How cells cope with stress and strain

opcio 13_webA study by the Institute for Bioengineering of Catalonia (IBEC) reveals how cells withstand breakage during the constant changes in shape and volume experienced in most biological processes

During critical biological processes such as embryonic development, breathing, the pumping of the heart, wound healing and tumor growth, the body’s cells are stretched and distorted to adapt to their environment. The cell’s membrane, though, is rigid and inflexible. So how does it withstand all these constant deformations, so that it doesn’t break?

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Image: A cell, after having modified its shape and volume. In red are the folds that appear after stretching, and in green those which occur after osmotic shock (when the volume is increased by adding wáter). Inset: a close-up and vertical view of the folds.

Researchers at the Institute for Bioengineering of Catalonia (IBEC), in collaboration with the Institute of Mechanobiology in Singapore and the University Polytechnic of Barcelona (UPC), have discovered how this phenomenon occurs. They demonstrate that every time a cell is compressed or stretched, it forms and then quickly eliminates small folds in its membrane to allow for changes and prevent tearing.

The fascinating thing about this system is its simplicity. For years, many research groups around the world have explored complex biochemical and molecular processes to try to explain how the membrane adapts to various processes. This study, however, shows that simply by applying the laws of physics and mechanics, cells can adapt to extreme conditions.

“To carry out this study, we tested the cells after stretching them introducing water to increase their volume,” says Anita J. Kosmalska, IBEC researcher and first author of the paper, which was published today in the journal Nature Communications. “In both cases, without taking into account the biological complexity of cells, the laws of mechanics and physics alone are able to explain where folds are formed or eliminated, what kind of folds they are, and how they protect the cell membrane from breaking.”

The study also reveals that the area of the cell membrane is able to increase or decrease to accommodate the cell shape almost immediately, which is essential for vital processes such as breathing or heartbeat.

“Given that continuous cellular shape changes also occur in cancer or during wound healing, the implications of this finding are very important,” says Pere Roca-Cusachs, group leader at IBEC and assistant professor at the University of Barcelona, who led the study. “The challenge now is to find out to what extent this new knowledge can help us to intercept during tumor progression, improve tissue regeneration, or to solve problems that occur in respiratory and cardiovascular diseases.”

Reference article: Anita Joanna Kosmalska, Laura Casares, Alberto Elosegui-Artola, Joseph Jose Thottacherry, Roberto Moreno-Vicente, Victor González-Tarrago, Miguel Angel del Pozo, Satyajit Mayor, Marino Arroyo, Daniel Navajas, Xavier Trepat, Nils C. Gauthier & Pere Roca-Cusachs (2015).“Physical principles of membrane remodelling during cell mechanoadaptation”. Nature Communications, 10.1038/ncomms8292