Abstract Rationale Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease characterized by repeated epithelial injury, fibroblast activation, and excessive matrix deposition. Existing in vitro and animal models fail to fully recapitulate the complexity of the human alveolus. To address this gap, we aim to develop a 3D-bioprinted, multicellular alveolar model using human-derived cells to better study the mechanisms that drive fibrosis in a physiologically relevant environment. Methods After acquiring commercially available human primary alveolar epithelial cells, fibroblasts, and pulmonary microvasculatory endothelial cells, we assessed cell viability, epithelial barrier function, and lineage-specific markers using immunofluorescence, TEER measurements, and gene expression analyses. Primary human cells were maintained and expanded in both two dimensional and matrigel models. Then, using surgical resin and gelatin methacryloyl (GelMA) hydrogel, we fabricated both a transwell model and a 3D alveolar model created using digital photopolymerization. Within the hydrogel matrix, we embedded primary human lung fibroblasts while epithelial cells were seeded on the apical side. The constructs were maintained under air-liquid interface (ALI) conditions to support differentiation and membrane formation. We assessed cell viability and epithelial barrier function. Results First, we show that we are able to expand and differentiate the three main cell types in the human alveolus, while maintaining basic cellular function by demonstrating epithelial barrier function and surfactant secretion of primary human alveolar cells in vitro, collagen secretion and myofibroblast differentiation in response to fibrotic signaling, and endothelial cell function via barrier maintenance and EndMT. Second, we were able to grow and expand human fibroblasts within the GelMA matrix while maintaining human epithelial cells on the apical side of our constructs. The bioprinted alveolar constructs remained viable and structurally stable for over two weeks. Conclusions Our findings show an advancement in the construction of 3D-bioprinted human alveolar models that aim to recreate key structural and cellular aspects of the human alveolus. This platform offers a modular, physiologically relevant system for modeling human parenchymal lung disease, dissecting epithelial-mesenchymal-endothelial interactions, and exploring new therapeutic strategies in pulmonary fibrosis. This abstract is funded by: DOD
Reyes et al. (Fri,) studied this question.