Osteogenic potential of alpha smooth muscle actin expressing muscle resident progenitor cells

Brya G. Matthews, Elena Torreggiani, Emilie Roeder, Igor Matic, Danka Grcevic, Ivo Kalajzic

Research output: Contribution to journalArticlepeer-review


Heterotopic ossification (HO) is a pathological process where bone forms in connective tissues such as skeletal muscle. Previous studies have suggested that muscle-resident non-myogenic mesenchymal progenitors are the likely source of osteoblasts and chondrocytes in HO. However, the previously identified markers of muscle-resident osteoprogenitors label up to half the osteoblasts within heterotopic lesions, suggesting other cell populations are involved. We have identified alpha smooth muscle actin (αSMA) as a marker of osteoprogenitor cells in bone and periodontium, and of osteo-chondro progenitors in the periosteum during fracture healing. We therefore utilized a lineage tracing approach to evaluate whether αSMACreERT2 identifies osteoprogenitors in the muscle. We show that in the muscle, αSMACreERT2 labels both perivascular cells, and satellite cells. αSMACre-labeled cells undergo osteogenic differentiation in vitro and form osteoblasts and chondrocytes in BMP2-induced HO in vivo. In contrast, Pax7CreERT2-labeled muscle satellite cells were restricted to myogenic differentiation in vitro, and rarely contributed to HO in vivo. Our data indicate that αSMACreERT2 labels a large proportion of osteoprogenitors in skeletal muscle, and therefore represents another marker of muscle-resident cells with osteogenic potential under HO-inducing stimulus. In contrast, muscle satellite cells make minimal contribution to bone formation in vivo.

Original languageEnglish
Pages (from-to)69-77
Number of pages9
Publication statusPublished - Mar 1 2016


  • Alpha smooth muscle actin
  • Heterotopic ossification
  • Mesenchymal progenitor
  • Osteogenesis
  • Satellite cell

ASJC Scopus subject areas

  • Physiology
  • Endocrinology, Diabetes and Metabolism
  • Histology

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