In a new research paper published in In Vitro Toxicology, scientists show that e-cigarette vapor has no cytotoxicity on human airway tissue.
One of the main problems in e-cigarette research is that there are currently no standards for the assessment of aerosol emissions. Different tests and methodologies each have their pros and cons, and sometimes faulty methodologies can lead to misleading results.
To tackle this problem, a team of scientists from the UK and US have developed a test method that is physiologically relevant which mimics the structure, function and exposure of normal human airway tissue. The researchers developed and optimized an assay using 3D reconstructed airway culture derived from primary human tracheal/bronchial epithelial cells grown in the air-liquid interface. They then employed a smoking robot, which gives the researchers precise control on the airflow, vacuum rate, and exposure time of vapor puffs.
By using the 3D human airway tissue culture and a smoking robot, the researchers were able to induce and measure aerosol irritancy generated from two kinds of e-cigarettes as well as cigarette smoke. They showed that e-cigarette aerosols used in this study have little, if any cytotoxic effect on human airway tissue.
The researchers used a rather aggressive procedure of continuous exposing the human airway tissue cultures for 6 hours. The results show that six hours of exposure to cigarette smoke resulted in near-complete cell death, but the same exposure to e-cigarette vapour did not affect the tissue viability. In fact, the results from e-cigarette vapors were similar to those of control cells exposed only to air.