Fibroblast growth factor-2 primes human mesenchymal stem cells for enhanced chondrogenesis

PLoS One. 2011;6(7):e22887. doi: 10.1371/journal.pone.0022887. Epub 2011 Jul 27.

Abstract

Human mesenchymal stem cells (hMSCs) are multipotent cells capable of differentiating into a variety of mature cell types, including osteoblasts, adipocytes and chondrocytes. It has previously been shown that, when expanded in medium supplemented with fibroblast growth factor-2 (FGF-2), hMSCs show enhanced chondrogenesis (CG). Previous work concluded that the enhancement of CG could be attributed to the selection of a cell subpopulation with inherent chondrogenic potential. In this study, we show that FGF-2 pretreatment actually primed hMSCs to undergo enhanced CG by increasing basal Sox9 protein levels. Our results show that Sox9 protein levels were elevated within 30 minutes of exposure to FGF-2 and progressively increased with longer exposures. Further, we show using flow cytometry that FGF-2 increased Sox9 protein levels per cell in proliferating and non-proliferating hMSCs, strongly suggesting that FGF-2 primes hMSCs for subsequent CG by regulating Sox9. Indeed, when hMSCs were exposed to FGF-2 for 2 hours and subsequently differentiated into the chondrogenic lineage using pellet culture, phosphorylated-Sox9 (pSox9) protein levels became elevated and ultimately resulted in an enhancement of CG. However, small interfering RNA (siRNA)-mediated knockdown of Sox9 during hMSC expansion was unable to negate the prochondrogenic effects of FGF-2, suggesting that the FGF-2-mediated enhancement of hMSC CG is only partly regulated through Sox9. Our findings provide new insights into the mechanism by which FGF-2 regulates predifferentiation hMSCs to undergo enhanced CG.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Lineage / genetics
  • Cell Proliferation / drug effects
  • Chondrogenesis / drug effects*
  • Fibroblast Growth Factor 2 / pharmacology*
  • Gene Expression Regulation / drug effects
  • Humans
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / drug effects*
  • Mesenchymal Stem Cells / metabolism*
  • SOX9 Transcription Factor / genetics
  • SOX9 Transcription Factor / metabolism

Substances

  • SOX9 Transcription Factor
  • Fibroblast Growth Factor 2