Cerebral aneurysms are abnormal widening or ballooning of a localized segment of an intracranial blood vessel. Surgical clipping is an important treatment for aneurysms which attempts to exclude blood from flowing into the aneurysmal segment of the vessel while preserving blood flow in a normal fashion. Improper clip placement may result in residual aneurysm with the potential for subsequent aneurysm rupture or partial or full occlusion of distal arteries resulting in cerebral infarction. Here we describe the use of an ultrasonic flow probe to provide quantitative evaluation of arterial flow before and after microsurgical clip placement at the base of a middle cerebral artery aneurysm. This information helps ensure adequate aneurysm reconstruction with preservation of normal distal blood flow.
23 Related JoVE Articles!
Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Institutions: University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, Veterans Affairs Medical Center, San Francisco.
The vascular endothelium is a monolayer of cells that cover the interior of blood vessels and provide both structural and functional roles. The endothelium acts as a barrier, preventing leukocyte adhesion and aggregation, as well as controlling permeability to plasma components. Functionally, the endothelium affects vessel tone.
Endothelial dysfunction is an imbalance between the chemical species which regulate vessel tone, thombroresistance, cellular proliferation and mitosis. It is the first step in atherosclerosis and is associated with coronary artery disease, peripheral artery disease, heart failure, hypertension, and hyperlipidemia.
The first demonstration of endothelial dysfunction involved direct infusion of acetylcholine and quantitative coronary angiography. Acetylcholine binds to muscarinic receptors on the endothelial cell surface, leading to an increase of intracellular calcium and increased nitric oxide (NO) production. In subjects with an intact endothelium, vasodilation was observed while subjects with endothelial damage experienced paradoxical vasoconstriction.
There exists a non-invasive, in vivo
method for measuring endothelial function in peripheral arteries using high-resolution B-mode ultrasound. The endothelial function of peripheral arteries is closely related to coronary artery function. This technique measures the percent diameter change in the brachial artery during a period of reactive hyperemia following limb ischemia.
This technique, known as endothelium-dependent, flow-mediated vasodilation (FMD) has value in clinical research settings. However, a number of physiological and technical issues can affect the accuracy of the results and appropriate guidelines for the technique have been published. Despite the guidelines, FMD remains heavily operator dependent and presents a steep learning curve. This article presents a standardized method for measuring FMD in the brachial artery on the upper arm and offers suggestions to reduce intra-operator variability.
Medicine, Issue 92, endothelial function, endothelial dysfunction, brachial artery, peripheral artery disease, ultrasound, vascular, endothelium, cardiovascular disease.
Evaluation of a Novel Laser-assisted Coronary Anastomotic Connector - the Trinity Clip - in a Porcine Off-pump Bypass Model
Institutions: University Medical Center Utrecht, Vascular Connect b.v., University Medical Center Utrecht, University Medical Center Utrecht.
To simplify and facilitate beating heart (i.e.,
off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e.,
occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.
Medicine, Issue 93, Anastomosis, coronary, anastomotic connector, anastomotic coupler, excimer laser-assisted nonocclusive anastomosis (ELANA), coronary artery bypass graft (CABG), off-pump coronary artery bypass (OPCAB), beating heart surgery, excimer laser, porcine model, experimental, medical device
A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Institutions: Bangor University, Russells Hall Hospital, University of Manchester.
The endothelium is the innermost lining of the vasculature and is involved in the maintenance of vascular homeostasis. Damage to the endothelium may predispose the vessel to atherosclerosis and increase the risk for cardiovascular disease. Assessments of peripheral endothelial function are good indicators of early abnormalities in the vascular wall and correlate well with assessments of coronary endothelial function. The present manuscript details the important methodological steps necessary for the assessment of microvascular endothelial function using laser Doppler imaging with iontophoresis, large vessel endothelial function using flow-mediated dilatation, and carotid atherosclerosis using carotid artery ultrasound. A discussion on the methodological considerations for each of the techniques is also presented, and recommendations are made for future research.
Medicine, Issue 96, Endothelium, Cardiovascular, Flow-mediated dilatation, Carotid intima-media thickness, Atherosclerosis, Nitric oxide, Microvasculature, Laser Doppler Imaging
Single-stage Dynamic Reanimation of the Smile in Irreversible Facial Paralysis by Free Functional Muscle Transfer
Institutions: University of Freiburg Medical Centre.
