title: Improving chondrogenesis: potential and limitations of SOX9 gene transfer and mechanical stimulation for cartilage tissue engineering.
abstract: Articular cartilage injuries and degeneration affect a large proportion of the population in developed countries world wide. Stem cells can be differentiated into chondrocytes by adding transforming growth factor-beta1 and dexamethasone to a pellet culture, which are unfeasible for tissue engineering purposes. We attempted to achieve stable chondrogenesis without any requirement for exogenous growth factors. Human mesenchymal stem cells were transduced with an adenoviral vector containing the SRY-related HMG-box gene 9 (SOX9), and were cultured in a three-dimensional (3D) hydrogel scaffold composite. As an additional treatment, mechanical stimulation was applied in a custom-made bioreactor. SOX9 increased the expression level of its known target genes, as well as its cofactors: the long form of SOX5 and SOX6. However, it was unable to increase the synthesis of sulfated glycosaminoglycans (GAGs). Mechanical stimulation slightly enhanced collagen type X and increased lubricin expression. The combination of SOX9 and mechanical load boosted GAG synthesis as shown by (35)S incorporation. GAG production rate corresponded well with the amount of (endogenous) transforming growth factor-beta1. Finally, cartilage oligomeric matrix protein expression was increased by both treatments. These findings provide insight into the mechanotransduction of mesenchymal stem cells and demonstrate the potential of a transcription factor in stem cell therapy.
authors.affiliation: AO Research Institute, Davos Platz, Switzerland.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Kupcsik
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Stoddart
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: Lorin M
authors.initials: LM
authors.lastname: Benneker
authors.forename: Mauro
authors.initials: M
authors.lastname: Alini
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D019149:Bioreactors; D002356:Cartilage / Q000166:cytology* / Q000378:metabolism; D002478:Cells, Cultured; D020219:Chondrogenesis / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D020100:Hydrogels; D007150:Immunohistochemistry; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000502:physiology*; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D053674:Aggrecans; D006025:Glycosaminoglycans; D020100:Hydrogels; D055758:SOX9 Transcription Factor; D053773:Transforming Growth Factor beta1