Development of An In Vitro Model to Assess Endothelial Dysfunction from Coarctation of the Aorta

Coarctation of the aorta (CoA) is a common congenital heart defect characterized by a stenosis of the descending thoracic aorta. Surgical treatment can alleviate the stenosis and restore physiologic blood flow; however, patients frequently develop cardiovascular morbidity with hypertension (HTN) being most common. Identifying the mechanisms involved with the onset of HTN in CoA patients is difficult due to confounding factors including the severity of coarctation, age of correction, and general lifestyle factors. To account for the variability seen in humans, a rabbit model of CoA and correction was developed previously. Microarray analysis of aortic samples from the model showed natriuretic peptide receptor type c (NPRC) is downregulated in the tissue of CoA rabbits exposed to adverse mechanical stimuli from CoA, which notably persists after correction. RNA-sequencing of samples collected from human CoA patients confirmed NPRC is similarly downregulated, suggesting a role for NPRC in response to CoA. Current efforts to study related mechanisms and function in mechanosensitive aortic endothelial cells (ECs) are limited due to the short-term viability of the tissue once harvested from the rabbit models. The purpose of this investigation is to develop a novel in vitro model using cultured ECs to mimic and complement the results from the rabbit model related to NPRC and endothelial dysfunction. Physiologic (12% elongation) and pathologic (17% elongation) strain conditions derived from Control and CoA rabbit aortic measurements were applied to cultured primary human aortic endothelial cells (HAECs) for 1 hour using the FX-6000T tension bioreactor (FlexCell Int. Corporation). Two-photon imaging of the strain-conditioned HAECs revealed cells that were exposed to pathologic CoA strain levels had significantly less intracellular calcium, [Ca2+]in, mobilization than those exposed to physiologic strain. Collectively, these results show that the in vitro model developed using HAECs generally mimics the in vivo effects that CoA-induced mechanical stimuli have on aortic tissue. Therefore, this model can reasonably be used to help unravel the mechanisms behind coarctation-induced downregulation of NPRC and its involvement in the development of HTN