An efficient serum-free medium for ex vivo expansion of myoblasts from Larimichthys crocea for cultured meat production.

The large-scale production of cultured meat has been restricted by high cost of serum, batch difference and unclear composition, thus it is important to develop serum-free media for cell growth. Here we obtained a serum-free medium (SFM), which was suitable for ex vivo culturing of myoblasts from larimichthys crocea. It offered simple composition and high effectiveness that supporting myoblast attachment, expansion and differentiation. Our findings revealed that the optimal SFM consisted of DMEM/F12 base medium, 5 mg/mL bovine serum albumin (BSA), 20 mmol HEPES, 1 % penicillin/streptomycin mixture (PS) and the exogenous additive hydrocortisone. The living cells of SFM could occupy about 65 % of the serum-containing medium (SM). Additionally, differentiation assays showed that myoblasts cultured without serum still differentiated into more muscle tubes, with a higher fusion index than those cultured with serum. Finally, transcriptome sequencing was conducted to demonstrate that hydrocortisone might act as a ligand binding to G protein-coupled receptors, triggering the downstream PI3K/AKT signaling pathway and leading to cell proliferation. Our findings will provide a basis for large-scale cell expansion and cell culture meat production in the future.