The study comprised a survey and an experimental part. Based on the survey, the authors hypothesized, that disparities between studies regarding the effects of electro-magnetic field exposure on osteoblasts result from the chosen cell line and depend on the cells' level of maturity. Hence, in the present study, the more immature MC3T3-E1 cells and the relatively mature SaOS-2 cells were investigated.
The following exposure groups were used: MC3T3-E1 cells seeded at 1) low seeding density, 2) recommended seeding density and 3) high seeding density and SaOS-2 cells seeded at 4) low seeding density, 5) recommended seeding density and 6) high seeding density. For each exposure group, a separate control group was used. Moreover, cells were tested with and without osteogenic differentiation medium.
Exposure duration: continuous for 30 minutes/day
|magnetic flux density||1 mT||-||-||-||-|
Cell proliferation and cell viability were significantly increased in exposed MC3T3-E1 cells at all points in time and all plating densities (groups 1-3) compared to the control groups, while they were significantly decreased in SaOS-2 cells (groups 4-6) compared to the control groups. The alkaline phosphatase enzyme activity was significantly increased in all exposure groups and at all points in time compared to the control groups. However, base line levels in SaOS-2 cells were higher than in MC3T3-E1 cells and SaOS-2 cells showed a stronger reaction towards the magnetic field.
Exposure to the magnetic field in combination with differentiation medium resulted in a significant increase in mineralization in all groups, with the most distinct effect in SaOS-2 cells.
The authors conclude that exposure of osteoblasts to a 50 Hz magnetic field might increase proliferation or osteogenic differentiation to different extents depending on the cell line. Different reactions of both cell lines indicated that EMF-induced effects on proliferation and differentiation could depend on the maturation stage of the cells.