Hyaluronate synthesis by synovial villi in organ culture

Extracellular mammalian polysaccharides: glycosaminoglycans and proteoglycans

This review of the mammalian extracellular matrix polysaccharides covered the glycosaminoglycans (GAGs) and their association into proteoglycans. As they necessarily pertain to the chromatographic and electrophoretic separations of these molecules, the structural features of the five principal GAGs were briefly reviewed. Much of the current structural work as well as the separation technology has been concerned with the sulfation state and copolymeric sequences of the individual classes of GAGs. The separation methods discussed included electrophoresis by agarose, acrylamide and cellulose acetate, high-performance liquid chromatography (HPLC), ion-exchange, gel permeation and biospecific affinity methods. Since detection systems are an integral part of chemical separation technology, current thoughts about the best methods to assay GAGs or detect column fractions were discussed. These included polysaccharide-specific detection systems such as Alcian blue dye, 1,9-dimethylmethylene blue, bovine serum albumin-Coomassie blue, as well as non-specific carbohydrate detection systems such as the carbazole or indole hydrochloride methods. Instrumentation used in the detection of chromatography fractions for these molecules was discussed, since the usual ultraviolet detector, standard with HPLC equipment, is often unsatisfactory. The most sensitive specific detection method for GAGs is the use of monoclonal antibodies, which are only now becoming commercially available. The use of these antibodies, combined with HPLC separation, appears to be the best available biochemical technology for studying the extracellular matrix polysaccharides. Finally, the association between proteoglycans, GAGs and mammalian disease processes was reviewed, emphasizing mucopolysaccharidoses and arthritis. The early detection of both of these diseases is desired for effective counselling and treatment. Many of the methods discussed here have been applied, but others are yet to be tried in efforts to further that goal.

Suppression of hyaluronic acid synthesis in synovial organ cultures by corticosteroid suspensions

The effects of sparingly soluble corticosteroid suspensions prepared for intraarticular therapy, of their vehicles, and of hydrocortisone on synovial hyaluronic acid (HA) synthesis were compared in organ cultures of normal canine villous synovium. Both hydrocortisone and the corticosteroid suspensions suppressed HA synthesis, as did 2 vehicle components, polysorbate 80 and myristyl-gamma-picrolinium chloride. Cultures of synovium from joints of dogs which, 1 day previously, had been injected with methylprednisolone acetate suspension synthesized less HA than did control cultures from noninjected joints of the same animals. The results indicate that suppression of HA synthesis is a mechanism by which these drugs can act to reduce joint HA content and promote resolution of synovial effusions.

Hyaluronic acid production in vitro by synovial lining cells from normal and rheumatoid joints

Organ cultures and primary cell cultures were established from synovial tissue collected from patients with rheumatoid arthritis. Hyaluronic acid measured by the incorporation of [3H]glucosamine into the polysaccharide was found to be synthesised in the cultures immediately after transfer from in-vivo to in-vitro conditions. This was in contrast to the primary cultures established from cells isolated from normal joints. The latter cells did not synthesise any detectable hyaluronate. 90-100% of the cells in primary culture were found to be esterase positive, indicating their macrophage nature. The molecular weight of the hyaluronate produced by the pathological cells was low (approximately 50 000) compared with the molecular weight of hyaluronate found in joint fluid from normal or rheumatoid joints. Cell lines of fibroblasts established from rheumatoid joints and studied after four or seven passages also produced hyaluronate of low molecular weight. It is known that similar cell lines from normal joints produce a high molecular weight polymer.

Canine platelet factors stimulate glycosaminoglycan synthesis by synovial cell and organ cultures

Glycosaminoglycan (GAG) synthesis in both canine synovial cell and organ cultures was stimulated by the addition of canine platelet extracts. Canine platelet factor (CPF) biologic activity obtained from acidic ethanol platelet extracts was partially purified, and resembled CTAP-III, a characterized human platelet protein known to stimulate human synovial cell GAG synthesis. These results identify a canine platelet CTAP factor activity, and indicate that the synoviocytes of organ-cultured synovial villi can respond to platelet factors which are potential mediators of synovial GAG synthesis.