Abstract TP468: Differential Effect of Ischemia and Thrombin Mediated Toxicity on Neurovascular Unit

Abstract

Objectives: Brain is a complex structure during ischemia along with neurons; components of vascular unit astrocytes, pericytes and endothelial cells play a major role in hypoxic and blood brain barrier leakage mediated injury. Thrombin acts via protease activated receptor-1 (PAR-1) and leads to neuronal survival or death, PAR-1 knockout cells survive ischemia. We hypothesize that different elements of the Brain vascular unit play different roles in responding to injury. The present study aimed to establish a correlation between astrocytes, pericytes and endothelial cells vulnerability via OGD model of ischemia and Thrombin mediated toxicity. Methods: Using highly reproducible oxygen glucose deprivation (OGD) model Primary cultured cells were exposed to OGD for various durations and Thombin doses to determine the optimum time point for 80 % cell death or cell viability measured using LDH release assay MTT assay. LD50 dose of OGD and Thrombin was used to determine the effect of various drugs mediating PAR-1 receptor pathway Results: The viability assay using MTT showed that the three elements of vascular unit respond differentially to longer durations of ischemia, with pericytes being the most vulnerable, followed by endothelial cells, followed by astrocytes. Our thrombin dose effect shows that Pericytes and endothelial respond to thrombin similarly whereas, astrocytes on lower concentration proliferate, but don’t survive the higher concentrations. Conclusion: An exciting, novel finding in our data is that different elements of the vascular unit—astrocytes, pericytes and endothelial cells—all exhibit effect of ischemia and reperfusion at different time scales. Up until recently, studies of neuroprotection addressed the brain as a homogenous unit, with the tacit assumption that all elements responded similarly. Our data on astrocytes, endothelial cells and pericytes—allows more focused investigation.