Electrohydrodynamic-direct-printed cell-laden microfibrous structure using alginate-based bioink for effective myotube formation

In this study, a fully aligned microfibrous structure fabricated using fibrin-assisted alginate bioink and electrohydrodynamic direct-printing was proposed for skeletal muscle tissue engineering. To safely construct the aligned alginate/fibrin microfibrous structure laden with myoblasts or endothelial cells, various printing conditions, such as an applied electric field, distance between the nozzle and target, and nozzle moving speed, were selected appropriately. Furthermore, to accelerate the formation of myotubes more efficiently, the alginate/fibrin bioink with vascular endothelial cells was co-printed into a spatially patterned structure within a myoblast-laden structure. The myoblast-laden structure co-cultured with endothelial cells presented fully aligned myotube formation and significantly greater myogenic differentiation compared to the myoblast-laden structure without the endothelial cells owing to the more abundant secretion of angiogenic cytokines. Also, when adipose stem cell- and endothelial cell-laden fibrous structure was implanted in a mouse volumetric muscle loss model, accelerated volumetric muscle repair was observed compared to the defect model. Based on the results, this study demonstrates an alginate-based bioink and new bio-fabricating method to obtain microfibrous cell-laden alginate/fibrin structures with mechanically stable and topographical cues. The proposed method can provide a myoblast/endothelial cell-laden fibrous alginate structure to efficiently induce engineering of skeletal muscle tissue, which could be used in muscle-on-a-chip or recovering structures of volumetric muscle defects.