Probing Critical Injury Thresholds for Maladaptive Epithelial Injury and Repair Processes with Photoresponsive Bioinspired Synthetic Basement Membrane

Microinjuries to the lung epithelium are hypothesized to initiate maladaptive processes that lead to fibrosis. Human in vitro models remain a great need for studying this injury-initiation process for mechanistic understanding and therapeutic development. We established a photoresponsive synthetic extracellular matrix (ECM) inspired by the basement membrane that enables triggered injuries of defined size and frequency for probing cellular responses. The synthetic matrix integrated a photolabile bis-coumarin linker for light-triggered injury and relevant integrin-binding peptides for cell function. Bio-orthogonal chemistry was used to create hydrogel-based ECMs with tunable elasticity in transwells, which are traditionally used for epithelial cell culture. Integrin-binding peptide combinations synergistically promoted model epithelial cell layer formation with increased E-cadherin expression and barrier function. An accessible photomasking approach was established for selectively photodegrading the synthetic matrix with cytocompatible visible light and achieving different injury depths and widths. Following a critical injury size, cell responses recapitulated key features of dysregulated re-epithelialization with decreased E-cadherin, proliferation, and barrier function and increased apoptosis. This work provides a new materials-based tool for probing injury and repair processes with tunable control of both the ECM and injury to it with opportunities for future mechanistic and therapeutic insights to address maladaptive wound healing processes.