Riding the cAMP Wave: Maximizing Cell Migration by Slow Chemoattractant Waves

Chemotaxis is the motion of cells in response to chemical signals in the environment. While experiments have been done to understand various aspects of chemotaxis in eukaryotes, few experiments have probed the physical limits of the process. Using a microfluidic device to generate waves of the chemoattractant cyclic AMP (cAMP) of controlled size and speed, we were able to record cell migration speeds of individual cells of the social amoeba Dictyostelium that are significantly higher than in static gradients. This was coupled with the observation that these fast-moving cells were concentrated at a particular location on the back of a wave, much like surfing, given the right range of wave speeds. Cells that are 'riding the waves' rarely turn back, displaying very high persistence. Furthermore, cells that were not able to follow the first wave were typically able to ride the second wave. The experimental results were incorporated into a model, which aims to uncover the fundamental cellular processes that regulate the limits of chemotaxis and cell motility. This study may help us devise strategies to maximize cell migration efficiency.