Inhibition of osteogenic differentiation of mesenchymal stem cells by copper supplementation

Objectives Copper has been added to scaffolds when investigating bone repair, as an agent to promote vascularization; however, little is known concerning its effect on mesenchymal stem cells (MSCs), which are considered to be the origin of osteoblasts. In this study, we have aimed to elucidate effects of copper on osteogenic differentiation of MSCs. Materials and methods Rat bone marrow MSCs (rBMSCs) were used as a model. Their viability was assessed by MTT assay and Roche's CASY cell counter test and calcium deposition was evaluated by staining with alizarin red S. Fluorescent phalloidin F-actin stain was used to evaluate cytoskeletal changes, protein expressions were investigated by western blotting and mRNA levels were analysed using Q-PCR. A rat model for ectopic bone formation was used to assess effects of copper on MSCs in vivo. Results Copper supplementation resulted in inhibition of osteogenesis of rBMSCs, along with reduction in expression of a number of osteogenic genes, alkaline phosphatase activity and formation of bone nodules. Cytoskeletal changes to cells during osteogenesis was inhibited by copper supplementation. In vivo study confirmed that copper could inhibit collagen formation whilst promoting angiogenesis. Conclusions Our study demonstrated that copper inhibited osteogenic differentiation of rBMSCs in vitro. The findings caution appropriate use of copper and have laid a foundation for further research.