The effect of collagen degradation on chondrocyte volume and morphology in bovine articular cartilage following a hypotonic challenge
- 484 Downloads
Collagen degradation is one of the early signs of osteoarthritis. It is not known how collagen degradation affects chondrocyte volume and morphology. Thus, the aim of this study was to investigate the effect of enzymatically induced collagen degradation on cell volume and shape changes in articular cartilage after a hypotonic challenge. Confocal laser scanning microscopy was used for imaging superficial zone chondrocytes in intact and degraded cartilage exposed to a hypotonic challenge. Fourier transform infrared microspectroscopy, polarized light microscopy, and mechanical testing were used to quantify differences in proteoglycan and collagen content, collagen orientation, and biomechanical properties, respectively, between the intact and degraded cartilage. Collagen content decreased and collagen orientation angle increased significantly (p < 0.05) in the superficial zone cartilage after collagenase treatment, and the instantaneous modulus of the samples was reduced significantly (p < 0.05). Normalized cell volume and height 20 min after the osmotic challenge (with respect to the original volume and height) were significantly (p < 0.001 and p < 0.01, respectively) larger in the intact compared to the degraded cartilage. These findings suggest that the mechanical environment of chondrocytes, specifically collagen content and orientation, affects cell volume and shape changes in the superficial zone articular cartilage when exposed to osmotic loading. This emphasizes the role of collagen in modulating cartilage mechanobiology in diseased tissue.
KeywordsArticular cartilage Mechanobiology Microscopy Enzymatic treatment Collagen Chondrocytes
Unable to display preview. Download preview PDF.
- Arokoski JPA, Hyttinen MM, Lapveteläinen T, Takacs P, Kosztaczky B, Modis L, Kovanen V, Helminen HJ (1996) Decreased birefringence of the superficial zone collagen network in the canine knee (stifle) articular cartilage after long distance running training, detected by quantitative polarised light microscopy. Ann Rheum Dis 55: 253–264CrossRefGoogle Scholar
- Bennett HS (1950) Methods applicable to the study of both fresh and fixed materials. Themicroscopical investigation of biological materials with polarized light. In: McClung JR (ed.) McClung’s handbook of microscopical technique. Paul B Hoeber, New York, pp 591–677Google Scholar
- Buschmann MD, Hunziker EB, Kim Y-J, Grodzinsky AJ (1996) Altered aggregan synthesis correlates with cell and nucleus structure in statically compressed cartilage. J Cell Sci 109: 499–508Google Scholar
- Kiraly K, Hyttinen MM, Lapveteläinen T, Elo M, Kiviranta I, Dobai J, Modis L, Helminen HJ, Arokoski JP (1997) Specimen preparation and quantification of collagen birefringence in unstained sections of articular cartilage using image analysis and polarizing light microscopy. Histochem J 29: 317–327CrossRefGoogle Scholar
- Korhonen RK, Han SK, Herzog W (2010b) Osmotic loading of in situ chondrocytes in their native environment. Mol Cell Biomech 7: 125–134Google Scholar
- Laasanen MS, Töyräs J, Korhonen RK, Rieppo J, Saarakkala S, Nieminen MT, Hirvonen J, Jurvelin JS (2003) Biomechanical properties of knee articular cartilage. Biorheology 40: 133–140Google Scholar
- Loeser RF (2000) Chondrocyte integrin expression and function. Biorheology 37: 109–116Google Scholar
- Mankin HJ, Mow VC, Buckwalter JA, Iannotti JP, Ratcliffe A (1994) Form and function of articular cartilage. In: Sheldon RS (ed.) Orthopaedic basic science. American Academy of Orthopaedic Surgeons, USA, pp 1–44Google Scholar
- Poole CA, Ayad S, Gilbert RT (1992) Chondrons from articular cartilage. V. Immunohistochemical evaluation of type VI collagen organisation in isolated chondrons by light, confocal and electron microscopy. J Cell Sci 103: 1101–1110Google Scholar
- Stockwell RA, Meachim G (1973) The chondrocytes. In: Freeman MAR (ed.) Adult articular cartilage. Alden Press, Oxford, pp 51– 99Google Scholar