Establishment and characterization of spontaneously immortalized Japanese eel muscle-derived preadipocyte cell lines for cultured seafood production

Cultured meat is attracting attention as an alternative sustainable food production system in which cells obtained from the organism are cultured to generate edible tissues in vitro. However, the lack of immortalized cell lines, which are important as raw materials for cultured meat, is an issue for livestock and fish. While several reported myoblast cell lines can be used to develop muscle, very few fat cell lines are available for research, let alone cultured meat. Here, we report the establishment and characterization of spontaneously immortalized cell lines (JE-KRT224, JE-EK9, and JE-F1140) derived from juvenile Japanese eels (Anguilla japonica) muscle tissue, which are capable of lipid accumulation. These cell lines absorbed exogenous fatty acids (oleic acid) and accumulated intracellular lipids when cultured in a growth medium supplemented accordingly. The resulting fatty acid profiles of the cultured cells were comparable to those of raw Japanese eel meat. Furthermore, all three cell lines differentiated into adipocytes when subjected to adipogenic induction conditions typically used for mammalian cells. In standard growth medium, all three lines expressed mesenchymal stem cell markers (CD29, CD73, CD105), the mesenchymal cell marker vimentin, and key adipogenic transcription factors/markers (PPARG, FABP4), supporting their characterization as preadipocyte likely derived from mesenchymal stem cells. This study provides novel, spontaneously immortalized fish cell lines with robust lipid accumulation. These cell lines represent a valuable and sustainable resource for advancing research in fish adipogenesis, developing cultured eel meat, and potentially for broader applications in cultured seafood production.