NEW YORK (Reuters Health) – An extracorporeal blood cleansing device works well in rats and in experiments with human blood, according to researchers in the US and in France.
"Based on our exciting results in rats, we are actively moving to test this approach in a large animal as the next step towards moving this to human clinical trials," Donald E. Ingber of Harvard School of Engineering and Applied Sciences Wyss Institute in Boston told Reuters Health by email.
In a September 14th online paper in Nature Medicine, Dr. Ingber and colleagues explain that infected blood flowing into this "biospleen" is mixed with magnetic nanobeads.
The nanobeads are coated with mannose binding lectin (MBL), an engineered human opsonin that captures a broad range of pathogens by binding to specific sugars on the surfaces of bacteria, fungi, viruses, protozoa as well as toxins without activating complement or coagulation.
The device then uses a magnet to capture these pathogen-coated nanobeads and cleanse the blood flowing through the device, which is then returned to the source. In fact, the single inflow channel leads to four branches that in turn lead to a total of 16 magnetic separator channels, which then merge into a single outlet channel.
The nanomagnetic opsonins are continuously injected into flowing whole blood and distributed via a mixer into an incubation loop composed of helically coiled tubing. They remain there for five to 10 minutes before entering the magnetic separator.
The team first tested the device using "spiked" whole human blood and found that it efficiently removed multiple gram negative and positive bacteria, fungi and endotoxins. A single biospleen unit allowed a flow rate of up to 1.25 L per hour.
In rats infected with S. aureus or E. coli, the biospleen cleared more than 90% of bacteria from blood, reduced pathogen and immune cell infiltration in multiple organs and decreased inflammatory cytokine levels.
In an endotoxemic shock model using LPS endotoxin in anesthetized rats, the biospleen increased survival rates after a five-hour treatment. All surviving animals were killed at five hours to minimize pain and distress. However, at this point, 86% of untreated animals had died whereas 89% of animals treated with the blood-cleansing device survived for the entire five hour experiment.
In a statement, co-researcher Dr. Mike Super, also with the Wyss Institute, said, "Even with the best current treatments, sepsis patients are dying in intensive care units at least 30% of the time. We need a new approach."
Dr. Ingber said that "as always" with new devices, the timing of when it will come to market "is never known, but it always takes longer than you expect."
"My hope," he said, "is that IF we can validate the efficacy of our blood cleansing technology in a large animal, then we would hope to request permission to initiate human trials within about two years."