Dynamics of intracellular calcium in cultured human keratinocytes after localized cell damage

Recovery of cultured keratinocytes after scratch damage is considered to be a wound-healing model. In this study, we observed changes in intracellular calcium concentration ([Ca(2+) ]i ) in cultured human keratinocytes after scratch damage. Immediately after scratch damage, a wave of increased [Ca(2+) ]i radiated outward from the damaged area and then disappeared gradually. But, [Ca(2+) ]i remained elevated in a peripheral layer of cells around the damaged area for several minutes. This layer did not appear in calcium-free medium. When the culture was switched to calcium-free medium for 30 min immediately after scratch damage, then switched back to standard (Ca(2+) -containing) medium, the recovery ratio after 24 h was approximately 25% lower than that of the culture in standard medium throughout. We speculate that delineation of damage sites by a layer of cells with increased [Ca(2+) ]i might be part of a signalling pathway that appropriately directs the wound-healing process in epidermis.