Knockdown of Gfi1 increases BMSCs exosomal <i>miR-150-3p</i> to inhibit osteoblast ferroptosis in steroid-induced osteonecrosis of the femoral head through BTRC/Nrf2 axis

The ferroptosis of osteoblasts has been demonstrated to play a significant role in the development of steroid-induced osteonecrosis of the femoral head (SONFH). Additionally, microRNAs (miRNAs) have been identified as regulators of SONFH progression. However, the precise role of miRNAs in the regulation of osteoblast ferroptosis remains unclear. This study explored the role of exosomal miR-150-3p, derived from bone marrow mesenchymal stem cells (BMSCs), in osteoblast ferroptosis in SONFH. Dexamethasone (DEX) was used to treat osteoblasts to induce ferroptosis. BMSCs exosomes with different levels of miR-150-3p were introduced into a co-culture with the cells. To verify the targeting relationship between growth factor independence 1 (Gfi1) and the miR-150-3p promoter, as well as between miR-150-3p and beta-transducin repeat containing E3 ubiquitin protein ligase (BTRC), respectively, chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), and dual luciferase assays were employed. It was found that BMSCs-Exos-miR-150-3p mitigated DEX-triggered ferroptosis in osteoblasts. MiR-150-3p directly targeted BTRC, leading to its downregulation in osteoblasts. The BTRC/Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was involved in the inhibition of DEX-induced osteoblast ferroptosis by BMSCs-Exos-miR-150-3p. Overexpression of BTRC reversed the inhibitory effect of BMSCs-Exos-miR-150-3p. In a SONFH rat model, BMSCs-Exos-miR-150-3p alleviated ferroptosis in osteoblasts through BTRC/Nrf2. In addition, Gfi1 bonded to the miR-150-3p promoter and inhibited its transcription. Gfi1 silencing elevated miR-150-3p levels and improves cell viability of BMSCs. In conclusion, our results suggest that BMSCs-Exos-miR-150-3p alleviates SONFH by suppressing ferroptosis through the regulation of BTRC/Nrf2 and miR-150-3p may be a potential target for SONFH treatment.