Induced collagen cross-links enhance cartilage integration

PLoS One. 2013 Apr 4;8(4):e60719. doi: 10.1371/journal.pone.0060719. Print 2013.

Abstract

Articular cartilage does not integrate due primarily to a scarcity of cross-links and viable cells at the interface. The objective of this study was to test the hypothesis that lysyl-oxidase, a metalloenzyme that forms collagen cross-links, would be effective in improving integration between native-to-native, as well as tissue engineered-to-native cartilage surfaces. To examine these hypotheses, engineered cartilage constructs, synthesized via the self-assembling process, as well as native cartilage, were implanted into native cartilage rings and treated with lysyl-oxidase for varying amounts of time. For both groups, lysyl-oxidase application resulted in greater apparent stiffness across the cartilage interface 2-2.2 times greater than control. The construct-to-native lysyl-oxidase group also exhibited a statistically significant increase in the apparent strength, here defined as the highest observed peak stress during tensile testing. Histology indicated a narrowing gap at the cartilage interface in lysyl-oxidase treated groups, though this alone is not sufficient to indicate annealing. However, when the morphological and mechanical data are taken together, the longer the duration of lysyl-oxidase treatment, the more integrated the interface appeared. Though further data are needed to confirm the mechanism of action, the enhancement of integration may be due to lysyl-oxidase-induced pyridinoline cross-links. This study demonstrates that lysyl-oxidase is a potent agent for enhancing integration between both native-to-native and native-to-engineered cartilages. The fact that interfacial strength increased manifold suggests that cross-linking agents should play a significant role in solving the difficult problem of cartilage integration. Future studies must examine dose, dosing regimen, and cellular responses to lysyl-oxidase to optimize its application.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cartilage / chemistry
  • Cartilage / cytology
  • Cartilage / drug effects
  • Cartilage / metabolism*
  • Cartilage, Articular / chemistry
  • Cartilage, Articular / cytology
  • Cartilage, Articular / drug effects
  • Cartilage, Articular / metabolism
  • Cattle
  • Collagen / metabolism*
  • Guided Tissue Regeneration
  • Male
  • Protein-Lysine 6-Oxidase / metabolism
  • Protein-Lysine 6-Oxidase / pharmacology
  • Tensile Strength

Substances

  • Collagen
  • Protein-Lysine 6-Oxidase

Grants and funding

This work was supported by the DHS Blue and White Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.