Mechanotransduction and Biophysical Regulation of Fibroblast Plasticity Under Prolonged Shear Stress

Complex interactions between mechanical stimuli and biochemical signaling shape the evolving fibrotic milieu. Fibroblasts contribute to this process, transitioning into myofibroblasts on stiffer substrates, and under low shear in 3D environments. The time-dependent effects of prolonged physiological shear stress on fibroblasts however remain poorly understood. We demonstrate that sustained shear stress (1.2 Pa) over 12 hours induces a temporal cascade of signaling and biophysical changes, driving fibroblast trans-differentiation into myofibroblasts. Cells adopt a spindle-shaped morphology under shear, actively remodeling through actin and -SMA to form elongated stress fibers. Myofibroblasts exhibit increased vinculin and zyxin expression in mature adhesions that remain elevated post-shear. Traction stresses progressively increased over the shear duration and persisted for 12 hours after the removal of the stimulus, indicating mechanical memory. Post-shear, deadhesion strengths increased significantly, accompanied by shifts in gene expressions governing extracellular matrix homeostasis. Prolonged shear enhanced MSD, directionality, and migration speed, all crucial for effective tissue repair. Finally, we demonstrate temporal changes in the biochemical gene expressions mediating the shear-induced remodeling of the extracellular matrix, cytoskeleton, and focal adhesions during the myofibroblast transition. These findings provide insights into the mechanobiological factors driving fibroblast-to-myofibroblast transitions which may inform the development of mechano-therapeutic strategies.