Matrix stiffness regulation of integrin-mediated mechanotransduction during osteogenic differentiation of human mesenchymal stem cells

Yu Ru V. Shih, Kuo Fung Tseng*, Hsiu Yu Lai, Chi Hung Lin, Oscar K. Lee

*Corresponding author for this work

Research output: Contribution to journalArticle

251 Scopus citations

Abstract

Mesenchymal stem cells (MSCs) cultured on extracellular matrices with different stiffness have been shown to possess diverse lineage commitment owing to the extracellular mechanical stimuli sensed by the cells. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through the mechanotransducers Rho kinase (ROCK) and focal adhesion kinase (FAK) and subsequently regulates the osteogenic phenotype of MSCs. MSCs were cultured in osteogenic medium on tunable polyacrylamide hydrogels coated with type I collagen with elasticities corresponding to Young's modulus of 7.0±1.2 and 42.1±3.2kPa. Osteogenic differentiation was increased on stiffer matrices, as evident by type I collagen, osteocalcin, and Runx2 gene expressions and alizarin red S staining for mineralization. Western blot analysis demonstrated an increase in kinase activities of ROCK, FAK, and ERK1/2 on stiffer matrices. Inhibition of FAK, an important mediator of osteogenic differentiation, and inhibition of ROCK, a known mechanotransducer of matrix stiffness during osteogenesis, resulted in decreased expression of osteogenic markers during osteogenic induction. In addition, FAK affects osteogenic differentiation through ERK1/2, whereas ROCK regulates both FAK and ERK1/2. Furthermore, α2-integrin was upregulated on stiffer matrices during osteogenic induction, and its knockdown by siRNA downregulated the osteogenic phenotype through ROCK, FAK, and ERK1/2. Taken together, our results provide evidence that the matrix rigidity affects the osteogenic outcome of MSCs through mechanotransduction events that are mediated by α2- integrin.

Original languageEnglish
Pages (from-to)730-738
Number of pages9
JournalJournal of Bone and Mineral Research
Volume26
Issue number4
DOIs
StatePublished - Apr 2011

Keywords

  • integrin
  • matrix stiffness
  • mechanotransduction
  • mesenchymal stem cell
  • osteogenic differentiation

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