Engineers at Duke University have developed a microfluidic chip that uses sound waves to separate exosomes from undiluted whole blood samples. The method is faster and could preserve more information than differential centrifugation, the standard technology for isolating the particles.
Exosomes are nanoscale extracellular vesicles secreted by cells and found in almost all biological fluids, including blood, saliva, and urine. Their surface and cargo includes proteins, RNA, lipids, and other molecules from their origin cells and tissues, making them potential biomarkers for organ-specific health monitoring and disease diagnosis.
Scientists are particularly interested in developing exosome-based biopsies of hard-to-reach organs, like the brain, heart, liver, kidneys, and placenta. But methods to isolate exosomes using centrifugation and newer techniques are low-yield, time-consuming—taking anywhere from hours to days—and can degrade the integrity of the particles.
The new separation method, developed by Duke biomedical engineer Tony Juan Huang, PhD, and colleagues combines microfluidics with acoustics in an emerging field called acoustofluidics.
In a 2-step, 30-minute process described in the Proceedings of the National Academy of Sciences, high-frequency sound waves were used in chip-based channels to first separate larger blood components—white and red blood cells and platelets—from subcellular particles and then to separate exosome-sized particles from other subcellular components. The method isolated exosomes from an extracellular vesicle mixture with a purity of 98.4%.
The investigators are now working to prove that the exosomes retain their cargo through the sorting process. For the chip to have clinical utility, researchers must also define membrane surface “barcodes” that identify exosomes arising from different cells, tissues, and organs, according to coinvestigator Yoel Sadovsky, MD, executive director of the Magee-Womens Research Institute at the University of Pittsburgh.
“If there’s a way to … identify those nanovesicles produced by specific tissues, one can potentially interrogate a tissue by studying those vesicles,” he said.
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Jennifer Abbasi. Laboratory-on-a-Chip Uses Acoustics to Isolate Tell-Tale Particles in Blood. JAMA. 2017;318(18):1750. doi:10.1001/jama.2017.16933