Use microfluidics to study cell migration in response to fluid shear stress gradients

Cells respond not only to biological regulatory factors but also to physical stimuli such as electric fields, light, and shear stress in their environment. These stimuli can lead to cell migration and morphological changes. In the human body, cells encounter fluid shear stress induced by interstitial flow, lymphatic flow, blood flow, or organ-specific conditions within their micro-environments. Therefore, fluid shear stress, a classic mechanical force, has gained significant attention in wound healing and cancer metastasis. In this study, a microfluidic chip was developed to both culture cells and generate a shear stress gradient to direct cell migration. The design of this device's geometry allows the generation of a shear stress gradient perpendicular to the direction of medium flow. This greatly eliminates the influence of flow-induced cell responses. Using mouse fibroblast cells (NIH3T3) and human lung cancer cells (CL1-5) as models, their migration directionality, migration rates, and alignment in response to the shear stress gradient were investigated. Within the stress range of 0.095–0.155 Pa and a gradient of 0.015 Pa/mm, NIH3T3 cells did not exhibit significant directional migration, differences in migration rates, or specific alignment patterns. In contrast, CL1-5 cells preferred higher shear stress environments and alignment parallel to the medium flow, suggesting that these conditions could induce higher mobility in these cancer cells.