WASHINGTON DC:
Researchers have now developed a device that can isolate individual cancer cells from patient blood samples. The research was carried out by researchers from the University of Illinois Chicago and Queensland University of Technology of Australia. The microfluidics device works by separating the various cell types found in blood by their size. The device may one day enable rapid, cheap liquid biopsies to help detect cancer and develop targeted treatment plans.
The findings are reported in the journal Microsystems & Nanoengineering. Speaking about it, corresponding author of the study, said, “This new microfluidics chip lets us separate cancer cells from whole blood or minimally-diluted blood,” adding, “While devices for detecting cancer cells circulating in the blood are becoming available, most are relatively expensive and are out of reach of many research labs or hospitals. Our device is cheap, and doesn’t require much specimen preparation or dilution, making it fast and easy to use.”
The ability to successfully isolate cancer cells is a crucial step in enabling liquid biopsy where cancer could be detected through a simple blood draw. This would eliminate the discomfort and cost of tissue biopsies which use needles or surgical procedures as part of cancer diagnosis. According to researchers, liquid biopsy could also be useful in tracking the efficacy of chemotherapy over the course of time, and for detecting cancer in organs difficult to access through traditional biopsy techniques, including the brain and lungs.
However, isolating circulating tumour cells from the blood is no easy task, since they are present in extremely small quantities. For many cancers, circulating cells are present at levels close to one per 1 billion blood cells. “A 7.5-milliliter tube of blood, which is a typical volume for a blood draw, might have ten cancer cells and 35-40 billion blood cells,” said Ian Papautsky, the Richard and Loan Hill Professor of Bioengineering in the UIC College of Engineering and corresponding author on the paper. “So we are really looking for a needle in a haystack.”
Microfluidic technologies present an alternative to traditional methods of cell detection in fluids. These devices either use markers to capture targeted cells as they float by, or they take advantage of the physical properties of targeted cells — mainly size — to separate them from other cells present in fluids. Papautsky and his colleagues developed a device that uses size to separate tumour cells from blood. “Using size differences to separate cell types within a fluid is much easier than affinity separation which uses ‘sticky’ tags that capture the right cell type as it goes by,” said Papautsky.
“Affinity separation also requires a lot of advanced purification work which size separation techniques don’t need,” Papautsky added. The device Papautsky and his colleagues developed capitalises on the phenomena of inertial migration and shear-induced diffusion to separate cancer cells from blood as it passes through ‘microchannels’ formed in plastic. “
Papautsky and his colleagues ‘spiked’ 5-milliliter samples of healthy blood with 10 small-cell-lung cancer cells and then ran the blood through their device. They were able to recover 93 per cent of the cancer cells using the microfluidic device. Previously-developed microfluidics devices designed to separate circulating tumour cells from blood had recovery rates between 50-80%. When they ran eight samples of blood taken from patients diagnosed with non-small-cell lung cancer, they were able to separate cancer cells from six of the samples using the microfluidic device.
