P-288 - Nrf2 redox signalling in brain endothelial cells adapted to physiological O2: an in vitro model for ischaemia-reperfusion injury in stroke

Sulforaphane (SFN) has been shown to protect against damage sustained following transient ischaemic stroke via activation of the redox-sensitive transcription factor Nrf2. To further understand the protective effects of SFN on the cerebral endothelium, mouse brain endothelial cell line bEnd.3 was subjected to oxygen-glucose deprivation (OGD), an in vitro model of cerebral stroke. Pre-treatment of bEnd.3 cells with SFN (2.5 µM, 12 h) afforded increased protection against OGD induced cell death. Our lab recently reported that long-term culture under physiological oxygen, 5% O2, results in a phenotype markedly different to cells cultured under ambient air, 18% O2, shown by downregulation of selected Nrf2 target genes by Nrf2 activator. In the present study, the bEnd.3 cell phenotype was determined following long-term (5 days) culture under 5% or 18% O2. Under 5% O2, the intracellular O2 content of bEnd.3 cells was 3.6% O2, and a reduced rate of cell proliferation was observed. Furthermore, bEnd.3 cells cultured under 5% O2 exhibited greater sensitivity to OGD-induced cell death. The present study highlights the importance of conducting cell culture studies under physiological O2 levels.