Mesenchymal stem cells (MSCs) are multi-potent cells that are able to differentiate and mature into various types of cells under a certain microenvironment for cell therapy and tissue regeneration.Scan-dium (Sc),an important rare earth element,recently has been intensively investigated in biomedical fields as well as industrial engineering,and chloride channels have been proven to be able to affect osteogenic differentiation.Thus,it is significant to investigate effects of ScCl3 on cell activities of MSCs.In this paper,rat bone MSCs (rBMSCs) were co-cultured with various concentrations of ScCl3 (1 × 10-8,1 × 10-6,and 1 × 10-4 mol/L) to evaluate their influence on cell proliferation as well as osteogenic and adipogenic differentiation in vitro.The results indicate that ScCl3 promotes the proliferation of rBMSCs initially,which is yet reduced upon ion accumulation.We used immunofluorescence staining,quanti-tative real time polymerase chain reactions,and assays measuring alkaline phosphatase activity,mineralized deposits,and intracytoplasmic lipids to reveal that rBMSCs treated with ScCl3 at concen-trations of 1 × 10-8-1 × 10-6 mol/L can enhance levels of osteogenic differentiation in a dose-dependent manner and reduce adipogenic differentiation to a certain degree through Wnt/β-catenin signaling pathway.These results indicate that appropriate concentrations of ScCl3 can improve osteo-genic differentiation in the lineage commitment of rBMSCs,and thus,promote bone remodeling.This study implies that ScCl3 possesses great potentials in the treatment of bone diseases and would provide new strategy of designing composites by SiCl3 doping for biomedical applications in the future.