Objectives: This study aims to investigate whether apoptosis repressor with caspase recruitment domain (ARC) could promote survival and enhance osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Materials and methods: The lentivirus transfection method was used to establish ARC-overexpressing BMSCs. The CCK-8 method was used to detect cell proliferation. The BD Pharmingen™ APC Annexin V Apoptosis Detection kit was used to detect cell apoptosis. The osteogenic capacity was investigated by OCN immunofluorescence staining, ALP analysis, ARS assays, and RT-PCR analysis. Cells were seeded into calcium phosphate cement (CPC) scaffolds and then inserted subcutaneously into nude mice and the defect area of the rat calvarium. Histological analysis was conducted to evaluate the in vivo cell apoptosis and new bone formation of the ARC-overexpressing BMSCs. RNA-seq was used to detect the possible mechanism of the effect of ARC on BMSCs. Results: ARC promoted BMSC proliferation and inhibited cell apoptosis. ARC enhanced BMSC osteogenic differentiation in vitro. An in vivo study revealed that ARC can inhibit BMSC apoptosis and increase new bone formation. ARC regulates BMSCs mainly by activating the Fgf-2/PI3K/Akt pathway. Conclusions: The present study suggests that ARC is a powerful agent for promoting bone regeneration of BMSCs and provides a promising method for bone tissue engineering.

The study aims to elucidate the mechanism through which 17β-estradiol facilitates osteogenic differentiation in bone marrow mesenchymal stem cells (BMSCs). In our study, lentiviral transfection was employed to establish apoptosis repressor with caspase recruitment domain (ARC) knockdown or overexpression in BMSCs. The impact of 17β-estradiol on ARC expression was assessed using western blot, RT-PCR and immunofluorescence. Techniques such as ALP staining, ALP activity assay, western blot, RT-PCR and immunofluorescence staining were utilized to examine the influence of ARC expression levels on the osteogenic differentiation of BMSCs and the osteoclastic differentiation of Raw264.7 cell lines. Mitophagy flux levels in BMSCs were detected using the mitophagy detection kit. RNA sequencing and bioinformatics analyses were conducted to explore potential mechanisms of ARC regulation in BMSCs osteogenic differentiation. To sum up, 17β-estradiol can modulate bone homeostasis by adjusting ARC expression. ARC stimulates mitophagy in BMSCs via MAPK/Akt pathway, identifying ARC as a promising therapeutic target for postmenopausal osteoporosis (PMOP) treatment.