Critical stresses for cancer cell detachment in microchannels (Cell detachment in microchannels)

We present experiments involving cancer cells adhering in microchannels, subjected to increasing shear stresses (0.1Pa to 30Pa). Morphological studies are carried out at different shear stresses. Cells exhibit spreading patterns similar to the ones observed in static conditions, as long as the shear stress is not too high. At critical wall shear stresses (around 2− 5Pa), cells decrease their cell-substrate contact area until detachment at the larger stresses. Critical shear stresses are found to be lower for higher confinements (i.e. smaller cell height to channel height ratio). Fluorescent techniques are also used to localize focal adhesions (typically 1 μm2 in size) under various shearing conditions, showing that cells increase the number of focal contacts in the region facing the flow. To analyze such data, we propose a model to determine the critical stress, resulting from the competition between hydrodynamic forces and the adhesive cell resistance. With this model typical adhesive stresses exerted at each focal contact can be determined and are in agreement with previous works.