TABLE 1

Methodological characteristics of in vitro studies

Cell culture models[References]
Electronic cigarette vapour exposure
 Air-liquid interface[11, 12, 16, 17, 19, 21, 28, 34, 54, 55, 65, 66, 71, 73, 74, 77, 78, 103]
 E-liquid mixed with cell medium or electronic cigarette vapour extracts[13–15, 18, 20, 22, 47, 50–53, 56–58, 70, 72, 75, 76, 79, 81, 104]
Cell types
 Lung epithelial cells
  16HBE (human)[16, 53f, 64]
  hTBE (human)[52]
  A549 cells (human)[12, 13, 18, 50, 58, 64, 73]
  NHBE (human)[17, 20, 28, 65, 73]
  Beas-2B (human)[11, 13, 19, 47, 55, 58, 76]
  H292 (human)[19, 47, 74]
  Primary bronchial epithelial cells (human)[16, 21, 55]
  Primary small airway epithelial cells (human)[54]
  3-dimensional epithelial cell model (human)[34, 78]
  Primary tracheal epithelial cells (mouse)[53]
  RLEC (rat)[76]
 Nasal epithelial cells
  HBEpC[58]
  3-dimensional epithelial cell model from healthy donors (human)[77]
 Immune cells
  White blood cells (human)[18]
  Blood neutrophils (human)[22, 56, 82]
  Blood monocyte-derived dendritic cells (human)[104]
  THP-1 monocytic cells (human)[15]
  Kupffer cells (rat)[72]
  Platelets[81]
 Endothelial cells
  HUVEC (human)[51, 70]
  Primary human microvascular cells-lung derived[76]
  MLEC (mouse)[76]
 Stem cells
  Embryonic stem cells (human)[14]
  Bone marrow-derived mesenchymal stem cells (human)[75]
  Neural stem cells (mouse)[14]
 Lung fibroblasts
  Human pulmonary fibroblasts[14]
  HFL-1 (human)[19, 47, 103]
 Skin cells
  HaCaTs (human)[12, 18]
  Primary gingival epithelial cells (human)[71, 80]
  Periodontal ligament fibroblasts (human)[80]
 Lung surfactant
  Infasurf (calf)[79]
 Bacteria
  Streptococcus pneumoniae[57]
  Streptococcus gordonii[66]
  Streptococcus intermedius[66]
  Streptococcus mitis[66]
  Streptococcus oralis[66]
Nicotine
 Low nicotine <6 mg·mL−1[14, 19, 55, 57, 70, 76]
 Medium nicotine 6–18 mg·mL−1[11, 14, 15, 19, 21, 47, 52, 75, 77, 81, 103–105]
 High nicotine >18 mg·mL−1[13, 14, 17, 19, 20, 22, 28, 47, 50, 54, 58, 66, 71–74, 78–80, 82, 104, 106]
 No nicotine[13, 14, 16, 17, 19–21, 28, 47, 53, 54, 56–58, 66, 72, 73, 79–82]
 Unspecified concentration[12]
Flavours
 Tobacco flavours[11, 14, 19, 52, 54, 58, 70–74, 76–78, 80–82, 103, 105]
 Menthol[11, 14, 74, 78–80]
 Cinnamon[55]
 Coffee[47]
 Fruit flavours[14, 15, 19, 50, 53, 57, 74, 75, 79]
 Dessert and sweet drink flavours[14, 19, 53, 74, 76]
 Other[12]
 Targeted aromatic molecules[19, 47, 51, 53, 56]
 Unflavoured[11, 13, 14, 16, 19–22, 28, 55, 66, 76, 79, 104, 106]

HBE: human bronchial epithelial; NHBE: normal and diseased bronchial epithelial.