077 The Bioelectric Field Imager: A New Tool for Measuring the Electric Field Around Skin Wounds

Abstract

We are studying in the role of endogenous electric fields in mammalian skin wound healing. The epidermis generates a transepithelial potential (TEP) of 20–50 mV across itself, inside positive. Any wound or break in the epidermis creates a low resistance pathway and the TEP at the wound site is 0 mV. However, the TEP of the intact epidermis around the wound is still present, resulting in a lateral voltage gradient or electric field along the skin surrounding the wound. We have evidence that this lateral electric field stimulates keratinocytes in the area to migrate towards the wound with the optimal response occurring at a field strength of 100 mV/mm. In order to determine the actual field strength present in mammalian wounds, we have developed a new instrument called the Bioelectric Field Imager (BFI). The BFI vibrates a small sensor perpendicular to the skin about 200 μm above the surface and uses the capacitance signal to determine the surface potential of the epidermis just beneath the stratum corneum. By measuring this surface potential in many positions around the wound, we generate a spatial map of the surrounding electric field. We have measured the wound field near a 1 mm long, full thickness skin wound in mice. A field of 100–200 mV/mm is present immediately following wounding and persists until wound healing is complete. The topical application of a blocker of Na+ channels (amiloride) reduces this wound field by about 50%, supporting the hypothesis that it is generated by the TEP. Preliminary measurements on human skin wounds detect lateral electric fields that are similar to those measured in mice. Acknowledgments: Supported by NIH R43 GM069194 to RPN and NIH NCRR P41 RR001395 to P.J.S.S