When a patient has sepsis, in which bacteria or fungi multiply too swiftly in a patient's blood for antibiotics to help, the result is often deadly. However, a new device inspired by the human spleen and developed by a team at Harvard's Wyss Institute for Biologically Inspired Engineering, Boston, MA, may transform the way that doctors treat sepsis, which is the leading cause of hospital deaths.

The device, called a "biospleen," exceeded the researchers’ expectations with its ability to cleanse human blood tested in the laboratory and increase survival in animals with infected blood. In a matter of hours, it can filter live and dead pathogens from the blood, as well as dangerous toxins that are released from the pathogens, they say.

The device works outside the body like a dialysis machine, and removes living and dead microbes of all varieties, as well as toxins. They modeled it after the microarchitecture of the human spleen, which removes pathogens and dead cells from the blood through tiny interwoven blood channels.

The biospleen consists of two adjacent hollow channels connected to each other by a series of slits. One channel contains flowing blood, and the other has a saline solution that collects and removes the pathogens traveling through the slits. Tiny nanometer-sized magnetic beads are coated with a genetically engineered version of a natural immune system protein. The hybrid proteins are attached to magnetic beads to create novel beads that could be added to the blood of an infected patient to bind to the pathogens and toxins. The sepsis device uses a magnet to pull the pathogen-coated magnetic beads through the channels to cleanse the blood flowing through the device. Then, the clean blood is returned to the patient.