Unilateral facial paralysis is a common disease that is associated with significant functional, aesthetic and psychological issues. Though idiopathic facial paralysis (Bell’s palsy) is the most common diagnosis, patients can also present with a history of physical trauma, infectious disease, tumor, or iatrogenic facial paralysis. Early repair within one year of injury can be achieved by direct nerve repair, cross-face nerve grafting or regional nerve transfer. It is due to muscle atrophy that in long lasting facial paralysis complex reconstructive methods have to be applied. Instead of one single procedure, different surgical approaches have to be considered to alleviate the various components of the paralysis.
The reconstruction of a spontaneous dynamic smile with a symmetric resting tone is a crucial factor to overcome the functional deficits and the social handicap that are associated with facial paralysis. Although numerous surgical techniques have been described, a two-stage approach with an initial cross-facial nerve grafting followed by a free functional muscle transfer is most frequently applied. In selected patients however, a single-stage reconstruction using the motor nerve to the masseter as donor nerve is superior to a two-stage repair. The gracilis muscle is most commonly used for reconstruction, as it presents with a constant anatomy, a simple dissection and minimal donor site morbidity.
Here we demonstrate the pre-operative work-up, the post-operative management, and precisely describe the surgical procedure of single-stage microsurgical reconstruction of the smile by free functional gracilis muscle transfer in a step by step protocol. We further illustrate common pitfalls and provide useful tips which should enable the reader to truly comprehend the procedure. We further discuss indications and limitations of the technique and demonstrate representative results.
Medicine, Issue 97, microsurgery, free microvascular tissue transfer, face, head, head and neck surgery, facial paralysis
Murine Model of Femoral Artery Wire Injury with Implantation of a Perivascular Drug Delivery Patch
Institutions: University of Texas at Austin.
Percutaneous interventions including balloon angioplasty and stenting have been used to restore blood flow in vessels with occlusive vascular disease. While these therapies lead to the rapid restoration of blood flow, these technologies remain limited by restenosis in the case of bare metal stents and angioplasty, or reduced healing and possibly enhanced risk of thrombosis in the case of drug eluting stents. A key pathophysiological mechanism in the formation of restenosis is intimal hyperplasia caused by the activation of vascular smooth muscle cells and inflammation due to arterial stretch and injury. Surgeries that induce arterial injury in genetically modified mice are useful for the mechanistic study of the vascular response to injury but are often technically challenging to perform in mouse models due to the their small size and lack of appropriate sized devices. We describe two approaches for a surgical technique that induces endothelial denudation and arterial stretch in the femoral artery of mice to produce robust neointimal hyperplasia. The first approach creates an arteriotomy in the muscular branch of the femoral artery to obtain vascular access. Following wire injury this arterial branch is ligated to close the arteriotomy. A second approach creates an arteriotomy in the main femoral artery that is later closed through localized cautery. This method allows for vascular access through a larger vessel and, consequently, provides a less technically demanding procedure that can be used in smaller mice. Following either method of arterial injury, a degradable drug delivery patch can be placed over or around the injured artery to deliver therapeutic agents.
Medicine, Issue 96, vascular injury, neointimal hyperplasia, perivascular drug delivery, wire injury, mouse surgical model of restenosis
Induction of Murine Intestinal Inflammation by Adoptive Transfer of Effector CD4+CD45RBhigh T Cells into Immunodeficient Mice
Institutions: University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill.
There are many different animal models available for studying the pathogenesis of human inflammatory bowel diseases (IBD), each with its own advantages and disadvantages. We describe here an experimental colitis model that is initiated by adoptive transfer of syngeneic splenic CD4+
T cells into T and B cell deficient recipient mice. The CD4+
T cell population that largely consists of naïve effector cells is capable of inducing chronic intestinal inflammation, closely resembling key aspects of human IBD. This method can be manipulated to study aspects of disease onset and progression. Additionally it can be used to study the function of innate, adaptive, and regulatory immune cell populations, and the role of environmental exposures, i.e.,
the microbiota, in intestinal inflammation. In this article we illustrate the methodology for inducing colitis with a step-by-step protocol. This includes a video demonstration of key technical aspects required to successfully develop this murine model of experimental colitis for research purposes.
Immunology, Issue 98, IBD, Colitis, Experimental Models, Adaptive Immunity, T cells, Mucosal Immunity, Inflammation
Th17 Inflammation Model of Oropharyngeal Candidiasis in Immunodeficient Mice
Institutions: Case Western Reserve University.
Oropharyngeal Candidiasis (OPC) disease is caused not only due to the lack of host immune resistance, but also the absence of appropriate regulation of infection-induced immunopathology. Although Th17 cells are implicated in antifungal defense, their role in immunopathology is unclear. This study presents a method for establishing oral Th17 immunopathology associated with oral candidal infection in immunodeficient mice. The method is based on reconstituting lymphopenic mice with in vitro
cultured Th17 cells, followed by oral infection with Candida albicans
Results show that unrestrained Th17 cells result in inflammation and pathology, and is associated with several measurable read-outs including weight loss, pro-inflammatory cytokine production, tongue histopathology and mortality, showing that this model may be valuable in studying OPC immunopathology. Adoptive transfer of regulatory cells (Tregs
) controls and reduces the inflammatory response, showing that this model can be used to test new strategies to counteract oral inflammation. This model may also be applicable in studying oral Th17 immunopathology in general in the context of other oral diseases.
Medicine, Issue 96, Th17, Treg, mouse model, oral inflammation, Candida, oral infection and immunopathology
Quantification of Neurovascular Protection Following Repetitive Hypoxic Preconditioning and Transient Middle Cerebral Artery Occlusion in Mice
Institutions: University of Texas Southwestern Medical Center, Washington University School of Medicine.
Experimental animal models of stroke are invaluable tools for understanding stroke pathology and developing more effective treatment strategies. A 2 week protocol for repetitive hypoxic preconditioning (RHP) induces long-term protection against central nervous system (CNS) injury in a mouse model of focal ischemic stroke. RHP consists of 9 stochastic exposures to hypoxia that vary in both duration (2 or 4 hr) and intensity (8% and 11% O2
). RHP reduces infarct volumes, blood-brain barrier (BBB) disruption, and the post-stroke inflammatory response for weeks following the last exposure to hypoxia, suggesting a long-term induction of an endogenous CNS-protective phenotype. The methodology for the dual quantification of infarct volume and BBB disruption is effective in assessing neurovascular protection in mice with RHP or other putative neuroprotectants. Adult male Swiss Webster mice were preconditioned by RHP or duration-equivalent exposures to 21% O2
room air). A 60 min transient middle cerebral artery occlusion (tMCAo) was induced 2 weeks following the last hypoxic exposure. Both the occlusion and reperfusion were confirmed by transcranial laser Doppler flowmetry. Twenty-two hr after reperfusion, Evans Blue (EB) was intravenously administered through a tail vein injection. 2 hr later, animals were sacrificed by isoflurane overdose and brain sections were stained with 2,3,5- triphenyltetrazolium chloride (TTC). Infarcts volumes were then quantified. Next, EB was extracted from the tissue over 48 hr to determine BBB disruption after tMCAo. In summary, RHP is a simple protocol that can be replicated, with minimal cost, to induce long-term endogenous neurovascular protection from stroke injury in mice, with the translational potential for other CNS-based and systemic pro-inflammatory disease states.
Medicine, Issue 99, Hypoxia, preconditioning, transient middle cerebral artery occlusion, stroke, neuroprotection, blood-brain barrier disruption
Mouse Naïve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets
Institutions: Rosalind Franklin University of Medicine and Science.
Antigen inexperienced (naïve) CD4+
T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition of cognate antigen presented on MHC class II. The cytokine signals present in the environment at the time of TCR activation are a major factor in determining the effector fate of a naïve CD4+
T cell. Although the cytokine environment during naïve T cell activation may be complex and involve both redundant and opposing signals in vivo
, the addition of various cytokine combinations during naive CD4+
T cell activation in vitro
can readily promote the establishment of effector T helper lineages with hallmark cytokine and transcription factor expression. Such differentiation experiments are commonly used as a first step for the evaluation of targets believed to promote or inhibit the development of certain CD4+
T helper subsets. The addition of mediators, such as signaling agonists, antagonists, or other cytokines, during the differentiation process can also be used to study the influence of a particular target on T cell differentiation. Here, we describe a basic protocol for the isolation of naïve T cells from mouse and the subsequent steps necessary for polarizing naïve cells to various T helper effector lineages in vitro
Immunology, Issue 98, Naïve CD4+ T cell, T helper cell, Th1, Th2, Th17, Treg
Mouse Model of Alloimmune-induced Vascular Rejection and Transplant Arteriosclerosis
Institutions: Simon Fraser University.
