To study the expression of insulin-like growth factor I and II (IGF I and II) in synovial tissue specimen of patients with rheumatoid arthritis (RA) and osteoarthritis (OA).
Synovial tissue sections were examined for the expression of IGF I and II by in situ hybridization using digoxigenin labeled antisense and sense RNA probes.
The antisense probe of IGF I reacted with all specimens. IGF II mRNA was expressed in 7/7 RA and 4/5 OA tissues. Cells of the synovial lining and subsynovial layer bound both antisense probes, whereas inflammatory infiltrates of RA tissues were labeled rarely.
The significant number of cells in the synovium that express IGF I and II mRNA suggests a role of IGF in repair mechanisms of articular cartilage in response to injury and effects on fibroblast growth within the synovium.