Interleukin 1 receptor antagonist (IL-1RA) is a member of the IL-1 family that binds to IL-1 receptors but does not induce any intracellular signaling (Arend et al.). IL-1RA is a natural regulator of IL-1’s biological activity. It binds to the IL-1 receptors with similar affinity as IL-1, thereby inhibiting the proinflammatory activities of IL-1ɑ and IL-1ꞵ (Kinne et al.). In particular, mesenchymal stem cells have been shown to enhance tissue repair in an IL-1RA-dependent manner through the suppression of IL-1ꞵ production in dermal macrophages and enhanced expansion of immunosuppressive regulatory T cells in the skin (Harrell et al.). IL-1RA has also been shown to help in the treatment of rheumatoid arthritis (Cutolo), sepsis, asthma (Mao et al.), and inflammatory bowel diseases (Dosh et al.). This product is animal component-free.