Morphological and cytoskeletal aspects of cultivated normal and osteoarthritic human articular chondrocytes after cyclical pressure: a pilot study.

OBJECTIVE: This study investigated the effect of hydrostatic cyclical pressure on the cell ultrastructure and cytoskeleton of normal and osteoarthritis (OA) human cultivated chondrocytes in vitro. METHODS: The different effects of pressurization with sinusoidal waves at a minimum pressure of 1 MPa, a maximum pressure of 5 MPa and a frequency of 0.25 Hz for 3 hrs on normal and OA chondrocytes were assessed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and immunoflurescence microscopy (IF). RESULTS: Structural differences exist between normal and OA chondrocytes at the nuclear, cytoplasmic and cytoskeletal level. Pressurization did not alter the normal chondrocytes, but had a beneficial effect on OA chondrocytes, by increasing the number of cell organelles responsible for synthesis activities. IF examination has shown that the distribution of actin protein in normal chondrocytes is polarized on the apical sides of the cellular cytoplasm. However, in OA chondrocytes the signal of the actin protein is not as well defined. Similarly, the localization of the tubulin protein in normal and OA cells also appears to be different. Hydrostatic pressure did not cause any modification in the cytoskeletal organization of the OA chondrocytes. CONCLUSION: This study confirms the different morphology, structure and cytoskeletal aspect of normal and OA chondrocytes and the important role played by pressure on cell morphology. The recovery of OA chondrocytes observed by an increase of cytoplasmic organelles does not seem to involve the cytoskeleton

Glucosamine sulfate modulates dysregulated activities of human osteoarthritic chondrocytes in vitro

International audienceObjective: The efficacy of glucosamine sulfate (GS) in the symptomatic treatment of patients with osteoarthritis (OA) is suggested to be mediated by still unknown effects on the altered OA cartilage. Design: Using human OA chondrocytes in culture, the effects of GS on protein synthesis, caseinase, collagenase, phospholipase A2 (PLA2) and protein kinase C (PKC) activities as well as production of nitric oxide and cyclic AMP were studied in both cells and culture medium. Results: GS significantly reduced PLA2 activity, and more modestly collagenase activity, in the OA chondrocytes in a dose-dependent manner. By contrast, PLA2 and collagenase activity of the culture medium was not modified. No effects on caseinase activity was seen. GS significantly and dose-dependently increased protein synthesis. GS did not modify nitric oxide and cAMP production but significantly increased PKC production. Conclusion: GS modified cultured OA chondrocyte metabolism by acting on PKC, cellular PLA2, protein synthesis and possibly collagenase activation. Extrapolation of the effect to the in-vivo situation remains hypothetical but they might represent some possible mechanisms of action of the drug in human

Osteoarthritic cartilage fibrillation is associated with a decrease in chondrocyte adhesion to fibronectin.

International audienceObjective: Cartilage destruction in osteoarthritis (OA) is generally accepted as a failed repair process. Cell adhesion is implicated in tissue repair. Therefore, adhesion of OA chondrocytes to extracellular matrix proteins was investigated.Design: Using chondrocytes from human OA femoral head cartilage, adhesion to fibronectin and type II collagen of cells from distinct areas showing an intact cartilage surface or a fibrillated cartilage surface was studied. Modulation of chondrocyte adhesion by both protein kinase C (PKC) inhibitors and glucosamine sulfate (GS) was also investigated.Results: A significant (P<0.05) decrease in adhesion to fibronectin of chondrocytes from fibrillated cartilage, relative to those from grossly normal OA cartilage, was demonstrated. Adhesion to type II collagen was not modified by the chondrocyte origins (either from normal or fibrillated OA cartilage) Adhesion to fibronectin of cells from grossly intact cartilage was decreased by the addition of PKC and calmodulin-dependent kinase inhibitors, W7 and sphingosine, to the cell culture. Adhesion to fibronectin of chondrocytes from fibrillated cartilage was significantly (P<0.05) increased after glucosamine sulfate treatment.Conclusion: Fibrillation of cartilage from OA femoral head is associated with a defective adhesion of chondrocytes to fibronectin. The process is suggested to be dependent of PKC and/or calmodulin-dependent kinases and potentially reversible. Conceivably, it could play a role in OA cartilage destruction

Amelioration of lapine osteoarthritis by treatment with glycosaminoglycan–peptide association complex (Rumalon)

The chondroprotective potential of glycosaminoglycan–peptide association complex (GP‐C) was examined in the medial meniscectomy model of lapine osteoarthritis (OA). Prophylactic treatment with increasing doses of intramuscular GP‐C (0.05–0.5 ml/kg) caused a significant reduction in OA lesion area and histologic scores, and the effect on disease activity appeared to be dose related. The DNA and uronic acid contents of OA tissue were unaffected by prophylactic treatment with GP‐C. However, levels of hydroxyproline in OA cartilage increased to near control levels with prophylactic treatment. Cartilage levels of active and total metalloproteinases that digest proteoglycans were elevated in rabbits with OA; prophylactic treatment with low‐dose GP‐C (0.05 ml/kg) produced a significant reduction in active, but not total, enzyme. Cartilage levels of tissue inhibitor of metalloproteinases in animals with OA were comparable with control levels, but rose with increasing doses of GP‐C. We also investigated GP‐C as a therapeutic treatment in animals that had already developed OA lesions. Carbon black retention and histologic score returned to near‐normal after therapeutic treatment with GP‐C. Uronic acid and hydroxyproline levels were decreased in OA cartilage. Therapeutic treatment with GP‐C had no statistically significant effect on uronic acid levels, but was associated with increased hydroxyproline content in the cartilage. The changes in metalloproteinase and metalloproteinase inhibitor were similar to those found in the studies of prophylactic treatment. The findings in this animal model may help explain some of the beneficial effects of GP‐C in human OA