Study of the Development of the Mouse Thoracic Aorta Three-Dimensional Macromolecular Structure using Two-Photon Microscopy

Abstract

SummaryUsing the intrinsic optical properties of collagen and elastin, two-photon microscopy was applied to evaluate the threedimensional (3D) macromolecular structural development of the mouse thoracic aorta from birth to 60 days old. Baseline development was established in the Scavenger Receptor Class B Type I-Deficient, Hypomorphic Apolipoprotein ER61 (SR-BI KO/ApoeR61 h/h ) mouse in preparation for modeling atherosclerosis. Precise dissection enabled direct observation of the artery wall in situ. En-face, optical sectioning of the aorta provided a novel assessment of the macromolecular structural development. During aortic development, the undulating lamellar elastin layers compressed consistent with the increases in mean aortic pressure with age. In parallel, a net increase in overall wall thickness (p<0.05, in day 60 compared with day 1 mice) occurred with age whereas the ratio of the tunicas adventitia and media to full aortic thickness remained nearly constant across age groups (~1:2.6, respectively). Histochemical analyses by brightfield microscopy and ultrastructure validated structural proteins and lipid deposition findings derived from two-photon microscopy. Development was associated with decreased decorin but not biglycan proteoglycan expression. This non-destructive 3D in situ approach revealed the aortic wall microstructure development. Coupling this approach with the intrinsic optical properties of the macromolecules may provide unique vascular wall 3D structure in many pathological conditions, including aortic atherosclerosis, dissections and aneurysms. (J Histochem Cytochem 63:8-21, 2015)

High-Resolution Morphological Approach to Analyse Elastic Laminae Injuries of the Ascending Aorta in a Murine Model of Marfan Syndrome

“…To date, some laboratories have used this technique to image aortic samples in a conventional transverse perspective (XZ or YZ axes) 25 , 28 , as in standard histological preparations. A few other groups have applied multiphoton microscopy to image the tissue in an en-face view, and subsequently generated a three-dimensional rendering of it 29 , 30 . The en-face histological perspective consists of visualizing the surface of the vessel (XY axes) along the depth of its wall.…”

Structural and Functional Differences Between Porcine Aorta and Vena Cava

“…Early research by Roach and Burton suggested the contributions of compliant elastin fibers at lower levels of stress and stiff collagen fibers at higher levels of stress result in the nonlinear mechanics of the arterial wall [19]. Arterial structure-function has since been further explored from the macro-to nanoscale with the advancement of experimental approaches including mechanical characterization and optical imaging [20][21][22][23][24], and in computational modeling [25][26][27]. Alterations in structure and function to the arterial wall due to various pathological conditions are also being extensively studied, with the goal of early diagnosis, prevention, and the development of treatment options [28][29][30].…”

Direct visualization of the arterial wall water permeability barrier using CARS microscopy

“…CARS signal in context with the cellular structures of the biological sample (15,16). For the remainder of this study all CARS images were generated with fs pulses.…”