Electrical stimulation influences mineral formation of osteoblast-like cells in vitro

The aim of the present study was to assess the structure of newly formed mi neral crystals after electrical stimulation of osteoblast-like cells in vit ro. Pulsed electrical stimulation was coupled capacitively or semi-capaciti vely to primary osteoblastlike cells derived from bovine metacarpals. Compu ter calculations revealed that the chosen input signal (saw-tooth, 100 V, 6 3 ms width, 16 Hz repetition rate) generated a short pulsed voltage drop of 100 muV (capacitive coupled mode) and of 350 muV (semi-capacitive coupled mode) across the cell-matrix layer. Stimulated cultures showed an enhanced mineral formation compared to the non stimulated controls. In cultures expo sed to capacitively coupled electric fields and in control cultures nodules and mineralized globules were found. Nodules with a diameter of less than 100 nm covered the cell surface, whereas mineral globules with a diameter o f up to 700 nm formed characteristic mineral deposits in the vicinity of th e cells similar to biomineral formations occurring in mineralizing tissues. In contrast, large rod-shaped crystals were found in cultures stimulated b y semi-capacitive coupled electric fields, indicating a non-physiological p recipitation process. In conclusion, osteoblasts in culture are sensitive t o electrical stimulation resulting in an enhancement of the biomineralizati on process. (C) 2001 Elsevier Science B.V. All rights reserved.