Chondrocyte Translocation Response to Direct Current Electric Fields

Abstract

Using a custom galvanotaxis chamber and time-lapse digital video microscopy, we report the novel observation that cultured chondrocytes exhibit cathodal migration when subjected to applied direct current (DC) electric fields as low as 0.8 V/cm. The response was dose-dependent for field strengths greater than 4 V/cm. Cell migration appeared to be an active process with extension of cytoplasmic processes in the direction of movement. In some cells, field application for greater than an hour induced elongation of initially round cells accompanied by perpendicular alignment of the long axis with respect to the applied field. Antagonists of the inositol phospholipid pathway, U-73122 and neomycin, were able to inhibit cathodal migration. Cell migration toward the cathode did not require the presence of serum during field application. However, the directed velocity was nearly threefold greater in studies performed with serum. Studies performed at physiologic temperatures (approximately 37 degrees C) revealed a twofold enhancement in migration speed compared to similar studies at room temperature (approximately 25 degrees C). Findings from the present study may help to elucidate basic mechanisms that mediate chondrocyte migration and substrate attachment. Since chondrocyte migration has been implicated in cartilage healing, the ability to direct chondrocyte movement has the potential to impact strategies for addressing cartilage healing/repair and for development of cartilage substitutes.

Roles of microtubules, cell polarity and adhesion in electric-field-mediated motility of 3T3 fibroblasts

“…Direct current at constant EF strength (0-6 V cm -1 for sparse cells, 0-2 V cm -1 for monolayers, 37°C) was applied to galvanotaxis chambers (Chao et al, 2000) connected to a power supply (Keithley SourceMeter 2410) through two salt bridges and Ag-AgCl electrodes. Time-lapse images (10 minute intervals) were captured and the average speed (the distance between the final and initial positions of the cell centroid divided by the total elapsed time) was analysed using a particle-tracking scheme in MetaMorph software (Universal Imaging).…”

“…Galvanotaxis and galvanotropism (i.e. EF-mediated migration and shape change, respectively) occur in keratinocytes, epithelial cells, bone cells, chondrocytes and fibroblasts (Chao et al, 2000;Ferrier et al, 1986;Sheridan et al, 1996;Soong et al, 1990;Zhao et al, 1996a). The EF strengths commonly used (1-10 V cm -1 ) are physiologically significant for vertebrates, because 1-2 V cm -1 gradients have been measured on either side of the cut surface of wounds owing to ion flux through leaky cell membranes (Soong et al, 1990) or transepithelial potential driven by Na + pumps (Vanable, 1989).…”

Effects of Applied DC Electric Field on Ligament Fibroblast Migration and Wound Healing

“…In the present study, we investigated the migratory response of fibroblasts derived from the ACL to an EF (E = 0-6V/cm, [31]), applied in a static or pulsing manner. The ACL is an intra-articular ligament that is often torn in sports-related injuries and is critical in stabilization of the knee joint [29,32].…”

Cellular mechanisms of direct-current electric field effects: galvanotaxis and metastatic disease

“…Indeed, in LNCaP cells and fish keratocytes, thapsigargin, which depletes internal Ca 2+ stores, blocks the response to dcEFs (Perrett et al, 1999;Brust-Mascher and Webb, 1998 (Berridge, 1993;Dawson, 1997). Neomycin, an antagonist of phosphoinositide signalling, inhibits the response of chondrocytes to dcEFs (Chao et al, 2000). Similar experiments on embryonic muscle cells showed that galvanotaxis is not restored even in the presence of a 16-fold increase in the level of extracellular Ca 2+ (McCaig and Dover, 1991).…”