Exosomes are tiny vesicles that are released by the body’s myriad of cells and that are found in blood, urine, and other bodily fluids. Their role within our bodies is still largely a mystery, but there’s already considerable evidence that they may be biomarkers of disease and indicators that certain processes are happening within the body. They’re rare and are so small that filtering them out of bodily fluids has proven to be exceedingly difficult. This has been a major roadblock preventing their study, which could lead to the development of potential clinical applications.
Now researchers from Duke University, the University of Pittsburgh, Magee Womens Research Institute, Massachusetts Institute of Technology, and Nanyang Technological University Singapore are reporting in Proceedings of the National Academy of Sciences on a new device that is able to separate exosomes from the rest of a fluid so they can be easily studied in a laboratory.
Their device relies on so-called “acoustofluidics,” which combines high-frequency sound waves with microfluidic technology. Essentially, a stream of a fluid containing exosomes is passed through a narrow channel, while high-frequency sound waves intersect it. By varying the angle and frequency of the sound waves, particles larger than about 1,000 nanometers can be sent down one pathway, while smaller ones travel down another. Platelets, cells, and other larger objects are removed at this stage.
Following, the smaller items are fed into another component of the device where the same essential mechanism filters out objects larger than 130 nanometers, which is about the size that exosomes get to. Once all the larger objects are removed, about 98% of what remains is mostly exosomes. Previous methods have only been able to achieve filtration levels of between five and 40% of present exosomes.
Here’s a short video demonstrating the technology in action: