Investigation of the osteogenic effects of ICA and ICSII on rat bone marrow mesenchymal stem cells

Icariin (ICA) serves as the primary biologically active compound in traditional Chinese medicine Epimedium, while Icariside II (ICSII) represents one of its gastrointestinal metabolites. Although ICA and ICSII have demonstrated osteogenic differentiation- promoting effects on BMSCs, there is limited literature comparing their effects and underlying mechanisms. This study aimed to compare the osteogenic effects of Icariin and Icariside II, along with their respective osteogenic mechanisms. In this study, we initially determined the optimal concentrations of Icariin (10−5 mol/L) and Icariside II (10−6 mol/L) for inducing rBMSCs osteogenic differentiation using CCK8, ALP activity assay, and flow apoptosis assay. Subsequently, we compared the vascularization and osteogenic capacity of the two groups through alizarin red staining assay, Western Blot, and RT-PCR. Subsequently, we assessed the phosphorylated and non-phosphorylated expression of JNK, ERK1/2, P38, and AKT at different time intervals. We observed their phosphorylated expression and the expression of angiogenic/osteogenic markers after blocking with their corresponding inhibitors. It was observed that both the Icariin and Icariside II groups promoted the expression of osteogenic/angiogenic markers RUNX2, OCN, OPN, VEGF, and ANG1. While there was no significant difference in their osteogenic abilities, ICSII exhibited a stronger promotion of angiogenic differentiation markers, VEGF, compared to ICA. Additionally, it was observed that both ICA and ICSII could activate ERK1/2 phosphorylation, thereby further promoting the osteogenic/angiogenic differentiation of rBMSCs through the activation of the MAPK/ERK1/2 signaling pathway.