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Ovine Models of Congenital Heart Disease and the Consequences of Hemodynamic Alterations for Pulmonary Artery Remodeling.

ABSTRACT: The natural history of pulmonary vascular disease associated with congenital heart disease (CHD) depends on associated hemodynamics. Patients exposed to increased pulmonary blood flow (PBF) and pulmonary arterial pressure (PAP) develop pulmonary vascular disease more commonly than patients exposed to increased PBF alone. To investigate the effects of these differing mechanical forces on physiologic and molecular responses, we developed two models of CHD using fetal surgical techniques: 1) left pulmonary artery (LPA) ligation primarily resulting in increased PBF and 2) aortopulmonary shunt placement resulting in increased PBF and PAP. Hemodynamic, histologic, and molecular studies were performed on control, LPA, and shunt lambs as well as pulmonary artery endothelial cells (PAECs) derived from each. Physiologically, LPA, and to a greater extent shunt, lambs demonstrated an exaggerated increase in PAP in response to vasoconstricting stimuli compared with controls. These physiologic findings correlated with a pathologic increase in medial thickening in pulmonary arteries in shunt lambs but not in control or LPA lambs. Furthermore, in the setting of acutely increased afterload, the right ventricle of control and LPA but not shunt lambs demonstrates ventricular-vascular uncoupling and adverse ventricular-ventricular interactions. RNA sequencing revealed excellent separation between groups via both principal components analysis and unsupervised hierarchical clustering. In addition, we found hyperproliferation of PAECs from LPA lambs, and to a greater extent shunt lambs, with associated increased angiogenesis and decreased apoptosis in PAECs derived from shunt lambs. A further understanding of mechanical force-specific drivers of pulmonary artery pathology will enable development of precision therapeutics for pulmonary hypertension associated with CHD.

SUBMITTER: Johnson Kameny R

PROVIDER: S-EPMC6503613 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Disordered angiogenesis is implicated in the pulmonary vascular remodeling secondary to congenital heart disease (CHD). However, the underlying genes are not well delineated. We have previously shown that an ovine model of CHD with increased pulmonary blood flow (PBF, Shunt) has an M-bM-^@M-^\angiogenesis burstM-bM-^@M-^] between 1-4 weeks of age. Thus, we hypothesized that the increased pulmonary blood flow elicited a pro-angiogenic gene expression profile prior to the onset of vessel growth. To test this we utilized microarray analysis to identify genes that could be responsible for the angiogenic response. Total RNA was isolated from the lungs of Shunt and Control lambs at 3 days of age and hybridized to Affymetrix GeneChips for microarray analyses (n=8 for each group). A total of 89 angiogenesis-related genes were found to be up-regulated and 26 angiogenesis-related genes down-regulated in Shunt lungs compared to control (cutting at 1.2 fold difference, P<0.05). We then confirmed the up-regulation of pro-angiogenic genes: FGF2, Angiopoietin2 (Angpt2), and Birc5 at both mRNA and protein levels and the up-regulation of ccl2 at mRNA level in the 3-day shunt lungs. Further, we found that pulmonary arterial endothelial cells (PAEC) isolated from juvenile lambs exhibited increased expression of FGF2, Angpt2, Birc5, and ccl2 as well as enhanced angiogenesis when exposed to elevated shear stress (35 dyn/cm2) compared to cells exposed to more physiological level shear stress (20 dyn/cm2). Finally, we demonstrated that blocking FGF2, Angpt2, or Birc 5 signaling, using neutralizing antibodies, significantly decreased the angiogenic response induced by shear stress. In conclusion, we have identified a pro-angiogenic gene expression profile in a lamb model of CHD with increased PBF that precedes the onset of pulmonary vascular remodeling. Further, our data indicate that FGF2, Angiopoietin2, Birc5, and ccl2 may play important roles in the angiogenic response. Total RNA was isolated from the lungs of Shunt and Control lambs at 3 days of age and hybridized to Affymetrix GeneChips for microarray analyses. Eight chips were employed for both control and shunt groups.

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Ovine Models of Congenital Heart Disease and the Consequences of Hemodynamic Alterations for Pulmonary Artery Remodeling.

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