The effect of rotation constancy static magnetic field on the expression of BMP-2 and PDGFs during fracture healing / 中华物理医学与康复杂志

ABSTRACT

Objective To evaluate the effect rotation constancy static magnetic field(RCSMF) on the expression of bone morphogenetic protein-2 (BMP-2) and platelet-derived growth factors (PDGFs) in fracture healing, and elucidate the possible mechanism of RCSMF promoting fracture healing.Methods A total of 80 rats with femur closed fracture were randomly divided into a magnetic treatment group (M) and a control group (C).The M group was given RCSMF treatment 30 minutes per day, 6 times per week, using 0.4 T 6 Hz magnetic field, while the C group was not given any intervention.Femurs and calluses were subjected to BMP-2, PDGF-A and PDGF-B immunohistochemistry assay at 2, 3, 4 and 8 weeks after the treatment.The integrated optical density (IOD) of positive staining was calculated.Two-factor variance analysis was used to compare the main effect of time, treatment and that of their interaction.Results For both groups, the IOD of immunoreactivity of BMP-2 at 2, 3 and 4 weeks after the treatment was significantly higher than that 8 weeks after the treatment, and the value at four weeks after the intervention was also significantly higher than that at 2 weeks after it.There was a significant interaction effect of time × treatment of BMP-2 (F =3.17, P ＜ 0.05).Significant differences were observed in the IOD of positive staining PDGF-A at different time points for both groups : the value at 2 weeks after treatment was significantly higher than that at 3, 4 and 8 weeks after the treatment, and that at 3 and 4 weeks after treatment was also significantly higher than that at 8 weeks after the treatment.The IOD of positive staining PDGF-B of the M group (57.6 ± 2.1) was significantly higher than that of the C group (50.11 ± 2.22, P ＜ 0.05).There was significant difference in the IOD of positive staining PDGF-B (F =50.06 ,P ＜ 0.01) at different time points : the IOD of positive staining PDGF-B at 3 weeks after treatment was significantly higher than that at 2 and 8 weeks group after the treatment, and the value at 2 and 4 weeks after treatment was also significantly higher that at 8 weeks after the treatment.Conclusion RCSMF may elevate the expression BMP-2 and PDGF-B to promote fracture healing.