From development to regeneration: the endothelial interface in lung injury and repair.

The pulmonary alveolar-capillary niche is a highly specialized interface that balances gas exchange with maintenance functions and repair. Advances in single cell transcriptomics have uncovered endothelial heterogeneity, which underlies developmental angiogenesis and plastic responses to injury. Emerging evidence from a neonatal hyperoxia model highlights CAP1 to CAP2 transitions and the role of p53 in maintaining lineage fidelity. Beyond intrinsic lineage plasticity, circulating mediators such as cell-free hemoglobin drive endothelial barrier disruption through oxidative injury and lipid modification. As new signaling pathways and therapeutics targets emerge, complementary strategies are being developed at the cellular level, including adoptive transfer of mesenchymal stromal and immune cells, although mechanisms of endothelial adhesion and homing remain incompletely defined. Finally, biomechanical forces such as shear stress have become critical contextual cues for endothelial signaling, yet remain underrepresented in some experimental models. Together, these insights underscore the central role of endothelial heterogeneity, injury responses, and environmental cues in shaping pulmonary vascular health and repair, with implications for designing targeted therapies in both pediatric and adult lung disease.