- Researchers proved that the coronavirus can infect a lab-grown nervous system
- While it can replicate itself in neural tissue, more research is needed to asses possible neurological damage
- It could mean developing brains in babies and children could be susceptible to the virus in the long run
How easily can the coronavirus infect the nervous system?
This is a question that could help us find better treatment - and prevent neurological damage that might incur in developing brains.
In Wuhan, 36% of Covid-19 patients showed signs of neurological symptoms, including viral inflammation of the brain. Researchers from Johns Hopkins University wanted to understand these symptoms better, and published their findings in ALTEX: Alternatives to Animal Experimentation.
The virus's most popular gateway - ACE2 receptors - are found in certain neurons in the human body, which could make it susceptible to direct infection. Other types of coronaviruses are known to have a neuropathological effect on humans, but until know this hasn't been officially proven with the SARS-CoV-2 strain yet.
The researchers ended up testing their theories on lab-grown mini-brains to see if the virus can attack neural tissue directly.
The virus managed to replicate itself in the mini-brain in 72 hours.
"Virus particles were found in the neuronal cell body extending into apparent neurite structures." This means that the virus is able to invade neural tissue, giving it neurotropic features.
Protection from the blood-brain-barrier
But the virus doesn't attack the neural system in all positive cases - the blood-brain-barrier normally prevents viral entry, but this can be impaired when the body's immunity is in distress.
This finding could also perhaps explain why the virus seems to cause a loss of taste and smell - a system controlled by our neural networks.
In the limited study time, however, the researchers saw no damage done to the mini-brain - just viral replication - but the lab-grown organ had no immune cells found in real human brains, thus neurological damage might still be possible.
"These experiments require repetition, including varied initial number of virus (MOI), analysis of neural pathology and functionality, inclusion of different donors of induced pluripotent stem cells of different genders, and extended time courses," adds the authors.
What it means for our children
The mini-brain is also a developing organ - much like a child's - and there might be neurological disorders brewing in infected babies and children because their blood-brain-barrier isn't fully developed yet. This could also mark a risk for babies still in the womb if their mother becomes infected.
"Clinical evidence cannot yet be expected, however, as most children at critical phases of embryo and fetal development are yet to be born and more subtle neurodevelopmental disorders often take time to manifest and diagnose after birth.
"It will be important to study whether brain infection occurs also in otherwise asymptomatic patients, especially children with possible long-term consequences."
Rise of organoids
Organoids - as these lab-grown organs are known - have increasingly become a vital method in fast-tracking Covid-19 understanding and possible treatment, especially as it lessens the need for animal testing.
Another recent study used lab-grown heart cells to also show how the coronavirus can infect one of our most vital organs - causing it to slowly stop beating.
It's critical for scientists to better understand how this coronavrius attacks the various functions of the body in order to advise more effective treatment - and watch out for yet unknown consequences lurking in the future.
Image credit: iStock