Identification and isolation of migratory subpopulations of cancer cells using microfluidics with fluid walls

Microfluidic assays have great potential for investigating cancer cell migration, a key process underlying metastasis which remains a major clinical challenge. However, adoption by biologists is limited due to complex fabrication and operation methods combined with difficulty in retrieving cells of interest. We jet-print dumbbell-shaped microfluidic environments with fluid walls in standard Petri dishes in seconds using standard growth media and immiscible oil. Prostate cancer cells and chemoattractant (bovine serum) are introduced into each end using local transient differences in Laplace pressure to enable spatial confinement. Automated live-cell imaging monitors chemotaxis towards serum using standard microscopes, as the confining fluid walls are optically transparent. Distinct subpopulations of migratory cells exhibit different morphologies and motilities, assessed using a custom machine-learning segmentation model. Then, we leverage the reconfigurability of fluid walls to isolate and retrieve rapidly-migrating single cells. This demonstrates that fluid-walled microfluidics is a versatile and accessible approach for investigating cancer cell migration at single-cell resolution, offering new opportunities to examine cellular heterogeneity in metastasis.