Analysis of human muscle stem cells reveals a differentiation-resistant progenitor cell population expressing Pax7 capable of self-renewal.

Studies using mouse models have established a critical role for resident satellite stem cells in skeletal muscle development and regeneration, but little is known about this paradigm in human muscle. Here, using human muscle stem cells, we address their lineage progression, differentiation, migration, and self-renewal. Isolated human satellite cells expressed alpha7-integrin and other definitive muscle markers, were highly motile on laminin substrates and could undergo efficient myotube differentiation and myofibrillogenesis. However, only a subpopulation of the myoblasts expressed Pax7 and displayed a variable lineage progression as measured by desmin and MyoD expression. Analysis identified a differentiation-resistant progenitor cell population that was Pax7+/desmin- and capable of self-renewal. This study extends our understanding of the role of Pax7 in regulating human satellite stem cell differentiation and self-renewal. Copyright (c) 2008 Wiley-Liss, Inc.