THE EFFECTS OF AGE ON RABBIT MCL FIBROBLAST MATRIX SYNTHESIS IN RESPONSE TO TGF-BETA(1) OR EGF

In this study, we examined the effects of age on collagen and total pr otein synthesis by ligament fibroblasts in response to growth factors. Three different doses of transforming growth factor-beta(1) (TGF-beta (1)) or epidermal growth factor (EGF) were individually added to in vi tro fibroblast cultures from the medial collateral ligament (MCL) of s keletally immature (age 3 months), mature (age 12 months) and senescen t (age 48-51 months) rabbits. Analysis of the effects of age revealed that fibroblasts from senescent rabbits produced significantly less co llagen in response to TGF-beta 1 or EGF stimulation when compared to f ibroblasts from immature rabbits. Furthermore, increased age was found to result in significant reductions in the baseline levels of collage n synthesis but not total protein synthesis. Additionally, collagen an d total protein synthesis by MCL fibroblasts were significantly affect ed by the TGF-beta(1) dose, but not by the EGF dose. When fibroblasts were normalized to their own controls, the increases in collagen and t otal protein synthesis due to TGF-beta(1) and EGF for the senescent gr oup were found to be greater than those for the skeletally immature ra bbits at all doses. This demonstrates that MCL fibroblasts from senesc ent rabbits are responsive to growth factors. (C) 1997 Elsevier Scienc e Ireland Ltd.