The influence of doxycycline of the attachment of fibroblasts to gelatin-coated surfaces and its cytotoxicity.

Because of their antimicrobial and anti-inflammatory properties, tetracyclines have been used systemically and locally in the treatment of periodontal disease. This study was done to evaluate the influence of doxycycline (Dc), a tetracycline, on fibroblast adherence to a protein coated surface and its cytotoxicity. Periodontal ligament derived fibroblasts (PLDFs) were either: 1) preincubated with Dc (0 to 100 micrograms/ml) and then allowed to adhere to a gelatin-coated surface or 2) adherence was first established and then Dc added to the system. After an appropriate time the number of PLDFs adherent, released, or lysed was estimated by a lactic dehydrogenase (LDH) assay. Preincubation of PLDFs in 25 micrograms Dc/ml or higher concentrations significantly (P < 0.01) reduced the number of adherent cells. Fifty micrograms Dc/ml and higher doses significantly (P < 0.01) increased PLDFs cytotoxicity as measured by LDH release. The same trend was noted if PLDFs were allowed to adhere and then subjected to the drug. Microscopic observation of fluorescein diacetate/propidium iodide-stained cells showed that attached-spread cells pulled in, rounded up, and detached in proportion to the increased dose of Dc and the percentage of red-stained cytotoxic cells rose in a similar manner. The data suggested that Dc can be cytotoxic and may inhibit PLDFs adherence and spread along a substratum.