Plant & Animal Genomes XIV Conference Plant & Animal Genomes XIV ConferenceJanuary 14-18, 2006
Town & Country Convention Center
San Diego, CA
Naoki Miura , James N. MacLeod
Articular cartilage is an avascular tissue. Normal oxygen tension is low, with estimates ranging from less than 10% (~70 mm Hg) at the joint surface to less than 1% (~7 mm Hg) in the deepest layers. To investigate the effect of oxygen tension on chondrocyte function, adherent monolayer and non-adherent aggregate cultures of primary equine articular chondrocytes were cultured under control (20%) and low (2%) oxygen conditions. Transcriptional profiling was used to compare patterns of gene expression after 7 days of culture. Total RNA was isolated, subjected to one round of linear amplification, and hybridized to a 9322 element equine-specific cDNA microarray. Three biological replicates of monolayer and aggregate cultures at both oxygen tensions were compared with a dye-swap experimental design. Hypoxia increased steady state levels of the transcripts encoding three marker proteins of chondrocyte differentiation, type II collagen, aggrecan, and the (V+C)- isoform of fibronectin. In broader analyses, hypoxia consistently caused greater changes (up-regulation or down-regulation of transcripts) in the monolayer cultures. One possible explanation is that relative hypoxic conditions may develop spontaneously within the interior of the cell clusters that form in nonadherent aggregate cultures, even when the cells are maintained under conditions of normoxia. The importance of oxygen tension for chondrocyte differentiation, normal chondrocyte function, and the repair of structural lesions in articular cartilage is undetermined.