Vascular rejection that leads to transplant arteriosclerosis (TA) is the leading representation of chronic heart transplant failure. In TA, the immune system of the recipient causes damage of the arterial wall and dysfunction of endothelial cells and smooth muscle cells. This triggers a pathological repair response that is characterized by intimal thickening and luminal occlusion. Understanding the mechanisms by which the immune system causes vasculature rejection and TA may inform the development of novel ways to manage graft failure. Here, we describe a mouse aortic interposition model that can be used to study the pathogenic mechanisms of vascular rejection and TA. The model involves grafting of an aortic segment from a donor animal into an allogeneic recipient. Rejection of the artery segment involves alloimmune reactions and results in arterial changes that resemble vascular rejection. The basic technical approach we describe can be used with different mouse strains and targeted interventions to answer specific questions related to vascular rejection and TA.
Medicine, Issue 99, Transplantation, Vascular rejection, Transplant arteriosclerosis, Artery, Aorta
Vascular Gene Transfer from Metallic Stent Surfaces Using Adenoviral Vectors Tethered through Hydrolysable Cross-linkers
Institutions: The Children's Hospital of Philadelphia, University of Pennsylvania.
In-stent restenosis presents a major complication of stent-based revascularization procedures widely used to re-establish blood flow through critically narrowed segments of coronary and peripheral arteries. Endovascular stents capable of tunable release of genes with anti-restenotic activity may present an alternative strategy to presently used drug-eluting stents. In order to attain clinical translation, gene-eluting stents must exhibit predictable kinetics of stent-immobilized gene vector release and site-specific transduction of vasculature, while avoiding an excessive inflammatory response typically associated with the polymer coatings used for physical entrapment of the vector. This paper describes a detailed methodology for coatless tethering of adenoviral gene vectors to stents based on a reversible binding of the adenoviral particles to polyallylamine bisphosphonate (PABT)-modified stainless steel surface via hydrolysable cross-linkers (HC). A family of bifunctional (amine- and thiol-reactive) HC with an average t1/2
of the in-chain ester hydrolysis ranging between 5 and 50 days were used to link the vector with the stent. The vector immobilization procedure is typically carried out within 9 hr and consists of several steps: 1) incubation of the metal samples in an aqueous solution of PABT (4 hr); 2) deprotection of thiol groups installed in PABT with tris(2-carboxyethyl) phosphine (20 min); 3) expansion of thiol reactive capacity of the metal surface by reacting the samples with polyethyleneimine derivatized with pyridyldithio (PDT) groups (2 hr); 4) conversion of PDT groups to thiols with dithiothreitol (10 min); 5) modification of adenoviruses with HC (1 hr); 6) purification of modified adenoviral particles by size-exclusion column chromatography (15 min) and 7) immobilization of thiol-reactive adenoviral particles on the thiolated steel surface (1 hr). This technique has wide potential applicability beyond stents, by facilitating surface engineering of bioprosthetic devices to enhance their biocompatibility through the substrate-mediated gene delivery to the cells interfacing the implanted foreign material.
Medicine, Issue 90, gene therapy, bioconjugation, adenoviral vectors, stents, local gene delivery, smooth muscle cells, endothelial cells, bioluminescence imaging
A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites
Institutions: Boston University School of Medicine, Boston University School of Medicine.
Chronic inflammation is a major driver of pathological tissue damage and a unifying characteristic of many chronic diseases in humans including neoplastic, autoimmune, and chronic inflammatory diseases. Emerging evidence implicates pathogen-induced chronic inflammation in the development and progression of chronic diseases with a wide variety of clinical manifestations. Due to the complex and multifactorial etiology of chronic disease, designing experiments for proof of causality and the establishment of mechanistic links is nearly impossible in humans. An advantage of using animal models is that both genetic and environmental factors that may influence the course of a particular disease can be controlled. Thus, designing relevant animal models of infection represents a key step in identifying host and pathogen specific mechanisms that contribute to chronic inflammation.
