title: Regional Differential Genetic Response of Human Articular Cartilage to Impact Injury.
abstract: OBJECTIVE
  Normal physiological movement creates different weightbearing zones within a human knee: the medial condyle bearing the highest and the trochlea bearing the lowest weight. Adaptation to different physiological loading conditions results in different tissue and cellular properties within a knee. The objective of this study was to use microarray analysis to examine gene expression differences among three anatomical regions of human knee articular cartilage at baseline and following induction of an acute impact injury.
  
  
  METHODS
  Cartilage explants were harvested from 7 cadaveric knees (12 plugs per knee). A drop tower was utilized to introduce injury. Plugs were examined 24 hours after impact for gene expression using microarray. The primary analysis is the comparison of baseline versus impacted samples within each region separately. In addition, pairwise comparisons among the three regions were performed at baseline and after impact. False discovery rate (FDR) was used to evaluate significance of differential gene expression.
  
  
  RESULTS
  In the comparison of before and after injury, the trochlear had 130 differentially expressed genes (FDR ≤ 0.05) while the condyles had none. In the comparison among regions, smaller sets of differentially expressed genes (n ≤ 21) were found, with trochlea being more different than the condyles. Most of more frequently expressed genes in trochlea are developmental genes.
  
  
  CONCLUSIONS
  Within the experimental setup of this study, only the trochlea was displaying an acute genetic response on injury. Our data demonstrated the regional-specific response to injury in human articular cartilage.
authors.affiliation: Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA; Division of Sports Medicine, UHealth Sports Performance and Wellness Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Lauren L
authors.initials: LL
authors.lastname: Vernon
authors.affiliation: Division of Sports Medicine, UHealth Sports Performance and Wellness Institute, University of Miami Miller School of Medicine, Miami, FL, USA; John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Danica D
authors.initials: DD
authors.lastname: Vance
authors.affiliation: John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Liyong
authors.initials: L
authors.lastname: Wang
authors.affiliation: John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Evadnie
authors.initials: E
authors.lastname: Rampersaud
authors.affiliation: John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Jeffery M
authors.initials: JM
authors.lastname: Vance
authors.affiliation: John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Margaret
authors.initials: M
authors.lastname: Pericak-Vance
authors.affiliation: Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.
authors.forename: C-Y Charles
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA; Division of Sports Medicine, UHealth Sports Performance and Wellness Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Lee D
authors.initials: LD
authors.lastname: Kaplan
keywords: articular cartilage; human knee; impact injury; regional genetic expression