Could nanosponges soak up SARS-CoV-2?

As we noted yesterday, with specific reference to physics, scientists from a range of disciplines are front and centre in the battle to deal with COVID-19 and its consequences.

Now there’s news from chemists in the US, who have proposed an alternative way to search for an effective treatment.

Rather than targeting a specific part of the virus, such as the spike protein, they used nanosponges coated with human cell membranes – the natural targets of the virus – to soak up SARS-CoV-2 and keep it from infecting cells in a petri dish.

The work to date by Anthony Griffiths, Liangfang Zhang and colleagues at the University of California, San Diego, is described in a paper in the journal Nano Letters.

“A novel approach to drug development is to place the focus on the affected host cells instead of targeting the causative agent,” they write.

“Inspired by the fact that the infectivity of SARS-CoV-2 relies on its binding with the protein receptors, either known or unknown, on the target cells, we create cellular nanosponges as a medical countermeasure to the coronavirus.”

To gain entry to cells, they say, SARS-CoV-2 uses its spike protein to bind to two known proteins on human cells, called ACE2 and CD147. Blocking these interactions should keep the virus from infecting cells.

The new approach involves making a nanoparticle decoy with the virus’ natural targets, including ACE2 and CD147, to lure SARS-CoV-2 away from cells. To test the idea, the UCSD team ran experiments with the actual SARS-CoV-2 virus in an appropriately secure lab.

They coated a nanoparticle polymer core with cell membranes from either human lung epithelial cells or macrophages – two cell types infected by SARS-CoV-2.

They showed that the nanosponges had ACE2 and CD147, as well as other cell membrane proteins, projecting outward from the polymer core. When administered to mice, they did not show any short-term toxicity.

The researchers then treated cells in a dish with SARS-CoV-2 and the lung epithelial or macrophage nanosponges. Both decoys neutralised SARS-CoV-2, they say, and prevented it from infecting cells to a similar extent.

“Crucially, the nanosponge platform is agnostic to viral mutations and potentially viral species, as well,” they write. “As long as the target of the virus remains the identified host cell, the nanosponges will be able to neutralise the virus.”

The researchers plan to test the nanosponges in animals before hopefully moving to human clinical trials.

In theory, they say, their approach would work even if SARS-CoV-2 mutates to resist other therapies – and could be used against other viruses.