Pulmonary Vascular Platform Models the Effects of Flow and Pressure on Endothelial Dysfunction in BMPR2 Associated Pulmonary Arterial Hypertension.

Endothelial dysfunction is a known consequence of bone morphogenetic protein type II receptor (BMPR2) mutations seen in pulmonary arterial hypertension (PAH). However, standard 2D cell culture models fail to mimic the mechanical environment seen in the pulmonary vasculature. Hydrogels have emerged as promising platforms for 3D disease modeling due to their tunable physical and biochemical properties. In order to recreate the mechanical stimuli seen in the pulmonary vasculature, we have created a novel 3D hydrogel-based pulmonary vasculature model ("artificial arteriole") that reproduces the pulsatile flow rates and pressures seen in the human lung. Using this platform, we studied both Bmpr2R899X and WT endothelial cells to better understand how the addition of oscillatory flow and physiological pressure influenced gene expression, cell morphology, and cell permeability. The addition of oscillatory flow and pressure resulted in several gene expression changes in both WT and Bmpr2R899X cells. However, for many pathways with relevance to PAH etiology, Bmpr2R899X cells responded differently when compared to the WT cells. Bmpr2R899X cells were also found not to elongate in the direction of flow, and instead remained stagnant in morphology despite mechanical stimuli. The increased permeability of the Bmpr2R899X layer was successfully reproduced in our artificial arteriole, with the addition of flow and pressure not leading to significant changes in permeability. Our artificial arteriole is the first to model many mechanical properties seen in the lung. Its tunability enables several new opportunities to study the endothelium in pulmonary vascular disease with increased control over environmental parameters.

Racial differences in patients referred for right heart catheterization and risk of pulmonary hypertension.

African Americans (AA) have a higher incidence of pulmonary hypertension (PH) risk factors. Few studies have examined the racial differences in the prevalence and etiology of PH and direct comparison of invasive hemodynamics between AAs and Caucasians has rarely been reported. In this study, we examined whether racial differences exist in patients referred for right heart catheterization (RHC) and hypothesized that AA race is an independent risk factor for PH and is associated with increased adjusted mortality. We extracted data for AA and Caucasian patients who underwent RHC at Vanderbilt between 1998 and 2014. Clinical information was obtained from Vanderbilt's Synthetic Derivative, a de-identified mirror of our Electronic Medical Record. A total of 4576 patients were analyzed, including 586 (13%) AAs and 3990 (87%) Caucasians. AAs were younger than Caucasians by an average of eight years, but had more prevalent heart failure, features of metabolic syndrome, and higher creatinine. AAs also had higher mean pulmonary artery pressure and pulmonary vascular resistance. After adjusting for relevant co-morbidities, the AA race is associated with 41% increased risk of PH (odds ratio [OR] = 1.41, 95% confidence interval [CI] = 1.12-1.79). Among patients with PH, AA race is associated with 24% increased adjusted mortality (hazard ratio [HR] = 1.24, 95% CI = 1.09-1.45). AAs were younger but had more prevalent cardiometabolic and renal disease and worse pulmonary hemodynamics. The AA race is an independent risk factor for PH. Among patients with PH, the AA race is associated with increased adjusted mortality. Future studies should focus on delineating whether genetic or environmental factors contribute to PH risk in AAs.