In vitro growth rate of fibroblast-like synovial cells is reduced by methotrexate treatment

Background: Fibroblast-like synovial cells (FLS) can be cultured and expanded in vitro in monolayer. Little is known about the growth characteristics of FLS derived from different patients. Objective: To study FLS cultures, with particular attention to differences in growth rate of FLS from patients with rheumatoid arthritis (RA) and from other arthritic patients. Additionally, to analyse the influence of methotrexate (MTX) treatment, patient age, and disease duration on FLS growth characteristics. Materials and methods: FLS were isolated from needle arthroscopy biopsy specimens. Twenty four patients (11 RA, 8 spondyloarthropathy, 1 osteoarthritis, and 4 undifferentiated arthritis) were studied. FLS population doubling time was determined between passage 2 and passage 5. Differences in population doubling time between RA and non-RA FLS and between FLS from patients receiving MTX and those not receiving this drug were analysed. In addition, possible correlations between FLS population doubling time and patient age or disease duration were examined. Results: In vitro monolayer FLS cultures from needle arthroscopy biopsy specimens showed linear growth characteristics. Cell growth rate was not correlated with type of disease. Cells from patients undergoing treatment with MTX showed a longer population doubling time than FLS from patients not receiving this drug (Mann-Whitney test, p<0.05). No correlation was found with patient age or disease duration. Conclusion: The results suggest that FLS growth in monolayer is not dependent on the disease affecting the joint. MTX treatment, however, was more relevant in determining FLS growth rate.