Newly defined ABCB5+ dermal mesenchymal stem cells promote healing of chronic iron overload wounds via secretion of interleukin-1 receptor antagonist

Here we report the beneficial effects of a newly identified dermal cell subpopulation expressing the ATP-binding cassette subfamily B member 5 (ABCB5) for the therapy of non-healing wounds. Local administration of dermal ABCB5+-derived MSCs attenuated macrophage-dominated inflammation and thereby accelerated healing of full-thickness excisional wounds in the iron overload mouse model mimicking the non-healing state of human venous leg ulcers. The observed beneficial effects were due to interleukin-1 receptor antagonist (IL-1RA) secreted by ABCB5+-derived MSCs, which dampened inflammation and shifted the prevalence of unrestrained pro-inflammatory M1 macrophages towards repair promoting anti-inflammatory M2 macrophages at the wound site. The beneficial anti-inflammatory effect of IL-1RA released from ABCB5+-derived MSCs on human wound macrophages was conserved in humanized NOD-scid IL2rγnull mice. In conclusion, human dermal ABCB5+ cells represent a novel, easy accessible and marker-enriched source of MSCs which holds substantial promise to successfully treat chronic non-healing wounds in humans.