Issue 4, 2017

Regulating temperature and relative humidity in air–liquid interface in vitro systems eliminates cytotoxicity resulting from control air exposures

Abstract

VITROCELL® systems permit cell exposures at the air–liquid interface (ALI); however, there are inconsistent methodologies in the literature for their operation. Some studies find that exposure to air (vehicle control) induced cytotoxicity relative to incubator controls; others do not mention if any cytotoxicity was encountered. We sought to test whether temperature and relative humidity (temp/RH) influence cytotoxicity with an unmodified (conditions A & B) and modified (condition C) VITROCELL® 6 CF with temp/RH controls to permit conditioning of the sampled air-flow. We exposed BEAS-2B cells for 1 h to air and measured viability (WST-1 cell proliferation assay) and lactate dehydrogenase (LDH) release 6 h post-exposure. Relative to controls, cells exposed to air at (A) 22 °C and 18% RH had a 47.9% ± 3.2% (p < 0.0001) reduction in cell viability and 10.7% ± 2.0% (p < 0.0001) increase in LDH release (B) 22 °C and 55% RH had a 40.3% ± 5.8% (p < 0.0001) reduction in cell viability and 2.6% ± 2.0% (p = 0.2056) increase in LDH release, or (C) 37 °C and >75% RH showed no changes in cell viability and no increase in LDH release. Furthermore, cells exposed to air at 37 °C and >75% RH 24 h post-exposure showed no changes in viability or LDH release relative to incubator controls. Thus, reductions in cell viability were induced under conditions used typically in the literature (conditions A & B). However, our modifications (condition C) overcome this shortcoming by preventing cell desiccation; regulating temp/RH is essential for conducting adequate ALI exposures.

Graphical abstract: Regulating temperature and relative humidity in air–liquid interface in vitro systems eliminates cytotoxicity resulting from control air exposures

Article information

Article type
Paper
Submitted
12 Apr 2017
Accepted
22 May 2017
First published
23 May 2017

Toxicol. Res., 2017,6, 448-459

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