ABSTRACT
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 cells 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 immunohistochemitistry 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 immunohistoehemistry.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.
ABSTRACT
Objective To investigate the effects of an electromagnetic field on the extra-cellularly regulated kinase(ERK)signalling pathway and to determine the impact of electromagnetic activation on osteogenic proliferation and differentiation in rat bone marrow mesenchymal stem cells.Methods Rat bone marrow mesenchymal stem cells were isolated and cultured in vitro.The third-passage cells were divided into 4 groups(Control,PD98059,EMF and EMF+PD98059).Western blotting Was used to detect the activation of the ERK signal pathway after exposure to an electromagnetic field.MTT assay Was used to determine the activation of proliferation in the celb in the different groups.The cells' alkaline phosphatase activities were also detected. Results (1)The ERK signal pathway in these rat bone marrow mesenchymal stem cells was activated after exposure to a 15 Hz.1 mT,sine wave form electromagnetic field for 5 min.Activation remained high for at least 1 h.PD98059 can effectively block the activation of the ERK signal pathway.(2)Cell proliferation was promoted after exposure to the electromagnetic field,and this effect could be significantly inhibited by PD98059.(3)Alkaline phosphatase was significantly elevated in these bone marrow mesenchymal stem cells after exposure to the electromagnetic field.The activation in the EMF+PD98059 group Was slightly greater than in the EMF group.Conclusion Electromagnetic fields of 15 Hz and 1 mT can activate the ERK signal pathway and alter proliferation and osteogenic differentiation in the bone marrow mesenchymal stem cells of rats.
ABSTRACT
In order to identify the differentially expressing gene of bone marrow mesenchymal stem cells (MSCs) stimulated by electromagnetic field (EMF) with osteogenesis microarray analysis, the bone marrow MSCs of SD rats were isolated and cultured in vitro. The third-passage cells were stimulated by EMFs and total RNA was extracted, purified and then used for the synthesis of cDNA and cRNA. The cRNA of stimulated group and the control group was hybridized with the rat oligo osteogenesis microarray respectively. The hybridization signals were acquired by using X-ray film after chemiluminescent detection and the data obtained were analyzed by employing the web-based completely integrated GEArray Expression Analysis Suite. RT-PCR was used to identify the target genes: Bmp1, Bmp7, Egf and Egfr. The results showed that 19 differentially expressing genes were found between the stimulated group and the control group. There were 6 up-regulated genes and 13 down-regulated genes in the stimulated group. Semi-quantitative RT-PCR confirmed that the expressions of Bmp1, Bmp7 mRNA of the stimulated group were up-regulated (P<0.05) and those of Egf, Egfr were down-regulated (P<0.05). It was suggested that the gene expression profiles of osteogenesis of the bone marrow MSCs were changed after EMF treatment. It is concluded that the genes are involved in skeletal development, bone mineral metabolism, cell growth and differentiation, cell adhesion etc.