Pathophysiological cascade of stroke and treatment strategies investigated in hiPSC-derived neuronal cultures modelling the ischemic penumbr
In ischemic stroke, there is an incredibly complex pathophysiological cascade which augment brain damage. Starting with energy failure caused by low perfusion levels, leading to e.g. synaptic failure, excitotoxicity, mitochondrial dysfunction and ending in different types of cell death like necrosis and apoptosis. The extensive and heterogenous cascade makes stroke a disease that is difficult to treat. In experimental research different treatment strategies are investigated that target one or more molecular events that occur in stroke. Most of these experimental studies show neuroprotection. Translation of these treatment strategies to patients is still difficult. Here we reviewed the pathophysiological cascade and candidate treatment strategies. Then we established a human model of the ischemic penumbra to test the effect of hypoxia on the synaptic puncta, cell viability and the mitochondria and neuronal network functionality. Furthermore, we investigated treatment strategies based on suppression of neuronal activity (NMDAR antagonist and hypothermia) and enhancement of neuronal activity (optogenetic stimulation). Neurons were generated from induced pluripotent stem cells derived from healthy donors and cultured on coverslips and micro-electrode arrays. The effect of different treatment strategies on cell viability and neuronal network functionality was tested. hiPSCs are vulnerable to hypoxia reflected by an increase of cell death and decrease in activity and synchronicity under low oxygen conditions. Results showed that NMDAR antagonist memantine did not rescue the cultures after 48h of hypoxia. Hypothermia and optogenetic stimulation on the other hand did improve resistance to hypoxia after 48h. We showed that hiPSC-derived neurons are vulnerable to hypoxia and that treatment strategies based on preservation of energy and enhancement of neuronal activity can be neuroprotective.
Faculteit der Sociale Wetenschappen