Retrospectively gated MRI forin vivoassessment of endothelium-dependent vasodilatation and endothelial permeability in murine models of endothelial dysfunction

Abstract

Endothelial dysfunction is linked to impaired endothelial-dependent vasodilatation and permeability changes. Here, we quantify both of these phenomena associated with endothelial dysfunction by MRI in vivo in mice. Endothelial function was evaluated in the brachiocephalic artery (BCA) and left carotid artery (LCA) in ApoE/LDLR(-/-) and high-fat diet (HFD)-fed mice as compared with control mice (C57BL/6J). The 3D IntraGate® FLASH sequence was used for evaluation of changes in vessels' cross-sectional area (CSA) and volume following acetylcholine (Ach) administration. Evaluation of endothelial permeability after administration of contrast agent (Galbumin, BioPAL) was based on the variable flip angle method for the assessment of parameters based on the relaxation time (T1 ) value. In order to confirm the involvement of nitric oxide (NO) in response to Ach, L-NAME-treated mice were also analyzed. To confirm that endothelial permeability changes accompany the impairment of Ach-dependent vasodilatation, permeability changes were analyzed in isolated, perfused carotid artery. In C57BL/6J mice, Ach-induced vasodilatation led to an approximately 25% increase in CSA in both vessels, which was temporarily dissociated from the effect of Ach on heart rate. In ApoE/LDLR(-/-) or HFD-fed mice Ach induced a paradoxical vasoconstriction that amounted to approximately 30% and 50% decreases in CSA of BCA and LCA respectively. In ApoE/LDLR(-/-) and HFD-fed mice endothelial permeability in BCA was also increased (fall in T1 by about 25%). In L-NAME-treated mice Ach-induced vasodilatation in BCA was lost. In isolated, perfused artery from ApoE/LDLR(-/-) mice endothelial permeability was increased. MRI-based assessment of endothelium-dependent vasodilatation induced by Ach and endothelial permeability using a retrospectively self-gated 3D gradient-echo sequence (IntraGate® FLASH) enables the reliable detection of systemic endothelial dysfunction in mice and provides an important tool for the experimental pharmacology of the endothelium in murine models of diseases in vivo. Copyright © 2016 John Wiley & Sons, Ltd.

Functional and Biochemical Endothelial Profiling In Vivo in a Murine Model of Endothelial Dysfunction; Comparison of Effects of 1-Methylnicotinamide and Angiotensin-converting Enzyme Inhibitor

“…Importantly, endothelium-dependent response was independent of the effect of Ach on the heart and respiration (Bar et al, 2016). Undoubtedly, the important advantage of the use of MRI-based method is a retrospective reconstruction of images from 3D data sets, which allows for assessment of response of the entire vessel instead of only one fragment of the vessel.…”

“…MRI experiments were performed using a 9.4T scanner (BioSpec 94/20 USR, Bruker, BioSpin GmbH, Germany), as described previously (Bar et al, 2016). Mice were anaesthetized using isoflurane (Aerrane, Baxter Sp.…”

“…Cross-sectional areas of BCA at each slices were obtained using thresholding segmentation and exported to Matlab, where BCA volumes were reconstructed and calculated. Detailed analysis was described in Supplementary Material of our previous work (Bar et al, 2016). In order to endothelial permeability assessment, obtained images were used to calculate the T 1 around the BCA lumen before and after CA administration.…”

“…Phinikaridou et al (2012) were the first to describe an MRI-based method for the noninvasive assessment of endothelial-dependent vasodilatation and permeability in vivo in mice, with the use of an albumin-binding magnetic resonance CA. In our recent studies, we developed a 3D MRI-based assessment of endothelium-dependent vasodilatation induced by acetylcholine (Ach) and endothelial permeability fully based on the use of retrospectively self-gated 3D gradient-echo sequence (Bar et al, 2016). The developed approach has been validated in two distinct murine models of endothelial dysfunction, including atherosclerotic (ApoE/LDLR -/- mice) and HFD-fed mice, showing that our approach allows for a reliable detection of the impairment of NO-dependent vasodilatation and changes in endothelial permeability.…”

Imaging the Permeable Endothelium

“…Firstly, previous results obtained in the brachiocephalic artery (BCA) of genetically modified ApoE−/− mice with the same 15 or similar 17 techniques, are here successfully translated into a rabbit model of disease. This result indicates that this approach can robustly detect changes in endothelial permeability in different animal models of atherosclerosis, an important feature for the future translation of these measurements into the clinics.…”