CD90-positive cells, an additional cell population, produce laminin α2 upon transplantation to dy3k/dy3k mice

Laminin α2 is a component of skeletal and cardiac muscle basal lamina. A defect of the laminin α2 chain leads to severe congenital muscular dystrophy (MDC1A) in humans and dy/dy mice. Myogenic cells including myoblasts, myotubes, and myofibers in skeletal muscle are a possible source of the laminin α2 chain, and myogenic cells are thus proposed as a cell source for congenital muscular dystrophy therapy. However, we observed production of laminin α2 in non-myogenic cells of normal mice, and we could enrich these laminin α2-producing cells in CD90+ cell fractions. Intriguingly, the number of CD90+ cells increased dramatically during skeletal muscle regeneration in mice. This fraction did not include myogenic cells but exhibited a fibroblast-like phenotype. Moreover, these cells were resident in skeletal muscle, not derived from bone marrow. Finally, the production of laminin α2 in CD90+ cells was not dependent on fusion with myogenic cells. Thus, CD90+ cells are a newly identified additional cell fraction that increased during skeletal muscle regeneration in vivo and could be another cell source for therapy for lama2-deficient muscular dystrophy.