Human fibroblast migration in three-dimensional collagen gel in response to noninvasive electrical stimulus. II. Identification of electrocoupling molecular mechanisms.
Cell adhesion and migration is regulated by a series of coordinated and integrated molecular mechanisms. In the accompanying article (Sun et al., Tissue Eng. 10, 1548, 2004), we demonstrate and characterize the human fibroblast movement in three-dimensional (3D) collagen gel induced by non-invasive electrical stimulus. The molecular mechanisms mediating 3D cell migration in response to physical stimuli including noninvasive electrical stimulus remain to be elucidated, however. Here we report that induced human fibroblast movement in 3D collagen gel is both integrin and Ca2+ dependent. Treatment of cells with anti-integrin antibodies prevents electrically induced cell movement. More interestingly, whereas the absence of extracellular Ca2+ suppresses cell movement, inhibition of the cell surface receptor-coupled phospholipase C (PLC) completely prevents 3D cell migration, suggesting molecular association between integrin, PLC, and intracellular Ca2+. Coupling of external electrical stimulus to PLC activation appears to be the primary event required to induce cell migration, while Ca2+ influx across the plasma membrane regulates the sustained cell movement. On the basis of the rather small strength (0.1 V/cm) of electrical stimulus used in this study, activation of the electrically operated voltage-gated Ca2+ channels is unlikely, but the mechanically operated stretch-activated cation channels appear to mediate Ca2+ influx. Elucidation of the electrocoupling molecular mechanisms involved in 3D cell movement could lead to controlled and designed manipulation of 3D cell adhesion and migration.