Production of food-grade microcarriers based on by-products from the food industry to facilitate the expansion of bovine skeletal muscle satellite cells for cultured meat production

A major challenge for successful cultured meat production is the requirement for large quantities of skeletal muscle satellite cells (MuSCs). Commercial microcarriers (MCs), such as Cytodex (R) 1, enable extensive cell expansion by offering a large surface-to-volume ratio. However, the cell-dissociation step post cell expansion makes the cell expansion less efficient. A solution is using food-grade MCs made of sustainable raw materials that do not require a dissociation step and can be included in the final meat product. This study aimed to produce food-grade MCs from food industry by-products (i.e., turkey collagen and eggshell membrane) and testing their ability to expand bovine MuSCs in spinner flask systems for eight days. The MCs' physical properties were characterized, followed by analyzing the cell adhesion, growth, and metabolic activity. All MCs had an interconnected porous structure. Hybrid MCs composed of eggshell membrane and collagen increased the mechanical hardness and stabilized the buoyancy compared to pure collagen MCs. The MuSCs successively attached and covered the entire surface of all MCs while expressing high cell proliferation, metabolic activity, and low cell cytotoxicity. Cytodex (R) 1 MCs were included in the study. Relative gene expression of skeletal muscle markers showed reduced PAX7 and increased MYF5, which together with augmented proliferation marker MKI67 indicated activated and proliferating MuSCs on all MCs. Furthermore, the expression pattern of cell adhesion receptors (ITGb5 and SDC4) and focal adhesion marker VCL varied between the distinct MCs, indicating different specific cell receptor interactions with the various biomaterials. Altogether, our results demonstrate that these biomaterials are promising prospects to produce custom-fabricated food-grade MCs intended to expand MuSCs.