Biomechanical Ratchet Traps Cancer Cells Before They Can Spread

Researchers have demonstrated the possibility of using a biomechanical ratchet to sort normal and cancerous cells as a means to trap tumor cells before they spread to other areas of the body.

In several important physiologic processes, particularly cancer metastasis, randomly moving cells can acquire a directional motility phenotype and bias their motions in response to environmental cues. Researchers still do not understand why cells migrate in a specific direction.

In the current study, researchers from Northwestern University (Evanston, IL, USA) incorporated molecular cues (cell-adhesive and cell-repellant chemical compounds) into a "microgeometry” substrate that was keyed to the difference in shape between normal epithelial (long and thin with long protrusions on the ends) and cancer (round and broad) cells.

The microscopic ratchets contained channels with "spikes” protruding at 45^o angles from the walls, alternating on opposite sides of the channel. This pattern funneled cancer cells in one direction while at the same time directing the normal cells in the opposite direction, as those cells could attach to the spikes and pull themselves through the channel. The cancer cells could be channeled into a closed chamber from which they could not escape.

The feasibility of the system was tested using melanoma, breast cancer, and normal cells, and the results were reported in the June 14, 2009, online edition of the journal Nature Physics.

"We have demonstrated a principle that offers an unconventional way to fight metastasis, a very different approach from other methods, such as chemotherapy,” said senior author Dr. Bartosz Grzybowski, associate professor of chemical and biological engineering at Northwestern University. "These are fundamental studies so the method needs to be optimized, but the idea has promise for a new approach to cancer therapy.”

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