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Matrix homeostasis in aging normal human ankle cartilage
Matthias Aurich1, A Robin Poole, Agnes Reiner
1Department of Biochemistry, Rush Medical College at Rush-Presbyterian-St. Luke's Medical Center, 1653 West Congress Parkway, Chicago, IL 60612, USA.
Arthritis and Rheumatism
|November 13, 2002
Summary
Aging intact ankle cartilage shows stable collagen and proteoglycan levels, with reduced collagen denaturation. This distinguishes normal aging from osteoarthritis molecular changes.
Area of Science:
- Biochemistry
- Biomaterials Science
- Orthopedics
Background:
- Articular cartilage aging involves changes in collagen and proteoglycan.
- Distinguishing age-related changes from osteoarthritis is crucial for understanding cartilage health.
Purpose of the Study:
- To investigate age-related alterations in collagen and proteoglycan turnover in normal ankle cartilage.
- To differentiate molecular changes due to aging from those seen in osteoarthritis.
Main Methods:
- Analyzed cartilage from 30 donors (16-75 years) for type IIB collagen mRNA, type II collagen (CII) C-propeptide (CPII), and cleavage neoepitopes using immunohistochemistry and immunoassay.
- Assessed glycosaminoglycan (GAG) content, aggrecan epitope 846, and collagenase levels via immunoblotting.
Main Results:
- Type II collagen (CII), GAG, and aggrecan epitope 846 content remained stable after age 30.
- Collagenase-cleaved CII showed a trend of increase with age, while denatured CII decreased, leading to a higher ratio of cleaved to denatured collagen.
- Collagenase levels were detectable but did not change significantly with age.
Conclusions:
- Collagen type II (CII) synthesis and degradation are maintained at a steady state throughout life in ankle cartilage.
- Aging articular cartilage exhibits reduced CII denaturation relative to collagenase-mediated cleavage.
- These findings indicate that molecular degenerative changes typical of osteoarthritis are absent in the aging process of intact ankle cartilage.