Platelet-released growth factors enhance the secretion of hyaluronic acid and induce hepatocyte growth factor production by synovial fibroblasts from arthritic patients

Objectives. Autologous platelet-secreted growth factors (GFs) may have therapeutic effects in osteoarthritis (OA) capsular joints via multiple mechanisms. Our aim was to examine the effect of a platelet-derived preparation rich in growth factors (PRGFs) in OA synovial cell biology. Methods. Synovial cells were isolated from 10 osteoarthritic patients and cultured in serum-free media (basal conditions) and exposed to either a platelet-poor preparation or PRGF for 72 h. Cells activated with interleukin-1� (IL-1� ) for 48 h were also exposed to PRGF. Changes in several events relevant to joint homeostasis including (i) hyaluronic acid (HA) secretion, (ii) the balance between metalloproteinase-1, -3 and -13 (MMP-1, MMP-3 and MMP-13) and tissue inhibitor-1 (TIMP-1) and (iii) the secretion of transforming growth factor-� 1(TGF-� 1), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF), were all assessed. Results. PRGF significantly enhanced HA secretion compared with platelet-poor preparations, P < 0.05; at the same time release of TIMP-1, MMP-1, MMP-3 and MMP-13 were not affected. An increased HGF production was observed (P < 0.05) but VEGF and TGF-� 1 levels remained unchanged. PRGF significantly enhanced the secretion of HA induced by IL-1� activation, P < 0.05, but it did not modify the IL-1� -induced rise in MMP-1, MMP-3 and VEGF. In contrast, PRGF-induced HGF production was abolished by the presence of IL-1� during PRGF treatment, P < 0.05. Conclusions. Intra-articular administration of PRGF might be beneficial in restoring HA concentration and switching angiogenesis to a more balanced status but does not halt the effects of IL-1� on synovial cells.