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Effects of minocycline on fibroblast attachment and spreading.

One of the initial events required for periodontal regeneration is the attachment and subsequent spreading of fibroblasts at the healing site (root surface). In order to further our understanding of the possible role of tetracyclines in connective tissue attachment, human gingival fibroblasts exposed to minocycline and tetracycline were evaluated for cell attachment and spreading properties in vitro. The results indicated that both minocycline and tetracycline enhanced cell attachment, but minocycline had greater efficacy. Enhanced cell attachment to polystyrene uncoated dishes was seen at a 20 μg/ml dose of minocycline, while maximum cell attachment was seen at 50 μg/ml. Exposure of cells to 200 μg/ml of minocycline resulted in a decline from maximum cell attachment. In addition, cell spreading was inhibited at the higher concentrations of drug. Cells exposed to 50 μg/ml of minocycline for 2 days had no change in total protein or collagen production when compared to control cells. This dose of minocycline had no effect on cell proliferation at 2 d, but over a 7-d time course there was a significant decline in cell proliferation. These findings are important to clinical assessment of tetracyclines and indicate that such evaluations should include establishment of doses that favor cell attachment and spreading.