A new animal model for pulmonary hypertension based on the overexpression of a single gene, angiopoietin-1.
BACKGROUND
Angiopoietin-1 gene expression in human pulmonary hypertensive lungs is directly proportional to increasing pulmonary vascular resistance. We hypothesized that targeted overexpresssion of angiopoietin-1 in the lung would cause persistent pulmonary hypertension in an animal model.


METHODS
We injected 2 x 10(10) genomic particles of adeno-associated virus-angiopoietin-1 (AAV-Ang-1) into the right ventricular outflow tract of 30 Fischer rats while using adeno-associated virus-lacZ (AAV-lacZ) injected rats and carrier-injected rats as our control groups. All animals underwent survival surgery and were sacrificed at serial timepoints postgene delivery. At each timepoint, pulmonary artery pressures were measured and pulmonary angiography using the Microfil polymer perfusion technique was performed. The lungs were harvested for pathologic analysis, mRNA analysis, Western blot assays, and in situ RNA hybridization to localize gene expression.


RESULTS
Pulmonary artery pressures of AAV-Ang-1 injected rats were significantly increased compared with the control groups (p < 0.01) at all timepoints. Pathologic analysis of AAV-Ang-1 lung specimens demonstrated increased smooth muscle cell proliferation within the medial layer of arterioles with obliteration of small vessels similar to that seen in human pulmonary hypertension. Angiograms of AAV-Ang-1 injected lungs showed blunting of small peripheral arterioles consistent with advanced pulmonary hypertension. In situ RNA hybridization localized angiopoietin-1 expression to the vascular wall of small-caliber pulmonary vessels. Protein and mRNA assays confirmed persistent angiopoietin-1 expression in the lung for up to 60 days postgene delivery.


CONCLUSIONS
Overexpression of angiopoietin-1 using an adeno-associated virus vector causes pulmonary hypertension in rats. These data provide a novel physiologic animal model for pulmonary hypertension.
Chu
Danny
D
Division of Cardiothoracic Surgery, University of California, San Diego, California, USA.
Sullivan
Christopher C
CC
Du
Lingling
L
Cho
Augustine J
AJ
Kido
Masakuni
M
Wolf
Paul L
PL
Weitzman
Matthew D
MD
Jamieson
Stuart W
SW
Thistlethwaite
Patricia A
PA
D042683:Angiopoietin-1 / Q000235:genetics*; D000818:Animals; D000229:Dependovirus / Q000235:genetics; D004195:Disease Models, Animal; D015870:Gene Expression / Q000502:physiology; D018014:Gene Transfer Techniques; D006976:Hypertension, Pulmonary / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology; D011669:Pulmonary Wedge Pressure / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011859:Radiography; D051381:Rats; D011916:Rats, Inbred F344; D014162:Transfection; D014655:Vascular Resistance / Q000235:genetics
D042683:Angiopoietin-1; D012333:RNA, Messenger