Development of an in vitro wound healing model for periodontal cells

Background: Periodontal wound healing and regeneration are influenced by a multitude of factors. While many in vitro investigations have compared the proliferation of periodontal ligament (PDL) cells and gingival fibroblasts (GF), there are no reports directly comparing the abilities of these 2 cell types to fill a wound site. As such, the goals of this research were: 1) t o develop an in vitro model of wound healing which would allow for the inve stigation of the biologic basis of periodontal wound healing and regenerati on:and 2) to compare the rates of PDL cells and GF to fill an in vitro woun d site. Methods: Using both human PDL cells and GF confluent cultures, in vitro wou nds were mechanically created, removing a 3 mm wide band of the cell layer. Wounded cultures were then incubated for time periods up to 12 days in med ia containing fetal bovine serum (FBS) concentrations (0, 0.1, 1, 5, 10, an d 20%) as appropriate for each experiment. Slides were fixed, stained, and cells quantified within the wound boundaries by computer-assisted histomorp hometry. The effect of wounding a cell layer was determined by comparing wo unded cells as described above with a cell layer margin created without phy sically disrupting the cell layer. Results: The in vitro model for periodontal wound healing established in th is study showed that GF fill in the wound site at a significantly (P <0.002 5) faster rate than PDL cells over 12 days of healing. In addition, PDL cel ls and GF were found to have unique concentration-dependent responses to FB S (P <0.0025). It was also shown that wounding resulted in a significant de lay (P <0.01) in the initial healing response of an in vitro wound. Conclusion: This in vitro model demonstrated that the characteristics of wo und healing are dependent on cell type, disruption (wounding) of the cell l ayer, and serum concentration. In addition, this model has incorporated bot h proliferation and migration to provide the first direct evidence demonstr ating GF has a significantly greater ability to fill a wound site than PDL cells. This in vitro model may be utilized in future investigations of the biologic basis of periodontal wound healing.