The capability of electrical stimulation (ES) in promoting bone regeneration has already been addressed in clinical studies. However, its mechanism is still being investigated and discussed. This study aims to investigate the responses of macrophages (J774A.1) and preosteoblasts (MC3T3‐E1) to ES and the faradic by‐products from ES. It is found that pH of the culture media was not significantly changed, whereas the average hydrogen peroxide concentration was increased by 3.6 and 5.4 µM after 1 and 2 hr of ES, respectively. The upregulation of Bmp2 and Spp1 messenger RNAs was observed after 3 days of stimulation, which is consistent among two cell types. It is also found that Spp1 expression of macrophages was partially enhanced by faradic by‐products. Osteogenic differentiation of preosteoblasts was not observed during the early stage of ES as the level of Runx2 expression remains unchanged. However, cell proliferation was impaired by the excessive current density from the electrodes, and also faradic by‐products in the case of macrophages. This study shows that macrophages could respond to ES and potentially contribute to the bone formation alongside preosteoblasts. The upregulation of Bmp2 and Spp1 expressions induced by ES could be one of the mechanisms behind the electrically stimulated osteogenesis.
In this study, the responses of macrophages and preosteoblasts to electrical stimulation (ES) were investigated. The mRNA expression from each cell type was measured after being exposed to ES. The effects of faradic by‐products were also investigated by treating the cells with electrically stimulated media. It is found in this study that Bmp2 and Spp1 mRNA expressions from both cells were upregulated by ES, whilst Spp1 mRNA expression from macrophages was partially influenced by the faradic by‐products.