In the study, Franck and co-lead author Stacey Maskarinec, who both conducted the experiments while graduate students at the California Institute of Technology, placed cells on top of a 50-micron-thick water-based gel designed to mimic human tissue. They added into the gel spheres about a half-micron in diameter that lit up when jostled by the cells' actions. By combining two techniques — laser scanning confocal microscopy and digital volume correlation — the scientists tracked the cells' movement by quantifying exactly how the environment changed each time the cell moved. The team recorded results every 35 minutes over a 24-hour period.
What they found was cells move in intriguing ways. In one experiment, a cell is clearly shown operating in three dimensions by extending feelers into the gel, probing at depth, as if thrusting a leg downward in a pool. The Brown and Caltech scientists also found that as a cell moves, it engages in a host of push-pull actions: It redistributes its weight, it coils and elongates its body, and it varies the force with which it "grips," or adheres, to a surface. Combined, the actions help the cell generate momentum and create a "rolling motion," as Franck described it, that is more like walking than shuffling, as many scientists had previously characterized the movement.
"The motion itself is in three dimensions," Franck said.
Franck's lab plans to use the new force-measurement technique to examine how the movement of normal healthy cells differs from mutant or malignant ones. "That promises to give us greater insight in how cells' behavior changes when they become diseased," Franck said.
Scientists at Brown University and the California Institute of Technology have for the first time tracked how cells move in three dimensions by measuring the force exerted by them on their surroundings. The video shows how cells engage in "pushing and pulling" as they probe their surroundings and move.
(Photo Credit: Christian Franck, Brown University)
Scientists at Brown University and the California Institute of Technology have for the first time tracked how cells move by measuring the force exerted by them on their surroundings. The method could lead to better understanding how healthy cells differ from malignant cells.
(Photo Credit: Christian Franck, Brown University)
Source: Brown University