Researchers from Brown University were able to image cancer cells that had undergone epithelial-mesenchymal transition (EMT) as they migrated across a device that mimics the tissue surrounding a tumour.
EMT is a process in which epithelial cells, which tend to stick together within a tissue, change into mesenchymal cells, which can disperse and migrate individually.
EMT is a beneficial process in developing embryos, allowing cells to travel throughout the embryo and establish specialised tissues.
But recently it has been suggested that EMT might also play a role in cancer metastasis, allowing cancer cells to escape from tumour masses and colonise distant organs.
In the new study, published in the journal Nature Materials, researchers found that cancer cells displayed two modes of motion.
A majority plod along together in a collectively advancing group, while a few cells break off from the front, covering larger distances more quickly.
"In the context of cell migration, EMT upgrades cancer cells from an economy model to a fast sports car," said lead author Ian Y Wong, assistant professor in the Brown School of Engineering and the Center for Biomedical Engineering, who performed the research as a postdoctoral fellow at Massachusetts General Hospital.
"Our technology enabled us to track the motion of thousands of 'cars' simultaneously, revealing that many sports cars get stuck in traffic jams with the economy cars, but that some sports cars break out of traffic and make their way aggressively to distant locations," Wong said.
Armed with an understanding of how EMT cancer cells migrate, the researchers hope they can use this same device for preliminary testing of drugs aimed at inhibiting that migration.
To get this new view of how cancer cells move, the researchers borrowed microelectronics processing techniques to pattern miniaturised features on silicon wafers, which were then replicated in a rubber-like plastic called PDMS.
The device consists of a small plate, about a half-millimetre square, covered in an array of microscopic pillars.
The pillars, each about 10 micrometres in diameter and spaced about 10 micrometres apart, leave just enough space for the cells to weave their way through. Using microscopes and time-lapse photography, the researchers can watch cells as they travel across the plate.