The relationship between proteoglycan loss, overloading-induced collagen damage, and cyclic loading in articular cartilage

Lorenza Henao Murillo, Maria Pastrama, Keita Ito, René van Donkelaar (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

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The interaction between proteoglycan loss and collagen damage in articular cartilage and the effect of mechanical loading on this interaction remain unknown. The aim of this study was to answer the following questions: (1) Is proteoglycan loss dependent on the amount of collagen damage and does it depend on whether this collagen damage is superficial or internal? (2) Does repeated loading further increase the already enhanced proteoglycan loss in cartilage with collagen damage?

Fifty-six bovine osteochondral plugs were equilibrated in phosphate-buffered saline for 24 hours, mechanically tested in compression for 8 hours, and kept in phosphate-buffered saline for another 48 hours. The mechanical tests included an overloading step to induce collagen damage, creep steps to determine tissue stiffness, and cyclic loading to induce convection. Proteoglycan release was measured before and after mechanical loading, as well as 48 hours post-loading. Collagen damage was scored histologically.

Histology revealed different collagen damage grades after the application of mechanical overloading. After 48 hours in phosphate-buffered saline postloading, proteoglycan loss increased linearly with the amount of total collagen damage and was dependent on the presence but not the amount of internal collagen damage. In samples without collagen damage, repeated loading also resulted in increased proteoglycan loss. However, repeated loading did not further enhance the proteoglycan loss induced by damaged collagen.

Proteoglycan loss is enhanced by collagen damage and it depends on the presence of internal collagen damage. Cyclic loading stimulates proteoglycan loss in healthy cartilage but does not lead to additional loss in cartilage with damaged collagen.
Original languageEnglish
Pages (from-to)1501S-1512S
Number of pages12
Issue number2 suppl
Early online date1 Dec 2021
Publication statusPublished - 1 Dec 2021

Bibliographical note

Funding Information:
The authors would like to thank Marina van Doeselaar for her valuable help with the laboratory procedures of collagen staining and quantification of PG loss. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by the grant program “Programa de Formación Doctoral Francisco José de Caldas Generación del Bicentenario” awarded by the Francisco José de Caldas Institute for the Development of Science and Technology (COLCIENCIAS), LASPAU ID 20110352.


  • collagen damage
  • proteoglycan loss
  • overloading
  • cyclic loading
  • col2-3/4m
  • col2-3
  • 4m


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