(A) Chronic wounds persist in the inflammatory phase through IL-1β- and TNF-α-mediated autocrine recruitment and activation of pro-inflammatory M1 macrophages.

(B) ABCB5+ MSCs, by adaptive release of IL-1RA, break the vicious cycle of autocrine M1 macrophage activation, thus shifting the balance from M1 macrophage-dominated inflammation to M2 macrophage-dominated healing-promoting tissue environment characterized by decreased levels of pro-inflammatory cytokines TNF-α, IL-12 and IL-23, and increased levels of anti-inflammatory cytokine IL-10.