Histochemical Analyses and Quantum Dot Imaging of Microvascular Blood Flow with Pulmonary Edema

Abstract

Light microscopic imaging of blood vessels and distribution of serum proteins are essential to analyze hemodynamics in living animal lungs under normal respiration or respiratory diseases. In this section, we visualized dynamically changing morphology of paraffin specimens of mouse lungs. By hematoxylin-eosin staining, morphological features, such as shapes of alveolar septum and sizes of alveolar lumen, reflected their respiratory conditions in vivo, and alveolar capillaries were filled with variously shaped erythrocytes. To capture accurate time courses of blood flow in peripheral pulmonary alveoli, glutathione-coated quantum dots (QDs) were injected into right ventricles. QDs were localized in most arterioles and some alveolar capillaries at 1 s and later in venules at 2 s, reflecting a typical blood flow direction in vivo. For pathological visualization, IVCT was also applied to lungs of acute pulmonary hypertension mouse model. Erythrocytes were crammed in blood vessels, and some serum components leaked into alveolar lumens, as confirmed by mouse albumin immunostaining. Some separated collagen fibers and connecting elastic fibers were still detected in edematous tunica adventitia near terminal bronchioles.