Muscle satellite cells are a rare regenerative population in adult skeletal muscle and have potential to repair damaged muscle tissue. In this episode, Simone Spuler and colleagues demonstrate that satellite cells can be successfully expanded from human adult muscle biopsies in culture and transplantation of satellite cell-containing human muscle fiber fragments into irradiated mice restores damaged muscle tissue. Isolated muscle fibers could be stored in the cold for a period of time and still retain the ability to engraft and regenerate muscle. Moreover, Spuler and colleague determined that adult-derived satellite cells could be genetically manipulated with Sleeping Beauty transposon–mediated gene transfer. Together, this study suggests that adult human muscle satellite cells have potential as a gene therapy tool for treating muscular dystrophies.
Muscle satellite cells promote regeneration and could potentially improve gene delivery for treating muscular dystrophies. Human satellite cells are scarce; therefore, clinical investigation has been limited. We obtained muscle fiber fragments from skeletal muscle biopsy specimens from adult donors aged 20 to 80 years. Fiber fragments were manually dissected, cultured, and evaluated for expression of myogenesis regulator PAX7. PAX7+ satellite cells were activated and proliferated efficiently in culture. Independent of donor age, as few as 2 to 4 PAX7+ satellite cells gave rise to several thousand myoblasts. Transplantation of human muscle fiber fragments into irradiated muscle of immunodeficient mice resulted in robust engraftment, muscle regeneration, and proper homing of human PAX7+ satellite cells to the stem cell niche. Further, we determined that subjecting the human muscle fiber fragments to hypothermic treatment successfully enriches the cultures for PAX7+ cells and improves the efficacy of the transplantation and muscle regeneration. Finally, we successfully altered gene expression in cultured human PAX7+ satellite cells with Sleeping Beauty transposon–mediated nonviral gene transfer, highlighting the potential of this system for use in gene therapy. Together, these results demonstrate the ability to culture and manipulate a rare population of human tissue-specific stem cells and suggest that these PAX7+ satellite cells have potential to restore gene function in muscular dystrophies.
Andreas Marg, Helena Escobar, Sina Gloy, Markus Kufeld, Joseph Zacher, Andreas Spuler, Carmen Birchmeier, Zsuzsanna Izsvák, Simone Spuler