Biochemical and molecular biologic aspects of early detection of human arthroses

New insights into the biochemical and cell-biological alterations occurring in articular cartilage during the early phase of osteoarthrosis (OA) have been gained in the past decade by analysing experimentally induced osteoarthrosis in animals, mostly dogs and rabbits, while early phases of OA in humans so far have escaped diagnostic evaluation. Before the beginning of surface fibrillation loss of proteoglycans from the cartilage matrix could already be detected, as could activation of the synthesis of proteoglycans, collagens and degradative enzymes in chondrocytes. The discovery of a variety of new proteoglycans, glycoproteins and collagens in hyaline cartilage has created new experimental possibilities of identifying specifically different types and stages of degradative alterations in articular cartilage. For the analysis of proteoglycans and collagens a number of biochemical, immunological and molecular biological methods have been developed that allow analysis of cartilage samples from animal experiments - arthroscopic as well as operation probes. In this article we present examples of such studies showing sepharose elution profiles of proteoglycans from normal and OA cartilage, types I, II, and VI collagen expression in articular chondrocytes by immunofluorescence, as well as type X collagen synthesis by cultured arthrotic chondrocytes by metabolic labelling and gel electrophoresis.