Chondrogenic potential of rat mesenchymal stem cells in vitro under the influence of electromagnetic fields

Abstract

Objective To determine the chondrogenic potential of mesenchymal stem cells (BMSCs) under exposure of extremely low frequency electromagnetic fields (ELF-EMF) and discuss the application prospect of EMF in cartilage tissue engineering.Methods Cell pellets of rat bone marrow-derived BMSCs were cultured in vitro under the addition of fibroblast growth factor 2 (FGF-2) and transforming growth factor-β3 (TGF-β3).Pellet cultures were exposed to sinusoidal ELF-EMF (1.0 mT,50 Hz).After 3 weeks of inductive differentiation culture,chondrogenesis was detected by alcian blue staining,and quantitative real-time polymerase chain reaction (real-time PCR) was used for detection of chondrogenesis related proteins.Glycosaminoglycan (GAG) contents of pellet cultures were determined using the dimethylmethylene blue (DMMB) dye-binding assay.Results With the effects of growth factors,EMF could significantly promote chondrogenic differentiation of BMSCs pellet cultures,and the gene expression of collagen type Ⅱ,X and aggrecan in rat BMSCs was also significantly up-regulated.The gene expression of sex determining region Y box 2 (SOX9) did not show significant difference between EMF exposed groups and nonexposed groups.The glycosaminoglycan (GAG)/DNA ratio of EMF exposed pellet cultures reached 3.108 ±0.341,which was significantly higer than those unexposed pellet cultures.Conclusion Increased expression of collagen type Ⅱ,X and GAG content in pellet cultures under EMF exposure may contribute to the chonderogenic differentiation of rat BMSCs.EMF was able to stimulate and maintain chondrogenic differentiation of rat BMSCs under influence of growth factors.EMF alone,however,could not induce chondrogenic differentiation. Key words: Electromagnetic fields; Mesenchymal stem cells; Pellet culture; Chondrogenic differentiation