A new 3-dimensional cell culture system was established to examine the invasion of rheumatoid synovial cells into cartilage.
Synovial cells from 20 patients with rheumatoid arthritis (RA) and 15 patients with osteoarthritis (OA) were co-cultured as multicellular spheroids with cartilage fragments.
After 4 weeks the rheumatoid spheroids eroded the cartilage. The destruction of cartilage was supported by a high expression level of cathepsin D and matrix metalloproteinases. In contrast, the OA tissue showed attachment to the cartilage only.
Our results indicate that spheroid/cartilage co-cultures seem to be a suitable in vitro model for the study of destructive cellular mechanisms that occur in RA.