Neutrophil dynamics during migration in microfluidic concentration gradients

This paper reports on the study of neutrophil dynamics during chemotaxis using the Microfluidic Quadrupole (MQ). The MQ is used to generate concentration gradients of the chemokine Interleukin-8 atop human neutrophils cultured in petri-dishes. The gradients are generated within the MQ in the gap between the microfluidic probe and the neutrophil-containing dish. We studied travelled distances and migration speeds of individual neutrophils using real time-lapse microscopy and observed heterogeneity with neutrophils dynamics. Results show that the migration distance of individual neutrophils is correlated to their initial position within the gradients. Interestingly, analysis revealed that neutrophils started migration with full speed at the beginning of the experiment when exposed to the gradients, and then slow down as they migrate toward higher concentrations until they stop, suggesting a desensitization mechanism that is gradually activated.