Cell sorting device improves detection of circulating tumor cells

By Lauretta Ihonor, medwireNews Reporter

An automated cell sorting device developed in the USA may allow circulating tumor cells (CTCs) to be detected with greater accuracy than by current methods, say researchers.

The device, called the CTC-iChip, "is capable of sorting rare CTCs from whole blood at 10⁷ cells per second," say Mehmet Toner (Harvard Medical School, Boston, Massachusetts, USA) and team.

They add: "Most importantly, the iChip is capable of isolating CTCs using strategies that are either dependent or independent of tumor membrane epitopes, and thus applicable to virtually all cancers."

When used on whole blood samples, the iChip's magnetic labeling and microfluidic sorting functions allowed CTCs to be isolated from a variety of epithelial and nonepithelial cancer types, such as breast, lung, and prostate cancer.

And this CTC isolation was performed with greater sensitivity than existing cell sorting devices, say Toner and team.

Writing in Science Translational Medicine, the researchers explain that the iChip's CTC-isolation process works in three phases. Firstly, the device removes all blood components except for white blood cells and CTCs. It then aligns the cells in a single line using the principles of microfluidics. Finally, the device magnetically labels target cells and sorts the CTCs from the white blood cells.

"The sorting of CTCs as unfixed cells in solution allows for the application of high-quality clinically standardized morphological and immunohistochemical analyses, as well as RNA-based single-cell molecular characterization," say the researchers.

The iChip is an updated version of two microchip-based CTC detecting devices previously developed by Toner and team. These systems can take up to 5 hours to analyze a blood sample and require a different setting for different cancer types. The iChip, by contrast, can analyze a blood sample in less than an hour.

They add that CTC detection technologies are likely to "continue to improve in sensitivity" and therefore that devices like the iChip "may ultimately provide novel approaches for early detection of invasive cancer before the establishment of metastatic disease."

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