Biomechanical forces enhance directed migration and activation of bone marrow-derived dendritic cells

Mechanical forces are pervasive in the inflammatory site where dendritic cells (DCs) are activated to migrate into draining lymph nodes. For example, fluid shear stress modulates the movement patterns of DCs, including directness and forward migration indices (FMIs), without chemokine effects. However, little is known about the effects of biomechanical forces on the activation of DCs. Accordingly, here we fabricated a microfluidics system to assess how biomechanical forces affect the migration and activity of DCs during inflammation. Based on the structure of edema, we proposed and experimentally analyzed a novel concept for a microchip model that mimicked such vascular architecture. The intensity of shear stress generated in our engineered chip was found as 0.2-0.6 dyne/cm² by computational simulation; this value corresponded to inflammation in tissues. In this platform, the directness and FMIs of DCs were significantly increased, whereas the migration velocity of DCs was not altered by shear stress, indicating that mechanical stimuli influenced DC migration. Moreover, DCs with shear stress showed increased expression of the DC activation markers MHC class I and CD86 compared with DCs under static conditions. Taken together, these data suggest that the biomechanical forces are important to regulate the migration and activity of DCs.