Cigarette smoke (CS) exposure is one of the leading risk factors for human health. Nicotine-containing inhalable products, such as e-cigarettes, can effectively support tobacco harm reduction approaches. However, there are limited comparative data on the effects of the aerosols generated from electronic vapor products (e-vapor) and CS on bone. Here, we report the effects of e-vapor aerosols and CS on bone morphology, structure, and strength in a 6-month inhalation study. Eight-week-old ApoE-/- mice were exposed to aerosols from three different e-vapor formulations-CARRIER (propylene glycol and vegetable glycerol), BASE (CARRIER and nicotine), TEST (BASE and flavor)-to CS from 3R4F reference cigarettes at matched nicotine concentrations (35 µg/L) or to fresh air (Sham) (N = 10 per group). Tibiae were analyzed for bone morphology by µCT imaging, biomechanics by three-point bending, and by histological analysis. CS inhalation caused a significant decrease in cortical and total bone volume fraction and bone density relative to e-vapor aerosols. Additionally, CS exposure caused a decrease in ultimate load and stiffness. In contrast, bone structural and biomechanical parameters were not significantly affected by e-vapor aerosol or Sham exposure. At the dissection time point, there was no significant difference in body weight or tibia bone weight or length among the groups. Histological findings revealed microcracks in cortical bone areas among all exposed groups compared to Sham control. In conclusion, because of the bone-preserving effect of e-vapor aerosols relative to CS exposure, e-vapor products could potentially constitute less harmful alternatives to cigarettes in situations in which bone health is of importance.

中文翻译：

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在ApoE-/-小鼠模型中，吸入6个月后，相对于香烟烟雾，E气雾剂不会损害骨骼完整性。

接触香烟烟雾（CS）是人类健康的主要危险因素之一。含尼古丁的可吸入产品，例如电子烟，可以有效地支持减少烟草危害的方法。但是，关于由电子蒸气产物（e-蒸气）和CS产生的气溶胶对骨骼的影响的比较数据有限。在这里，我们在一个为期6个月的吸入研究中报告了电子气雾剂和CS对骨骼形态，结构和强度的影响。八周大的ApoE-/-小鼠暴露于来自三种不同电子蒸汽制剂的气溶胶-CARRIER（丙二醇和植物甘油），BASE（CARRIER和尼古丁），TEST（BASE和香精）-来自3R4F参考的CS匹配尼古丁浓度（35微克/升）或新鲜空气（假）的香烟（每组N = 10）。通过µCT成像分析了胫骨的骨形态，生物力学通过三点弯曲，并通过组织学分析。相对于e气溶胶，CS吸入引起皮质和总骨体积分数以及骨密度显着降低。另外，CS暴露导致极限载荷和刚度降低。相比之下，骨结构和生物力学参数不受电子蒸汽气溶胶或深水暴露的影响。在解剖时间点，两组之间的体重或胫骨重量或长度没有显着差异。组织学研究发现，与假手术对照组相比，所有暴露组的皮质骨区域均出现微裂纹。总之，由于e-蒸气气雾剂相对于CS暴露具有保骨作用，