Comparative proliferation of non-rheumatoid and rheumatoid human synovial cells

While normal synovial membrane cells have a very long doubling time, rheumatoid arthritis increases cell turn-over leading to the formation of a pannus. We studied the comparative proliferative behaviour in culture of synoviocytes of rheumatoid (RA) and non-rheumatoid (NR) origin in order to evaluate the usefulness of this model to investigate the drugs used in the treatment of inflammatory diseases. First-passage cultures of cells from patients with clinically defined non-inflammatory joint disease or rheumatoid arthritis were observed for 8 days. In the presence of various combinations of supplemented media, 3H-thymidine incorporation, protein content and cell density were assessed. In addition to a relationship between the fetal calf serum (FCS) concentration and cell growth, it was found that RA cells proliferated more rapidly than NR cells. In 1% FCS, protein content and cell density increased in RA cultures whereas NR synoviocytes accumulated in the quiescent phase. In 5% and 10% FCS, RA cells responded more strongly than NR in terms of protein and DNA synthesis and cell division. After 48 hours of relative FCS deprivation, NR cells abruptly started to proliferate; the response of RA cultures was delayed, but the synoviocytes quickly reached preconfluence.