Figure 21.

Bioprinting of skeletal muscle tissues. (A) (Left) photograph, (middle) micrograph, and (right) microCT image of a 3D-bioprinted PEG-fibrinogen scaffold for skeletal muscle fabrication. (B) Immunofluorescent staining of muscle networks displaying alignment of formed myotubes after 15 days of in vitro culture. (C) Schematic of the implantation of 3D muscle constructs into the back of immunocompromised SCID mice. (D) (Top) photographs and (bottom) immunofluorescent staining images against MHC (red) and LAM (green) of the explants after 28 days of in vivo culture. Reproduced with permission from ref.^[238]. (E) (Left) schematic showing the designed fiber bundle structure for bioprinted skeletal muscle organization and (right) 3D visualized motion program of the different bioinks within the construct. (F) The 3D patterning outcome of designed muscle organization (left) before and (after) removing sacrificial Pluronic F127 using the ITOP bioprinter. (G) (Left) schematic diagram and (middle) photograph of ectopic implantation of bioprinted muscle construct in vivo. (Right) immunostaining of skeletal muscle marker desmin to confirming the presence of organized muscle fibers and innervating capability. (H) Immunostaining of (left) MHC⁺ (red) and α-BTX⁺ (orange) structures, (middle) neurofilaments (NF, red) and α-BTX⁺ (orange) structures, and (right) van Willebrand factor (red). Nuclei were stained with DAPI (blue) in all images. (I) Functional assessment of the bioprinted muscle constructs after 4 weeks of implantation. Reproduced with permission from ref.^[64].