Sticky Nanobeads Can Strip Bacteria, Viruses From Blood

By Carl Engelking | September 16, 2014 8:59 am
Scanning electron micrograph of HIV-1 budding (in green) from cultured lymphocyte (Credit: Centers for Disease Control and Prevention)

Scanning electron micrograph of HIV-1 budding (in green) from cultured lymphocyte. Credit: Centers for Disease Control and Prevention

A new device uses magnetism to rid the bloodstream of pathogens that are the source of deadly infections.

Bioengineers at Harvard’s Wyss Institute have developed a blood filter that quickly grabs toxins, such as E.coli or Ebola, from the bloodstream using protein-coated nanobeads and magnets. In early tests, the biomechanical treatment removed more than 90 percent of toxins from infected human blood within a few hours.

Cleansing the Blood

When our immune system fights an infection, the dying virus releases toxins into the bloodstream that can cause sepsis, a life-threatening immune response. Doctors can’t always pinpoint the specific pathogen that causes sepsis, so they use antibiotics to carpet-bomb the bloodstream, a strategy that’s not always effective and can lead to drug-resistance.

The new device, dubbed an “artificial spleen,” instead mechanically clears pathogens from the bloodstream, thereby reducing reliance on heavy doses of antibiotics. Its trick lies in magnetic nanobeads coated with a modified human protein. This protein binds to sugar molecules on the surfaces of more than 90 different bacteria, viruses and fungi, as well as to the toxins released by dead bacteria.

When those nanobeads are mixed with infected blood they adhere to pathogens, and then, as the blood passes through channels inside the device, magnets pull out the beads with pathogens attached. Clean blood is routed back into the patient.

blood cleaner

Researchers’ blood-cleansing machine. (Wyss Institute)

Putting it to the Test

Scientists tested their device by infecting rats with lethal doses of either Escherichia coli or Staphylococcus aureus and then cleaning their blood. The device removed more than 90 percent of the bacteria from the rats’ bloodstream within the first hour of treatment. After five hours, 89 percent of the rats with filtered blood survived, but only 14 percent of the untreated rats lived.

Researchers then tested their device by cleaning 5 liters of human blood spiked with a variety of pathogens. The device cleared blood at a rate of 1 liter per hour, and again removed over 90 percent of the pathogens. Several devices could be linked together to speed up the rate of filtration in humans. The team published their findings Sunday in the journal Nature Medicine.

Fighting Fatal Viruses

The next step for researchers is to test their device in pigs, after which human trials could begin within a couple years, Nature reports.

Researchers say that the blood filter could someday play a role in treating HIV and Ebola by lowering the level of the virus in the blood to manageable levels. The device could also help scientists harvest viruses from the blood to study better ways to treat them.

In an era of increasing antibiotic resistance, we’ll take all the ingenuity we can get.

CATEGORIZED UNDER: Health & Medicine, Technology
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  • Nikola Kerekov

    Great article and very ennovative new approach for artificial cleansing
    of blood but there is something in the press release I just cannot
    agree, namely: “Bioengineers at Harvard’s Wyss Institute have developed a
    blood filter that quickly grabs toxins, such as E.coli or Ebola…”. Why Ebola?
    Because it’s so modern these days? Readers here does not need to have
    special training in all fields of science. The responsibility for the
    scientific scrutiny falls on authors and editors. The truth here is that
    the magnetic nanobeats are loaded with the lectin domain of a protein
    called MBL. This lectin recognizes special mannose-containing molecular
    patterns which are characteristic for many bacteria. It also have some
    limited ability to recognize other targets including the endotoxin
    compound of Gram-negative bacteria known as LPS which is a main
    contributor for the septic shock syndrome. Ebola on the other hand is a
    VIRUS. It forms it’s particle by shedding some parts of the membrane of a
    host (human) cell which it had infected. It does NOT have mannose/LPS
    in its virion particles so it would not be cleaned. In the original text
    the authors speculate it might be possible to use the principle of the
    technique to clean viruses too, but this haven’t been tested yet as it
    would need magnetic beats loaded with another protein which could
    recognize some of the Ebola virus-specific molecules. I think a small
    correction would make the article sound way more accurate.

    • Facebook User

      Very well put and well said, I think that the references to HIV and Ebola were dropped in for effect and to lend importance to the article.

  • katlo

    We need this for patients with Chronic Lyme disease!

  • Facebook User

    I really hope this treatment becomes main-stream sooner rather than later as I am currently being treated for cellulitis in my leg with copious amounts of antibiotics. There are some very clever people in the world and I for one am grateful for their continued research work.

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