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Slow, silent 'scream' of epithelial cells detected for first time

It has long been thought that only nerve and heart cells use electric impulses to communicate, while epithelial cells—which compose the linings of our skin, organs and body cavities—are mute, serving mostly as protective barriers that can absorb and secrete various substances.

But two researchers from the University of Massachusetts Amherst have upended the status quo by showing that epithelial cells do indeed "talk" to each other, albeit with slow electrical signals.

Led by Steve Granick, Robert K. Barrett Professor of Polymer and Science and Engineering, and postdoctoral fellow Sun-Min Yu, the discovery, published in the , could enable new applications for everything from wearable bioelectric sensors to wound healing.

"Epithelial cells do things that no one has ever thought to look for," says Granick. "When injured, they 'scream' to their neighbors, slowly, persistently and over surprising distances. It's like a nerve's impulse, but 1,000 times slower." His team's curiosity-driven approach, blending polymer science and biology, unveiled this hidden cellular signaling.

Granick and Yu used an epithelial-cell-coated chip with 60 precisely placed electrodes to eavesdrop. Yu, a cell-culture expert, grew a single layer of human epithelial cells on the chip, which detected minute electric shifts.

Using a precise laser to produce "sting" patterns of individual cells, they watched as signals rippled outward. "We tracked how cells coordinated their response," Yu explained. "It's a slow-motion, excited conversation."

Unlike the swift neurotransmitter bursts of nerve cells, epithelial cells rely on ion flows—of calcium, especially—that produce signals that are far slower than those in nerve cells, but with similar voltages. These signals can be long-lived: Granick and Yu observed cells that "talked" for over five hours across distances nearly 40 times their own length.

Though Granick and Yu showed that calcium ions are necessary for epithelial conversation, they have yet to test what else might contribute to the conversation. And though the immediate applications of their new discovery remain to be seen, the implications are vast.

"Wearable sensors, implantable devices and faster wound healing could grow from this," Granick noted. "Understanding these screams between wounded cells opens doors we didn't know existed," Yu added.