Researchers are developing a new way to separate the cells by exposing them to sound waves

Researchers are developing a new way to separate the cells by exposing them to sound waves -

Researchers from MIT, Pennsylvania State University and Carnegie Mellon University have a new way to separate the cells by exposing them to sound waves as they flow through a tiny channel. Their device, about the size of a penny, could be used to detect extremely rare tumor cells circulating in the blood of cancer patients, to help physicians predict whether a tumor will spread.

cell separation with sound offers a gentler alternative to cell sorting technologies, which require labeling cells with chemicals or expose them to stronger mechanical forces that can damage existing.

"sound pressure is very mild and much smaller in terms of strengths and disruption to the cell. This is a gentler way to separate cells, and no artificial labeling necessary, "said Dao Ming, senior researcher at the MIT Department of Materials science and Engineering and a senior author of the paper, which appears this week in the Proceedings of the national Academy of sciences .

Subra Suresh, president Carnegie Mellon Professor Emeritus of engineering Vannevar Bush and former dean of engineering at MIT, and Tony in June Huang, professor of science and engineering at Penn State, are also the main authors the document. the main authors are MIT postdoc Ding Xiaoyun and Zhangli Peng, a former postdoc in MIT who is now an assistant professor at the University of Notre Dame.

the researchers have filed a patent on the device, the technology they have shown can be used to separate rare circulating cancer cells from white blood cells.

to sort cells using sound waves, scientists have already constructed microfluidic devices with two acoustic transducers that produce sound waves of opposite sides of a microchannel. When both waves meet, they combine to form a standing wave (a wave which remains constant position). This produces a pressure wave node, or a low pressure line, parallel to the cell flow direction. Cells that meet this node are pushed to the side of the channel; the distance of cell movement depends on their size and other properties such as compressibility

However, these existing devices are ineffective: .. Because there is only one pressure node the cells can be pushed aside as short distances

the new device overcomes this obstacle by the inclination of the sound waves so that they pass through the microchannel at an angle - meaning that each cell meeting more pressure nodes as it flows through the channel. Whenever it encounters a node, the pressure guide a little further from the center cell, making it easier to capture cells of different sizes when they reach the end of the chain.

In this study, the researchers first tested the system with plastic balls, finding that he could separate the beads with diameters of 9.9 and 7.3 microns (thousandths of a millimeter ) with about 97 percent accuracy. They also developed a computer simulation to predict the trajectory of a cell through the channel depending on its size, density and compressibility as well as the angle of the sound waves, which allows them to customize the means for separating the different cell types.

to test if the device could be useful for the detection of circulating tumor cells, researchers have attempted to separate the breast cancer cells known as MCF-7 cells from white blood cells. Both types of cells differ in size (20 micrometers in diameter for MCF-7 and 12 micron for white blood cells), and the density and compressibility. The device has successfully recovered about 71 percent of cancer cells; the researchers plan to test blood samples from cancer patients to see how it can detect circulating tumor cells in clinical settings. These cells are very rare. A sample of 1 milliliter of blood can contain only a few tumor cells

"If you can detect these rare tumor cells circulating, it is a good way to study the biology of cancer and diagnose if the primary cancer moved to a new site to generate metastatic tumors, "says Dao." This method is a step forward for the detection of circulating tumor cells in the body. It has the potential to offer a new safe and effective tool for cancer researchers, clinicians and patients, "says Suresh.