Human CD133+ Progenitor Cells Promote the Healing of Diabetic Ischemic Ulcers by Paracrine Stimulation of Angiogenesis and Activation of Wnt Signaling

We evaluated the healing potential of human fetal aorta-derived CD133(+) progenitor cells and their conditioned medium (CD133(+) CCM) in a new model of ischemic diabetic ulcer. Streptozotocin-induced diabetic mice underwent bilateral limb ischemia and wounding. One wound was covered with collagen containing 2 X 10(4) CD133(+) or CD133(+) cells or vehicle. The contralateral wound, covered with only collagen, served as control. Fetal CD133(+) cells expressed high levels of wingless (Wnt) genes, which were downregulated following differentiation into CD133(+) cells along with upregulation of Wnt antagonists secreted frizzled-related protein (sFRP)-1, -3, and -4. CD133(+) cells accelerated wound closure as compared with CD133(-) or vehicle and promoted angiogenesis through stimulation of endothelial cell proliferation, migration, and survival by paracrine effects. CD133(+) cells secreted high levels of vascular endothelial growth factor (VEGF)-A and interleukin (IL)-8. Consistently, CD133(+) CCM accelerated wound closure and reparative angiogenesis, with this action abrogated by coadministering the Wnt antagonist sFRP-1 or neutralizing antibodies against VEGF-A or IL-8. In vitro, these effects were recapitulated following exposure of high-glucose-primed human umbilical vein endothelial cells to CD133(+) CCM, resulting in stimulation of migration, angiogenesis-like network formation and induction of Wnt expression. The promigratory and proangiogenic effect of CD133(+) CCM was blunted by sFRP-1, as well as antibodies against VEGF-A or IL-8. CD133(+) cells stimulate wound healing by paracrine mechanisms that activate Wnt signaling pathway in recipients. These preclinical findings open new perspectives for the cure of diabetic ulcers. (Circ Res. 2009;104:1095-1102.)