Abstract
Unlike mammals, teleost fish exhibit lifelong skeletal muscle growth, characterized by continued fiber hypertrophy and the formation of new muscle fibers maintained by a persistent progenitor cell population. However, the limited availability of stable muscle progenitor cell lines from commercially important species such as Atlantic salmon ( Salmo salar ) constrains mechanistic studies and emerging applications in cellular aquaculture. Here, we report the establishment and characterization of a novel embryonic-derived salmon muscle progenitor cell line, termed SsEC. These cells were derived from late embryonic stages and exhibited a spindle-shaped morphology, robust proliferative capacity, and sustained expansion beyond 30 passages under defined culture conditions. SsECs demonstrated a distinct extracellular matrix preference, with vitronectin supporting long-term maintenance and expansion. Molecular characterization confirmed stable expression of canonical myogenic markers, including myf5 and myod1 , while transcriptomic profiling revealed enrichment of genes associated with muscle development and sarcomere organization relative to a non-myogenic salmon cell line. Directed differentiation to muscle, using a two-step protocol, induced efficient formation of multinucleated myotubes expressing myosin heavy chain and sarcomeric α-actinin, with upregulation of key differentiation markers such as myog and tnnt3a . Together, these findings establish SsECs as a robust in vitro model cell line for studying salmon muscle development and provide a novel platform for applications in aquaculture research and cellular seafood production.