Novel Device Developed Could Improve Cancer Detection

Circulating tumor cells (CTCs) are malignant cells that have escaped from a primary tumor into the bloodstream with the potential to form metastases at anatomically distant sites.

A newly developed method to isolate cancer cells that have escaped from a tumor could soon pave the way for improved diagnosis and treatment. The simple process involves a special device that squeezes cells in a blood sample through tiny funnels, which drive the cancer cells and blood cells into separate streams based on differences in their size and softness.

Scientists at University of British Columbia (Vancouver, BC, Canada) used polydimethylsiloxane (PDMS) to fabricate the microfluidic device. Cell separation processes involved initially filling the microfluidic device using phosphate buffered saline (PBS) with 0.2% Pluronic F127 to prevent nonspecific adsorption of cells to the wall of the device. Whole blood samples from patients with metastatic castrate-resistant prostate cancer (mCRPC) and four healthy control donors were infused through the device through the sample inlet, while buffer solutions were infused through the buffer and oscillation inlets.

For the assessment of the role of cell deformability in separation performance the scientists measured the cell size, suspending the cell samples in PBS and visualized using an Ti-U inverted microscope (Nikon, Tokyo, Japan) and Nikon’s CCD camera DS-2MBW. The size of CTCs and leukocytes from mCRPC patients were measured from the bright field image of the separated cells in suspension by drawing a circle on the outer edge of each target cells. At least 25 CTCs and leukocytes were measured for each mCRPC data set.

The scientists were able to show in patients with metastatic castration-resistant prostate cancer, where CTCs are not significantly larger than leukocytes; CTCs can be captured based on deformability at 25× greater yield than with the conventional CellSearch system (Raritan, NJ, USA). Finally, the CTCs separated using this approach are collected in suspension and are available for downstream molecular characterization.

Kim N. Chi, MD, the director of clinical research at the B.C. Cancer Agency a co-author of the study said, “In the first study, the device was able to capture more than 90% of the cells. Importantly, in patient samples the device captured about 25 times the number of cancer cells and produced fewer false positives compared to the conventional CellSearch system, which also analyzes blood samples.” The study was published on April 7, 2016, in the journal Small.

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University of British Columbia
Nikon
CellSearch