Combined effects of growth factors and static mechanical compression on meniscus explant biosynthesis

Objective: To compare the actions of fibroblast growth factor-basic (bFGF), insulin-like growth factor-I (IGF-I), platelet derived growth factor-AB (PDGF-AB), and transforming growth factor-beta 1 (TGF-beta1) on bovine meniscus tissue explants with and without static mechanical compression. Design: Meniscus tissue explants were cultured in a serum-free environment supplemented with an individual growth factor (1) over a range of concentrations for 4 days, (2) at a single concentration for 2-14 days, and (3) at a single concentration for 4 days coupled with graded levels of static compression. Explants were analyzed for accumulation of newly synthesized proteoglycan and total protein as measured by S-35-sulfate and H-3-proline incorporation, respectively. Results: Over the range of chosen concentrations, TGF-beta1 was the most potent stimulator of both protein and proteoglycan production, whereas bFGF was the least effective stimulator. Over a 2-week period for all four growth factors, the stimulation of proteoglycan production was sustained while there was no stimulation of protein production during this period. The superposition of static mechanical compression inhibited matrix production in the presence of each anabolic factor, with comparable inhibition relative to uncompressed controls for all factors. Conclusions: The growth factors chosen exhibited an anabolic effect on the meniscus tissue explants, encouraging matrix production and deposition. The addition of static mechanical compression produced comparable relative inhibition of matrix production for each growth factor, suggesting that static compression and growth factors may modulate meniscal fibrochondrocyte biosynthesis via distinct pathways. (C) 2004 OsteoArthritis Research Society International. Published by Elsevier Ltd. All rights reserved.