APOPTOSIS IN HUMAN OSTEOARTHRITIC CARTILAGE - A MICROSCOPY REPORT

Knee articular cartilage samples obtained by arthroscopy from four pat ients with well defined knee osteoarthritis (OA) and four obtained aft er corrective surgery from non-osteoarthritic patients (normal) were s tudied by light, confocal and transmission electron microscopy. Sample s were processed by morphological and cytochemical (acid phosphatase) methods as well as by a histoenzymatic TUNEL technique for DNA fragmen tation. The electron microscopy study showed degenerating cells charac terised by fragmentation of the nuclei and cytoplasm, all typical of p rogrammed cell death. The TUNEL technique also demonstrated DNA fragme ntation in the nuclei of chondrocytes from the deep zone of the cartil age from OA patients. 'Clonal' cells displayed fine granular labels. T here were different numbers of labelled nuclei in the four patients. I n non-AO patients, normal cartilage displayed labels mainly in chondro cytes from the superficial zone of the tissue. There was lysosomal act ivity (acid phosphatase) in the OA cartilage, mainly in the non-clonal cells. This activity could be related to the mechanism of cell degene ration in apoptotic chondrocytes.