Biosynthesized Silver Nanoparticles from Cyperus conglomeratus Root Extract Inhibit Osteogenic Differentiation of Immortalized Mesenchymal Stromal Cells

Background: Silver nanoparticles (AgNPs) are a focus of huge interest in biological research, including stem cell research. AgNPs synthesized using Cyperus conglomeratus root extract have been previously reported but their effects on mesenchymal stromal cells have yet to be investigated. Objectives: The aim of this study is to investigate the effects of C. conglomeratus-derived AgNPs on adipogenesis and osteogenesis of mesenchymal stromal cells. Methods: AgNPs were synthesized using C. conglomeratus root extract, and the phytochemicals involved in AgNPs synthesis were analyzed using gas chromatography-mass spectrometry (GCMS). The cytotoxicity of the AgNPs was tested on telomerase-transformed immortalized human bone marrow-derived MSCs-hTERT (iMSC3) and human osteosarcoma cell line (MG-63) using MTT and apoptosis assays. The uptake of AgNPs by both cells was confirmed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Furthermore, the effect of AgNPs on iMSC3 adipogenesis and osteogenesis was analyzed using stain quantification and reverse transcription- quantitative polymerase chain reaction (RT-qPCR). Results: The phytochemicals predominately identified in both the AgNPs and C. conglomeratus root extract were carbohydrates. The AgNP concentrations tested using MTT and apoptosis assays (0.5-64 µg/ml and 1,4 and 32 µg/ml, respectively) showed no significant cytotoxicity on iMSC3 and MG-63. The AgNPs were internalized in a concentration-dependent manner in both cell types. Additionally, the AgNPs exhibited a significant negative effect on osteogenesis but not on adipogenesis. Conclusion: C. conglomeratus-derived AgNPs had an impact on the differentiation capacity of iMSC3. Our results indicated that C. conglomeratus AgNPs and the associated phytochemicals could exhibit potential medical applications.