Scientists Develop Microscopic Sponges That Soak Up and Neutralize Coronavirus

Nanoparticles cloaked in human lung cell membranes and human immune cell membranes are capable of attracting and neutralizing the SARS-CoV-2 virus in cell culture, making the virus lose its ability to hijack host cells and reproduce.

The "nanosponges" were developed by engineers at the UC San Diego (La Jolla, CA, USA) and tested by researchers at Boston University (Boston, MA, USA), creating a new direction for fighting COVID-19. The researchers call their nano-scale particles "nanosponges" because they soak up harmful pathogens and toxins. Each COVID-19 nanosponge, which is 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. The membranes cover the sponges with all the same protein receptors as the cells they impersonate—and this inherently includes whatever receptors SARS-CoV-2 uses to enter cells in the body.

The researchers prepared several different concentrations of nanosponges in solution to test against the novel coronavirus. 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. Instead of targeting the virus itself, these nanosponges are designed to protect the healthy cells the virus invades. Additionally, the nanosponges cloaked with fragments of the outer membranes of macrophages could also be capable of soaking up inflammatory cytokine proteins, which are implicated in some of the most dangerous aspects of COVID-19 and are driven by immune response to the infection.

In the next few months, the researchers will evaluate the efficacy of these nanosponges in animal models. The researchers have already shown short-term safety in the respiratory tracts and lungs of mice, and hope to test these COVID-19 nanosponges in humans as early as possible. The researchers also expect these nanosponges would work against any new coronavirus or even other respiratory viruses, including whatever virus might trigger the next respiratory pandemic. Additionally, the research team plans to study whether the macrophage sponges also have the ability to quiet cytokine storms in COVID-19 patients. 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.

“Traditionally, drug developers for infectious diseases dive deep on the details of the pathogen in order to find druggable targets. Our approach is different. 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. “Another interesting aspect of our approach is that even as SARS-CoV-2 mutates, as long as the virus can still invade the cells we are mimicking, our nanosponge approach should still work. I’m not sure this can be said for some of the vaccines and therapeutics that are currently being developed.”

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UC San Diego
Boston University