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INTRODUCTION
A sustainable alternative to traditional meat is cultivated meat, which is the growth of animal muscle tissue in laboratories. This technology aims to create a cell-laden product that replicates the texture, composition, and structure of conventional meat.[1] However, the hydrogels commonly used in tissue engineering techniques, whether as cast scaffolds or bioinks, often lack the dual capacity to provide both the mechanical properties of meat and the extracellular matrix (ECM)-like environment needed to support cell viability and muscle fiber differentiation.[2][3] Here, we present a bioprinting method using a custom core-shell nozzle to print a filament with a robust gellan gum (GG) shell and an ECM-mimicking core made of recombinant elastin-like protein (ELP).
MATERIALS AND METHODS
We first tested different extrusion rates and concentrations of GG as a shell material in combination with a core of 3 wt% ELP. Naturally derived, edible thickeners, including methyl cellulose (MC) and cellulose nanofibers (CnF), were blended to achieve different core–shell material distributions. Ink formulations were assessed for printability by calculating a printability index, which was based on quantitative evaluation of printed grid structures, flow behavior, and mechanical properties measured using an oscillatory plate rheometer. The ELP core ink was mixed with a model muscle-like cell type (C2C12 cells) and coextruded with the GG shell to produce a multimaterial scaffold. Cell viability and myotube formation after 7 days in differentiation medium was quantified using confocal microscopy.
RESULTS AND DISCUSSION
The results showed that adding GG as a shell and incorporating thickeners into ELP as the core significantly improved the printability of the material system, enabling the fabrication of a continuous multimaterial filament. This approach also enhanced the mechanical properties of the final construct, better mimicking those of commercially available bovine meat. Adding 3% MC to the ELP improved mechanical properties of the core ink, increasing its stiffness to approximately 100 Pa compared to about 10 Pa for the ELP ink alone. A stable core–shell structure, with the core representing approximately 20% of the total cross-sectional area of the filament and achieving a printability index exceeding 0.85, was consistently obtained under optimized conditions. The printed scaffolds maintained cell viability above 90% and supported myotube formation, as confirmed by immunostaining.
CONCLUSIONS
Multi-material bioprinting allowed for the fabrication of a construct with a bioactive core and a robust shell. This strategy of coaxially extruded filaments was able to overcome key limitations of traditional bioprinting materials with low printability. The mechanical properties of the shell supported the fabrication of mechanically robust 3D constructs, while the core supported tissue-like cell viability and differentiation.
REFERENCES
[1] Ahmad, Khurshid, et al. ”Extracellular matrix and the production of cultured meat.” Foods 10.12 (2021): 3116.
[2] Lee, Da Young, and Sun Jin Hur. ”Gaps and solutions for large scale production of cul-
tured meat: a review on last findings.” Current Opinion in Food Science 61 (2025).
[3] Skardal, Aleksander, et al. ”A hydro- gel bioink toolkit for mimicking native tissue biochemical and mechanical properties in bio- printed tissue constructs.” Acta Biomaterialia 25 (2015).
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