Dynamic compressive strain inhibits nitric oxide synthesis by equine chondrocytes isolated from different areas of the cartilage surface.
BACKGROUND
Chondrocytes within articular cartilage respond to the mechanical stresses associated with normal joint loading via a series of signalling pathways. Specific biomolecules, such as nitric oxide (NO), have been implicated in these mechanotransduction processes. It has been shown that the synthesis of NO can be inhibited by dynamic compressive strain of chondrocytes in vitro which, in turn, leads to an up-regulation of specific metabolic parameters.


OBJECTIVE
Chondrocytes isolated from different joint locations and seeded in agarose constructs respond in a distinct manner to the application of dynamic compression.


METHODS
Chondrocytes were isolated separately from the equine patella groove and the femoral condyle, representing high loaded areas (HLA) and low loaded areas (LLA), respectively, of 6 specimens of different ages. The cells were seeded in agarose constructs and cultured either in an unstrained state or strained under dynamic loading at 1 Hz for 48 h. The synthesis of nitric oxide (NO), proteoglycan synthesis and chondrocyte proliferation were assessed.


RESULTS
Equine chondrocytes were found to synthesise significant basal levels of NO, regardless of topographical origin or age of tissue. Marked differences in both proteoglycan synthesis and cell proliferation were, however, revealed between the 2 chondrocyte subpopulations. Dynamic compression inhibited NO synthesis but significant alterations in proteoglycan synthesis and cell proliferation were apparent in a minority of cases.


CONCLUSIONS
The differential response of the subpopulations of chondrocytes derived from the HLA and LLA provides a potential mechanism which enables the biomechanical demands of differing joint regions to be maintained.
Wiseman
M
M
IRC Biomedical Materials, Institute of Orthopaedics, Stanmore, London, UK.
Henson
F
F
Lee
D A
DA
Bader
D L
DL
D000362:Agar; D000367:Age Factors; D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism; D002455:Cell Division; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism / Q000502:physiology*; D006025:Glycosaminoglycans / Q000378:metabolism; D006736:Horses; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D013314:Stress, Mechanical
D006025:Glycosaminoglycans; D009569:Nitric Oxide; D000362:Agar