Engineering assembloids to mimic graft-host skeletal muscle interaction

Abstract

Skeletal muscle (SkM) tissue engineering aims to generate in vitro three-dimensional (3D) products that can be implanted in patients to replace or repair damaged muscles. Having a humanized in vitro model able to mimic the interaction between the innervated recipient and the engineered SkMs at a functional level would greatly help in the evaluation of the graft potential. Here we developed a 3D in vitro model that allowed to investigate the function, stability, and adaptability of the human NM system in response to an engineered SkM construct. To achieved this, we used decellularized SkMs (dSkM)-based constructs as engineered SkM and human neuromuscular organoids (NMOs) as the recipient-like NM system to create graft-host SkM assembloids. We observed migration of myogenic cells and invasion of neural axons from the NMO to the engineered SkM construct in the assembloids, with the generation of functional neuromuscular junctions (NMJs). Finally, we showed that assembloids were able to regenerate following acute damage, with SkM regeneration and functional recovery. Despite limited by the absence of immunocompetent cells and vasculature, our data showed that our assembloid represents a useful tool to evaluate in vitro the response of the human innervated SkM to a potential tissue-engineered SkM graft.