Fig. 1.

Selected synovial fluid cytokine concentrations (pg/mL) in normal horses injected into the carpal joint with umbilical cord (UC) allograft or saline control (C) expressed as a percentage of baseline. A A dramatic increase in Il-1ra after UC injection was significantly greater than Day 0 baseline and C (P < 0.001) and remained greater than baseline values in seven of eight horses until the end of the study, a finding that did not occur in control. B Il-1concentrations were low and did not significantly increase after UC injection. C The Il-1/Il-1ra ratio was an even greater difference from C due to the very low Il-1 that exaggerated the ratio change (P < 0.001). D VEGF was significantly greater after UC injection than baseline Day 0 or C (P < 0.01). VEGF growth factor is a biologic potent promoter of blood vessel synthesis, particularly during development and tissue differentiation. In damaged and degenerate tissues, vascularization is a key first step to repair. E Il-10 is a potent anti-inflammatory cytokine with reported chondroprotective effects and was significantly increased to greater (P < 0.01) than both baseline and C after UC injection. F MCP-1 is a chemokine, a group of secreted proteins within the cytokine family, whose generic function is to induce cell migration. The significant (P < 0.05) increase in MCP-1 after UC injection compared to baseline and C, along with rapid return to baseline values without any other increase in 20 days suggests lack of continued immune stimulation and inflammation in vivo