A bioengineered niche preserves the quiescence of muscle stem cells and enhances their therapeutic efficacy

Here, the authors describe a system for maintaining muscle stem cells (MuSCs) in vitro in a potent, quiescent state. They screen for factors that could maintain mouse MuSC quiescence and defined a quiescence medium. The authors also designed artificial muscle fibers (AMFs) that mimic the native myofiber of the MuSC niche. Mouse MuSCs maintained in quiescence medium on AMFs showed enhanced potential for engraftment, tissue regeneration, and self-renewal after transplantation in mice. That also evaluated if the muscle fiber specific membrane protein laminin-211 could maintain MuSCs quiescence. The AMFs were coated with recombinant Integrin α4β1 followed by recombinant laminin-211. Indeed, the results showed similarly prolonged quiescence in vitro and enhanced potency in vivo. When seeded onto the laminin-coated AMFs and cultured for three days, mouse MuSCs showed reduced activation as assessed by EdU incorporation, increased viability as assessed by ATP levels, and higher Pax7 and lower MyoD protein expression when compared to AMFs alone or functionalized with integrin α4β1 only.