Effects of hydrostatic pressure on morphological and ultrastructural aspects on normal and osteoarthritic human articular chondrocytes

In this work we studied the morphological and ultrastructural aspects of normal and osteoarthritic (OA) human articular chondrocytes cultivated in alginate gel for 48 hours. After this period the chondrocytes in Petri dishes were exposed to cyclic pressurization (minimum pressure 1 MPa and maximum pressure 5 MPa) at 0.25 Hz frequency for three hours. In other loading procedures the cells were exposed to continuous pressure (24 MPa) for three hours. Some dishes were not pressurised and these served as controls. The cells were then fixed for transmission electron microscopy (T.E.M.) and for scanning electron microscopy (S.E.M.). No ultrastructural changes were observed in normal chondrocytes exposed at physiological pressure. OA cells placed under physiological pressure showed a partial recovery on morphological and ultrastructural aspects. Normal and OA samples exposed to continuous pressure (24 MPa) showed a morphological worsening in both T.E.M. and S.E.M. studies.