Three-dimensional vascular and metabolic imaging using inverted autofluorescence

Abstract

Significance: Three-dimensional (3D) vascular and metabolic imaging (VMI) of whole organs in rodents provides critical and important (patho)physiological information in studying animal models of vascular network.Aim: Autofluorescence metabolic imaging has been used to evaluate mitochondrial metabolites such as nicotinamide adenine dinucleotide (NADH) and flavine adenine dinucleotide (FAD). Leveraging these autofluorescence images of whole organs of rodents, we have developed a 3D vascular segmentation technique to delineate the anatomy of the vasculature as well as mitochondrial metabolic distribution.Approach: By measuring fluorescence from naturally occurring mitochondrial metabolites combined with light-absorbing properties of hemoglobin, we detected the 3D structure of the vascular tree of rodent lungs, kidneys, hearts, and livers using VMI. For lung VMI, an exogenous fluorescent dye was injected into the trachea for inflation and to separate the airways, confirming no overlap between the segmented vessels and airways. Results:The kidney vasculature from genetically engineered rats expressing endothelial-specific red fluorescent protein TdTomato confirmed a significant overlap with VMI. This approach abided by the "minimum work" hypothesis of the vascular network fitting to Murray's law. Finally, the vascular segmentation approach confirmed the vascular regression in rats, induced by ionizing radiation.Conclusions: Simultaneous vascular and metabolic information extracted from the VMI provides quantitative diagnostic markers without the confounding effects of vascular stains, fillers, or contrast agents.

Translational rapid ultraviolet-excited sectioning tomography for whole-organ multicolor imaging with real-time molecular staining

“…For example, the axon ( Figure 2g ), nerve tracts (e.g., lateral olfactory tract Figure 2h or anterior commissure Figure 2i ), and myelinated fiber bundles in the caudate putamen ( Figure 2j ) have been identified with TRUST even without any labeling. Also, blood vessels ( Figure 2k ) can be identified based on negative contrast because their autofluorescence signal intensity is lower than that of the surrounding tissues Mehrvar et al, 2021 ; Staniszewski et al, 2013 . To further enhance the contrast of the vessel network in the brain ( Figure 2w and x ), the mouse was perfused transcardially with a mixture of black ink and 3% w/v gelatin ( Figure 2—figure supplement 3 ).…”

Biomarkers to Predict Lethal Radiation Injury to the Rat Lung

“…SPECT imaging with 99m Tc-MAA detected changes as early as 2 weeks in rats, providing a structural biomarker of perfused lung volume that correlates with lung function, since perfusion plays an important role in gas exchange in the lung. There are many reports of a decrease in perfusion in the lungs after radiation [ 50 , 51 , 52 ]. In the future, SPECT/CT values in nonirradiated humans will be useful to provide a baseline for this biomarker to make it informative after radiation.…”

3D autofluorescence imaging of hydronephrosis and renal anatomical structure using cryo-micro-optical sectioning tomography

“…In cryo-MOST images, we can directly measure the functional capillary density due to the autofluorescence absorption of red blood cells 26 , 68 . The functional capillary density is a useful indicator of the quality of capillary perfusion and tissue oxygen content under both physiological and pathophysiological conditions 69 .…”

“…In cryo-MOST images, we can directly measure the functional capillary density due to the autofluorescence absorption of red blood cells [26,68].…”

“…Therefore, autofluorescence imaging can be easily performed at low temperatures. Mahsa Ranji et al obtained metabolic and vascular information of kidneys and lungs in normal and irradiated rats by autofluorescence imaging at -40 ℃ 26 . However, this method is also limited by low spatial resolution, and renal tubules and capillaries are difficult to distinguish.…”