Identification of E-selectin as a novel target for the regulation of postnatal neovascularization: implications for diabetic wound healing.
OBJECTIVE
We previously reported that stromal cell-derived factor-1α (SDF-1α, a homing signal for recruiting endothelial progenitor cells (EPC) to areas of neovascularization), is down-regulated in diabetic wounds (Gallagher et al, J Clin Invest. 2007;117:1249-1259). We now investigate signals whereby mature endothelial cells (EC) and circulating EPC achieve SDF-1α-mediated EPC homing.


METHODS
SDF-1α in diabetic wounds were therapeutically increased by injection of SDF-1α-engineered bone marrow-derived fibroblasts versus control cells (N = 48 [20, non-obese diabetic (NOD)], [28, streptozotocin-C57]). Polymerase chain reaction-array gene expression differences were validated by Western blotting and immunohistochemistry. The role of adhesion molecule(s) in mediating SDF-1α-induced EPC homing, and wound healing was furthered studied using antagonists in vitro and in vivo.


RESULTS
Increasing wound SDF-1α via cell-based therapy promotes healing in diabetic mice (∼20% increase in healing rates by day 3, P = 0.006). SDF-1α increased EC-EPC adhesion and specifically upregulated E-selectin expression in human microvascular EC (2.3-fold increase, P < 0.01). This effect was also significant in blood vessels of the experimental mice and resulted in increased wound neovascularization. The regulatory effects of SDF-1α on EC-EPC adhesion and EPC homing were specifically mediated by E-selectin, as the application of E-selectin antagonists significantly inhibited SDF-1α-induced EC-EPC adhesion, EPC homing, wound neovascularization, and wound healing.


CONCLUSIONS
SDF-1α-engineered cell-based therapy promotes diabetic wound healing in mice by specifically upregulating E-selectin expression in mature EC leading to increase EC-EPC adhesion, EPC homing, and increased wound neovascularization. These findings provide novel insight into the signals underlying the biological effect of SDF-1α on EPC homing and point to E-selectin as a new potential target for therapeutic manipulation of EPC trafficking in diabetic wound healing.
Liu
Zhao-Jun
ZJ
Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA.
Tian
Runxia
R
An
Weijun
W
Zhuge
Ying
Y
Li
Yan
Y
Shao
Hongwei
H
Habib
Bianca
B
Livingstone
Alan S
AS
Velazquez
Omaida C
OC
D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000502:physiology; D000229:Dependovirus; D003920:Diabetes Mellitus / Q000503:physiopathology*; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology; D019040:E-Selectin / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology; D005260:Female; D005347:Fibroblasts / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D017078:Laser-Doppler Flowmetry; D016086:Lentivirus; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D018919:Neovascularization, Physiologic / Q000502:physiology*; D016133:Polymerase Chain Reaction; D013234:Stem Cells / Q000502:physiology; D014945:Wound Healing / Q000502:physiology*
D054377:Chemokine CXCL12; D019040:E-Selectin