Sponges remove toxins from the bloodstream which punch holes in human cells

Bit by a snake?  Nanosponges might soon be what the doctor orders.

A large variety of animal venoms share a class of dangerous compounds called pore-forming toxins.  Bee stings, the bites of some venomous snakes, and even the drug-resistant "super-bug" MRSA (an infectious bacteria) all contain chemicals of this class, which can cause death in mammals in sufficient doses.  The toxins puncture cell membranes causing an influx of ions and cell death.

The new nanosponges soak of the dangerous chemical.  In a test mice were given a fatal dose of alpha-haemolysin -- a pore-forming toxin -- produced by MRSA.  The mice that were "inoculated" with a dose of nanosponges survived thanks to the helpful little sponges.

To maintain biocompatibility -- to prevent the host's immune system from attacking the helper sponges -- they are "cloaked" in red blood cell membranes with sugar profiles compatible to the host.  This technology was developed by Liangfang Zhang's lab at UC San Diego.

Nanoengineering professor Liangfang Zhang who invented the cloaking technology also masterminded the nanosponge application.  The cloaking technology proved opportune, as red blood cells are one of the primary targets of the class of toxins.

Wrapped in segments of red blood cell (RBC) membrane and biocompatible polymers, the finished nanosponges measure 85 nanometers in diameter.  The RBC skins are extracted via centrifuging and then treatment with a swelling solution.  The next step is to coat the nanoparticles, which are about 1/3,000th of the size of a red blood cell.

Red blood cells
The therapy uses membranes from the patient's own red blood cells. [Image Source: Deskarti]

Even at a 70:1 ratio of toxin to nanosponge, the tiny nanoparticles effectively blocked the toxin in mice by outnumbering the standard RBC targets.  One nanosponge can soak up to 85 alpha-haemolysin toxin produced by MRSA, 30 stretpolysin-O toxins and 850 melittin monomers, which are part of bee venom.

The nanosponges are sequestered by the liver, which has more robust cells that can withstand and break down the toxic contents.  The half-life of the toxin-soaked nanosponges is around 40 hours, according to the researchers.

nanosponge pictures
Electron microscopy images of the toxin-blocking nanosponges. [Image Source: UCSD]

Professor Zhang elates [press release], "This is a new way to remove toxins from the bloodstream.  Instead of creating specific treatments for individual toxins, we are developing a platform that can neutralize toxins caused by a wide range of pathogens, including MRSA and other antibiotic resistant bacteria."

The findings of the study on rodents are published [abstract] in the prestigious peer-reviewed journal Nature Nanoscience.

His team is already looking ahead to clinical trials on humans; the drug has great potential due to its ubiquity -- most antivenoms only target one or a handful of toxins.

Sources: Nature Nanotechnology, UC San Diego [Press Release]

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