In Vitro Study of the Adverse Effect of Nicotine and Physical Strain on Human Gingival Fibroblasts as a Model of the Healing of Wounds Commonly Found in the Military

Abstract

Significant adverse effects on fibroblast growth and metabolism are observed with nicotine. We investigated the synergistic effects of nicotine and cyclical mechanical strain (CMS) on human gingival fibroblasts (HGFs) in a wound-healing model. HGFs were isolated and grown in Dulbecco's modified Eagle's medium. Three-millimeter wounds were created on a confluent cell monolayer grown in a media containing 0, 1, 2, or 4 mM nicotine, with or without CMS. The applied deformation regimen remains constant for 6 days. On days 1, 2, 4, and 6, the cells were stained with hematoxylin and eosin Y for the evaluation of wound repopulation. The application of CMS alone demonstrates a biphasic response, with an initial stimulatory effect on wound repopulation (days 1-2) and less repopulation during the later phase (days 4-6). The addition of nicotine clearly demonstrated a time and inverse dose-dependent relationship on wound repopulation, with no effect during the early phase and reduced wound repopulation during the later phase. Initial treatment of HGF wounds with CMS resulted in faster wound repopulation regardless of nicotine presence. By day 6, wound healing of HGF exposed to both nicotine and CMS is delayed. These findings suggest that CMS and nicotine may affect fibroblasts and delay wound healing at other sites in the body as well.