Clickable, hybrid hydrogels as tissue culture platforms for modeling chronic pulmonary diseases in vitro

Abstract

Statement of Purpose: Many chronic pulmonary diseases, including idiopathic pulmonary fibrosis (IPF), pulmonary hypertension (PH) and chronic obstructive pulmonary disease (COPD), are complex and poorly understood. While great progress has been made to elucidate the cellular and molecular pathways underlying these diseases, treatment options remain limited. The dynamic alterations in mechanical properties and composition of the ECM that occur during pathologic tissue remodeling have been extensively studied as a major driver of cellular activation and disease progression. However, current in vitro models of pulmonary tissues rely almost exclusively on naturally derived materials, such as Matrigel, collagen or decellularized ECM (dECM), which provide biological activity but cannot be easily tuned to emulate the time-dependent changes in mechanical properties that occur during disease progression. We aim to develop a new class of clickable, dynamically tunable hybrid hydrogels that will allow for the manipulation of microenvironmental mechanical properties through a two-stage polymerization process while also maintaining the complex biological composition of the lung ECM to provide a new tool for studying cell behavior in vitro. Using PH as a model, this hydrogel system will contain dECM from healthy and pathologic lung tissue in order to study the influence of both composition and dynamic mechanical properties on the initiation and progression of PH. Here, we determined the primary amine content in Rat-Tail Collagen Type I (Col I) and three decellularized porcine lung samples. We converted free amines to thiol groups using Traut’s reagent. These thiol groups will ultimately be used to crosslink polyethylene glycol alpha methacrylate (PEGαMA) off-stoichiometry in a Michael addition reaction to form the hybrid hydrogel that can later be stiffened through a secondary, light-initiated homopolymerization of MA moieties to emulate disease progression in vitro (Fig 1A)