The blood-brain barrier is dysregulated in COVID-19 and serves as a CNS entry route for SARS-CoV-2.

Neurological complications are common in COVID-19. Although SARS-CoV-2 has been detected in patients' brain tissues, its entry routes and resulting consequences are not well understood. Here, we show a pronounced upregulation of interferon signaling pathways of the neurovascular unit in fatal COVID-19. By investigating the susceptibility of human induced pluripotent stem cell (hiPSC)-derived brain capillary endothelial-like cells (BCECs) to SARS-CoV-2 infection, we found that BCECs were infected and recapitulated transcriptional changes detected in vivo. While BCECs were not compromised in their paracellular tightness, we found SARS-CoV-2 in the basolateral compartment in transwell assays after apical infection, suggesting active replication and transcellular transport of virus across the blood-brain barrier (BBB) in vitro. Moreover, entry of SARS-CoV-2 into BCECs could be reduced by anti-spike-, anti-angiotensin-converting enzyme 2 (ACE2)-, and anti-neuropilin-1 (NRP1)-specific antibodies or the transmembrane protease serine subtype 2 (TMPRSS2) inhibitor nafamostat. Together, our data provide strong support for SARS-CoV-2 brain entry across the BBB resulting in increased interferon signaling

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Establishment of a human blood-brain barrier co-culture model mimicking the neurovascular unit using induced pluripotent stem cells

Human blood-brain barrier (BBB) in vitro models pose a promising tool in drug development and understanding of mechanistic regulations during health and disease. Human-induced pluripotent stem cells (hiPS cells) represent an unlimited cell source to generate functional cells of the neurovascular unit (NVU), independent of variations or limitations during isolation and in vitro cultivation. This unit describes the standardized 2-D differentiation of adherent hiPS cells into BBB endothelial cells and neuronal stem cells (NSCs). Both cell types are combined with primary astrocytes and pericytes to develop complex, physiological BBB in vitro models. The endothelial cells in the apical compartment of the transwell models are separated from the basolateral seeded co-culture mixture by a synthetic membrane, simplifying analyses. The barrier integrity and functionality of the endothelium is improved by the specific mixture of NVU niche cells, determined here by decrease in the paracellular permeability of sodium-fluorescein and transendothelial electrical resistance (TEER) measurement