Now in 3-D: cell traction

Scientists can now measure in 3-D the amount of force wielded by cells as they spread and move, which could help investigations into tumor growth.

Bioengineers have just come up with a way to measure – in three-dimensions! – the amount of force a single cell exerts while it moves.

Spreading its long, slender extensions, a cell in movement comes in constant contact with the matrix surrounding it. These cell-generated forces are behind all kinds of mechanics and structures in the body – driving cell migration, guiding tissue development, and contributing to tumor growth.

When cells are taken out of context from their native 3-D environments and studied in only two dimensions, they behave differently. Yet, 3-D studies remain rare.

In a new Nature Methods study, University of Pennsylvania bioengineer Christopher Chen and his colleagues took cells from cow arteries, human embryonic tissue, and lung cancer tumors, and then put them into a gel matrix that contained tens of thousands of fluorescent beads.

As the cells probed their way through the gelatinous matrix -- made mostly of water and polyethylene glycol, commonly found in skin creams, toothpaste, and eye drops -- they would displace the beads. The researchers used that bead displacement to visualize and then calculate the amount of force that the different cell parts would exert as they moved over time.

They found that the strongest forces were located at the tips of the cells’ long extensions. In this video of a 3-D stereogram, red denotes the highest magnitude of bead displacement while blue is the lowest.

Because this synthetic gel has similar elasticity as living tissue, the authors anticipate that their techniques can help investigations into various cellular processes, such as cell-cell interactions and metastasis in cancer.

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