A preliminary study of type I collagen expression of bone marrow mesenchymal stem cells promoted by pulsed electromagnetic fields

Objective To study the influence of pulsed electromagnetic fields on the expression of type Ⅰ collagen by bone marrow mesenchymal stem cells and it＇s mechanism. Methods The bone marrow mesenchymal stem cells of SD rats were isolated and cultured in vitro. The third passage ceils were harvested and exposed to pulsed electromagnetic fields （PEMFs） at 15 Hz and 1 mT 8 h/d for 3 days. A semi-quantitative RT-PCR technique was used to measure the type Ⅰ collagen mRNA expression; ELISA and immunohistochemistry techniques were used to measure type Ⅰ collagen expression. Inhibitors and promoters of the cAMP-dependent protein kinase A （cAMP-PKA） pathway were added. After the cAMP-PKA pathway had been inhibited or promoted, the effects of the PEMF on type Ⅰ collagen expression were measured again using ELISA and immunohistochemistry. Results PEMFs at 15 Hz and 1 mT induced significant promotion of the expression of type Ⅰ collagen （P≤〈0.01） in comparison with the controls. The type Ⅰ collagen expression was reduced when the cAMP-PKA pathway inhibitor H-89 was added, and raised when the promoter 8-Br-cAMP was added. Conclusion PEMFs at 15 Hz 1 mT can promote type Ⅰ collagen expression of bone marrow mesenchymal stem cells, and the effect is correlated with the cAMP-PKA pathway. Key words: Pulsed electromagnetic fields;  Bone marrow mesenchymal stem cells;  Type Ⅰ collagen