Pelvic floor muscle function recovery using biofabricated tissue constructs with neuromuscular junctions

Damages in pelvic floor muscles often cause dysfunction of the entire pelvic urogenital system, which is clinically challenging. A bioengineered skeletal muscle construct that mimics structural and functional characteristics of native skeletal muscle could provide a therapeutic option to restore normal muscle function. However, most of the current bioengineered muscle constructs are unable to provide timely innervation necessary for successful grafting and functional recovery. We previously have demonstrated that post-synaptic acetylcholine receptors (AChR) clusters can be pre-formed on cultured skeletal muscle myofibers with agrin treatment and suggested that implantation of AChR clusters containing myofibers could accelerate innervation and recovery of muscle function. In this study, we develop a 3-dimensional (3D) bioprinted human skeletal muscle construct, consisting of multi-layers bundles with aligned and AChR clusters pre-formed human myofibers, and investigate the effect of pre-formed AChR clusters in bioprinted skeletal muscle constructs and innervation efficiency in vivo. Agrin treatment successfully pre-formed functional AChR clusters on the bioprinted muscle constructs in vitro that increased neuromuscular junction (NMJ) formation in vivo in a transposed nerve implantation model in rats. In a rat model of pelvic floor muscle injury, implantation of skeletal muscle constructs containing the pre-formed AChR clusters resulted in functional muscle reconstruction with accelerated construct innervation. This approach may provide a therapeutic solution to the many challenges associated with pelvic floor reconstruction resulting from the lack of suitable bioengineered tissue for efficient innervation and muscle function restoration. Statement of significance While bioengineered skeletal muscle constructs have been tested as a treatment option for muscle defects, most of the bioengineered muscle constructs are unable to provide timely innervation necessary for successful grafting and functional recovery. In this study, we fabricated a 3D bioprinted human skeletal muscle construct with biomimetic features of structural, myogenic and innervation characteristics of normal muscle tissue. To increase innervation efficiency, acetylcholine receptors were pre-formed on aligned muscle fibers in the bioprinted muscle construct. We demonstrated that the pelvic floor muscle function can be readily restored by the accelerated innervation through neuromuscular junctions created in the bioprinted muscle constructs. We believe that this strategy may provide suitable bioengineered tissue for efficient innervation and muscle function restoration. (c) 2020ActaMaterialiaInc. PublishedbyElsevierLtd. Allrightsreserved.

Automated summary

Efficient innervation is crucial for successful grafting and functional recovery of bioengineered skeletal muscle constructs. In this study, a 3D bioprinted human skeletal muscle construct with pre-formed AChR clusters is developed and shown to accelerate innervation in vivo, leading to functional muscle reconstruction in a rat model of pelvic floor muscle injury.