PROJECT SUMMARY Fibrotic disorders account for a significant source of global morbidity and mortality. Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and life-threatening lung disease most prevalent in elderly populations. IPF impacts 100,000 patients in the U.S. alone and there are approximately 34,000 new global diagnoses each year. Most patients with IPF succumb to respiratory failure within 3-5 years and the only clinically available therapeutic treatments do not cure the disease. As the average age of the U.S. population increases, it is imperative for researchers and practitioners to work together to identify new targets to halt or reverse IPF. Discovery of new therapeutic targets for IPF through traditional cell culture techniques and pre-clinical animal models has several limitations because these systems do not adequately reproduce key aspects of human physiology. Most importantly, dynamic cell-matrix and cell-cell interactions that are difficult to recapitulate in vitro drive the progression of fibrosis: it is not clear, for example, whether changes in the extracellular matrix (ECM) composition or the subsequent alterations in mechanical properties of the surrounding tissues are the more potent drivers of IPF, i.e., the best target for therapeutics. New tools and technologies that enable us to dynamically study the pathogenesis of fibrosis over time remain an unresolved challenge. My laboratory has developed novel methods to synthesize and microfabricate a new class of biomaterials to conduct dynamic cell-ECM studies, not currently possible in traditional models of fibrosis. Our innovative platform combines a phototunable poly(ethylene glycol) (PEG) backbone with clickable decellularized ECM (dECM) from healthy or diseased lung tissue so that we may decouple fibrotic tissue composition (e.g., increased collagen content) from subsequent changes in mechanical properties (e.g., increased stiffness). Specifically, healthy or IPF lung dECM will be incorporated into soft (1-5 kPa) hydrogel matrices that mimic healthy tissue, then exposure to focused light will dynamically initiate stiffening to fibrotic levels (>10 kPa). Three aims are proposed to engineer and implement this biomaterials-based strategy for building novel, high- fidelity in vitro models of IPF. AIM I: Engineer the structure, composition, and dynamic mechanics of PEG- dECM cell culture platforms to recapitulate distal lung tissue; AIM II: Interrogate the impact of composition and mechanical properties on fibroblast activation using dynamic PEG-dECM biomaterial platforms; and AIM III: Identify druggable mechanosensitive targets of the fibrotic activity recreated in dynamic 3D models. Successful completion of these aims will advance our understanding of the cellular and molecular drivers of IPF, building the foundation for high-throughput discovery and screening of therapeutics for precision medical treatments.