Platelet-rich plasma increases matrix metalloproteinases in cultures of human synovial fibroblasts.

BACKGROUND: The effect of platelet-rich plasma on chondrocytes has been studied in cell and tissue culture. Less attention has been given to the effect of platelet-rich plasma on nonchondrocytic cell lineages within synovial joints, such as fibroblast-like synoviocytes, which produce cytokines and matrix metalloproteinases (MMPs) that mediate cartilage catabolism. The purpose of the present study was to determine the effect of platelet-rich plasma on cytokines and proteases produced by fibroblast-like synoviocytes. METHODS: Platelet-rich plasma and platelet-poor plasma from harvested autologous blood were prepared with a commercially available system. Fibroblast-like synoviocytes were treated with platelet-rich plasma, platelet-poor plasma, recombinant PDGFßß (platelet-derived growth factor ßß), or phosphate-buffered saline solution and incubated at 37°C for forty-eight hours. The concentrations of IL-1ß (interleukin-1ß), IL-1RA (IL-1 receptor antagonist), IL-6, IFN-γ (interferon-γ), IP-10 (interferon gamma-induced protein 10), MCP-1 (monocyte chemotactic protein-1), MIP-1ß (macrophage inflammatory protein-1ß), PDGFßß, RANTES, TNF-α (tumor necrosis factor-α), VEGF (vascular endothelial growth factor), MMP-1, MMP-3, and MMP-9 in the culture medium were determined by multiplex immunoassay. RESULTS: Platelet-rich plasma cultured in medium contained multiple catabolic mediators in substantial concentrations, including MMP-9 (15.8 ± 2.3 ng/mL) and MMP-1 (2.5 ± 0.8 ng/mL), as well as proinflammatory mediators IL-1ß, IL-6, IFN-γ, IP-10, MCP-1, MIP-1ß, RANTES, and TNF-α in concentrations between 20 pg/mL and 20 ng/mL. Platelet-poor plasma contained significantly lower concentrations of these compounds. Platelet-rich plasma was used to treat human fibroblast-like synoviocytes, and the resulting concentrations of mediators were corrected for the concentrations in the platelet-rich plasma alone. Compared with untreated fibroblast-like synoviocytes, synoviocytes treated with platelet-rich plasma exhibited significantly greater levels of MMP-1 (363 ± 94.0 ng/mL, p = 0.018) and MMP-3 (278 ± 90.0 ng/mL, p = 0.018). In contrast, platelet-poor plasma had little effect on mediators secreted by the synoviocytes. PDGFßß-treated fibroblast-like synoviocytes exhibited a broad proinflammatory cytokine response at four and forty-eight hours. CONCLUSIONS: Platelet-rich plasma was shown to contain a mixture of anabolic and catabolic mediators. Synoviocytes treated with platelet-rich plasma responded with substantial MMP secretion, which may increase cartilage catabolism. Synoviocytes responded to PDGF with a substantial proinflammatory response.

Identification of a complex between fibronectin and aggrecan G3 domain in synovial fluid of patients with painful meniscal pathology.

OBJECTIVES: We previously described a panel of four cytokines biomarkers in knee synovial fluid for acute knee pain associated with meniscal pathology. The cytokine biomarkers included interferon gamma (IFN-gamma), interleukin 6 (IL-6), monocyte chemotactic protein 1 (MCP-1), and macrophage inflammatory protein-1 beta (MIP-1beta). Validation studies using other immunologic techniques confirmed the presence of IL-6, MCP-1 and MIP-1beta, but not IFN-gamma. Therefore we sought the identity of the IFN-gamma signal in synovial fluid. METHODS: Knee synovial fluid was collected from patients with an acute, painful meniscal injury, as well as asymptomatic volunteers. A combination of high-pressure chromatography, mass spectrometry and immunological techniques were used to enrich and identify the protein components representing the IFN-gamma signal. RESULTS: A protein complex of fibronectin and the aggrecan G3 domain was identified in the synovial fluid of patients with a meniscal tear and pain that was absent in asymptomatic controls. This protein complex correlated to the IFN-gamma signal. A novel enzyme-linked immunosorbent assay (ELISA) was developed to specifically identify the complex in synovial fluid. CONCLUSIONS: We have identified a protein complex of fibronectin and aggrecan G3 domain that is a candidate biomarker for pain associated with meniscal injury.