Polygonatum sibiricum polysaccharide attenuates BMSC senescence by inhibiting NCOA4-mediated ferritinophagy

Abstract

Context BMSC senescence is associated with osteoporosis progression. Polygonatum sibiricum polysaccharide (PSP) shows potential anti-senescence activity, but its effects on bone marrow mesenchymal stem cells (BMSCs) remain unclear.Objective To investigate the protective effects and molecular mechanisms of PSP against tert-butyl hydroperoxide (TBH)-induced senescence in BMSCs.Materials and methods Senescence was induced in primary rat BMSCs with TBH, followed by PSP intervention. Viability was assessed using the Cell Counting Kit-8 assay, while senescence-associated β-galactosidase, alkaline phosphatase, and Oil Red O staining assessed senescence and osteogenic/adipogenic differentiation. Ferritinophagy-associated proteins (NCOA4, FTH1, and LC3) and intracellular Fe2+ were quantified using western blot, immunofluorescence, and FerroOrange staining. Mitochondrial function was evaluated using MitoSOX and JC-1 assays and ATP quantification. Cytosolic mtDNA accumulation and the cGAS–STING pathway were assessed using immunofluorescence colocalization, quantitative polymerase chain reaction, and Western blotting. NCOA4 involvement was examined using an NCOA4-overexpressing lentiviral vector.Results PSP concentration-dependently attenuated TBH-induced senescence phenotypes in BMSCs, partially restored osteogenic differentiation, and reduced adipogenic differentiation. PSP downregulated NCOA4 expression, attenuating ferritinophagy-associated changes and intracellular Fe2+ accumulation. Reduced Fe2+ accumulation preserved mitochondrial membrane potential, reduced mitochondrial reactive oxygen species generation, and reduced cytosolic mtDNA accumulation, alongside attenuated cGAS–STING signaling. Lentiviral overexpression of NCOA4 attenuated the protective effects of PSP on mitochondrial homeostasis and cGAS–STING pathway suppression.Discussion and conclusions PSP may attenuate BMSC senescence by suppressing NCOA4-mediated ferritinophagy, thereby preserving mitochondrial homeostasis and inhibiting cGAS–STING signaling. These findings provide a rationale for further investigation of PSP as a potential therapeutic strategy for osteoporosis-associated BMSC dysfunction.