Anti-inflammatory effects of two platelet-rich gel supernatants in an in vitro system of ligament desmitis

Background. There is not even a knowledge of what is the perfect concentration of cells that should be present in platelet-rich plasma (PRP) to induce an effect for treatment of desmitis. Our aims were determining the temporal effects (48 and 96 h) of leukocyte-concentrated platelet-rich gel supernatant (Lc-PRGS) and leukocyte-reduced platelet-rich gel supernatant (Lr-PRGS) of ligament explants (LEs) challenged with lipopolysaccharide (LPS). The production and degradation of growth factors, proinflammatory and anti-inflammatory cytokines were measured. Methods. LEs from horses were challenged with LPS and cultured for 96 hours with Lc-PRGS and Lr-PRGS at both 25% and 50% concentrations. Culture medium was changed every 48 h and used for determination, by ELISA, of platelet-derived growth factor isoform BB (PDGF-BB), transforming growth factor beta-1 (TGF-beta 1), interleukin 1 beta (IL-1 beta) , tumor necrosis factor alpha (TNF-alpha), interleukin 4 (IL-4) and interleukin 1 receptor antagonist (IL-1ra). Results. LEs cultured with both concentrations of Lc-PRGS showed the lowest release of IL-1 beta in comparison with the other LE groups at 48 and 96 hours, whereas 50% Lr-PRGS induced the lowest TNF-alpha release from LEs at 96 hours. IL-1ra was mainly released from LEs cultured with both concentrations of Lc-PRGS at 48 and 96 hours, whereas IL-4 was mainly produced in LEs cultured with 50% Lr-PRGS at 48 and 96 hours. Conclusions. The anti-inflammatory effect of Lc-PRGS in LEs challenged with LPS seems to be related with heightened concentrations of PDGF-BB that apparently induced a higher release of IL-1ra. On the other hand, the anti-inflammatory action of Lr-PRGS could be associated with a higher release of IL-4 that may reduce the release of TNF-alpha). Although we observed significant correlations between some mediators evaluated in this study, these findings should be considered with caution because a correlation does not necessary mean a causal relationship. Additional in vivo studies which evaluating the effects of both Lc-PRP and Lr-PRP in either animal models or in human patients are necessary, for determination in clinical future application's. It will be easy, safe, rational and cheaper in cases for desmopaties.