Human Pluripotent Stem Cell-Derived Neural Cells and Brain Organoids Reveal SARS-CoV-2 Neurotropism

Abstract

SUMMARYNeurological complications are common in patients with COVID-19. While SARS-CoV-2, the causal pathogen of COVID-19, has been detected in some patient brains, its ability to infect brain cells and impact their function are not well understood, and experimental models using human brain cells are urgently needed. Here we investigated the susceptibility of human induced pluripotent stem cell (hiPSC)-derived monolayer brain cells and region-specific brain organoids to SARS-CoV-2 infection. We found modest numbers of infected neurons and astrocytes, but greater infection of choroid plexus epithelial cells. We optimized a protocol to generate choroid plexus organoids from hiPSCs, which revealed productive SARS-CoV-2 infection that leads to increased cell death and transcriptional dysregulation indicative of an inflammatory response and cellular function deficits. Together, our results provide evidence for SARS-CoV-2 neurotropism and support use of hiPSC-derived brain organoids as a platform to investigate the cellular susceptibility, disease mechanisms, and treatment strategies for SARS-CoV-2 infection.

Broad transcriptional dysregulation of brain and choroid plexus cell types with COVID-19

“…Thus, unlike recent reports where SARS-CoV-2 was added directly to neuroglial organoids lacking brain-barrier cells 21–25 , we do not observe significant virus invasion in cortex parenchymal cells. On the other hand, SARS-CoV-2 infection of the CSF-barrier forming choroid plexus and meninges corroborates recent in vitro, in silico , CSF, and postmortem case studies suggesting CNS barrier cells can support productive infection at relatively low titers 5,23,24,42,43 . We note however that this absence of detectable SARS-CoV-2 neuroinvasion does not exclude its possibility.…”

“…There are, however, limitations to consider given the unique logistical circumstances of a pandemic. With most postmortem COVID-19 brain tissue immediately fixed 42 or not handled with snRNA-seq studies in mind for safety and regulatory reasons, there is a lack of the high-quality tissue necessary for such studies 21,23,24 . This has precluded larger study cohorts that could be more representative of COVID-19 patients as a whole.…”

“…Missing so far is an unbiased view of the molecular and cellular perturbations across brain cell types in COVID-19 patients. This is in part because high-quality human brain tissue from patients for such studies is largely inaccessible 21,23,24 . Furthermore, several brain regions highly relevant to COVID-19, such as the choroid plexus 23,24 , have not yet been successfully profiled in humans at single-cell resolution, in health or disease 29 .…”

ApoE-Isoform-Dependent SARS-CoV-2 Neurotropism and Cellular Response

“…Human-induced pluripotent stem cells (hiPSCs) have emerged as valuable in vitro platforms to model human brain development and diseases for which human cells and tissues are not easily accessible ( Takahashi et al., 2007 ; Yu et al., 2007 ; Marchetto et al., 2011 ; Shi et al., 2017a ; Li et al., 2018a ; Li and Shi, 2020 ). In response to the COVID-19 pandemic, hiPSC-derived NPCs, neurons, and brain organoids have been used to model SARS-CoV-2 neurotropism ( Jacob et al., 2020 ; Mesci et al., 2020 ; Pellegrini et al., 2020 ; Ramani et al., 2020 ; Song et al., 2020 ; Zhang et al., 2020 ). These studies all reported infection of neurons and/or astrocytes by SARS-CoV-2; however, different extents of infection have been reported.…”

“…These studies all reported infection of neurons and/or astrocytes by SARS-CoV-2; however, different extents of infection have been reported. Some reported sparse infection of neurons and astrocytes ( Jacob et al., 2020 ; Pellegrini et al., 2020 ), whereas others showed more extensive infection of these cell types in either 2D or 3D cultures ( Mesci et al., 2020 ; Ramani et al., 2020 ; Song et al., 2020 ; Zhang et al., 2020 ). The cause for this discrepancy remains to be explored.…”