title: Effects of matrix elasticity and cell density on human mesenchymal stem cells differentiation.
abstract: Human mesenchymal stem cells (hMSCs) can differentiate into various cell types, including osteogenic and chondrogenic cells. The matrix elasticity and cell seeding density are important factors in hMSCs differentiation. We cultured hMSCs at different seeding densities on polyacrylamide hydrogels with different stiffness corresponding to Young's moduli of 1.6 ± 0.3 and 40 ± 3.6 kPa. The promotion of osteogenic marker expression by hard gel is overridden by a high seeding density. Cell seeding density, however, did not influence the chondrogenic marker expressions induced by soft gel. These findings suggest that interplays between cell-matrix and cell-cell interactions contribute to hMSCs differentiation. The promotion of osteogenic differentiation on hard matrix was shown to be mediated through the Ras pathway. Inhibition of Ras (RasN17) significantly decreased ERK, Smad1/5/8 and AKT activation, and osteogenic markers expression. However, constitutively active Ras (RasV12) had little effect on osteogenic marker expression, suggesting that the Ras pathways are necessary but not sufficient for osteogenesis. Taken together, our results indicate that matrix elasticity and cell density are important microenvironmental cues driving hMSCs proliferation and differentiation.
authors.affiliation: 111 Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing, 400044, PR China.
authors.forename: Ruyue
authors.initials: R
authors.lastname: Xue
authors.forename: Julie Yi-Shuan
authors.initials: JY
authors.lastname: Li
authors.forename: Yiting
authors.initials: Y
authors.lastname: Yeh
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Shu
authors.initials: S
authors.lastname: Chien
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D055119:Elastic Modulus / Q000502:physiology; D004548:Elasticity / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation; D011905:Genes, ras; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051785:Smad Proteins / Q000378:metabolism
chemical_list: D015415:Biomarkers; D051785:Smad Proteins; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: cell density; chondrogenesis; matrix elasticity; mesenchymal stem cells; osteogenesis