The in vitro toxicological evaluation of e-liquid aerosol is an important aspect of consumer protection, but the cell model is of great significance. Due to its water solubility, e-liquid aerosol is deposited in the conducting zone of the respiratory tract. Therefore, primary normal human bronchial epithelial (NHBE) cells are more suitable for e-liquid aerosol testing than the widely used alveolar cell line A549. Due to their prolonged lifespan, immortalized cell lines derived from primary NHBE cells, exhibiting a comparable in vitro differentiation, might be an alternative for acute toxicity testing. In our study, A549 cells freshly isolated NHBE cells and the immortalized cell line CL-1548 were exposed at the air-liquid interface to e-liquid aerosol and cigarette mainstream smoke in a CULTEX(®) RFS compact module. The cell viability was analyzed 24 h post-exposure. In comparison with primary NHBE cells, the CL-1548 cell line showed lower sensitivity to e-liquid aerosol but significantly higher sensitivity compared to A549 cells. Therefore, the immortalized cell line CL-1548 is recommended as a tool for the routine testing of e-liquid aerosol and is preferable to A549 cells.
Keywords: CL-1548; CULTEX® RFS; air-liquid interface; cytotoxicity; electronic cigarette; immortalized normal bronchial epithelial cells; nicotine; public health; smoking; tobacco.