Right heart hypertrophy, angiogenic remodeling, and morbidity induced by CD133⁺ cells. (A-B) Right ventricular hypertrophy in human PAH and in mice engrafted with human CD133 cells, respectively. Germ agglutinin staining was performed to visualize the myocyte wall. Scale bar indicates 100 μm. (C) Planimetric analysis of myocyte cross-sectional area of right ventricles per total tissue area. Germ agglutinin and lectin stainings were performed to visualize myocyte wall and blood vessels, respectively. (D) Immunohistochemistry of VWF-positive vessels in lungs of mice engrafted with control or PAH CD133⁺ cells. Scale bar indicates 200 μm. (E) Quantification of microvessel density of lungs, heart, and liver. *P = .001 compared with control. (F) Plasma levels of VWF quantified by ELISA are higher in mice receiving PAH cells. (G) Immunohistochemistry of nitrotyrosine identified increased oxidative stress in the pulmonary vascular wall among PAH recipients. In the control engrafted mice, gray arrows indicate weak positivity in airway epithelial cells, which normally produce nitric oxide and reactive nitrogen species via expression of nitric oxide synthases,⁵⁰  and black arrowheads indicate negative immunoreactivity of healthy vascular endothelium. In the PAH-engrafted mice, black arrowheads identify nitrotyrosine-positive vascular cells. Scale bar indicates 100 μm. (H-I) Mass spectrometric quantification of nitrotyrosine and chlorotyrosine in the lungs. (J) Morbidity of CD133⁺-engrafted mice. NOD-SCID mice were engrafted by IV injection with sorted CD133⁺ cells after total body irradiation. Animals were monitored for 6 weeks. Morbid events in each group are shown.