Mechanistic link between SARS-CoV-2 infection and increased risk of stroke using 3D printed models and human endothelial cells
Reporter: Adina Hazan, PhD
Kaneko, et al. from UCLA aimed to explore why SARS-CoV-2 infection is associated with an increased rate of cerebrovascular events, including
- ischemic stroke and
- intracerebral hemorrhage
While some suggested mechanisms include an overall systemic inflammatory response including increasing circulating cytokines and leading to a prothrombotic state, this may be only a partial answer. A SARS-CoV-2 specific mechanism could be likely, considering that both angiotensin-converting enzyme-2 (ACE2), the receptor necessary for SARS-CoV-2 to gain entry into the cell, and SARS-CoV-2 RNA have been reportedly detected in the human brain postmortem.
One of the difficulties in studying vasculature mechanisms is that the inherent 3D shape and blood flow subject this tissue to different stressors, such as flow, that could be critically relevant during inflammation. To accurately study the effect of SARS-CoV-2 on the vasculature of the brain, the team generated 3D models of the human middle cerebral artery during intracranial artery stenosis using data from CT (computed tomography) angiography. This data was then exported with important factors included such as
- shear stress during perfusion,
- streamlines, and
- flow velocity to be used to fabricate 3D models.
These tubes were then coated with endothelial cells isolated and sorted from normal human brain tissue resected during surgery. In doing so, this model could closely mimic the cellular response of the vasculature of the human brain.
Surprisingly, without this 3D tube, human derived brain endothelial cells displayed very little expression of ACE2 or, TMPRSS2 (transmembrane protease 2), a necessary cofactor for SARS-COV-2 viral entry.
Interestingly,
- horizontal shear stress increased the expression of ACE2 and
- increased the binding of spike protein to ACE2, especially within the stenotic portion of the 3D model.
By exposing the endothelial cells to liposomes expressing the SARS-CoV-2 spike protein, they also were able to explore key upregulated genes in the exposed cells, in which they found that
- “binding of SARS-CoV-2 S protein triggered 83 unique genes in human brain endothelial cells”.
This included many inflammatory signals, some of which have been previously described as associated with SARS-COV-2, and others whose effects are unknown. This may provide an important foundation for exploring potential therapeutic targets in patients susceptible to cerebrovascular events.
Overall, this study shows important links between the
- mechanisms of SARS-CoV-2 and the
- increase in ischemic events in these patients. It also has important implications for
- treatment for SARS-CoV-2, as high blood pressure and atherosclerosis may be increasing ACE2 expression in patients, providing the entry port for viral particles into brain endothelia.
SOURCE:
https://www.ahajournals.org/doi/10.1161/STROKEAHA.120.032764
Other related articles published in this Open Access Online Scientific Journal include the following:
The Impact of COVID-19 on the Human Heart
Reporters: Justin D. Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2020/09/29/the-impact-of-covid-19-on-the-human-heart/
SAR-Cov-2 is probably a vasculotropic RNA virus affecting the blood vessels: Endothelial cell infection and endotheliitis in COVID-19
Reporter: Aviva Lev-Ari, PhD, RN – Bold face and colors are my addition