Figure 2.

Actin cytoskeleton reorganization. Fluorescent images of osteoblasts are in the left column and hMSCs in the right column. Immunofluorescent images of a thin filamentous actin meshwork (red) and vinculins (green) showed that osteoblasts contain fewer and smaller focal adhesions (A). In contrast, hMSCs showed thick actin stress fibers, and multiple and large adhesion contacts (B). Actins were partially disassembled in both osteoblast (C) and hMSC (D) after cell exposure to a 2 V/cm field for 60 min in serum-free HBSS. Cells treatment with 10 μM ionomycin for 40 min in HBSS produced analogous actin dismantling effects both in osteoblast (E) and hMSC (F). When cells were placed in cell culture medium with serum, the electrical stimulation again caused redistribution of actins in osteoblast (G) and stem cells (H), but in a manner that was different than (C) and (D) without serum. Cell incubation in the complete culture medium for 60 min at 37°C after the dc field exposure resulted in a partial recovery of the actin structure in both osteoblasts (I) and hMSC (J). The arrows indicate the direction of the electric field applied.