Scientists unveil magnetic device for extracting bacteria, toxins from blood

Scientists said Sunday they had invented a device that uses a magnet to extract bacteria, fungi and toxins from blood, potentially throwing a lifeline to patients with sepsis and other infections.

The external gadget -- tested so far in rats but not yet humans -- could be adapted one day for stripping Ebola and other viruses from blood, they hoped.

Acting rather like a spleen, the invention uses magnetic nanobeads coated with a genetically-engineered human blood protein called MBL.

The MBL binds to pathogens and toxins, which can then be "pulled out" with a magnet, the developers wrote in the journal Nature Medicine.

The "bio-spleen" was developed to treat sepsis, or blood infection, which affects 18 million people in the world every year, with a 30-50 percent mortality rate.

The microbes that cause it are often resistant to antibiotics, and spread fast.

If the invention is shown to be safe for humans, "patients could be treated with our bio-spleen and this will physically clean up their blood, rapidly removing a wide spectrum of live pathogens as well as dead fragments and toxins from the blood," study co-author Donald Ingber told AFP.

The cleansed blood is then returned to the circulatory system.

"This treatment could be carried out even before the pathogen has been formally identified and the optimal antibiotic treatment has been chosen," said Ingber, of Harvard University, Massachusetts.

The MBL protein is known to bind to the Ebola virus "and so it potentially might be useful for treatment of these patients," said Ingber in an email exchange.

"We potentially could treat patients with this bio-spleen during the most infectious, viraemic phase of the disease and reduce the amount of virus in their blood."

MBL has also been reported to bind to the Marburg and HIV viruses.

In live rats infected with the notorious bugs Staphylococcus aureus or Escherichia coli, the device removed 90 percent of bacteria from the blood, said the study.

"When we injected rats with a lethal dose of LPS endotoxin (a bacteria type)... we found that we could significantly improve animal survival" with the bio-spleen, it said.

Tests with human blood in the lab also showed the bio-spleen cleaned out multiple species of bacteria, fungi and toxins.

Years of testing in larger animals and then in humans lie ahead before the bio-spleen can be approved, Ingber cautioned.