In Vitro Model for Ischemic Stroke: Functional Analysis of Vascular Smooth Muscle Cells

The Neurovascular Unit (NVU) is formed by vascular and neural cells controlling the cerebral hyperaemia. All the components are anatomically and functionally linked to each other, resulting in a highly efficient regulation of the cerebral blood flow, which, when interrupted, can lead to stroke. An ischemic stroke (IS) is the most common type of stroke with high rates of morbidity, mortality and disability. Therefore, it is of extreme importance to protect the functional and structural integrity of the NVU in patients with IS, understanding the mechanisms involved and how it affects each component of the NVU. Thus, the aim of this work is to analyse how the vascular smooth muscle cells from the rat middle cerebral artery function/react after an ischemic event. To mimic this event, primary cortical cultures were challenged to oxygen and glucose deprivation (OGD) for 4 h and 6 h, and the smooth muscle cells (SMCs) contractility was analysed after exposure to different media previously conditioned by the cortical cultures upon reperfusion. The results show a dual effect on the SMCs response to the vasorelaxant agent, only for cells exposed to the reperfusion media conditioned by neuron-glia cultures challenged by OGD, leading to increased relaxation of the SMCs for OGD 4 h, whereas for OGD 6 h the effect is reversed leading to contraction of the SMCs. These differences demonstrate that the astrocytes mediate the vasoactive response of vascular smooth muscle by releasing factors into the reperfusion medium, and the hypoxia time is fundamental for a beneficial/harmful response by the vascular smooth muscle.