Abstract 16504: Human Gene Profiling Reveals Contribution of Tissue Plasminogen Activator to Intimal Thickening of the Ductus Arteriosus
Introduction: Intimal thickening (IT) formation is required to lead complete closure of the ductus arteriosus (DA). The initial step of intimal thickening is disruption of the internal elastic lamina, which is followed by smooth muscle cell (SMC) migration toward luminal side. Although prominent IT is well recognized in humans, gene profiling of IT in the human DA has not been reported. We aimed to identify IT-specific genes using a comprehensive analysis of human DA and investigate the role of the identified gene in endothelial cells and IT formation of the DA.
Methods and Results: Human DA tissues were obtained at the surgery from 6 patients with congenital heart diseases including hypoplastic left heart syndrome and coarctation of the aorta with approval of institutional review board and written informed consents. The tunica media and IT were isolated from the human DA tissues and subjected to DNA microarray analysis. Among total 6,267 genes detected in the tunica media and IT, 12 genes were expressed more than 3-fold in IT than in the tunica media. Notably, expression of tissue plasminogen activator (PLAT) was 3.8-fold greater in IT than in the tunica media (n=6, p<0.001). Next, we examined using fetal rats whether PLAT was highly expressed in the DA compared to the aorta, since the paired aortic tissue could not be obtained from human patients. We obtained the DA and aorta from fetal rats on day 21 of gestation and isolated ECs by fluorescence-activated cell sorting (FACS). Quantitative RT-PCR revealed that expression of PLAT was significantly higher in ECs of the DA than in aortic ECs (2.5-fold, n=8, p<0.05). Immunohistochemistry in human DA and rat fetus demonstrated that PLAT localized in ECs of the DA. We further investigated the role of PLAT using gelatin zymography. When ECs were cultured with plasminogen, plasmin-induced activation of matrix metalloproteinase-2 (MMP-2) which disrupts elastic lamina was markedly enhanced in the rat DA compared to aortic ECs (8.0-fold, n=8-10, p=0.09).
Conclusions: PLAT was identified as an IT-selective gene in the human DA. The data suggests that PLAT activates MMP-2 and may lead disruption of the internal lamina and subsequent IT formation in the DA. Activation of PLAT may be a strategy for DA closure.
Author Disclosures: J. Saito: None. U. Yokoyama: None. M. Masuda: None. T. Asou: None. Y. Ishikawa: None.
- © 2016 by American Heart Association, Inc.