In Vitro Cytotoxicity and Risk Assessments of Environmental Pollutants Using Fibroblasts of a Stranded Finless Porpoise (Neophocaena asiaeorientalis)

Abstract

Cetaceans accumulate high levels of environmental pollutants, yet their toxicological studies have been difficult due to technical and ethical issues. It is essential to identify and fill the current knowledge gaps in the in vitro assays available for cetaceans. The present study establishes a novel in vitro assay that uses the fibroblasts of a finless porpoise (Neophocaena asiaeorientalis) (FF) stranded in the Seto Inland Sea (SIS) to answer questions about the cytotoxicity and risks of environmental pollutants. FF were treated with 17 compounds including polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane and their metabolites (DDTs) and evaluated for cytotoxicity, viability, and apoptosis. The results of FF were compared with those of human fibroblasts (HF). The relative potencies of the test compounds were comparable between the two species, as EC50 of these compounds significantly correlated for FF and HF. Exposure-activity ratios (EARs) revealed that accumulation of PCBs and DDTs are likely to pose adverse effects at the cellular level in the SIS finless porpoises, as their tissue concentrations exceeded EC50 values obtained in this study. This study successfully evaluated the risks of environmental pollutants using cetacean fibroblasts isolated by a non-invasive method that may be applied to various cetacean species and compounds.

Directly Reprogrammed Neurons as a Tool to Assess Neurotoxicity of the Contaminant 4-Hydroxy-2′,3,5,5′-tetrachlorobiphenyl (4′OH-CB72) in Melon-Headed Whales

“…Primary cell cultures of melon-headed whales were established from the tissue samples using a primary explant technique, according to a previous study. 14 Detailed information on the fibroblast cell culture is described in the Supporting Information.…”

“…In a study by Dreiem et al in 2009, exposure to 20 μM OH-PCB congener (4-OH-CB36) caused cell death in approximately 35% of rat cerebellar granule cells. In a previous study investigatng the effects of pollutants in finless porpoise and human fibroblasts, exposure to 4′OH-CB72 caused apoptosis in both species. At the same exposure concentration (20 μM) as in the present study, about 30% of cells in both species were apoptotic, and the EC 50 values of these species were comparable (finless porpoise 76 nM, human 50 nM).…”

“…Necropsy was conducted for 15 individuals on site, and pieces of the muscle, kidney, and spleen were obtained from four specimens (PE12, PE26, PE33, and PE34) for cell culture within 24 h of death (Table S1). Primary cell cultures of melon-headed whales were established from the tissue samples using a primary explant technique, according to a previous study . Detailed information on the fibroblast cell culture is described in the Supporting Information.…”

“…In a previous study, fibroblasts were cultured from a stranded finless porpoise (Neophocaena asiaeorientalis) to assess the risk of POPs. 14 However, the types of whale cells that can be cultured are limited, and cell-specific assays for whales have not been developed. To overcome this difficulty, this study adapted methods used in the field of regenerative medicine.…”

“…In addition, since different effects are also expected even between cetacean species, it is desirable to test cetacean species of concern. In a previous study, fibroblasts were cultured from a stranded finless porpoise ( Neophocaena asiaeorientalis ) to assess the risk of POPs . However, the types of whale cells that can be cultured are limited, and cell-specific assays for whales have not been developed.…”