Mechanostimulatory Cues Determine Intestinal Fibroblast Fate and Profibrotic Remodeling in a Physiodynamic Human Gut-on-a-Chip.

Biomechanical cues such as fluid shear stress and mechanical strain regulate intestinal physiology, yet their roles in shaping fibroblast fate during early fibrotic remodeling remain poorly defined. Here, we use a microengineered human gut-on-a-chip model that enables independent control of shear stress and mechanical strain under conditions of intact or impaired epithelial barrier function to interrogate fibroblast dynamics. Inflammation-associated fibroblasts derived from an ulcerative colitis patient exhibit intrinsic tolerance to biomechanical stress, maintaining myofibroblast-like phenotypes marked by hypertrophy and elevated α-smooth muscle actin aligned with actin stress fibers. In contrast, normal fibroblasts from healthy donors are highly susceptible to fluid shear stress, undergoing matrix metalloproteinase-dependent disruption of focal adhesion signaling, extracellular matrix remodeling, and apoptotic cell death, whereas mechanical strain alone exerts minimal effects. Importantly, an intact epithelial barrier is necessary and sufficient to protect fibroblasts from shear-induced injury, suggesting that "good fences make good neighbors." Under barrier dysfunction, prolonged shear exposure promotes the emergence of stiff 3D aggregates composed of mechanoadaptive, myofibroblast-like cells embedded within a complex fibrillar network. These findings identify that fluid shear stress contributes as a key driver of early profibrotic remodeling and highlight epithelial barrier integrity as a critical biomechanical safeguard in inflammatory bowel disease.