Mucopolysaccharides in tissue cultures of human and mammalian synovial membrane

Heritability and control of differentiated function in cultured cells

An established tissue culture cell line which retains a differentiated function in vitro is described. The cell line is of connective tissue origin, and its characteristic property is the synthesis and secretion of acid mucopolysaccharides, mainly hyaluronic acid. This differentiated cell function, the activity of which depends on continuous gene action, was found to be possessed by each of eleven clonal substrains, and is therefore a genetically heritable cell character. Rate of acid mucopolysaccharide biosynthesis falls sharply under the influence of the environmental conditions existing in crowded cultures, and this rate also declines if protein synthesis is directly inhibited with puromycin. Environmental modification of a differentiated product of gene action is thus illustrated in this study.

THE UPTAKE OF IRON IN RABBIT SYNOVIAL TISSUE FOLLOWING INTRA-ARTICULAR INJECTION OF IRON DEXTRAN. A LIGHT AND ELECTRON MICROSCOPE STUDY

Iron dextran (molecular weight 7,000) diffuses rapidly from the joint cavity through the synovium, along lymphatics and extracellular tissue spaces; articular cartilage is impermeable to iron dextran. There is also rapid cellular uptake by synovial lining cells, particularly of the vacuolar type; endoplasmic reticulum-containing lining cells rarely take up iron dextran. Cellular uptake is probably effected by pseudopodial folds projecting from the cell surface and enclosing extracellular material. Cells containing iron may degenerate and be ingested by phagocytes, and this may account for the concentration of iron in a smaller proportion of cells on or below the synovial surface in the later stages. At 6 to 18 hours after injection there is a mild inflammatory reaction and some synovial proliferation; from this stage onwards intracellular iron occurs in the form of haemosiderin. Granules of haemosiderin are present in the synovium 3 months after injection and possibly longer.

Hyaluronate synthesis by synovial villi in organ culture

Individual canine synovial villi were used to establish short-term synovial organ cultures. These villi incorporated 3H-glucosamine into highly-polymerized 3H-hyaluronic acid (3H-HA), which was the only 3H-glycosaminoglycan identified in the culture medium. Some 3H-HA, and larger amounts of other 3H-glycosaminoglycans, were recovered from cultured tissues. Culture medium 3H-HA content was proportional to the surface area of cultured villi. Organ cultures of nonvillous synovium were compared with villi; nonvillous cultures synthesized less 3H-HA per mm2 of their synovial intimal surface than villi. These cultures complement cell culture techniques for in vitro studies of synovial lining cell function.

Glycosaminoglycans produced by human synovial cell cultures

Human synovial cells in culture are known to synthesize hyaluronic acid, but the production of sulfated glycosaminoglycans (GAG) has received less attention. Using 14C-glucosamine as a precursor, GAG content was studied in the medium, trypsin-solubilized pericellular layer, and cell residue fraction of cultured synovial cells derived from the synovial membranes of nonrheumatoid and rheumatoid joints. Over 90% of the total non-dialyzable counts appeared in the culture medium, for the most part in hyaluronic acid. The remaining nondialyzable counts were cell-associated, almost equally divided between the pericellular layer and cell residues. In these fractions, only part of the counts were in GAG susceptible to testicular hyaluronidase digestion, and GAG were significantly lower in the cell residue of the rheumatoid synovial cells compared to the nonrheumatoid cells. Analysis of the chondroitinase ABC and AC digestion products of these GAG indicated the presence of chondroitin-4 and -6 sulfates, and dermatan sulfate, but not heparan sulfate. Similar findings with respect to the identity of the GAG in nonrheumatoid and rheumatoid synovial cell culture media were obtained with 35SO4 as a precursor.

Synthesis of sulphated proteoglycans by rheumatoid and normal synovial tissue in culture

Synthesis of sulphated proteoglycans by cell lines derived from explants of 7 rheumatoid and 9 normal specimens of synovial tissue, as well as by 7 lines of skin fibroblasts from non-rheumatoid patients, was examined. Cells of all 3 types were cultured as monolayers. They were then disaggregated and their capacity to synthesise proteoglycan estimated in cell suspensions by the incorporation of [35S]-sulphate into CPC-precipitable material during 2 hours of incubation. Cell suspensions incorporated somewhat more [35S]-sulphate than corresponding duplicate monolayers. Synovial cells from rheumatoid patients incorporated 2 to 3 times as much [35S]-sulphate as synovial cells from normals. Skin fibroblasts, however, incorporated less [35S]-sulphate than rheumatoid or normal synovial cells up to the fifth passage. Thereafter their incorporation gradually increased to overtake that of synovial cells. About one-half to one-third of the total [35S]-sulphate labelled material was closely associated with cells from synovial tissues and fibroblasts respectively.

Distribution of biologically labelled radioactive hyaluronic acid injected into joints

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Enzymatic degradation of cartilage by dialysed urine of rheumatoid patients

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Synovial cells. A study of the morphology and an examination of protein synthesis of synovial cells

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Cellular origin of hyaluronateprotein in human synovial membrane

Bright fluorescent staining, which indicates the presence of hyaluronateprotein, was observed in the lining cells of the synovial membrane following application of rabbit antiserum to hyaluronateprotein and a fluorescein-labeled antiserum to rabbit gamma-globulin. Staining was shown to be specific and due to antigenic determinants on or closely associated with the protein moiety of hyaluronateprotein.

Culture of synovial cells in vitro. Notes on isolation and propagation

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