OBJECTIVETo evaluate the influence of minocycline on the proliferation and biosynthesis of human periodontal ligament cells (HPDLCs) in vitro.

METHODSVarious concentrations of minocycline (1, 5, 20, 100, 500, 2 500 mg/L) were added to the medium of cultured HPDLCs respectively. After co-incubated for 2 days, cell morphology was observed under reverse microscope, cell proliferation activity was assayed using MTT, the total amount of protein was detected with Coumassie Bright Blue method and DNA synthesis was measured by (3)H-TdR.

RESULTSThe presence of minocycline not exceeding 500 mg/L in the medium resulted in no morphological change of HPDLCs. Moreover, at a concentration range of 5 to 100 mg/L, minocycline significantly enhanced the proliferative activity and biosynthesis of HPDLCs (P < 0.01). However, higher concentration (2 500 mg/L) not only changed cell morphology under microscope, but also significantly inhibited cellular activity.

CONCLUSIONSThe results suggest that proper doses of minocycline could promote biobehavior of HPDLCs, while higher concentrations of minocycline had cytotoxic effect which may intervene affect tissue repair and regeneration.