Optimum microcurrent stimulation intensity for galvanotaxis in human fibroblasts

In this study, we develop methods to measure galvanotaxis of fibroblasts and determined the optimum conditions of electrical stimulation.

An inverted 35mm dish containing cell suspensions (3×105 primary human skin fibroblasts, DMEM, and 10% FBS) was placed on the centre of a 100mm dish. The 35mm dish was removed 24 hours later, and culture medium was added to the 100mm dish. Fibroblasts were randomised (double-blind) into three groups, where electrical stimulation was given at varying intensities: 0UA (control), 50UA, and 100UA. Electrical stimulation (frequency=0.3Hz) was conducted, for a duration of 4 hours, with platinum electrodes in a CO2 incubator. We took pictures immediately before and 20 hours after stimulation. We calculated the migration ratio to the negative pole by dividing the area of attached fibroblasts after stimulation with that before stimulation.

The migration ratio to the negative pole was significantly higher in the 100UA group than in the control group (p<0.05). The ratios were 0.902±0.292 in the control group, 1.128±0.253 in the 50UA group, and 1.24±0.300 in the 100UA group.

This study observed the change in cell proliferation during the initial 24-hour period after plating and was thus able to quantitatively evaluate the migration. The results suggest that a low-intensity direct current promotes migration to the negative pole of human dermal fibroblasts, which is charged with positive electricity. Several clinical reports using the methods in this study showed the microcurrent efficacy for pressure ulcer healing. Electrical stimulation based on our in vitro experiment might be important for the development of physical therapy for pressure ulcers.