Parallel comparison of fibroblast-like synoviocytes from the surgically removed hyperplastic synovial tissues of rheumatoid arthritis and osteoarthritis patients

BACKGROUND: Fibroblast-like synoviocytes (FLS) are essential cellular components in inflammatory joint diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA). Despite the growing use of FLS isolated from OA and RA patients, a detailed functional and parallel comparison of FLS from these two types of arthritis has not been performed. METHODS: In the present study, FLS were isolated from surgically removed synovial tissues from twenty-two patients with OA and RA to evaluate their basic cellular functions. RESULTS: Pure populations of FLS were isolated by a sorting strategy based on stringent marker expression (CD45(−)CD31(−)CD146(−)CD235a(−)CD90(+)PDPN(+)). OA FLS and RA FLS at the same passage (P2-P4) exhibited uniform fibroblast morphology. OA FLS and RA FLS expressed a similar profile of cell surface antigens, including the fibroblast markers VCAM1 and ICAM1. RA FLS showed a more sensitive inflammatory status than OA FLS with regard to proliferation, migration, apoptosis, inflammatory gene expression and pro-inflammatory cytokine secretion. In addition, the responses of OA FLS and RA FLS to both the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) and the anti-inflammatory drug methotrexate (MTX) were also evaluated here. CONCLUSION: The parallel comparison of OA FLS and RA FLS lays a foundation in preparation for when FLS are considered a potential therapeutic anti-inflammatory target for OA and RA.