MIT scientists have made a dime-sized microfluidic device that can separate hard-to-find cancer cells from healthy ones using angled sound waves—sending an early warning that cancer cells are spreading.

Cell separation methods help in genetic research, clinical diagnosis, and therapeutics. These techniques are already being used in regenerative medicine, multiple sclerosis treatments, and cancer therapy.

Technicians and researchers currently use methods such as Single Cell Sorting, Fluorescent Activated Cell Sorting (FACS) and Magnetic Activated Cell Sorting (MACS) which rely on cell surface markers and mechanical forces to separate cells. But staining the markers and shearing forces can damage cell membranes and produce unreliable results.

New No-Damage Technique

Now, scientists at MIT, Carnegie Mellon University, and Pennsylvania State University have devised a technique that does not damage cells. Using sound waves, this method sorts cells based on size and other physical properties without making direct contact with the cells.

“Acoustic pressure is very mild and much smaller in terms of forces and disturbance to the cell. This is a most gentle way to separate cells, and there’s no artificial labeling necessary,” Ming Dao, researcher at MIT’s Department of Materials Science and Engineering, said in a press release.

Acoustic methods of cell separation have been around for some time, but early trials have proved inefficient. Knowing these limitations, the group refined the method and experimented with what they call “tilted-angle standing surface acoustic waves (taSSAW)” to separate the cells, according to the research study.

Unlike previous techniques using sound waves that hit straight across, the new method “tilts” the sound waves at an angle from both sides of the channel of a dime-sized microfluidic device as the cells flow—creating several continuous pressure nodes. As the cells encounter pressure continuously while flowing through the channel, they get separated from each other based on properties like size, density and compressibility.

Research Supports Success

In the study published recently in the Proceedings of the National Academy of Sciences (PNAS), the researchers said that they have successfully proven “the effectiveness of the present technique for biological-biomedical applications by sorting MCF-7 human breast cancer cells from non-malignant leukocytes, while preserving the integrity of the separated cells.”

Per the findings, they were able to separate the MCF-7 cells (20 microns in diameter) from white blood cells (12 microns in diameter), and recovered 71 percent of the cancer cells. With these promising results, the researchers now want to test it in cancer patients to detect hard-to-find cancer cells that could plant seeds of metastasis.

“If you can detect these rare circulating tumor cells, it’s a good way to study cancer biology and diagnose whether the primary cancer has moved to a new site to generate metastatic tumors,” Dao said in the MIT statement. Finding sneaky circulating tumors—one milliliter of blood may only have a few tumor cells—is important for clinicians to detect the spread of cancer, both for those with active cancer and those in remission. They are patenting the device and hope that it will soon help in many clinical settings.

Lab-on-a-chip Technology

Lab-on-a-chip devices using microfluidic technology are being developed as instant, point-of-care diagnostic devices. With MIT’s study, it has been proven to work as a monitoring tool for cancer metastases as well.

This will greatly benefit cancer patients around the world especially in regions like the Middle East, where cancer incidence is expected to double in the next decade—the fastest rate in the world—according to the journal Nature.