Israeli study points to new possibilities for tissue engineering
Baku, November 11, AZERTAC
Israeli researchers have identified a previously unrecognized mechanism through which living cells can generate forces that draw them toward one another, offering a possible new explanation for why cells tend to gather in clusters, TPS-IL news agency reported. The findings could eventually help scientists develop better ways to grow replacement tissues in laboratories, potentially benefiting patients with severe burns who need skin grafts and people with damaged cartilage.
Dr. Assaf Zemel of the Hebrew University of Jerusalem developed a mathematical model showing how neighboring cells can generate an additional attractive force by adjusting their pulling forces in response to one another. The findings suggest that cells do more than sense and respond to mechanical forces in their surroundings: Their responses can also create forces that bring them closer together.
Understanding these interactions could help researchers design materials that encourage cells to assemble into organized tissues.
Cells are surrounded by a network of fibers called the extracellular matrix, which provides structural support and transmits mechanical forces. When a cell pulls on this material, it changes the physical environment experienced by neighboring cells. Those cells sense the resulting deformation and adjust their own pulling forces, which in turn affects the forces experienced by the first cell.
While scientists have long known that cells communicate through such mechanical interactions, Zemel examined what happens when neighboring cells continuously adjust their forces in response to one another.
His mathematical analysis found that this reciprocal adjustment produces an additional, short-range attractive interaction. When cells strengthen their pulling forces in response to stretching, the resulting stresses in the surrounding material tend to draw them together.
“What drew me to this problem is that a question about living cells leads to a familiar idea from molecular physics: how stereotyped cellular responses to external perturbations can give rise to a universal attraction between cells,” Zemel said.
“Cells are far more complex than molecules — they actively sense and respond to their surroundings. Bringing a fundamental physical principle into biology helps us understand how those responses could turn a neighbor’s pull into a force that brings cells together,” he added.
How Cells Draw Together
The mechanism resembles van der Waals forces, weak attractive forces between molecules that help hold matter together. In Zemel’s model, however, the attraction arises from the deformation of the material surrounding living cells and the cells’ active responses to those changes.
The model may also help explain why cells grown on soft surfaces often gather into clusters or networks, while those on harder surfaces can remain more dispersed.
Earlier models predicted that conventional elastic interactions between cells are strongest when the supporting material has an intermediate level of stiffness, weakening as the material becomes very soft. The newly identified attraction follows a different pattern: It becomes stronger as the surrounding material softens.
The model also predicts that cells can shift from repulsion to attraction as they approach one another. Even when their overall mechanical interaction is repulsive at greater distances, their reciprocal adjustments can generate an attractive force at closer range.
The research, published in the peer-reviewed Proceedings of the National Academy of Sciences (PNAS), was based on mathematical analysis rather than experiments with living cells.
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