Quercetin ameliorates senescence and promotes osteogenesis of BMSCs by suppressing the repetitive element‑triggered RNA sensing pathway.

Cell senescence impedes the self‑renewal and osteogenic capacity of bone marrow mesenchymal stem cells (BMSCs), thus limiting their application in tissue regeneration. The present study aimed to elucidate the role and mechanism of repetitive element (RE) activation in BMSC senescence and osteogenesis, as well as the intervention effect of quercetin. In an H2O2‑induced BMSC senescence model, quercetin treatment alleviated senescence as shown by a decrease in senescence‑associated β‑galactosidase (SA‑β‑gal)‑positive cell ratio, increased colony formation ability and decreased mRNA expression of p21 and senescence‑associated secretory phenotype genes. DNA damage response marker γ‑H2AX increased in senescent BMSCs, while expression of epigenetic markers methylation histone H3 Lys9, heterochromatin protein 1α and heterochromatin‑related nuclear membrane protein lamina‑associated polypeptide 2 decreased. Quercetin rescued these alterations, indicating its ability to ameliorate senescence by stabilizing heterochromatin structure where REs are primarily suppressed. Transcriptional activation of REs accompanied by accumulation of cytoplasmic double‑stranded (ds)RNA, as well as triggering of the RNA sensor retinoic acid‑inducible gene I (RIG‑I) receptor pathway in H2O2‑induced senescent BMSCs were shown. Similarly, quercetin treatment inhibited these responses. Additionally, RIG‑I knockdown led to a decreased number of SA‑β‑gal‑positive cells, confirming its functional impact on senescence. Induction of senescence or administration of dsRNA analogue significantly hindered the osteogenic capacity of BMSCs, while quercetin treatment or RIG‑I knockdown reversed the decline in osteogenic function. The findings of the current study demonstrated that quercetin inhibited the activation of REs and the RIG‑I RNA sensing pathway via epigenetic regulation, thereby alleviating the senescence of BMSCs and promoting osteogenesis.