Can We Prevent Metastasis by Separating Cancer Cells from Normal Cells?

Although it is widely understood that most cancer deaths are the result of metastasis, our knowledge of many aspects of metastatic cell movement is incomplete at best.

Although it is widely understood that most cancer deaths are the result of metastasis, our knowledge of many aspects of metastatic cell movement is incomplete at best. As part of ongoing efforts to learn to control the movements of metastatic cells, Northwestern University researchers have developed a device that takes advantage of the physical principle called “ratcheting.” Actually a very tiny system of channels—each less than one-tenth of a millimeter wide—for cell locomotion, the device includes asymmetric obstacles within the channels that direct cell movement in a designated direction. The hope is that the cancer cells could be “sequestered permanently in a soft of ‘cancer trap’ made of implantable and biodegradable materials.”

"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 Bartosz Grzybowski, associate professor of chemical and biological engineering, McCormick School of Engineering and Applied Science, and associate professor of chemistry, Weinberg College of Arts and Sciences. "These are fundamental studies so the method needs to be optimized, but the idea has promise for a new approach to cancer therapy."

How the researchers got to this point is rather remarkable. They first learned that they could design channels—cell-adhesive and cell-repellant chemical compounds patterned onto a substrate—of various geometries that cells could move through in one direction, as the cells gravitated away from repellant areas and onto the “ratchet” channels. The team then created channels that could move cancerous and non-cancerous cells in opposite directions by taking advantage of their different shapes and mobility characteristics, thus partly sorting them. Because cancerous cells tend to be more round and broad and epithelial cells are long and thin and have long protrusions on the ends, Grzybowski and colleagues designed channels with “spikes” that stick out at 45-degree angles from the sides, thus funneling cancer cells and normal cells in opposite directions.

Organizing several of these channels like spokes on a wheel and leading to a central reservoir and then stacking them could be used as a “cancer trap.”

"When implanted next to a tumor the particles would guide cancer cells, but not normal cells, inward to the reservoir, where they would be trapped," said Grzybowski. "The particles could also be part of the sutures used during surgical procedures."

For more, see the article published online in Nature Physics.