Decoys designed to intercept COVID-19 viruses show 90% success in lab experiments.

UC San Diego researchers call their nano-scale particles “nanosponges” because they soak up harmful pathogens and toxins.

“We only need to know what the target cells are. And then we aim to protect the targets by creating biomimetic decoys,” said Liangfang Zhang, a nanoengineering professor at the UC San Diego Jacobs School of Engineering.

The basic construction for these nanosponges is the same: a biodegradable, FDA-approved polymer core is coated in a specific type of cell membrane so that it might be disguised as a red blood cell, or an immune T cell or a platelet cell.

The first data describing this new direction for fighting COVID-19 was published on June 17, 2020, in the journal Nano Letters.

Nanosponges Cloaked in Human Lung Cells

Researchers say each COVID-19 nanosponge — a thousand times smaller than the width of a human hair — consists of a polymer core coated in cell membranes extracted from either lung epithelial type II cells or macrophage cells.

Nanoparticles cloaked in human lung cell membranes and human immune cell membranes can attract and neutralize the SARS-CoV-2 virus in cell culture, causing the virus to lose its ability to hijack host cells and reproduce.

Here is a video depiction of how it works.

Another Trick Planned Against COVID-19

Zhang and his colleagues thought it would make sense to cloak a nanoparticle in fragments of the outer membranes of lung cells to see if the virus could be tricked into latching on it instead of a lung cell.

Macrophages, which are white blood cells that play a major role in inflammation, also are very active in the lung during the course of a COVID-19 illness, so Zhang and colleagues created a second sponge cloaked in macrophage membrane.

“We will see if the macrophage nanosponges can neutralize the excessive amount of these cytokines as well as neutralize the virus,” said Zhang.

In a paper published in 2017 in Proceedings of the National Academy of Sciences, Zhang and other researchers showed that macrophage nanosponges can safely neutralize both endotoxins and pro-inflammatory cytokines in the bloodstream of mice.

In lab experiments, both the lung cell and immune cell types of nanosponges caused the SARS-CoV-2 virus to lose nearly 90% of its “viral infectivity” in a dose-dependent manner.

Clinical Trials Possible

If the sponges reach the clinical trial stage, there are multiple potential ways of delivering the therapy that include direct delivery into the lung for intubated patients, via an inhaler like for asthmatic patients, or intravenously, especially to treat the complication of cytokine storm.

A therapeutic dose of nanosponges might flood the lung with a trillion or more tiny nanosponges that could draw the virus away from healthy cells. Once the virus binds with a sponge, “it loses its viability and is not infective anymore, and will be taken up by our own immune cells and digested,” said Zhang.

“I see potential for a preventive treatment, for a therapeutic that could be given early because once the nanosponges get in the lung, they can stay in the lung for some time,” Zhang said. “If a virus comes, it could be blocked if there are nanosponges waiting for it.”