title: The effect of hypoxia on the chondrogenic differentiation of co-cultured articular chondrocytes and mesenchymal stem cells in scaffolds.
abstract: In this work, we investigated the effects of lowered oxygen tension (20% and 5% O2) on the chondrogenesis and hypertrophy of articular chondrocytes (ACs), mesenchymal stem cells (MSCs) and their co-cultures with a 30:70 AC:MSC ratio. Cells were cultured for six weeks within porous scaffolds, and their cellularity, cartilaginous matrix production (collagen II/I expression ratio, hydroxyproline and GAG content) and hypertrophy markers (collagen X expression, ALP activity, calcium accumulation) were analyzed. After two weeks, hypoxic culture conditions had expedited chondrogenesis with all cell types by increasing collagen II/I expression ratio and matrix synthesis by ~2.5-11 and ~1.5-3.0 fold, respectively. At later times, hypoxia decreased cellularity but had little effect on matrix synthesis. ACs and co-cultures showed similarly high collagen II/I expression ratio and GAG rich matrix formation, whereas MSCs produced the least hyaline cartilage-like matrix and obtained a hypertrophic phenotype with eventual calcification. MSC hypertrophy was further emphasized in hypoxic conditions. We conclude that the most promising cell source for cartilage engineering was co-cultures, as they have a potential to decrease the need for primary chondrocyte harvest and expansion while obtaining a stable highly chondrogenic phenotype independent of the oxygen tension in the cultures.
authors.affiliation: Department of Bioengineering, Rice University, Houston, TX 77005, USA.
authors.forename: Ville V
authors.initials: VV
authors.lastname: Meretoja
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Dahlin
authors.forename: Sarah
authors.initials: S
authors.lastname: Wright
authors.forename: F Kurtis
authors.initials: FK
authors.lastname: Kasper
authors.forename: Antonios G
authors.initials: AG
authors.lastname: Mikos
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology*; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects / Q000235:genetics; D018920:Coculture Techniques / Q000379:methods*; D003094:Collagen / Q000096:biosynthesis; D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006025:Glycosaminoglycans / Q000378:metabolism; D006909:Hydroxyproline / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D006025:Glycosaminoglycans; D003094:Collagen; D004247:DNA; D000469:Alkaline Phosphatase; D006909:Hydroxyproline; D010100:Oxygen; D002118:Calcium