Design and Testing of Electrostatic Aerosol In Vitro Exposure System (EAVES): An Alternative Exposure System for Particles

Abstract

Conventional in vitro exposure methods for cultured human lung cells rely on prior suspension of particles in a liquid medium; these have limitations for exposure intensity and may modify the particle composition. Here electrostatic precipitation was used as an effective method for such in vitro exposures. An obsolete electrostatic aerosol sampler was modified to provide a viable environment within the deposition field for human lung cells grown on membranous support. Particle deposition and particle-induced toxicological effects for a variety of particles including standardized polystyrene latex spheres (PSL) and diesel exhaust emission particle mixtures are reported. The Electrostatic Aerosol in Vitro Exposure System (EAVES) efficiently deposited particles from an air stream directly onto cells. Cells exposed to the electric field of the EAVES in clean air or in the presence of charged PSL spheres exhibited minimal cytotoxicity, and their release of inflammatory cytokines was indistinguishable from that of the controls. For the responses tested here, there are no significant adverse effects caused neither by the electric field alone nor by the mildly charged particles. Exposure to diesel exhaust emissions using the EAVES system induced a threefold increase in cytokines and cytotoxicity as compared to the control. Taken together, these data show that the EAVES can be used to expose human lung cells directly to particles without prior collection in media, thereby providing an efficient and effective alternative to the more conventional particle in vitro exposure methods.

This work was supported in part by the U.S. Environmental Protection Agency Cooperative Agreements R829762 and CR829522, American Chemistry Council Long Range Research Initiative, project ID CIE-0102-02, and Exxon Mobil Foundation Basic research support gift. Although the research described in this article has been funded wholly or in part by the U.S. Environmental Protection Agency through cooperative agreement CR829522 with the Center for Environmental Medicine, Asthma, and Lung Biology, it has not been subjected to the agency's required peer and policy review, and therefore does not necessarily reflect the views of the agency and no official endorsement should be inferred. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. We thank Wenli Zhang, Missy Brighton, and Jonathan Ciencewicki from the Center for Environmental Medicine, Asthma, and Lung Biology for all their technical advice; and Beth Fowler from the Department of Environmental Sciences and Engineering for administrative assistance. We also thank Dr. Leith, Jim Jetters, Randy Goodman, and Glenn W. Walters for their help in modifying the ESP to house the cell culture inserts.