Morphology of Cortical Microglia in the Hyperacute Phase of Subarachnoid Hemorrhage.

Hemorrhagic stroke is the deadliest type of stroke. Cellular and molecular biomarkers are important for understanding the pathophysiology of stroke. Microglia are among the most promising biological markers. However, the morphological and physiological characteristics of microglia, as well as the structural and functional aspects of their interactions with neurons and other cells, are largely unknown. Due to the large number of different morphological phenotypes and very limited information on microglial changes in subarachnoid hemorrhage (SAH), we performed this study aimed at identifying the features of the distribution of various microglial phenotypes in the layers of the cerebral cortex in the hyperacute phase of non-traumatic SAH. We studied the distribution of various microglial phenotypes in the layers of the cerebral cortex of SAH non-survivors with a control group (coronary heart disease and sudden cardiac death were the underlying causes of death). An immunohistochemical study using antibodies to iba-1 (a marker of microglia) revealed changes in the morphological phenotypes of microglia in the cerebral cortex after subarachnoid hemorrhage. Significant differences between the groups indicate a rapid microglial response to injury. The findings indicate that there are quantitative and phenotypic changes in microglia in the cerebral cortex during early SAH in the human cortex.