Modeling Endothelial Dysfunction in IPF: Bridging Mechanistic Insights and Translational Applications

Background Gas exchange in the alveolus, the lung’s primary unit, relies on coordinated interactions between epithelial and endothelial layers. In idiopathic pulmonary fibrosis (IPF), the structural and functional integrity of this alveolar unit is profoundly disrupted, leading to impaired respiratory capacity. Although epithelial and mesenchymal compartments have been extensively studied in this context, far less attention has been given to pulmonary microvascular endothelial cells (PMVECs), whose contribution to IPF pathogenesis remains underexplored. Methods We investigated PMVEC alterations in IPF by re‑analyzing publicly available single‑cell RNA sequencing and spatial transcriptomics datasets, identifying subtype‑specific markers and their progressive loss in fibrotic lungs. To model endothelial dysfunction, we established protocols for isolating and culturing primary human endothelial cells and applied the IPF‑relevant cytokine cocktail (IPF‑RC) that mimics the IPF microenvironment. Results We analyzed microvascular marker expression across passages in primary PMVECs and observed progressive downregulation, highlighting the gradual loss of microvascular identity in 2D culture, a critical factor to consider when establishing reliable pharmacological assays and biological models. In addition, we provide the first detailed characterization of PMVEC alterations in a profibrotic environment in vitro , where exposure to the IPF‑RC induced hallmark features of endothelial injury, including VE‑cadherin loss and increased ICAM1/VCAM1 signaling, alongside impaired barrier integrity and reduced wound‑healing and angiogenic capacity. These functional assays enabled quantitative assessment of therapeutic responses and supported mechanistic back‑translation to IPF pathology. Importantly, treatment with a cAMP analog partially restored endothelial function, underscoring the utility of these models for both regenerative research and pharmacological screening. Conclusions Our findings position PMVECs as active participants in IPF progression and present novel, scalable test systems that connect mechanistic insight to translational applications. These models provide a valuable platform for identifying endothelial‑targeted therapies aimed at restoring alveolar capillary integrity in patients with fibrotic lung disease. Trial registration Not applicable.