Biomimetic Urethra-on-a-Chip Platform for Modelling Fibrosis: 3D-Printing and Near-Field Electrospinning in BAM-Functionalized Microenvironment.

Urethral stricture, a prevalent urological disorder characterized by fibrosis of periurethral tissues, severely compromises urinary function and patient quality of life. Despite various clinical interventions, recurrence remains frequent, largely due to the lack of physiologically relevant in vitro models for mechanistic investigation and drug screening. Here, we present a biomimetic urethra-on-a-chip platform that integrates microfluidics, three-dimensional (3D) printing, and near-field electrospinning to recapitulate the structural and biochemical complexity of the native urethra. The device features polydimethylsiloxane (PDMS) microchannels coupled with a multilayered polycaprolactone (PCL) membrane, functionalized using a bladder acellular matrix (BAM)-gelatin bioink to emulate the extracellular matrix (ECM) microenvironment. A bilayer microchamber configuration supports spatially organized coculture of fibroblasts and urothelial cells under dynamic perfusion, reproducing physiological shear stress and nutrient gradients. Under fibrotic stimulation by transforming growth factor beta 1 (TGF-β1), the system faithfully mimicked fibroblast activation and epithelial injury, while rapamycin treatment effectively attenuated fibrotic responses, validating its potential for pharmacological testing. This urethra-on-a-chip provides a robust, reproducible, and cost-efficient platform for modeling urethral fibrosis and evaluating antifibrotic therapeutics. By bridging biofabrication, microfluidics, and tissue pathophysiology, this work establishes a versatile organ-on-a-chip model with significant implications for translational research and personalized regenerative medicine.