Different Responds To Mechanical Injury: In Neonatal And Adult Ovine Articular Cartilage

Objective. To investigate the molecular response of adult and neonate ovine articular cartilage to acute mechanical injury.Methods. An established in vitro model was used to compare gene expression difference of different development stage ovine articular cartilage explants 24 hours after mechanical injury with that of uninjured controls by microarray analysis of gene expression. Total RNA was isolated from the tissue samples, linearly amplified, and applied to a 15,208 Ovine probes cDNA microarray (Agilent). Validation for selected genes (PPARG, GRO, TOM, TNC,HIF1Αand LDHA) was obtained by real-time polymerase chain reaction.Results. 86 genes were significantly regulated at least 2-fold following mechanical injury for neonate sheep and 83 genes for adult sheep (p<0.05); 132 probes were up-regulated (p<0.05) in chondrocytes of injury neonatal articular cartilage relative to adult articular cartilage. Conversely, 185 probes were up-regulated (p<0.05) in chondrocytes of injury adult articular cartilage compare to neonatal articular cartilage; Significant functional clusters included genes associated with wound healing, articular protect, inflammation and energy metabolism.Conclusion. There are significant differences in gene expression between neonatal and adult ovine articular cartilage after acute mechanical injury. They are partly due to the intrinsic differences in the process of development, partly due to different biological response to mechanical trauma between neonatal and adult ovine articular cartilage. Both of them contribute to the different self-repair capacity. Of these, specifically PPARG, GRO and TOM could be identified as novel target molecules and potential chondroprotective agent involved in traumatic cartilage injury and cartilage integrated repair.