Objective: To investigate the effect of wood smoke condensate (WSC) on proliferation and necrosis of human airway smooth muscle cells (HASMCs).
Methods: Primary cultured HASMCs between passage 2 and 8 were divided into 3 groups: a control group, a WSC group and a cigarette smoke condensate (CSC) group. The viability of cells was examined by the CCK8 assays. The ratio of cellular proliferative stage (S phase) and cell cycle index were examined by fluorescent-labeled thymidine analogue uptake assays and flow cytometry. The expression of cyclin D1 was detected by quantitative reverse transcriptase polymerase chain reaction (Q-PCR) and Western blot. Cell apoptosis and necrosis were observed by the annexin-V and PI staining. Statistical analysis was performed by using the One-way ANOVA and LSD-t test.
Results: Cell viability reached peak at WSC 1 mg/L[(126 ± 12)%] and at CSC 10 mg/L exposure level [(142 ± 11) %] respectively. While at WSC 10 mg/L and CSC 60 mg/L exposure levels, cell viability decreased significantly to 86% and 76%, respectively, as compared with that of the blank control group[(100 ± 0)%] (q = 3.63- 9.33, P < 0.05). In the WSC 1 mg/L group, the cell proliferation ratio and the expression of cyclin D1 protein were (124 ± 20)% and 1.31 ± 0.64, respectively, the differences being significant as compared with the blank control group [(100 ± 0)%, 1.0 ± 0.0] (q = 5.85, 5.91, P < 0.05), while the expression of cyclin D1 mRNA and the percentage of S+G2M phase were 1.18 ± 0.21 and (103 ± 4)%, respectively, not significantly different as compared to the control group [(100 ± 0)%, 1.0 ± 0.0], (q = 1.16, 2.05, P > 0.05). In the CSC 10 mg/L group, the above-mentioned values were (204 ± 45)%, 1.80 ± 0.25, (140 ± 6)%, 1.48 ± 0.2, respectively, which were significantly higher than those in the blank control group (q = 5.38-16.51, P < 0.05) and in the WSC group (q = 3.33-15.35, P < 0.05). However, when HASMCs were exposed to WSC 10 mg/L, the cell death ratio was (13.39 ± 0.15)%, higher than that of the blank control group [(1.57 ± 0.41)%] and the CSC group [(6.61 ± 1.91)%] (q = 18.03, 10.34, P < 0.05). Apoptosis ratio in the CSC 40 mg/L group was [(61.8 ± 10.6)%], higher than that of the blank control group [(0.0 ± 0.0)%] and the WSC group [(1.7 ± 0.4)%] (q = 17.44, 16.95, P < 0.05).
Conclusions: Exposure to WSC caused a weak proliferation of HASMCs, but resulted in cell necrosis instead of apoptosis at high doses. There was a slight difference in cell effects between the WSC group and the CSC group.