Hoffe Brendan, Mazurkiewicz Ashley, Thomson Hannah, Banton Rohan, Piehler Thuvan, Petel Oren E, Holahan Matthew R
Departement of Neuroscience, Carleton University, Ottawa Ontario K1S 5B6, Canada.
Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa Ontario K1S 5B6, Canada.
J Biomech. 2021 Nov 9;128:110708. doi: 10.1016/j.jbiomech.2021.110708. Epub 2021 Aug 27.
The biomechanical response of brain tissue to strain and the immediate neural outcomes are of fundamental importance in understanding mild traumatic brain injury (mTBI). The sensitivity of neural tissue to dynamic strain events and the resulting strain-induced changes are considered to be a primary factor in injury. Rodent models have been used extensively to investigate impact-induced injury. However, the lissencephalic structure is inconsistent with the human brain, which is gyrencephalic (convoluted structure), and differs considerably in strain field localization effects. Porcine brains have a similar structure to the human brain, containing a similar ratio of white-grey matter and gyrification in the cortex. In this study, coronal brain slabs were extracted from female pig brains within 2hrs of sacrifice. Slabs were implanted with neutral density radiopaque markers, sealed inside an elastomeric encasement, and dropped from 0.9 m onto a steel anvil. Particle tracking revealed elevated tensile strains in the sulcus. One hour after impact, decreased microtubule associated protein 2 (MAP2) was found exclusively within the sulcus with no increase in cell death. These results suggest that elevated tensile strain in the sulcus may result in compromised cytoskeleton, possibly indicating a vulnerability to pathological outcomes under the right circumstances. The results demonstrated that the observed changes were unrelated to shear strain loading of the tissues but were more sensitive to tensile load.
脑组织对应变的生物力学反应以及直接的神经学结果对于理解轻度创伤性脑损伤（mTBI）至关重要。神经组织对动态应变事件的敏感性以及由此产生的应变诱导变化被认为是损伤的主要因素。啮齿动物模型已被广泛用于研究撞击诱导的损伤。然而，光滑脑结构与人类的脑回脑（卷曲结构）不一致，并且在应变场定位效应方面有很大差异。猪脑与人类大脑结构相似，皮层中白质与灰质的比例以及脑回形成情况相似。在本研究中，在处死后2小时内从雌性猪脑中提取冠状脑切片。切片植入中性密度不透射线标记物，密封在弹性包裹物中，并从0.9米高处落到钢砧上。粒子追踪显示脑沟处拉伸应变升高。撞击后一小时，仅在脑沟内发现微管相关蛋白2（MAP2）减少，细胞死亡没有增加。这些结果表明，脑沟处拉伸应变升高可能导致细胞骨架受损，这可能表明在适当情况下易出现病理结果。结果表明，观察到的变化与组织的剪切应变负荷无关，而对拉伸负荷更敏感。
