Comparative effects of electronic cigarette aerosol, conventional cigarette smoke, and cannabis smoke on the cellular properties of osteogenically induced gingival fibroblasts/gingival mesenchymal stem cells

Abstract Background Tobacco smoking remains a major global health burden. Although electronic cigarettes (EC) are considered less harmful than conventional cigarette, their effects on oral health are not fully defined. Cannabis use is increasing worldwide, yet its impact on oral tissues is poorly understood. This investigation evaluated the effects of EC aerosol, conventional cigarettes smoke and cannabis smoke on cellular viability, mitochondrial integrity and gene expression in osteogenically induced gingival fibroblast/gingival mesenchymal stem cells (GF/GMSCs). Methods Isolation and characterization of human GF/GMSCs ( n = 32) were performed, followed by osteogenic induction using (BMP-2) and aerosol/smoke application. Osteogenically induced GF/GMSCs were assessed via MTT-assay, mitochondrial depolarization assessed using JC-1 dye, ATM, p21, Oct4 and Nanog gene expression, and osteogenic differentiation. Results Viability (OD450nm) was significantly reduced in the cannabis/BMP- (mean ± SD: 1.02 ± 0.24) and cigarettes/BMP-(1.05 ± 0.39; p < 0.05), with no reduction in viability in the EC/BMP-(1.78 ± 0.47) and BMP-group (1.74 ± 0.59; p > 0.05). Upregulated expression of ATM, Oct4, and Nanog (gene copies/GAPDH) was significant with cannabis/BMP-(2.23 ± 0.34, 1.73 ± 0.53 and 2.04 ± 0.33 respectively), cigarettes/BMP-(2.58 ± 0.69, 1.91 ± 1.03 and 2.26 ± 0.6; p < 0.05 respectively), with no significant upregulation in EC/BMP-(0.72 ± 0.37; 0.91 ± 0.56; 1.11 ± 0.49) compared to BMP-group (0.51 ± 0.17, 0.64 ± 0.2, and 1.01 ± 0.58; p > 0.05 respectively). p21 expression was significantly downregulated in EC/BMP-(1.97 ± 0.52), cannabis/BMP-(1.26 ± 0.29) and cigarettes/BMP-(1.38 ± 0.74) compared to BMP-group (4.24 ± 0.69; p < 0.05). Osteogenic differentiation was impeded with reduced Alizarin-red straining and significant downregulation of osteopontin expression in EC/BMP-(2.12 ± 0.47), cannabis/BMP-(1.48 ± 0.99), and cigarettes/BMP- -(1.36 ± 0.38) compared to BMP-group (3.95 ± 0.88;p˂0.05). Conclusion Cannabis smoke and cigarette smoke negatively influence the viability, gene expression, and cause DNA damage in osteogenically induced GF/GMSCs, with a lesser effect of EC-aerosol on these findings. Still, all tested exposures negatively affected the differentiation of osteogenically induced GF/GMSCs.