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Tug of War is Not the Answer

A BYU mathematics professor has discovered a different, more effective way to measure the movement of cells within a living organism. Discovering the mechanisms for cell motion is important because it is easier to change the cell’s speed if the process is understood.
Dr. John Dallon

To measure the speed with which cells move within a living organism, most scientists focus on how hard cells push and pull against each other. But Dr. John Dallon, a professor in the Department of Mathematics, has discovered a different, more effective way.

Years ago, when Dallon began this research, he focused on simpler “rounded cells,” but now he focuses on more dynamic, star-shaped cells. “Recently, I’ve been much more interested in the forces involved in how cells pull and tug on their environment.  In wound repair, cells pull and tug on the tissue as they repair the wound,” Dallon explained.

Dallon saw that these cells would play a sort of tug of war, pulling and pushing on each other and on the cell substrate as their adhesion sites attach and detach. To better understand this interaction, Dallon developed a new model using mathematical formulas. What he discovered from his model was not what he expected.

“It became obvious to me that sometimes these attachment sites will release and then that long stretched-out arm will quickly retract.  I became interested in these attachments and understanding them better,” Dallon said.

Most previous research on this topic has focused on measuring the force of the pushing and pulling of cells, but Dallon says that scientists should instead pay more attention to when they grab onto and let go of things.

“It’s the dynamics of how the cell grabs on to things as opposed to how hard it pulls on them that determines its speed,” Dallon explained.

By focusing on the attachment activity instead of the pulling and pushing, scientists can better control the speed at which cells move. Discovering the mechanisms for cell motion is important because it is easier to change the cell’s speed if the process is understood.

“The main point of this [study] is to say, if I want to slow a cell down, I don’t change the forces on the cell; I change how it’s attaching and detaching to the substrate,” Dallon said. “Altering the attachment and detachment dynamics of cell adhesion is more effective at changing cell speed than altering cell force.  So understanding those dynamics is key.

For example, if people have a tumor or growth in their body, treatment is easier when the cells remain localized.  When they start to move and go to other parts of the body it is more life threatening.  If the cell mobility could be slowed down, these diseases would be simpler to manage and treat. There are many reasons scientists and doctors are interested in speeding up or slowing down cells.

While they have a basic understanding of the current model, Dallon and his peers had to make many simplifying assumptions and they look forward to strengthening their results by making more realistic formulas with fewer assumptions.

“Eventually what would be nice is if you tell me how the forces on an adhesion site affect its dynamics, [then] I can tell you how the cell will move.  Then by changing the dynamics in the right way we can control how the cell moves,” Dallon said.

If Dallon and his team could solidify this, it would lead to new achievements in potentially treating diseases.

“That’s sort of a lofty goal, but that’s where I want to go because then you have more control over these cells,” Dallon said. “And if you understand how to modify those adhesion dynamics and how that affects the overall motion of the cell, that would be quite useful.”

Being able to slow down cells would be useful in situations such as disease because it would give patients an upper hand on their own “tug of war” with their illness. Any advantage science can give to patients is always a good thing.