Abstract TP86: The Ischemic Blood-brain Barrier In A Dish

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Abstract

The blood-brain barrier (BBB) constitutes a component of the neurovascular unit formed by specialized brain microvascular endothelial cells (BMECs) surrounded by astrocytes, pericytes and neurons. During ischemic stroke injury, the BBB constitutes the first responding element resulting in the opening of the BBB and eventually neural cell death by excitotoxicity. A better understanding of the cellular mechanisms underlying the opening of the BBB during ischemic stroke is essential to identify targets to restore such barrier function after injury. Current in vitro models of the human BBB, based on primary or immortalized BMECs monocultures, display poor barrier properties but also lack one or two cellular components of the neurovascular unit.In this study, we designed an integrative in vitro model of the BBB by generating BMECs, astrocytes and neurons using patient-derived BMECs from two iPSC lines (IMR90-c4 and CTR66M). We were able to obtain all three cell types from these two cell lines. iPSC-derived BMECs showed barrier properties similar or better barrier function than hCMEC/D3 monolayer (an immortalized adult somatic BMEC). Furthermore, iPSC—derived astrocytes were capable to induce barrier properties in BMECs upon co-cultures. whereas iPSC-derived neurons were capable to form extensive and branched neurites. Upon OGD stress, iPSC-derived BMECs showed a disruption of their barrier function as early as 6 hours of OGD stress and showed a complete disruption by 24 hours. Such disruption was reversed by reoxygenation. Interestingly such barrier disruption occurs through a VEGF-independent mechanism. In the other hand, iPSC-derived neurons showed a significant decrease in cell metabolic activity preceding neurites pruning. Finally, astrocytes showed the most robust phenotype, as we noted no cell death by 24 hours OGD.In this study, we demonstrated the ability to differentiate three cell types from the same patient in two iPSC lines. We also demonstrated the ability of these cells to respond to OGD/reoxygenation stress in agreement with the current literature. We are currently investigating the molecular mechanisms by which OGD/reoxygenation drive the cellular response in these cell types.

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