Abstract:

BACKGROUND: Our early study has found that the effect of pulsed electromagnetic fields (PEMF) can promote the proliferation of the precartilaginous stem cells (PSCs). However, the mechanism remains unclear.

OBJECTIVE: To investigate the effect of PEMF on proliferation and differentiation of PSCs, and to explore the effect on activity of Ihh-PTHrP signal pathway.

METHODS: PSCs were obtained and purified using the method of magnetic-activated cell sorting, and the cells were then exposed in PEMF (1 mT, 50 MHz) for 30 minutes twice a day and the cells were continued to stimulate for 2, 4 and 6 days. Control group did not receive the stimulation of PEMF. Gene expression levels of type II collagen and aggrecan were detected by the method of RT-PCR and protein expression levels of Ihh and PTHrp were detected using Western blot method.

RESULTS AND CONCLUSION: The results of RT-PCR showed that with the time prolonging, the gene expression levels of type II collagen and aggrecan were increased. Comparing with the control group, aggrecan of cartilage stem cells were significantly increased before PEMF (P < 0.05, P < 0.01). Western blot indicated that protein expression levels of Ihh and PTHrp were increased with the time prolonging of PEMF stimulation, while Ihh protein expression in PEMF group was significantly higher than in the control group (P < 0.01). Additionally, PTHrp expression was also increased, but there was significant difference between PEMF and control group at days 4 and 6 after PEMF stimulation (P < 0.05, P < 0.01). This suggested that PEMF (1 mT, 50 MHz) could promote proliferation and differentiation from PSCs into mature chondrocytes, and the mechanism of this effect could probably correlate with the changes of Ihh-PTHrP signal pathway.