Stem cell shape regulates a chondrogenic versus myogenic fate through Rac1 and N-cadherin

Stem Cells. 2010 Mar 31;28(3):564-72. doi: 10.1002/stem.308.


Human mesenchymal stem cells (hMSCs) are multipotent cells that can differentiate into many cell types. Chondrogenesis is induced in hMSCs cultured as a micromass pellet to mimic cellular condensation during cartilage development, and exposed to transforming growth factor beta (TGFbeta). Interestingly, TGFbeta can also induce hMSC differentiation to smooth-muscle-like cell types, but it remains unclear what directs commitment between these two lineages. Our previous work revealed that cell shape regulates hMSC commitment between osteoblasts and adipocytes through RhoA signaling. Here we show that cell shape also confers a switch between chondrogenic and smooth muscle cell (SMC) fates. Adherent and well-spread hMSCs stimulated with TGF beta 3 upregulated SMC genes, whereas cells allowed to attach onto micropatterned substrates, but prevented from spreading and flattening, upregulated chondrogenic genes. Interestingly, cells undergoing SMC differentiation exhibited little change in RhoA, but significantly higher Rac1 activity than chondrogenic cells. Rac1 activation inhibited chondrogenesis and was necessary and sufficient for inducing SMC differentiation. Furthermore, TGF beta 3 and Rac1 signaling upregulated N-cadherin, which was required for SMC differentiation. These results demonstrate a chondrogenic-SMC fate decision mediated by cell shape, Rac1, and N-cadherin, and highlight the tight coupling between lineage commitment and the many changes in cell shape, cell-matrix adhesion, and cell-cell adhesion that occur during morphogenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD / drug effects
  • Antigens, CD / genetics
  • Antigens, CD / metabolism*
  • Cadherins / drug effects
  • Cadherins / genetics
  • Cadherins / metabolism*
  • Cell Adhesion / drug effects
  • Cell Adhesion / genetics
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Cell Lineage / drug effects
  • Cell Lineage / physiology*
  • Cell Shape / drug effects
  • Cell Shape / physiology*
  • Cells, Cultured
  • Chondrocytes / cytology
  • Chondrocytes / drug effects
  • Chondrocytes / metabolism*
  • Chondrogenesis / drug effects
  • Chondrogenesis / physiology
  • Extracellular Matrix / metabolism
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • Humans
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / drug effects
  • Mesenchymal Stem Cells / metabolism*
  • Muscle Development / drug effects
  • Muscle Development / physiology
  • Myocytes, Smooth Muscle / cytology
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / metabolism*
  • Transforming Growth Factor beta3 / metabolism
  • Transforming Growth Factor beta3 / pharmacology
  • Up-Regulation / drug effects
  • Up-Regulation / genetics
  • rac1 GTP-Binding Protein / drug effects
  • rac1 GTP-Binding Protein / genetics
  • rac1 GTP-Binding Protein / metabolism*


  • Antigens, CD
  • CDH2 protein, human
  • Cadherins
  • Transforming Growth Factor beta3
  • rac1 GTP-Binding Protein