IN-VITRO MODULATION OF HUMAN GINGIVAL EPITHELIAL-CELL ATTACHMENT AND MIGRATION BY MINOCYCLINE-HCL

Although the influence of tetracyclines on periodontal connective tiss ue cells has been the topic of many in vitro and in vivo studies, data regarding their effects on gingival epithelial cells are scarce. The present in vitro study was designed to examine the influence of minocy cline, a semi-synthetic analog of tetracycline, on human gingival kera tinocyte (HGK) attachment and migration. Attachment tests were perform ed with HGK prelabeled by tritiated amino-acids. Increasing concentrat ions of minocycline (10, 50, 100 mu g/ml) in the medium produced no si gnificant modification of cell adhesion kinetics compared to control c onditions, except for 100 mu g/ml which statistically significantly (p <0.05) reduced the number of attached cells beyond 6 h. A 24-h cell pr eincubation in 10 mu g/ml of minocycline did not alter the kinetics of HGK attachment. Scanning electron microscopic observations of attache d HGK showed that the presence of 10 mu g/ml of minocyline in the ''at tachment medium'' induced the production of multiple filopodial extens ions. Migration tests in Boyden chambers for 40 h demonstrated that HG K preincubation for 24 h in a 10 mu g/ml minocycline-HCl solution incr eased significantly (p<0.005) cell migation towards a gradient of feta l calf serum. The presence of 10 mu g/ml of minocycline in contact wit h the keratinocytes in the upper compartment of the migration chambers also produced a significant (p<0.005) result. In contrast, the presen ce of minocycline in the lower compartments did not produce any chemoa ttractive effect. Within the limits of their significance, these resul ts suggest that, at concentrations not beyond 50 mu g/ml, minocycline could fasten the periodontal wound coverage by epithelial cells and al low the normal reformation of a junctional epithelium.