Effects of nicotine on proliferation and osteoblast differentiation in human alveolar bone marrow-derived mesenchymal stem cells

Aims: Nicotine is a risk factor for various diseases, including osteoporosis, oral cancer, and periodontal disease. Numerous studies have elucidated the effects of nicotine on cell proliferation and differentiation. The purpose of this study was to determine the effects of nicotine on the proliferation and osteoblast differentiation of human alveolar bone marrow-derived mesenchymal stem cells (hABMMSCs). Main methods: In this study, we treated hABMMSCs with different doses (1 μM to 5 mM) of nicotine. The survival and proliferation of hABMMSCs were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay and crystal violet assay. TUNEL and propidium iodide (PI) double staining assay were also performed. The effect of nicotine on osteoblast differentiation of hABMMSCs was determined by measuring calcium accumulation using alizarin red-sulfate (AR-S) staining, measurement of alkaline phosphatase (ALP) activity, and semi-quantitative PCR of osteoblast markers. Key findings: The survival and proliferation of hABMMSCs did not differ when they were exposed to nicotine at concentrations ranging from 1 μM to 100 μM; however, cell proliferation increased when the cells were exposed to nicotine at concentrations of 1-2 mM and decreased significantly when exposed to 5 mM of nicotine. A number of cells were stained by PI but not by TUNEL, and membrane vacuolization was observed in hABMMSCs treated with 5 mM nicotine. Calcium accumulation; ALP activity; and mRNA levels of ALP, bone sialoprotein (BSP), collagen type I α 1 (Col1αI), and runt-related transcription factor 2 (Runx2) were significantly decreased by treatment with 2 mM of nicotine, while osteocalcin transcripts decreased by treatment with 1 to 2 mM of nicotine. Significance: These results suggest that nicotine has a bimodal effect on the proliferation and osteoblast differentiation in hABMMSCs.