Title: “A novel microfluidic assay foradhesion-free migration reveals a polarized motility mode”
Cell motility is a key factor in various processes such ascancer metastasis, immune response, and wound healing. The mode ofcell migration depends on the chemical, mechanical andgeometrical properties ofthe extra-cellular environment. While adhesive modes of motilityare well understood, the mechanisms underlying migration in the absence ofcell-matrix and cell-cell adhesions are yet to be understood. Here, wepresent a novel high-resolution microfluidic assay for the study of cellularmotility in confined environments. We employ this setup to study cellularcrawling motility under different conditions, where cellular ability to exerttraction forces on their environment is modulated. Our results uncovered a previouslyuncharacterized, adhesion-free, motility mode in MDA-MB 231 breast cancercells. In the absence of traction forces and low friction environments, confinementalone is sufficient to enable a non-adhesive migration phenotype. We find thatunder asymmetric confinement conditions, non-adhesive cellular migrationbecomes polarized, with a directionality that is determined by extra-cellulargeometrical cues, as well as by cellular characteristics, such as cell size.Our results suggest that topography cues play a significant role in regulatingcell behaviors. Understanding the mechanisms governing cell migration inconfinement is critical to fully understand key processes, such as theplasticity of cancer cells motility modes. Our micro-channel essay may be usedin further studies for characterization of cellular response to variedconfinement conditions.