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.