OBJECTIVETo study the effect of the inhibitory concentration minocycline on the proliferation, differentiation, and expression of Runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and osteopontin (OPN) mRNA of osteoblasts.

METHODSPrimary osteoblasts were cultured in osteogenic induction medium containing 0, 0.1, 0.5, 1, 10 μg·mL⁻¹ minocycline. Cell counting kit-8 was used to observe cell proliferation. ALP activity assay, alizarin red S staining, and real-time quantitative polymerase chain reaction (PCR) were used to determine cell differentiation and mineralization.

RESULTSThe groups with 0.1, 0.5, 1 μg·mL⁻¹ minocycline promoted cell proliferation. The mRNA expression levels of ALP and Runx2 were up-regulated. Osteoblast-mediated mineralization was increased. The group with 1 μg·mL⁻¹ showed maximal promotion effect (P<0.05). When the concentration increased to 10 μg·mL⁻¹, the promoting effect began to decline, and the ALP activity and OPN expression were significantly inhibited (P<0.01).

CONCLUSIONSAppropriate concentration of minocycline can promote osteoblasts proliferation, up-regulate the expression levels of Runx2, ALP and OPN, and increase the differentiation and mineralization of osteoblasts.