Collagen IX in weight-bearing areas of human articular cartilage in late stages of osteoarthritis.
OBJECTIVE
To determine if the amounts of collagen IX mRNA and protein are higher in osteoarthritic cartilage from weight-bearing areas of the knee joint compared to non-weight bearing areas in patients with stage IV osteoarthritis (OA).


METHODS
Normal and OA cartilage samples were obtained from 15 patients undergoing total knee replacement or necropsies. mRNA was measured by real time RT-PCR and proteins were detected by Western blot and localized at the light and ultrastructural level.


RESULTS
Collagen IX was found throughout all cartilage layers in healthy and OA tissue. Cells deposited collagen IX in the pericellular and interterritorial matrix and a 66% higher amount of collagen IX was detected in the pericellular matrix of the weight-bearing areas adjacent to the main defect in comparison to the macroscopically intact areas. This is in line with a 3.72 times higher amount of the respective mRNA.


CONCLUSIONS
The increased levels of collagen IX protein and its mRNAs found in the weight-bearing areas adjacent to the main cartilage defect might reflect an attempt on the part of the diseased cartilage tissue to stabilize and protect the remaining matrix of late-stage osteoarthritic cartilage from further destruction.
Koelling
Sebastian
S
Department of Prosthodontics, Work Group Tissue Regeneration, Robert-Koch-Strasse 40, 37075 Göttingen, Germany.
Kruegel
Jenny
J
Klinger
Michael
M
Schultz
Wolfgang
W
Miosge
Nicolai
N
D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000032:analysis; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000378:metabolism*; D016022:Case-Control Studies; D019902:Chondrocytes / Q000378:metabolism / Q000648:ultrastructure; D003094:Collagen / Q000145:classification / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008853:Microscopy; D020370:Osteoarthritis, Knee / Q000378:metabolism* / Q000473:pathology; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis*; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D046509:Tissue Culture Techniques; D016474:Weight-Bearing
D015415:Biomarkers; D012333:RNA, Messenger; D003094:Collagen