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Artificial Spleen Sorts Things Out

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Science Translational Medicine  15 Oct 2014:
Vol. 6, Issue 258, pp. 258ec177
DOI: 10.1126/scitranslmed.aaa0477

Sepsis is a lethal disease caused by systemic microbial infection spreading through the bloodstream to overwhelm the body's defenses. Identifying the responsible pathogen can take days—in fact, in most patients the causative agent is never uncovered. In those cases, physicians treat patients empirically with broad-spectrum antibiotics. However, these often fail and are likely to have dangerous side effects.

Now, an article in Nature Medicine by Kang and colleagues introduces an external microfluidic device that, by mimicking the structure of the spleen, filters bacterial pathogens from the circulation. This blood-cleansing device, dubbed the “biospleen,” shares similarities with a dialysis machine: the patient’s blood is mixed with magnetic nanobeads coated with a modified version of mannose-binding lectin, a protein that captures a broad range of pathogens and toxins. Magnets in the biospleen sequester the bound pathogens before the cleansed blood is returned to the patient. First, the researchers established in vitro that the device can sort out ~9 ~`0% of yeast and both Gram-negative and -positive bacteria from human blood samples spiked with a mixture of pathogens, including Candida albicans, Staphylococcus aureus and Escherichia coli. Then theyhooked the biospleen up to the jugular veins of rats infected with either E. coli or S. aureus, and found it removed up to 99% of the pathogens within a few hours.

Clinical studies will be needed to establish the therapeutic value of this device, especially considering that it did not eliminate pathogens completely in their tests. Other dialysis-like devices developed to mitigate sepsis have already entered clinical testing, but they are designed to remove toxins from the blood rather than the causative bacteria. Thus, the biospleen may provide the means to treat a wide range of infectious diseases quickly without having to wait days for test results.

J. H. Kang et al., An extracorporeal blood-cleansing device for sepsis therapy, Nat. Med. 10.1038/nm.3640 (2014). [Full Text]

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