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Invasion of human cartilage by cultured multicellular spheroids of rheumatoid synovial cells--a novel in vitro model system for rheumatoid arthritis.

OBJECTIVE
A new 3-dimensional cell culture system was established to examine the invasion of rheumatoid synovial cells into cartilage.


METHODS
Synovial cells from 20 patients with rheumatoid arthritis (RA) and 15 patients with osteoarthritis (OA) were co-cultured as multicellular spheroids with cartilage fragments.


RESULTS
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.


CONCLUSION
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.