Table 1.

Various bioinks formulated for engineering skeletal muscle tissue through additive manufacturing technologies.

Bioprinting strategy	Bioink composition	Myogenic progenitors	In vitro/In vivo results	Reference
FDM/DIW(ITOP)	Gelatin/fibrinogen/HA	C2C12	• Multi-cellular constructs aimed at mimicking the myotendinous junction (MTJ) were fabricated intercalating hydrogel fibers loaded with C2C12 or NIH/3T3 between PU or PCL fibers • Zonal cellular organization typical of MTJ was recapitulated	Merceron et al. [82]
Microfluidic/Co-axial bioprinting	Alginate/PEG-Fibrinogen	C2C12	• Multi-cellular constructs with compartmentalized cell spatial organization • Anisotropic aligned structures support myoblast 3D organization and differentiation	Costantini et al. [88]
Inkjet printing	Suspension of cells in sterile phosphate-buffered saline (PBS) solution	C2C12	• High resolution (85 εm) and cell viability (>90%) • Development of bio-MEMS • Formation of confluent myotubes after 4 days on cantilevers	Gao et al. [95]
SLA	Matrigel/Fibrinogen/Collagen I	C2C12	• Maturation of myotubes after electrical stimulation • Formation of biohybrid robot powered by an antagonistic pair of skeletal muscle tissues • Inchworm-like crawling locomotion of the structure at 117.8 εm/s	Cvetkovic et al. [96]
SLA	Matrigel/Fibrinogen	Optogenetic C2C12	• Bio-bots powered by bioactuators controlled by noninvasive light stimuli • Directional locomotion (310 μm/s or 1.3 body lengths/min) and 2D rotational steering (2°/s)	Raman et al. [98]
SLA	Matrigel/Fibrinogen	C2C12	• Development of a mesoscale model for studying skeletal muscle physiology in vitro • Larger active tension forces created in muscle rings (184 ± 20 μN) after 17 days of growth in response to optical stimulation	Raman et al. [99]
FDM/Electrospinning/DIW	Alginate/PEO	C2C12	• Control of myoblast proliferation and organization by assembling a cell-laden hierarchical scaffold containing additional multi-layered PCL struts and micro/nanofibers	Yeo et al. [100], [101]
FDM	–	C2C12	• Aligned scaffolds were fabricated out of PVA/PCL (3:7 ratio). After leaching PVA, samples were coated with collagen • Micropatterned/fibrous PCL bundles guided C2C12 alignment	Kim et al. [102]
FDM/DIW	Muscle-derived ECM	C2C12	• Biomimetic matrix supported higher cell viability, increased cell proliferation and myogenic gene expression compared to constructs prepared with collagen bioink. • Pre-patterning of acetylcholine receptors	Choi et al. [103]
FDM/DIW	Gelatin/fibrinogen/HA/Glycerol	C2C12	• Myotube formation after 7 days of in vitro culture • Bioprinted constructs implanted subcutaneously in nude rats showed organized muscle fibers, acetylcholine receptors, nerve contacts, and vascularization	Kang et al. [104]
FDM/DIW(ITOP)	Fibrinogen/Gelatin	Human muscle progenitor cells (hMCs) isolated from biopsies	• Transplantation of the construct in a rat tibialis anterior (TA) muscle defect model • 82% restoration of the muscle force after 8 weeks post-surgery • Bioprinted constructs well-integrated with the vascular and neural networks	Kim et al. [105]
3D printing/gel casting	Silk fibroin/Collagen I/Matrigel	Human primary skeletal myoblasts (hSKMs)	• Myoblasts can be differentiated in co-culture with NG108–15 and hiNSC-derived motoneuron-like cells in 2D and 2.5 with mature cell-specific phenotypic expression • 3D neuromuscular co-cultures can be formed with active anisotropic myofiber function.	Dixon et al. [106]