Nicotine Deteriorates the Osteogenic Differentiation of Periodontal Ligament Stem Cells through a7 Nicotinic Acetylcholine Receptor Regulating wnt Pathway

Aims: Cigarette smoking is one of the high risk factors of adult chronic periodontitis and nicotine is the well established toxic substance in cigarette. However, the mechanism of nicotine induced periodontitis is still unknown. Here we studied whether nicotine impaired the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) through activating a7 nicotinic acetylcholine receptor (a7 nAChR). Methods: hPDLSCs with multi differentiation potential and surface makers for mesenchymal stem cells were harvested by limiting dilution technique. The level of mineralized nodule formation was assessed by alizarin red S staining. Expression level of ostegenic related genes and proteins were detected by real-time PCR and western blot analysis. The expression of a7 nAChR and its downstream signaling pathway were examined by western blot. The role of the receptor and related signaling pathway in nicotine impairing the osteogenic potential of hPDLSCs were also studied in different levels. Results: Nicotine deteriorated the ostegenic differentiation of hPDLSCs in a dose dependent manner. Activation of a7 nAChR by nicotine treatment activated wnt/b-catenin signaling pathway, leading to osteogenic deficiency of hPDLSCs. Blockage of a7 nAChR and wnt pathway inhibitor treatment rescued nicotine induced osteogenic differentiation deficiency. Conclusions: These data suggested that nicotine activated a7 nAChR expressed on PDLSCs and further activated wn