Abstract: Objective To investigate the effects of hyaluronic acid (HA) against nicotine in human periodontal ligament fibroblasts (HPDLFs), and to explore the molecular mechanism underlying nicotine-induced cytotoxicity Methods This experiments using in vitro cultured human periodontal ligament fibroblasts (HPDLFs), divided into four groups: (1) normal group: cultured in DMEM medium continue; (2) the nicotine groups: add DMEM culture group concentration respectively (10 mu g/ml, 100 mu g/ml, 250 mu g/ml, 500 mu g/ml, 1000 mu g/ml) of nicotine. (3) hyaluronic acid groups: join in DMEM hyaluronic acid concentration was 0.1% and 0.2%; (4) the nicotine + hyaluronic acid groups: add concentration of 0.1% and 0.2% in DMEM HA and different concentrations of nicotine jointly develop 10 subgroups (total). Four groups were determined by MTT method (thiazole blue tetrazoliumbromide) cells, hence application kit of alkaline phosphatase (ALP) , Runt related transcription for - 2 (Runx2), collagen Ⅰ (Col Ⅰ) and osteopontin (OPN), osteocalcin (OCN) mRNA level, cell calcium mineralization ability .Results 1, compared with the control group, the concentration of nicotine can inhibit the proliferation activity of PDLFs and alkaline phosphatase activity, pure nicotine to join the group of Runx2, type I collagen, OPN and OCN had significantly lower levels of mRNA expression. Pure nicotine treatment group did not see calcification mineralized nodules.2, compared with the control group, respectively (0.1% and 0.2%) of hyaluronic acid on the periodontal ligament fibroblasts have obvious promoting effect, both kinds of concentration of hyaluronic acid can promote the proliferation activity of HPDLFs and alkaline phosphatase activity, and promote the rise of Runx2, type I collagen, the level of mRNA expression of OPN and OCN ,and obsered in mineralized nodules.3, compared with the pure nicotine effect group, hyaluronic acid + nicotine group of HPDLFs proliferation activity and alkaline phosphatase activities play a role, the Runx2, type I collagen, OPN and OCN mRNA expression level has improved, and observed calcification mineralized nodules. Conclusion HA can increase the activity of ALP and mineralized tissue-associated proteins, including Runx2, Col I, OPN and OCN, etc and can resist the toxic effect of nicotine on HPDLFs, and thus play a protective role.

Key words: HPDLFs, hyaluronic acid, nicotine, cell proliferation