Treating Sepsis With a "Bionic Spleen"

As with any surgery, including gynecologic or obstetric surgery, there is a risk of sepsis as a postoperative complication. In addition, sepsis in pregnant women in the United States is still uncommon but has increased in recent years. The tricky thing about sepsis is that it can occur in women (and men) who have no risk factors.

When a patient has an infection that could develop into sepsis but the pathogen is unknown, what is the standard treatment? A broad-spectrum antibiotic is often administered, but this may give rise to complications. If the bacteria are not sensitive to the antibiotic used, the infection won't be cleared and could actually lead to antibiotic-resistant bacteria. Considering this, a better way to treat patients with blood infections that could lead to sepsis is needed.

Enter the "artificial spleen." A study published in the September 14 edition of Nature Medicine details a device that could actually filter pathogens from a patient's blood. What researchers at the Wyss Institute for Biologically Inspired Engineering in Boston are calling a "biospleen" could be the next step in treating patients who are at risk for sepsis.

The biospleen process is similar to kidney dialysis and employs magnetic nanobeads. These beads are coated with a protein created in the human body called mannose-binding lectin (MBL). MBL is made in the liver when there is an infection present in the body. This protein can bind itself to carbohydrates on the surface of some species of bacteria, viruses, protozoa, and fungi. A few of the pathogens MBL can bind to include Candida albicans, the influenza A virus, Salmonella, streptococci, and Leishmania. Once a pathogen is bound by MBL, it is then susceptible to being absorbed by white blood cells and rendered inactive.

The device created by researchers contains the nanobeads coated with MBL. When blood is passed through the biospleen, the MBL can bind to the susceptible foreign bodies in it. The MBL and the pathogens are then removed from the blood using magnets. The blood, now clear of toxins, can be introduced back into the patient.

The study details the results of this process being applied on rats that were infected with Staphylococcus aureus or Escherichia coli. More than 90% of the bacteria were removed from the rats' blood, inflammatory cytokines were reduced, and the rats were far more likely to survive than those whose blood was not filtered.

When 5 liters of human blood was processed in the biospleen, it was discovered that it took about 5 hours to complete the process. Human trials are expected to begin in a few years.

References:

Bauer ME, Bateman BT, Bauer ST, Shanks AM, Mhyre JM. Maternal sepsis mortality and morbidity during hospitalization for delivery: temporal trends and independent associations for severe sepsis. Anesth Analg. 2013 Oct;117(4):944-50. doi: 10.1213/ANE.0b013e3182a009c3. Epub 2013 Sep 10. Available at: http://www.ncbi.nlm.nih.gov/pubmed/24023020

Kang JH, Super M, Yung CW, et al. An extracorporeal blood-cleansing device for sepsis therapy. Nat Med. 2014 Sep 14. doi: 10.1038/nm.3640. [Epub ahead of print]