How coronavirus infects brain cells?

   Mini-brain study: How coronavirus can infect human brain cells?

A study revealed that the SARS-CoV-2 can infect the organoids – tiny tissue cultures made from human cells that replicate entire body organs known as “mini-brains”. The study was carried out by a team from two Johns Hopkins University institutions, consisting of infectious disease specialists from the school of medicine, and neurotoxicologists and virologists from the Bloomberg School of Public Health.

The outcomes of the study titled “Infectability of human BrainSphere neurons suggest neurotropism of SARS-CoV-2” were posted in the journal ALTEX: Alternatives to Animal Experimentation.

According to the early reports from Wuhan, 36% of patients with the COVID-19 show neurological signs and symptoms, however, whether or not the coronavirus infects human brain cells is not clear yet. The research showed the ACE2 receptor that the SARS-CoV-2 virus uses to enter the lungs is also present in the human neurons. So, they theorized, ACE2 may also offer access to the brain.

The study found – evidence of infection and replication of the pathogen when SARS-CoV-2 virus particles were introduced into a human mini-brain model – what is thought to be the first time.

Naturally, the blood-brain barrier protects the human

brain from numerous viruses, bacteria, and chemical agents, it often protects against brain infections. Thomas Hartung, M.D., Ph.D., chair for evidence-based toxicology, the Bloomberg School of Public Health said, whether the SARS-CoV-2 virus passes this barrier or not is yet to be shown. But, it is understood that the blood barrier disintegrates during severe inflammations, such as those observed in COVID-19 individuals.

He added the impermeability of the blood-brain barrier can also offer a problem for drug designers targeting the brain.

The impact of SARS-CoV-2 on the developing brain is an additional issue elevated by the research. Prior research from Paris-Saclay University has shown that the virus crosses the placenta, and most notably during the early development, the embryos lack the blood-brain barrier – this can increase the risk of brain infections. Hartung said we have no proof that the developmental disorders can be caused by the viruses.

But, the ACE2 receptor is present in the “mini-brains” from their earliest stages of development. Hartung claims that the outcomes of the study suggest that during pregnancy extra care needs to be taken.

William Bishai, M.D., Ph.D., professor of medicine, the Johns Hopkins University School of Medicine, and leader of the infectious disease team for the study said this study is an additional crucial step in our understanding of how infection results to symptoms, and where we might treat COVID-19 with drugs.

The mini-brain models known as BrainSpheres were derived from human stem cells and developed at the Bloomberg School of Public Health 4 years ago. These BrainSpheres were the first mass-produced, highly standardized organoids of their kind, and have actually been utilized to model a number of diseases, consisting of infections by viruses such as HIV, dengue, and Zika.


Author: Sruthi S