A spontaneously immortalized cell line from the muscle of red sea bream (Pagrus major)

Cell culture plays a crucial role in various fields of life science research such as cancer, immunology, and virology. Numerous cell lines have been established in mammals, while fish cell lines remain comparatively limited in number. This study established a spontaneously immortalized cell line from the muscle of red sea bream, Pagrus major, which is a commercially important fish in Japan. Primary cells were isolated from muscle tissue using 0.2% collagenase and cultured in Leibovitz's L-15 medium without CO₂. The cells required fetal bovine serum in a dose-dependent manner at 28 °C for optimal growth. The cells were also able to grow in F12 medium, but not in Dulbecco's modified Eagle's medium. RNA-sequencing analysis raised the possibility that myosatellite cells/myoblasts in primary culture would gradually be replaced with fibroblasts or epithelial-like cells with an increasing number of passages because collagen-related genes were expressed more than in muscle tissue. Upon serum starvation, the cells differentiated into adipocyte-like cells because of slight lipid accumulation. Therefore, the established cells were considered to lack myogenic potential. In conclusion, we established the Nagasaki University Fisheries-P. major 1 (NUF-PM1) cell line, which consisted of fibroblast/epithelial-like cells, but not myosatellite cells/myoblasts, from the muscle of P. major, and we observed the cells over 80 passages. This study adds to the limited number of fish cell lines available for research, which can be used to develop fish cultured meat and as a model for fish adipocyte differentiation.