Chondrocyte translocation response to direct current electric fields

Using a custom galvanotaxis chamber and time-lapse digital video microscopy , we report the novel observation that cultured chondrocytes exhibit cathod al 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 gre ater than 4 V/cm. Cell migration appeared to be an active process with exte nsion 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 r espect to the applied field. Antagonists of the inositol phospholipid pathw ay, U-73122 and neomycin, were able to inhibit cathodal migration. Cell mig ration toward the cathode did nor require the presence of serum during fiel d application. However, the directed velocity was nearly threefold greater in studies performed with serum. Studies performed at physiologic temperatu res (similar to 37 degreesC) revealed a twofold enhancement in migration sp eed compared to similar studies at room temperature (similar to 25 degreesC ). Findings from the present study may help to elucidate basic mechanisms t hat mediate chondrocyte migration and substrate attachment. Since chondrocy te migration has been implicated in cartilage healing, the ability to direc t chondrocyte movement has the potential to impact strategies for addressin g cartilage healing/repair and for development of cartilage substitutes.