Establishing a human lung model of radiation-induced senescence using precision-cut lung slices

Stress-induced premature senescence has been implicated in impaired lung function. A key barrier to translating senolytic drugs, which specifically eliminate senescent cells, is the lack of clinically relevant human models. Hence, we hypothesised that cellular senescence is a key pathological response to radiation-induced lung injury and aimed to develop a human lung model of radiation-induced premature senescence. Human precision-cut lung slices (PCLS) generated from lungs deemed unsuitable for transplantation were exposed to 0, 8, 15, and 30Gy radiation to induce senescence. Over a 14-day culture period, PCLS viability was assessed using propidium iodide staining, while metabolic activity was monitored through calcein staining and the WST-1 assay. The expression of DNA damage marker γH2AX and oxidative stress level were measured to evaluate the radiation-induced lung injury phenotypes of irradiated PCLS. Senescence induction was validated by measuring the gene expression of senescence markers, p21 and Ki67, and lipofuscin accumulation in specific cell types was detected. Our results revealed a preserved metabolic activity in PCLS for at least 7 days of culture, despite a decrease in the viability. Higher γH2AX expression was observed in irradiated PCLS compared to the 0Gy control. Oxidative stress level remained high in irradiated PCLS throughout the culture period but decreased in the 0Gy control by Day7. A trend of increasing p21 expression and significant downregulation of Ki67 were also observed in irradiated PCLS from Day4. Collectively, these results demonstrate the feasibility of using human PCLS as a model of radiation-induced premature senescence to study senolytic drugs.