Tabagismo e diferencia？？o óssea: efeito de níveis sanguíneos e salivares de nicotina no comportamento de células osteoblásticas de medula óssea humana. Estudo in vitro

the use of tobacco has been implicated in bone pathologies like osteoporosis and alveolar bone loss associated to periodontal disease. bone formation involves the differentiation of osteoprogenitor cells into osteoblasts and the formation of a mineralised colagenous matrix. therefore, the aim of this work was to characterise the behaviour of human bone marrow derived osteoblastic cells in the presence of nicotine at concentrations representatives of those present in plasma and saliva of tobacco users. cell cultures were maintained for 28 days in experimental conditions that favour the differentiation of the osteoblastic phenotype and cultured in the absence (control) and in the presence of nicotine (10 ng/ml - 1 mg/ml). results showed that nicotine, at 10 ng/ml (representative of plasmatic levels), did not affect significantly cell proliferation and functional activity. the presence of higher levels, 0.01 - 1mg/ml (representative of the salivary levels), affected cell behaviour in a dose dependent manner. cultures exposed to 0.01 - 0.2 mg/ml presented increased cell proliferation and alkaline phosphatase activity, associated to an anticipation of the matrix mineralization. treatment with 0.3 mg/ml caused an initial inhibitory effect followed by a recovery of the cell growth and functional parameters. in the presence of higher concentrations, negative effects on cell behaviour were observed throughout the incubation time; cultures presented decreased numbers of adherent cells, low alkaline phosphatase levels and cytoplasm vacuolation. results suggest the possibility of local modulation of the osteoblastic activity by nicotine, at the oral cavity.