Basic Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Stem Cells. Aug 26, 2020; 12(8): 841-856
Published online Aug 26, 2020. doi: 10.4252/wjsc.v12.i8.841
Assessment of tobacco heating system 2.4 on osteogenic differentiation of mesenchymal stem cells and primary human osteoblasts compared to conventional cigarettes
Romina H Aspera-Werz, Sabrina Ehnert, Monja Müller, Sheng Zhu, Tao Chen, Weidong Weng, Johann Jacoby, Andreas K Nussler
Romina H Aspera-Werz, Department of Traumatology, BG Trauma Clinic, Siegfried Weller Institute for Trauma Research, Eberhard Karls Universität Tübingen, Tübingen 72076, Germany
Sabrina Ehnert, Monja Müller, Sheng Zhu, Tao Chen, Weidong Weng, Andreas K Nussler, Department of Traumatology, BG Trauma Clinic, Siegfried Weller Institute for Trauma Research, Eberhard Karls Universität Tübingen, Tübingen 71076, Germany
Johann Jacoby, Institute for Clinical Epidemiology and Applied Biometry, Eberhard Karls Universität Tübingen, Tübingen 71076, Germany
Author contributions: Aspera-Werz RH, Ehnert S, and Nussler AK designed and coordinated the study; Müller M, and Aspera-Werz RH performed the experiments, acquired and analyzed data; Aspera-Werz RH, Ehnert S, Müller M, Jacoby J, and Nussler AK interpreted the data; Aspera-Werz RH wrote the manuscript; Ehnert S, Müller M, Zhu S, Chen T, Weng W, Jacoby J, and Nussler AK made critical revisions to the manuscript; all authors approved the final version of the article.
Institutional review board statement: This study was conducted under ethical approval by committee at the Medical Faculty of Eberhard-Karls-University Tübingen, No. 538/2014BO2.
Informed consent statement: All patients gave their written informed consent to participate in the study.
Conflict-of-interest statement: The authors have not conflict of interest.
Data sharing statement: The data used to support the findings of this study are available from the corresponding author upon reasonable request.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Andreas K Nussler, Dr. rer.nat., Professor, Department of Traumatology, BG Trauma Clinic, Siegfried Weller Institute for Trauma Research, Eberhard Karls Universität Tübingen, Schnarrenbergstraße 95, Tübingen 71076, Germany.
Received: February 25, 2020
Peer-review started: February 25, 2020
First decision: May 26, 2020
Revised: July 17, 2020
Accepted: August 1, 2020
Article in press: August 1, 2020
Published online: August 26, 2020
Research background

Cigarette smoking (CS) is the most common method of consuming tobacco. Deleterious effects on bone integrity, increased incidence of fractures, and delayed fracture healing are all associated with CS. Tobacco combusted at about 800 °C generates approximately 6500 molecular species, more than 150 of which have been identified as toxic compounds. New approaches have been on developing reduced-risk alternatives for smokers that maintain the smoking ritual, while providing the same levels of nicotine as conventional cigarettes with less harmful constituents.

Research motivation

New technologies designed to develop a reduced-risk alternative for smokers are based on electronic nicotine delivery systems, such as e-cigarettes and tobacco heating systems (THS). Instead of burning tobacco, THS heat tobacco rolled up in a stick form up to 350 °C (avoiding combustion and formation of ashes). THS contain tobacco and convey the feeling of smoking a conventional cigarette. Several studies have demonstrated reduced levels of toxic and harmful compounds from electronic nicotine delivery systems.

Research objectives

The present study aim to examine the effects of THS on osteoprogenitor cell viability and function compared to conventional CS.

Research methods

Human immortalized mesenchymal stem cells and primary human pre-osteoblasts isolated from cancellous bone samples were osteogenically differentiated with aqueous extracts generated from either the THS 2.4 “IQOS” or conventional “Marlboro” cigarettes for up to 21 d. Cell viability was analyzed using resazurin conversion assay (mitochondrial activity) and calcein-AM staining (esterase activity). Osteogenic differentiation and bone cell function were evaluated using alkaline phosphatase (AP) activity, while matrix formation was analyzed through alizarin red staining. Primary cilia structure was examined by acetylated α-tubulin immunofluorescent staining. Free radical production was evaluated with 2′,7′-dichlorofluorescein-diacetate assay.

Research results

THS is significantly less toxic to bone cells than CS when analyzed by mitochondrial and esterase activity (P < 0.001). No significant differences in cytotoxicity between the diverse flavors of THS were observed. Harmful effects from THS on bone cell function were observed only at non-physiological concentrations. In contrast, conventional cigarettes significantly reduced the AP activity (by two-fold) and matrix mineralization (four-fold) at low concentrations. Moreover, morphologic analysis of primary cilia revealed no significant changes in the length of the organelle involved in osteogenesis of osteoprogenitor cells, nor in the number of ciliated cells following THS treatment. Assessment of free radical production demonstrated that THS induced significantly less oxidative stress than conventional CS in osteoprogenitor cells.

Research conclusions

The present study demonstrate reductions in the harmful effects on bone-forming cells and bone progenitor cells treated with THS compared to conventional cigarettes.

Research perspectives

THS could be a potential alternative for smokers to maintain appropriate bone homeostasis and delay development of secondary osteoporosis, which consequently would reduce health system costs.