Single blood vessel occlusion in mouse sub-pial vessels to study astrocyte-vasculature interactions in a mini-stroke model

Abstract

Ischemic stroke is a devastating disease, affecting millions of people annually. Research striving to better characterise the mechanisms following ischemic stroke, has identified the astrocyte as being central to the pathogenesis of this disease. Over the years, several studies have sufficiently characterised the effect of prolonged ischemia on astrocyte morphology. In doing so, a gap in our knowledge regarding the immediate effect of ischemia on astrocyte structure has emerged. The aim of this study was to characterise the progression of astrocyte injury immediately following ischemic stroke for up to a one hour post occlusion in mice. In addition, we also characterised the changes in astrocyte morphology following global ischemia, while thoroughly evaluating which techniques were best suited to achieve the aims and objectives of this project. In the majority of instances vessel occlusion was achieved using a 532 nm laser, and the clot was visualised under two photon microscopy through an open cranial window. Global ischemia severely damaged astrocytes producing ‘holes’ within the cytoplasm. Swelling of astrocyte soma and processes, as well as process retraction was observed within one hour following focal vessel occlusion. Repeat experiments are required to confirm our observations, to augment this data in a meaningful statistical manner. Changes in astrocyte morphology which were observed as a direct consequence of the ischemic insult, may hinder astrocytes from carrying out their normal homeostatic functions, thus aggrevating ischemic injury.