Aspal, M. | bioRxiv Science

bioRxiv2025

Modeling the Aging Human Lung: Generation of a Senescent Human Lung Organoid Culture System

IntroductionThe aging lung enters into a state of irreversible cellular growth arrest characterized by senescence. While senescence is beneficial in preventing oncogenic cell proliferation, it becomes detrimental when persistent, promoting chronic inflammation and fibrosis through the senescence-associated secretory phenotype (SASP). Such senescence-related pathophysiological processes play key roles in lung diseases like chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). However, few models accurately represent senescence in the human lung. MethodsTo generate a human lung senescence in vitro model, we first generated a human induced pluripotent stem cell (hiPSC)-derived lung organoid (LO) system which was dissociated into monolayers and air-liquid interface (ALI) cultures to enhance visualization and allow uniform exposure to agents. Cellular senescence was induced using doxorubicin, a DNA-damaging agent. Senescence markers, such as {beta}-galactosidase ({beta}-gal) activity, SASP cytokine production and secretion, cell morphology, proliferative capacity, and barrier integrity were evaluated to validate the senescent phenotype. ResultsThe doxorubicin-induced senescent hiPSC-derived lung cells demonstrated the hallmark characteristics of cellular senescence, including increased {beta}-gal activity and increased production of the pro-inflammatory SASP cytokine IL-6 and increased secretion of TNF-. Senescent cells displayed enlarged morphology, decreased proliferation, and reduced wound repair capacity. Barrier integrity was impaired with decreased electrical resistance, and increased permeability, as well as expression of abnormal tight junction proteins and increased fibrosis, all consistent with the senescent lung. ConclusionOur hiPSC-derived lung cell senescent model reproduces key aspects of human lung senescence and offer an in vitro tool for studying age-related lung disease mechanisms and therapeutic interventions. This model has potential applications in exploring the impact of environmental factors (e.g., toxins, infectious pathogens, etc.) on the senescent lung and assessing treatments that could mitigate pathologies associated with pulmonary aging including barrier impairment, inflammation and fibrosis.

cell biology↗

bioRxiv2021

Ineffectual AEC1 Differentiation from KRT8hi Transitional Cells without Fibrosis Associated with Fatal Acute Respiratory Failure in COVID-19 ARDS

ARDS due to COVID-19 and other etiologies results from injury to the alveolar epithelial cell (AEC) barrier resulting in noncardiogenic pulmonary edema, which causes acute respiratory failure; clinical recovery requires epithelial regeneration. During physiologic regeneration in mice, AEC2s proliferate, exit the cell cycle, and transiently assume a transitional state before differentiating into AEC1s; persistence of the transitional state is associated with pulmonary fibrosis in humans. It is unknown whether transitional cells emerge and differentiate into AEC1s without fibrosis in human ARDS and why transitional cells differentiate into AEC1s during physiologic regeneration but persist in fibrosis. We hypothesized that incomplete but ongoing AEC1 differentiation from transitional cells without fibrosis may underlie persistent barrier permeability and fatal acute respiratory failure in ARDS. Immunostaining of postmortem ARDS lungs revealed abundant transitional cells in organized monolayers on alveolar septa without fibrosis. They were typically cuboidal or partially spread, sometimes flat, and occasionally expressed AEC1 markers. Immunostaining and/or interrogation of scRNAseq datasets revealed that transitional cells in mouse models of physiologic regeneration, ARDS, and fibrosis express markers of cell cycle exit but only in fibrosis express a specific senescence marker. Thus, in severe, fatal early ARDS, AEC1 differentiation from transitional cells is incomplete, underlying persistent barrier permeability and respiratory failure, but ongoing without fibrosis; senescence of transitional cells may be associated with pulmonary fibrosis.

pathology↗