Video-based kinetic analysis of calcification in live osteogenic human embryonic stem cell cultures reveals the developmentally toxic effect of Snus tobacco extract.

Affiliation

Department of Molecular, Cell & Systems Biology and Stem Cell Center, College of Natural and Agricultural Sciences, University of California Riverside, Riverside, CA 92521, United States; IGERT Graduate Program in Video Bioinformatics and Cell, Molecular and Developmental Biology Graduate Program, University of California Riverside, Riverside, CA, United States; Environmental Toxicology Graduate Program, University of California Riverside, Riverside, CA, United States. Electronic address: [Email]

Abstract

Epidemiological studies suggest tobacco consumption as a probable environmental factor for a variety of congenital anomalies, including low bone mass and increased fracture risk. Despite intensive public health initiatives to publicize the detrimental effects of tobacco use during pregnancy, approximately 10-20% of women in the United States still consume tobacco during pregnancy, some opting for so-called harm-reduction tobacco. These include Snus, a type of orally-consumed yet spit-free chewing tobacco, which is purported to expose users to fewer harmful chemicals. Concerns remain from a developmental health perspective since Snus has not reduced overall health risk to consumers and virtually nothing is known about whether skeletal problems from intrauterine exposure arise in the embryo. Utilizing a newly developed video-based calcification assay we determined that extracts from Snus tobacco hindered calcification of osteoblasts derived from pluripotent stem cells early on in their differentiation. Nicotine, a major component of tobacco products, had no measurable effect in the tested concentration range. However, through the extraction of video data, we determined that the tobacco-specific nitrosamine N'-nitrosonornicotine caused a reduction in calcification with similar kinetics as the complete Snus extract. From measurements of actual nitrosamine concentrations in Snus tobacco extract we furthermore conclude that N'-nitrosonornicotine has the potential to be a major trigger of developmental osteotoxicity caused by Snus tobacco.

Keywords

Calcification,Developmental toxicity,Embryonic stem cells,Nicotine,N′-nitrosonornicotine,Osteogenesis,Snus,Tobacco,Tobacco-specific nitrosamine,