Effects of cigarette smoke and nicotine on cell viability, migration and myofibroblastic differentiation

Background and Objective: Several studies have analysed the role of nicotine as a prominent agent affecting wound repair in smokers. However, tobacco smoke contains several components that may alter gingival wound healing. The present study aimed to analyse the roles of cigarette smoke condensate (CSC) and nicotine on cell viability, cell migration/invasion and myofibroblastic differentiation using primary cultures of human gingival fibroblasts. Material and Methods: To compare the effects of CSC and nicotine, gingival fibroblasts were stimulated with CSC (0.4-500μg/mL) and the corresponding nicotine concentrations (0.025-32μg/mL) present in research cigarettes (1R3F). Cell viability was evaluated through the MTS assay. Cell migration and invasion were assessed through scratch wound assays, collagen nested matrices and transwell migration. α-Smooth muscle actin production was evaluated by western blotting. Results: Cigarette smoke condensate at 50μg/mL induced a moderate increase in cell viability, whereas the corresponding nicotine concentration (3.2μg/mL) did not produce this response. Cigarette smoke condensate at 250μg/mL, but not nicotine at 16μg/mL (the corresponding nicotine concentration), induced cell death. Both nicotine and CSC stimulated cell migration (50μg/mL CSC; 3.2μg/mL nicotine). At 150μg/mL, CSC inhibited cell migration; however, the corresponding concentration of nicotine (9.6μg/mL), did not have this effect. Although both nicotine and CSC inhibited α-smooth muscle actin production, only the latter induced a statistically significant effect on this response. Conclusion: Cigarette smoke condensate may stimulate cell survival and migration at low concentrations and inhibit these cell responses at higher levels of exposure. Moreover, CSC may interfere in myofibroblastic differentiation. These results show that cigarette smoke, but not nicotine, may significantly alter cell viability, cell migration and myofibroblastic differentiation in gingival mesenchymal cells.