With the help of DTU Physics, researchers from MIT and the University of Lund have developed a new method to analyse and separate cells in blood. The method can accelerate and improve measurements of cancer treatment efficacy in patients.
Mechanical cell sorting plays an important role in efforts to shorten the time between medical sample and diagnosis. In a new study published in Nature Communications, researchers from MIT and the University of Lund in collaboration with DTU Physics have developed a method to separate healthy cells from cancer cells.
In the method known as iso-acoustophoresis, the researchers exploit the fact that different types of cells are affected differently by ultrasound. When waves of ultrasound strike a material such as a cell or a liquid, the material will typically be set in motion. The degree of movement created by the sound waves is directly linked to the material’s acoustic impedance.
Different types of cells can be separated
In iso-acoustophoresis, sample cells are placed in a special fluid whose acoustic impedance is known to the researchers. The liquid and the cells are then sent through a microchannel while being exposed to ultrasound. Depending on their acoustic impedance, the cells will distribute themselves differently in the liquid. By studying the cells’ position, the researchers are able to characterize and separate different types of cells—e.g. white blood cells and circulating cancer cells.
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Ultrasound waves (red) affect the blood cells differently. Depending on their acoustic impedance, the cells will distribute themselves differently in the liquid and can thus be separated and analysed.
“The principle of iso-acoustophoresis can be illustrated by a hot air balloon rising until it reaches a height where the density of the balloon and the surrounding air are the same. In the experiments carried out at MIT, the ultrasound moves a given cell in the same way to a position in which the cell and the fluid acoustic impedance are identical. It thus becomes possible to gather cancer cells in one area and healthy cells in another,” says Jonas T. Karlsen, PhD student at DTU Physics. Together with his supervisor—Professor Henrik Bruus—he has contributed to the theoretical explanation of the physics of iso-acoustophoresis.
Not only innovation
“The process of cooperation surrounding iso-acoustophoresis—headed by Per Augustsson from the University of Lund—is a good example of how the combination of application-oriented experimental research and theoretical research can lead to both technological innovation and new scientific discoveries. Although the focus has been on developing new technology, we have discovered a previously undescribed fundamental acoustic force—despite the fact that modern acoustics has been studied for more than 150 years,” says Henrik Bruus, Head of Section of Biophysics and Fluids (FLUIDS).
The research results were published online in the journal Nature Communications on 16 May 2016.