Blood testing with sound waves promises ‘new paradigm’ in disease diagnosis

Technology News | September 28, 2017

By Rich Pell

To do so, the scientists developed a device that uses a combination of microfluidics and acoustic waves to isolate exosomes – nanoscale packets secreted by cells that carry “messages” from one part of the body to another – from blood. Such an approach promises a portable and quicker alternative for analyzing blood samples for signs of cancer and other diseases than the time-consuming ultracentrifugation methods often used today.

“These exosomes often contain specific molecules that are a signature of certain abnormalities. If you isolate them from blood, you can do biological analysis and see what they reveal,” says Ming Dao, a principal research scientist in MIT’s Department of Materials Science and Engineering and a senior author of a study on the research.

Previously, the scientists had shown that their technology could be used to separate cells by exposing them to sound waves as they flowed through a tiny channel, and that it could isolate rare, circulating tumor cells from a blood sample. Now, by being able to capture exosomes the approach offers a way to identify markers for disorders such as cancer, neurodegenerative disease, and kidney disease without having to subject the particles to high-speed centrifugation, which not only takes 24 hours to perform in a large machine but can damage the exosomes.

“Acoustic sound waves are much gentler,” says Dao. “These particles are experiencing the forces for only a second or less as they’re being separated, which is a big advantage.”

The original acoustic cell-sorting technique comprised a microfluidic channel exposed to two tilted acoustic transducers, which produced sound waves that resulted in standing waves being formed in the channel generating a series of pressure nodes. When cells or particles flowing through the channel encounter a node, they are moved off center by an amount determined by their size and other properties, allowing them to be separated by the time they reach the end of the channel.

For isolating exosomes, the researchers built a device using two such microfluidic units in series. The first uses sound waves to remove cells and platelets from a blood sample, while the second uses sound waves of a higher frequency to separate exosomes from slightly larger extracellular vesicles.

According to the researchers, it takes less than 25 minutes to process a 100-microliter undiluted blood sample using their device.

“The new technique can address the drawbacks of the current technologies for exosome isolation, such as long turnaround time, inconsistency, low yield, contamination, and uncertain exosome integrity,” says Tony Jun Huang, a professor of mechanical engineering and materials science at Duke University. “We want to make extracting high-quality exosomes as simple as pushing a button and getting the desired samples within 10 minutes.”

“The capability of this method to separate these nanoscale vesicles, essentially without altering their biological or physical characteristics, offers appealing possibilities for developing new ways of assessing human health as well as the onset and progression of diseases,” adds Subra Suresh, president-designate of Nanyang Technological University in Singapore, MIT’s Vannevar Bush Professor of Engineering Emeritus, and a former dean of engineering at MIT.

The researchers now plans to use this technology to seek biomarkers that can reveal disease states. For more, see “Isolation of exosomes from whole blood by integrating acoustics and microfluidics.”