gms | German Medical Science

German Congress of Orthopaedics and Traumatology (DKOU 2019)

22. - 25.10.2019, Berlin

E-cigarette aerosols do not compromise bone integrity compared with mainstream cigarette smoke after six-month inhalation in ApoE-/- mouse model

Meeting Abstract

  • presenting/speaker Jenny Schäfer - Eberhard Karls Universität Tübingen, BG Unfallklinik, Siegfried Weller Institut für Unfallchirurgische Forschung, Tübingen, Germany
  • Bjoern Titz - PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
  • Ee Tsin Wong - PMI R&D, Philip Morris International Laboratories Pte. Ltd., Science Park II, Singapore
  • Victor Häussling - Eberhard Karls Universität Tübingen, BG Unfallklinik, Siegfried Weller Institut für Unfallchirurgische Forschung, Tübingen, Germany
  • Peter Augat - Berufsgenossenschaftliche Unfallklinik Murnau, Institut für Biomechanik, Murnau, Germany
  • Julia Hoeng - PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
  • Andreas K. Nüssler - Eberhard Karls Universität Tübingen, BG Unfallklinik, Siegfried Weller Institut für Unfallchirurgische Forschung, Tübingen, Germany
  • Marie K. Reumann - Eberhard Karls Universität Tübingen, BG Unfallklinik, Siegfried Weller Institut für Unfallchirurgische Forschung, Tübingen, Germany

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019). Berlin, 22.-25.10.2019. Düsseldorf: German Medical Science GMS Publishing House; 2019. DocAB48-365

doi: 10.3205/19dkou433, urn:nbn:de:0183-19dkou4330

Published: October 22, 2019

© 2019 Schäfer et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

Text

Objectives: Electronic cigarettes (e-cigs) are currently used as a replacement for cigarettes. However, there are limited data on the safety profile of e-cig usage in terms of toxicology or disease risks as compared with that of cigarette smoking. The main objective of this study was to characterize the impact of six-months of inhalation of mainstream cigarette smoke (CS) from a 3R4F reference cigarette and e-cig aerosols on the bone morphology, structure, and bone strength of female ApoE-/- mice.

Methods: In the current study, two-month-old female ApoE-/- mice were randomly allocated to five exposure groups: sham (exposure to fresh, conditioned air), CS from the 3R4F reference cigarette, or three variations of e-cig aerosols. Capillary aerosol generators were used to generate e-cig aerosols using various e-liquids ("CARRIER“ containing humectants alone, „BASE“ containing humectants and 4% nicotine, and „TESTMIX“ containing humectants, 4% nicotine, and flavors). ApoE-/- mice were exposed at matched nicotine concentration, 36 µg/L, to CS and the e-cig aerosols ("BASE“ and „TESTMIX"). Ten animals per group were exposed for three hours per day, five days per week, for six months. Bone integrity analysis was performed using the tibiae. µCT imaging served for cortical and whole bone structure analysis. Three-point bending was used to test biomechanical properties, and histological stainings showed bone morphological details.

Results and conclusion: Animals of all groups showed no significant difference across the groups in body weight or tibial bone weight and lengths. Bone structure analysis using µCT revealed significant reduction in bone volume/total volume (BV/TV) of total bone as well as midshaft cortical bone in the CS group compared to the e-cig aerosol groups: CS versus CARRIER (total bone p<0.001, cortical p<0.05), CS versus BASE (total bone p<0.05), and CS versus TESTMIX (total bone p<0.05). Accordingly, biomechanical analysis showed significantly reduced ultimate load (UL) and stiffness (S) in CS versus Sham (S p<0.05), CS versus CARRIER (UL p<0.05), and CS versus TESTMIX (S p<0.05, UL p<0.01). Histology indicated variation in cortical composition, mainly in the sham group, using Masson Trichrome staining. Also, micro cracks in cortical bone were identified among all groups, showing hypertrophic chondrocytes as signs for endochondral healing identified by Alcian blue staining. In conclusion, mainstream CS significantly compromised bone structure and strength in the ApoE-/- mouse model. In contrast, in the ApoE-/- mouse model none of the e-cig aerosols showed significant changes of biomechanical properties or the ratio of BV/TV after a six-month inhalation exposure.