Biology subjects

Bahnson, E. M.

Publications and source records attributed to Bahnson, E. M..

5 recordsLinked to original sources

bioRxiv2025

Temporal evolution of hemodynamics in murine arteriovenous fistula: a micro-CT based computational fluid dynamics study

In this study, we investigated the hemodynamic characteristics of arteriovenous fistulae (AVF) in murine models using micro-CT based computational fluid dynamics (CFD). By combining high-resolution micro-CT imaging with ultrasound flow measurements, our methodology offers a cost-effective and efficient alternative to traditional MRI-based approaches. CFD simulations performed at 7 and 21 days post-surgery revealed significant temporal changes in both geometry and hemodynamics. Geometric analysis showed that: the proximal artery diameter increased from 0.29 mm to 0.38 mm, while the initial 2 mm fistula segment showed a 21.6% decrease (0.74 mm to 0.58 mm). Blood flow through the AVF nearly doubled from 1.33 mL/min to 2.57 mL/min. Time-averaged wall shear stress (TAWSS) peak values increased from 142 Pa (day 7) within the proximal artery to 200 Pa (day 21), in the stenotic region. The oscillatory shear index (OSI) showed marked elevation at the anastomosis (increasing from 0.22 to 0.48), indicating disturbed flow development. An inverse relationship between TAWSS and OSI was identified consistent with previous studies. Our methodology demonstrates the capability to analyze relationships between early hemodynamics and subsequent geometric changes. This approach could enable identification of regions susceptible to stenosis development and monitoring of AVF maturation, which could ultimately lead to quantitative metrics to evaluate surgical outcomes and early therapeutic interventions.

bioengineering↗

bioRxiv2022

Application of Machine Learning for Volumetric Analysis of Atherosclerotic Burden

Cardiovascular disease (CVD) remains the leading cause of mortality worldwide. Preclinical studies to research and validate therapeutic interventions for CVD often depend on two- dimensional histological surveys. The use of light sheet fluorescence microscopy together with optical clearing methods amenable to immunofluorescence staining are recent advances, all of which deliver detailed three-dimensional rendering of vessels. This offers the ability to describe and quantify features critical in CVD models, specifically, atherosclerotic plaque burden in atherosclerotic animal models and neointimal hyperplasia in surgical models. The main challenge for this approach remains the lengthy, hands-on, analysis time. Labkit is a user- friendly Fiji plugin that applies a machine-learning algorithm to create 3D renderings from large microscopy data. Likewise, syGlass a virtual reality (VR) software, allows for 3D visualization and analysis of information-rich image datasets. The application of these tools is expected to decrease the hands-on analysis time required to generate accurate volumetric renderings of arterial disease and injury features in animal models of CVD. For atherosclerotic burden analysis, Ldlr-/- (C57/BL6) mice aged 6-8 weeks were fed a high-fat diet for 15 weeks to allow the development of atherosclerotic plaque along the aorta. For neointimal hyperplasia analysis, surgically intervened carotid arteries from rats and mice were collected 2 weeks post-surgery. iDISCO+ or AdipoClear and immunolabeling together with light-sheet fluorescence microscopy allowed for three-dimensional visualization of the vessels. Both Imaris software v9.9.1 and the built-in bridge to ImageJ/Labkit were used to quantify plaque burden and neointimal hyperplasia manually or automatically. syGlass was also utilized for the quantification of plaque burden and other disease-associated characteristics. Our findings indicate that both Labkit and syGlass offer effective and user-friendly platforms for the segmentation of atherosclerotic plaque and/or neointimal hyperplasia in animal models.

physiology↗

bioRxiv2021

Antioxidant Response Activating nanoParticles (ARAPas) localize to atherosclerotic plaque and locally activate the Nrf2 pathway

Atherosclerotic disease is the leading cause of death world-wide with few novel therapies available despite the ongoing health burden. Redox dysfunction is a well-established driver of atherosclerotic progression; however, the clinical translation of redox-based therapies is lacking. One of the challenges facing redox-based therapies is their targeted delivery to cellular domains of redox dysregulation. In the current study, we sought to develop Antioxidant Response Activating nanoParticles (ARAPas), encapsulating redox-based interventions, that exploit macrophage biology and the dysfunctional endothelium in order to selectively accumulate in atherosclerotic plaque. We employed flash nanoprecipitation (FNP) to synthesize bio-compatible polymeric nanoparticles encapsulating the hydrophobic Nrf2 activator drug, CDDO-Methyl (CDDOMe-ARAPas). Nuclear factor erythroid 2-related factor 2 (Nrf2)-activators are a promising class of redox-active drug molecules whereby activation of Nrf2 results in the expression of several antioxidant and cyto-protective enzymes that can be athero-protective. In this study, we characterize the physiochemical properties of CDDOMe-ARAPas as well as confirm their in vitro internalization by murine macrophages. Drug release of CDDOMe was determined by Nrf2-driven GFP fluorescence. Moreover, we show that these CDDOMe-ARAPas exert anti-inflammatory effects in classically activated macrophages. Finally, we show that CDDOMe-ARAPas selectively accumulate in atherosclerotic plaque of two widely-used murine models of atherosclerosis: ApoE-/- and LDLr-/- mice, and are capable of increasing gene expression of Nrf2-transcriptional targets in the atherosclerotic aortic arch. Future work will assess the therapeutic efficacy of intra-plaque Nrf2 activation with CDDOMe-ARAPas to inhibit atherosclerotic plaque progression. Overall, our present studies underline that targeting of atherosclerotic plaque is an effective means to enhance delivery of redox-based interventions.

