A Self-Renewing Biomimetic Skeletal Muscle Construct Engineered using Induced Myogenic Progenitor Cells.

Skeletal muscle represents a highly organized tissue that primarily regenerates by myogenic stem cells. Mimicking an in vitro skeletal muscle differentiation program that contains self-renewing muscle stem cells and aligned myotubes is considered challenging. This study presents the engineering of a biomimetic muscle construct that can self-regenerate and produce aligned myotubes using induced myogenic progenitor cells (iMPCs), a heterogeneous culture consisting of skeletal muscle stem, progenitor, and differentiated cells. Utilizing electrospinning, polycaprolactone (PCL) substrates are fabricated to facilitate iMPC-differentiation into aligned myotubes by controlling PCL fiber orientation. Newly-conceived constructs contain organized multinucleated myotubes alongside self-renewing stem cells, whose differentiation capacity is augmented by Matrigel supplementation. Furthermore, this work utilizes single-cell RNA-sequencing (scRNA-seq) to demonstrate that iMPC-derived constructs faithfully recapitulate a step-wise myogenic differentiation program. Notably, when subjected to a damaging myonecrotic agent, self-renewing stem cells rapidly differentiate into aligned myotubes within the constructs, akin to skeletal muscle repair in vivo. Finally, this study demonstrates that the iMPC derivation protocol can be adapted to engineer human myoblast-derived muscle constructs containing aligned myotubes, showcasing potential for translational applicability. Taken together, this work reports a novel in vitro system that mirrors myogenic regeneration and skeletal muscle alignment for basic research and regenerative medicine.