Flow-Mediated Susceptibility and Molecular Response of Cerebral Endothelia to SARS-CoV-2 Infection

Stroke. 2021 Jan;52(1):260-270. doi: 10.1161/STROKEAHA.120.032764. Epub 2020 Nov 9.


Background and purpose: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is associated with an increased rate of cerebrovascular events including ischemic stroke and intracerebral hemorrhage. The mechanisms underlying cerebral endothelial susceptibility and response to SARS-CoV-2 are unknown yet critical to understanding the association of SARS-CoV-2 infection with cerebrovascular events.

Methods: Endothelial cells were isolated from human brain and analyzed by RNA sequencing. Human umbilical vein and human brain microvascular cells were used in both monolayer culture and endothelialized within a 3-dimensional printed vascular model of the middle cerebral artery. Gene expression levels were measured by quantitative polymerase chain reaction and direct RNA hybridization. Recombinant SARS-CoV-2 S protein and S protein-containing liposomes were used to measure endothelial binding by immunocytochemistry.

Results: ACE2 (angiotensin-converting enzyme-2) mRNA levels were low in human brain and monolayer endothelial cell culture. Within the 3-dimensional printed vascular model, ACE2 gene expression and protein levels were progressively increased by vessel size and flow rates. SARS-CoV-2 S protein-containing liposomes were detected in human umbilical vein endothelial cells and human brain microvascular endothelial cells in 3-dimensional middle cerebral artery models but not in monolayer culture consistent with flow dependency of ACE2 expression. Binding of SARS-CoV-2 S protein triggered 83 unique genes in human brain endothelial cells including upregulation of complement component C3.

Conclusions: Brain endothelial cells are susceptible to direct SARS-CoV-2 infection through flow-dependent expression of ACE2. Viral S protein binding triggers a unique gene expression profile in brain endothelia that may explain the association of SARS-CoV-2 infection with cerebrovascular events.

Keywords: cerebrovascular circulation; endothelial cells; endothelium, vascular; models, theoretical; viruses.

MeSH terms

  • Angiotensin-Converting Enzyme 2 / metabolism*
  • Brain / metabolism
  • Brain / virology
  • COVID-19 / metabolism
  • COVID-19 / virology*
  • Cells, Cultured
  • Cerebrovascular Circulation / physiology
  • Endothelial Cells / metabolism
  • Endothelial Cells / virology*
  • Humans
  • Models, Anatomic
  • SARS-CoV-2 / metabolism*
  • Spike Glycoprotein, Coronavirus / metabolism*
  • Stress, Mechanical
  • Transcriptome*


  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • ACE2 protein, human
  • Angiotensin-Converting Enzyme 2