Establishment and Characterization of a Swim Bladder-Derived Cell Line from Chu's Croaker (Nibea coibor) for Studying Collagen Regulation

Collagen is a major structural component of the extracellular matrix (ECM) and an important component contributing to the quality of fish maw. The collagen-rich swim bladder provides a suitable tissue source for investigating collagen regulation in fish. Therefore, systematic characterization of long-term cultured swim bladder-derived cells is needed to evaluate their utility as an in vitro model for investigating collagen regulation in fish. Here, we systematically characterized a previously established swim bladder-derived cell line from Chu's croaker (Nibea coibor), designated NCSB, and examined its collagen-related responses to TGF-β1. NCSB cells exhibited fibroblast-like morphology and grew stably in DMEM/F12 medium with 15% FBS at 28 °C for over 40 passages. COI gene sequencing confirmed their species origin as N. coibor, while their fibroblast-like morphology and Vimentin expression were consistent with the mesenchymal-like phenotype. Transient transfection with pEGFP-N1 resulted in detectable GFP expression in NCSB cells. TGF-β1 treatment induced responses consistent with a myofibroblast-like phenotype, including increased α-SMA and collagen-related gene and protein expression, together with increased collagen-associated hydroxyproline in the culture supernatant and Sirius Red staining. Transcriptomic analysis further identified enrichment of the TGF-β signaling and ECM-receptor interaction pathways in TGF-β1-treated NCSB cells. Overall, the systematic characterization and functional evaluation of NCSB may support its utility as an in vitro model for studying collagen regulation in N. coibor.