title: Different responses to mechanical injury in neonatal and adult ovine articular cartilage.
abstract: BACKGROUND
  Articular cartilage injury remains a major challenge in orthopedic surgery. This study aimed to identify differences in gene expression and molecular responses between neonatal and adult articular cartilage during the healing of an injury.
  
  
  METHODS
  An established in vitro model was used to compare the transcriptional response to cartilage injury in neonatal and adult sheep by microarray analysis of gene expression. Total RNA was isolated from tissue samples, linearly amplified, and 15,208 ovine probes were applied to cDNA microarray. Validation for selected genes was obtained by real-time quantitative polymerase chain reaction (RT-qPCR).
  
  
  RESULTS
  We found 1,075 (11.6%) differentially expressed probe sets in adult injured cartilage relative to normal cartilage. A total of 1,016 (11.0%) probe sets were differentially expressed in neonatal injured cartilage relative to normal cartilage. A total of 1,492 (16.1%) probe sets were differentially expressed in adult normal cartilage relative to neonatal normal cartilage. A total of 1,411 (15.3%) probe sets were differentially expressed in adult injured cartilage relative to neonatal injured cartilage. Significant functional clusters included genes associated with wound healing, articular protection, inflammation, and energy metabolism. Selected genes (PPARG, LDH, TOM, HIF1A, SMAD7, and NF-κB) were also found and validated by RT-qPCR.
  
  
  CONCLUSIONS
  There are significant differences in gene expression between neonatal and adult ovine articular cartilage following acute injury. They are partly due to intrinsic differences in the process of development, and partly to different biological responses to mechanical trauma between neonatal and adult articular cartilage.
authors.affiliation: Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Xuhong
authors.initials: X
authors.lastname: Xue
authors.forename: Qixin
authors.initials: Q
authors.lastname: Zheng
authors.forename: Hongbin
authors.initials: H
authors.lastname: Wu
authors.forename: Lixue
authors.initials: L
authors.lastname: Zou
authors.forename: Peng
authors.initials: P
authors.lastname: Li
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002358:Cartilage, Articular / Q000293:injuries* / Q000378:metabolism*; D016000:Cluster Analysis; D055595:Mechanical Phenomena; D058977:Molecular Sequence Annotation; D012756:Sheep; D059467:Transcriptome