Researchers at IBEC, located at the Parc Científic de Barcelona, and Harvard School of Public Health have found that epithelial cells move in a group, propelled by forces both from within and from nearby cells, to fill any spaces they encounter. The study appears this week in an advance online edition of Nature Materials (DOI:10.1038/nmat3689). This new finding may provide with crucial information about disease mechanisms such as the spread of cancer or the constriction of airways caused by asthma.

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“We were trying to understand the basic relationship between collective cellular motions and collective cellular forces, as might occur during cancer cell invasion, for example. But in doing so we stumbled onto a phenomenon that was totally unexpected,” said senior author Jeffrey Fredberg, professor of bioengineering and physiology in the HSPH Department of Environmental Health and co-senior investigator of HSPH’s Molecular and Integrative Cellular Dynamics lab.

Biologists, engineers, and physicists worked together to shed light on collective cellular motion because it plays a key role in functions such as wound healing, organ development, and tumor growth. Using a technique called monolayer stress microscopy—which they invented themselves—they measured the forces affecting a single layer of moving epithelial cells. They examined the cells’ velocity and direction as well as traction—how some cells either pull or push themselves and thus force collective movement.

As they expected, the researchers found that when an obstacle was placed in the path of an advancing cell layer—in this case, a gel that provided no traction—the cells moved around it, tightly hugging the sides of the gel as they passed. However, the researchers also found something surprising—that the cells, in addition to moving forward, continued to pull themselves collectively back toward the gel, as if yearning to fill the unfilled space. The researchers dubbed this movement “kenotaxis,” from the Greek words “keno” (vacuum) and “taxis” (arrangement), because it seemed the cells were attempting to fill a vacuum.

This new finding could help researchers better understand cell behavior—and evaluate potential drugs to influence that behavior—in a variety of complex diseases, such as cancer, asthma, cardiovascular disease, developmental abnormalities, and glaucoma,” explains co-author Xavier Trepat, group leader at IBEC and ICREA research professor. “The findings could also help with tissue engineering and regenerative medicine, both of which rely on cell migration.”

In carcinomas, for instance—which represent 90% of all cancers and involve epithelial cells—the new information on cell movement could improve understanding of how cancer cells migrate through the body. Asthma research could also get a boost, because scientists think migration of damaged epithelial cells in the lungs are involved in the airway narrowing caused by the disease.

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