bioengineering↗

bioRxiv2020

Targeting of atherosclerotic plaque is achieved with polymeric nanoparticles encapsulating Nrf2 activator and LDL-like nanoparticles

Atherosclerotic vascular disease is the leading cause of death world-wide with few novel therapies available in spite of the ongoing health burden. Oxidative stress is a well-established driver of atherosclerotic progression; however the clinical translation of redox-based therapies is lacking. One of the challenges facing redox-based therapies is their targeted delivery to cellular domains of redox dysregulation. In the current study we sought to develop NPs encapsulating redox-based interventions that exploit passive means of targeting to selectively accumulate in atherosclerotic plaque with the aim of enhancing the intra-plaque bioavailability of interventions. Herein we present two types of nanoparticles (NPs): (i) We have employed flash nanoprecipitation to synthesize polymeric NPs encapsulating the hydrophobic Nrf2 activator drug, CDDO-Methyl, (ii) we have generated LDL-like NPs encapsulating the anti-inflammatory compound, oleic acid (OA). Nrf2-activators are a promising class of redox-active drug molecules whereby activation of Nrf2 results in the expression of several antioxidant and cyto-protective enzymes. Moreover, local activation of Nrf2 within the atherosclerotic plaque can be athero-protective. In this study we characterize the physiochemical properties of these NPs as well as confirm in vitro association of NPs with murine macrophages. In vitro drug release of CDDO-Me from polymeric NPs was determined by Nrf2-ARE-driven GFP fluorescence. In vivo localization was assessed through immunofluorescence of histological sections as well as whole-tissue light sheet fluorescence microscopy. We show that CDDO-Me-NPs and LDL-OA-NPs selectively accumulate in atherosclerotic plaque of two widely-used murine models of atherosclerosis: ApoE-/- and LDLr-/- mice. Overall, these studies underline that targeting of atherosclerotic plaque is an effective means to enhance delivery of redox-based interventions. Future work will assess the therapeutic efficacy of intra-plaque Nrf2 activation or anti-inflammatory actions with CDDO-Me-NPs or LDL-OA-NPs, respectively.

bioengineering↗

bioRxiv2020

Light Sheet Fluorescence Microscopy as a New Method for Unbiased Three-Dimensional Analysis of Vascular Injury

AimsAssessment of preclinical models of vascular disease are paramount in the successful translation of novel treatments. The results of these models have traditionally relied on 2-D histological methodologies. Light sheet fluorescence microscopy (LSFM) is an imaging platform that allows for 3-D visualization of whole organs and tissues. In this study, we describe an improved methodological approach utilizing LSFM for imaging of preclinical vascular injury models while minimizing analysis bias. Methods and ResultsThe rat carotid artery segmental pressure-controlled balloon injury and mouse carotid artery ligation injury were performed. Arteries were harvested and processed for LSFM imaging and 3-D analysis, as well as for 2-D area histological analysis. Artery processing for LSFM imaging did not induce vessel shrinkage or expansion, and was reversible by rehydrating the artery, allowing for subsequent sectioning and histological staining a posteriori. By generating a volumetric visualization along the length of the arteries, LSFM imaging provided different analysis modalities including volumetric, area, and radial parameters. Thus, LSFM-imaged arteries provided more precise measurements compared to classic histological analysis. Furthermore, LSFM provided additional information as compared to 2-D analysis in demonstrating remodeling of the arterial media in regions of hyperplasia and periadventitial neovascularization around the ligated mouse artery. ConclusionsLSFM provides a novel and robust 3-D imaging platform for visualizing and quantifying arterial injury in preclinical models. When compared with classic histology, LSFM outperformed traditional methods in precision and quantitative capabilities. LSFM allows for more comprehensive quantitation as compared to traditional histological methodologies, while minimizing user bias associated with area analysis of alternating, 2-D histological artery cross-sections. Translational PerspectiveA more reproducible and robust quantitation of vascular pathology in preclinical models is necessary to accelerate translational discovery. Current methodology to assess vascular disease has significant limitations. The methodology described herein employs a modern imaging modality, light sheet fluorescence microscopy (LSFM), to improve assessment of established preclinical vascular injury models. LSFM provides more comprehensive and precise analysis capabilities than classical histological approaches. Hence, LSFM applied to vascular research has the potential to drive new basic discoveries, and ultimately translation of novel therapies.

pathology↗