Effects of pulsed electromagnetic fields on the differentiation of mouse bone marrow mesenchymal stem cells into osteoblasts in vitro

Zhenhua FANG; Ming CHEN; Ming XIE; Qiong ZHENG; Wusheng KAN

ABSTRACT

BACKGROUND:

The proliferation and differentiation of mesenchymal stem cells (MSCs) lack of regulatory functions. Following combining with suitable vectors, MSCs cannot highly effectively proliferate and differentiate, which are keys to prevent MSCs entering the clinic. It is of great importance to effectively regulate the differentiation of stem cells into osteoblasts using pulse electromagnetic field.

OBJECTIVE:

To investigate the differentiation of mouse MSCs into osteoblasts in vitro following stimulation of pulse electromagnetic field.DESIGN, TIME AND

SETTING:

The cytological in vitro controlled study was conducted at the Laboratory of Department of Orthopaedics, Puai Hospital of Tongji Medical College, Huazhong University of Science and Technology from May 2004 to October 2007.MATEIRALS Totally 20 BALB/C mice were supplied by the Experimental Animal Center of Tongji Medical College. Pulse electromagnetic field deviser was designed and made by the Department of Electric Machine, Naval University of Engineering.

METHODS:

Mouse bilateral femur was sterilely isolated. BMSCs were harvested by the Percoll density gradient centrifugation,and purified and proliferated by the adherent method. Cells at the third passage (2×10~7/L) were incubated in a 6-well plate, and then divided into 4 groups. Cells in the blank control group were incubated in the complete medium. Cells in the pulse electromagnetic field underwent pulse electromagnetic field radiation of 50 Hz, sinusoidal wave, and 1 mT, twice a day, once 30 minutes, with an interval of 12 hours, totally 10 days. Cells in the osteogenic induction group were incubated in the complete medium, supplemented with dexamethasone, sodium glycerophosphate and VitC. Cells in the pulse electromagnetic field + osteogenic induction group were subjected to the same pulse electromagnetic field radiation and then incubated in the complete medium.MAIN OUTCOME

MEASURES:

The differentiation of BMSCs was measured.

RESULTS:

Results of alkaline phosphatase staining showed that cells were negative in the blank control group, but weakly positive in the pulse electromagnetic field group, positive in the osteogenic induction group, and strongly positive in the pulse electromagnetic field + osteogenic induction group 10 days following intervention. Compared with the blank control group,absorbance value of type I collagen immunohistochemistry was significantly greater in the osteogenic induction group, pulse electromagnetic field + osteogenic induction group (P < 0.05, P < 0.01).

CONCLUSION:

Pulsed electromagnetism fields of 50 Hz, waves of sine, with the intensity of 1 mT could promote alkaline phosphatase and type I collagen expression and enhance the differentiation of mouse BMSCs into osteoblasts in vitro.