Electrotaxis and wound healing: experimental methods to study electric fields as a directional signal for cell migration

Electric fields were measured at human skin wounds over one and half centuries ago. Modern techniques have verified and greatly extended our understanding of the existence of endogenous wound electric fields. In virtually all wounds studied, disruption of an epithelial layer instantaneously generates endogenous electric fields. As electric fields have the intrinsic property of being vectorial, it has long been proposed that these fields may serve as a directional signal guiding cell migration in wound healing. We have established several experimental systems to study the guidance effects and mechanisms of electric fields on cell migration. Most types of cells migrate directionally in a small electric field, a phenomenon called galvanotaxis/electrotaxis. Remarkably, electric fields of strength equal to those detected at in vivo wounds direct cell migration and override some other well-accepted coexistent guidance cues such as contact inhibition. The naturally occurring endogenous electric fields therefore may be an important signaling mechanism that regulates directional cell movement in vivo. Applied electric fields may have a potential clinical role in guiding cell migration in wound healing. The magnitude and direction of the electric field can be more precisely and quickly changed than most other guidance cues such as chemical cues. Application of electric fields thus offers a robust experimental system for study of directional cell migration with extensive flexibility. We present a brief review of the background and describe the experimental system for studying electrotaxis.