Effect of tissue maturity on cell viability in load-injured articular cartilage explants

Adam S. Levin, Chih Tung Christopher Chen, Peter A. Torzilli

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Objective: During joint maturation, articular cartilage undergoes compositional, structural, and biomechanical changes, which could affect how the chondrocytes within the cartilage matrix respond to load-induced injury. The objective of this study was to determine the effects of tissue maturity on chondrocyte viability when explanted cartilage was subjected to load-induced injury. Design: Cartilage explants from immature (4-8-week-old) and mature (1.5-2-year-old) bovine humeral heads were cyclically loaded at 0.5 hertz in confined compression with a stress of 1 or 5 megapascals for 0.5, 1, 3, 6 and 16 h. Cell death was assessed at 0, 24 and 48 h after load removal using cell viability dyes and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The organization of pericellular matrix (PCM), biochemical composition and biomechanical properties of the cartilage were also determined. Results: For the immature and mature cartilage, cell death began at the articular surface and increased in depth with loading time up to 6 h. No increase of cell death was found after load removal for up to 48 h. In both groups, cell death increased at a faster rate with the increase of stress level. The depth of cell death in the immature cartilage was greater than the mature cartilage, despite the immature cartilage having a higher bulk aggregate modulus. A less organized PCM in immature cartilage was found as indicated by the weak staining of type VI collagen. Conclusion: Cells in the mature cartilage are less vulnerable to load-induced injury than those in immature cartilage.

Original languageEnglish (US)
Pages (from-to)488-496
Number of pages9
JournalOsteoarthritis and Cartilage
Issue number6
StatePublished - Jun 2005


  • Cell death
  • Load-induced injury
  • Pericellular matrix
  • Tissue maturity

ASJC Scopus subject areas

  • Rheumatology
  • Biomedical Engineering
  • Orthopedics and Sports Medicine


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