© Wyss Institute/Harvard UniversityThe rat study shows a variety of pathogens can be 'pulled out' from blood that is circulated through the external bio-spleen.
A device that uses magnets to extract bacteria, fungi and toxins from blood could one day throw a lifeline to patients with sepsis and other infections, researchers say.

They say the external gadget - tested so far in rats but not yet humans - might also eventually be modified to strip Ebola and other viruses from blood.

The device was inspired by the spleen, which can continuously remove pathogens and toxins from blood without first identifying the infectious agent.

Dubbed a 'bio-spleen', the invention uses magnetic nanobeads coated with a genetically-engineered human blood protein called mannose-binding lectin (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 per cent 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," says study co-author Dr from the Wyss Institute for Biologically Inspired Engineering .

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," says Ingber.

The MBL protein is known to bind to the Ebola virus "and so it potentially might be useful for treatment of these patients," Ingber told AFP.

"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 virus and HIV.

In live rats infected with the notorious bugs Staphylococcus aureus or Escherichia coli, the device removed 90 per cent of bacteria from the blood, the researchers report.

"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, they add.

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 cautions.

Source: Agence France-Presse