Evaluation of the anti-inflammatory effects of two platelet-rich gel supernatants in an in vitro system of cartilage inflammation

Objectives: To study, in normal cartilage explants (CEs) challenged with lipopolysaccharide (LPS), the temporal effects (at 48 and 96h) of leukocyte- and platelet-rich gel (L-PRG) and pure platelet-rich gel (P-PRG) supernatants on the production and degradation of platelet-associated growth factors (GFs) (platelet-derived GF isoform BB [PDGF-BB] and transforming growth factor beta-1 [TGF-β1]), pro-inflammatory (tumour necrosis factor alpha [TNF-α]) and anti-inflammatory cytokines (interleukin 4 [IL-4] and IL-1 receptor antagonist [IL-1ra]).

Methods: CEs from six horses were challenged with LPS and cultured for 96h with L-PRG and P-PRG supernatants at concentrations of 25% and 50%, respectively. The CE culture medium was changed every 48h and used for determination, by ELISA, of PDGF-BB, TGF-β1, TNF-α, IL-4 and IL-1ra.

Results: Both the 25% and 50% PRG supernatants produced a different molecular profile in the culture media, unlike that of the CE challenged with LPS only. 50% L-PRG produced the most sustained release of growth factors and anti-inflammatory cytokines, although it produced the highest TNF-α release. PDGF-BB was significantly correlated with IL-1ra and TNF-α concentrations, whereas TNF-α was correlated with IL-4.

Conclusions: 50% L-PRG supernatant produced a more sustained concentration of growth factors and anti-inflammatory cytokines than the other hemoderivatives evaluated. This substance could be evaluated in animal models of arthritis or in patients with arthropathies.