Fibroblast-Specific Deletion of Hypoxia Inducible Factor-1 Critically Impairs Murine Cutaneous Neovascularization and Wound Healing.
BACKGROUND
Diabetes and aging are known risk factors for impaired neovascularization in response to ischemic insult, resulting in chronic wounds, and poor outcomes following myocardial infarction and cerebrovascular injury. Hypoxia-inducible factor (HIF)-1α, has been identified as a critical regulator of the response to ischemic injury and is dysfunctional in diabetic and elderly patients. To better understand the role of this master hypoxia regulator within cutaneous tissue, the authors generated and evaluated a fibroblast-specific HIF-1α knockout mouse model.


METHODS
The authors generated floxed HIF-1 mice (HIF-1) by introducing loxP sites around exon 1 of the HIF-1 allele in C57BL/6J mice. Fibroblast-restricted HIF-1α knockout (FbKO) mice were generated by breeding our HIF-1 with tamoxifen-inducible Col1a2-Cre mice (Col1a2-CreER). HIF-1α knockout was evaluated on a DNA, RNA, and protein level. Knockout and wild-type mice were subjected to ischemic flap and wound healing models, and CD31 immunohistochemistry was performed to assess vascularity of healed wounds.


RESULTS
Quantitative real-time polymerase chain reaction of FbKO skin demonstrated significantly reduced Hif1 and Vegfa expression compared with wild-type. This finding was confirmed at the protein level (p < 0.05). HIF-1α knockout mice showed significantly impaired revascularization of ischemic tissue and wound closure and vascularity (p < 0.05).


CONCLUSIONS
Loss of HIF-1α from fibroblasts results in delayed wound healing, reduced wound vascularity, and significant impairment in the ischemic neovascular response. These findings provide new insight into the importance of cell-specific responses to hypoxia during cutaneous neovascularization.
Stanford, Calif. From the Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine.
Dominik
D
Duscher
Zeshaan N
ZN
Maan
Alexander J
AJ
Whittam
Michael
M
Sorkin
Michael S
MS
Hu
Graham G
GG
Walmsley
Hutton
H
Baker
Lauren H
LH
Fischer
Michael
M
Januszyk
Victor W
VW
Wong
Geoffrey C
GC
Gurtner
D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D017353:Gene Deletion; D005786:Gene Expression Regulation; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000235:genetics*; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014945:Wound Healing / Q000235:genetics* / Q000502:physiology
D051795:Hypoxia-Inducible Factor 1, alpha Subunit