Worldwide, many animals are used in regulatory and academic studies to determine the environmental fate and impact of xenobiotic compounds that may be released into the environment. Fish are commonly used in these tests as they inhabit the aquatic environment, the sink into which many pharmaceuticals eventually enter. Fish gills are the primary site of xenobiotic uptake. In line with the replacement, reduction and refinement (3Rs) of the use of animals in scientific practices, alternative methods to in vivo fish testing are required. For rainbow trout (Oncorhynchus mykiss), a commonly used species in European and American in vivo regulatory testing, two gill epithelial models exist – primary gill cells cultured in a two compartment model (termed DSI – double seeded inserts) and the immortalised gill cell line RTgill-‐W1. This work uses these gill cell models to characterise the physiology of the in vitro gill epithelium and assess their suitability as epithelial gill surrogates. DSI cultures were found to have characteristics similar to the in tact gill, whilst experiments investigating the co-‐culture of RTgill-‐W1 with primary gill cells failed to produce epithelia with such features, like high TER and low paracellular permeability. The DSI cell culture system was used to investigate the uptake and efflux of pharmaceuticals over the gill and found that for some, active uptake plays a small but significant role. This work further investigates the metabolism of pharmaceuticals at the gill and shows the relevance of the primary gill cell DSI technique as an appropriate in vitro model, as the metabolite hydroxypropranolol was detected, which in single-‐seeded primary cultures (SSI) and RTgill-‐W1, it was not. This work is an important step forward in the development of alternative in vitro methods to assess the ecotoxicology of xenobiotic compounds in fish and provides evidence that the primary gill cell DSI technique provides the most accurate in vitro gill model. Experimental information obtained from DSI uptake, efflux and metabolism assays has the potential to be incorporated into and supplement in vivo regulatory studies, therefore reducing the numbers of fish used in such tests.
Development and Uses of a Primary Fish Gill Cell Culture System to investigate the Uptake, Efflux and Metabolism of Pharmaceuticals in Ecotoxicology
Stott, L. C. (Author). 2016
Student thesis: Doctoral Thesis › Doctor of Philosophy