离钙的增加；这种钙反应的传播是嘌呤能信号的结果。我们提出，该系统在体外模拟了剪切力引起的基本损伤波，这些剪切力是由于爆炸冲击波穿过人中枢神经系统细胞中的密度不均匀性而产生的。
