Ang-1 gene therapy inhibits hypoxia-inducible factor-1alpha (HIF-1alpha)-prolyl-4-hydroxylase-2, stabilizes HIF-1alpha expression, and normalizes immature vasculature in db/db mice.
OBJECTIVE
Diabetic impaired angiogenesis is associated with impairment of hypoxia-inducible factor-1alpha (HIF-1alpha) as well as vasculature maturation. We investigated the potential roles and intracellular mechanisms of angiopoietin-1 (Ang-1) gene therapy on myocardial HIF-1alpha stabilization and vascular maturation in db/db mice.


METHODS
db/db mice were systemically administrated adenovirus Ang-1 (Ad-CMV-Ang-1). Myocardial HIF-1alpha, vascular endothelial growth factor (VEGF), hemeoxygenase-1 (HO-1), endothelial nitric oxide synthase (eNOS), Akt, and HIF-1alpha-prolyl-4-hydroxylase-2 (PHD)2 expression were measured. Vasculature maturation, capillary and arteriole densities, and cardiac interstitial fibrosis were analyzed in the border zone of infarcted myocardium.


RESULTS
Systemic administration of Ad-CMV-Ang-1 results in overexpression of Ang-1 in db/db mice hearts. Ang-1 gene therapy causes a significant increase in Akt and eNOS expression and HIF-1alpha stabilization. This is accompanied by a significant upregulation of VEGF and HO-1 expression. Intriguingly, Ang-1 gene therapy also leads to a significant inhibition of PHD2 expression. Smooth muscle recruitment and smooth muscle coverage in the neovessels of the border zone of infarcted myocardium are severely impaired in db/db mice compared with wild-type mice. Ang-1 gene therapy rescues these abnormalities, which leads to a dramatic increase in capillary and arteriole densities and a significant reduction of cardiac hypertrophy and interstitial fibrosis at 14 days after ischemia. Taken together, our data show that Ang-1 increases myocardial vascular maturation and angiogenesis together with suppression of PHD2 and the upregulation of HIF-1alpha signaling.


CONCLUSIONS
Normalization of immature vasculature by Ang-1 gene therapy may represent a novel therapeutic strategy for treatment of the diabetes-associated impairment of myocardial angiogenesis.
Department of Pediatrics, Division of Neonatology, Vanderbilt University Medical Center, Nashville, TN, USA. jian-xiong.chen@vanderbilt.edu
Jian-Xiong
JX
Chen
Amanda
A
Stinnett
D042683:Angiopoietin-1 / Q000235:genetics* / Q000627:therapeutic use*; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D006332:Cardiomegaly / Q000473:pathology; D003925:Diabetic Angiopathies / Q000188:drug therapy; D004719:Endomyocardial Fibrosis / Q000473:pathology; D015316:Genetic Therapy / Q000379:methods*; D051547:Heme Oxygenase-1 / Q000235:genetics; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
D042683:Angiopoietin-1; D001786:Blood Glucose; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D042461:Vascular Endothelial Growth Factor A; D011393:Procollagen-Proline Dioxygenase; D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse