The response of elderly human articular cartilage to mechanical stimuli in vitro

• Published in: Osteoarthritis and cartilage Vol. 13; no. 12; pp. 1084 - 1091
• Main Authors: Plumb, M.S., Aspden, R.M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2005
• Subjects: Aged; Aged, 80 and over; Ageing; Aging - physiology; Analysis of Variance; Articular cartilage; Biomechanical Phenomena; Cartilage, Articular - metabolism; Cartilage, Articular - pathology; Cartilage, Articular - physiopathology; Cell Count; Chondrocytes - pathology; DNA - analysis; Extracellular Matrix Proteins - analysis; Extracellular Matrix Proteins - biosynthesis; Female; Humans; Male; Matrix biosynthesis; Mechanical stimulation; Osteoarthritis - metabolism; Osteoarthritis - pathology; Osteoarthritis - physiopathology; Radioisotopes; Stress, Mechanical; Tissue Culture Techniques; Articular cartilage; Mechanical stimulation; Ageing; Matrix biosynthesis
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2005.07.002

To investigate the biosynthetic response of elderly human femoral head articular cartilage to mechanical stimulation in vitro and its variation with site. Full-depth cartilage biopsies of articular cartilage were removed from defined sites on 10 femoral heads from patients aged 68–95 years. Cartilage explants were subjected to either static or cyclic (2 s on/2 s off) loading in unconfined compression at a stress of 1 MPa for 24 h, or no load. Metabolic activity was assessed by adding medium containing 35S-sulphate and 3H-leucine during the last 4 h of loading and measuring the incorporated radioisotope. Matrix composition was measured in terms of the amounts of collagen, sulphated glycosaminoglycans (GAG) and water content. Loading of elderly human articular cartilage at 1 MPa significantly inhibited incorporation of 35S-sulphate ( P = 0.023) into cartilage explants. Pairwise comparisons showed that the difference in incorporation was only for static loading (43% decrease compared to unloaded) ( P < 0.05). 3H-leucine incorporation appeared to follow the same trends but neither static nor cyclic load was significantly different from control ( P = 0.31). Significant topographical variation was found for % GAG wet and GAG:collagen but not water content, % GAG dry or collagen. Isotope incorporation rates were in the order anterior > superior > posterior. Static loading inhibits matrix biosynthesis in elderly human cartilage, and cyclic loading is not stimulatory. This is in contrast to previous studies on young bovine tissue where cyclic loading is stimulatory.