Here we describe a mouse model of pathogen-induced chronic inflammation at local and systemic sites following infection with the oral pathogen Porphyromonas gingivalis
, a bacterium closely associated with human periodontal disease. Oral infection of specific-pathogen free mice induces a local inflammatory response resulting in destruction of tooth supporting alveolar bone, a hallmark of periodontal disease. In an established mouse model of atherosclerosis, infection with P. gingivalis
accelerates inflammatory plaque deposition within the aortic sinus and innominate artery, accompanied by activation of the vascular endothelium, an increased immune cell infiltrate, and elevated expression of inflammatory mediators within lesions. We detail methodologies for the assessment of inflammation at local and systemic sites. The use of transgenic mice and defined bacterial mutants makes this model particularly suitable for identifying both host and microbial factors involved in the initiation, progression, and outcome of disease. Additionally, the model can be used to screen for novel therapeutic strategies, including vaccination and pharmacological intervention.
Immunology, Issue 90,
Pathogen-Induced Chronic Inflammation; Porphyromonas gingivalis; Oral Bone Loss; Periodontal Disease; Atherosclerosis; Chronic Inflammation; Host-Pathogen Interaction; microCT; MRI
Gene Transfer for Ischemic Heart Failure in a Preclinical Model
Institutions: Mount Sinai School of Medicine .
Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine their efficacy and safety.
Gene therapy using viral vectors is one of the most promising approaches for treating cardiac diseases. Viral delivery of various different genes by changing the carrier gene has immeasurable therapeutic potential.
In this video, the full process of an animal model of heart failure creation followed by gene transfer is presented using a swine model. First, myocardial infarction is created by occluding the proximal left anterior descending coronary artery. Heart remodeling results in chronic heart failure. Unique to our model is a fairly large scar which truly reflects patients with severe heart failure who require aggressive therapy for positive outcomes. After myocardial infarct creation and development of scar tissue, an intracoronary injection of virus is demonstrated with simultaneous nitroglycerine infusion. Our injection method provides simple and efficient gene transfer with enhanced gene expression. This combination of a myocardial infarct swine model with intracoronary virus delivery has proven to be a consistent and reproducible methodology, which helps not only to test the effect of individual gene, but also compare the efficacy of many genes as therapeutic candidates.
Medicine, Issue 51, Myocardial infarction, Gene therapy, Intracoronary injection, Viral vector, Ischemic heart failure
Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT)
Institutions: University of Pennsylvania, Perelman School of Medicine, University of Pennsylvania, Perelman School of Medicine, University of Pennsylvania, Perelman School of Medicine.
Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC)1
and carotid intimal medial thickness (C-IMT)2
provide information about the burden of disease. However, despite multiple validation studies of CAC3-5
, and C-IMT2,6
, these modalities do not accurately assess plaque characteristics7,8
, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events9-13
F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism14,15
. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity16
, an important source of cellular inflammation in vessel walls. More recently, we17,18
and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries9,16,19,20
. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo
imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors21,22
and is also highly associated with overall burden of atherosclerosis23
. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy24
as well as longer term therapeutic lifestyle changes (16 months)25
The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability26
. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.9,20,27,28
Medicine, Issue 63, FDG-PET/CT, atherosclerosis, vascular inflammation, quantitative radiology, imaging
Depletion and Reconstitution of Macrophages in Mice
Institutions: University of British Columbia , Vrije Universiteit Amsterdam, University of British Columbia .
Macrophages are critical players in the innate immune response to infectious challenge or injury, initiating the innate immune response and directing the acquired immune response. Macrophage dysfunction can lead to an inability to mount an appropriate immune response and as such, has been implicated in many disease processes, including inflammatory bowel diseases. Macrophages display polarized phenotypes that are broadly divided into two categories. Classically activated macrophages, activated by stimulation with IFNγ or LPS, play an essential role in response to bacterial challenge whereas alternatively activated macrophages, activated by IL-4 or IL-13, participate in debris scavenging and tissue remodeling and have been implicated in the resolution phase of inflammation. During an inflammatory response in vivo
, macrophages are found amid a complex mixture of infiltrating immune cells and may participate by exacerbating or resolving inflammation. To define the role of macrophages in situ
in a whole animal model, it is necessary to examine the effect of depleting macrophages from the complex environment. To ask questions about the role of macrophage phenotype in situ
, phenotypically defined polarized macrophages can be derived ex vivo
, from bone marrow aspirates and added back to mice, with or without prior depletion of macrophages. In the protocol presented here clodronate-containing liposomes, versus PBS injected controls, were used to deplete colonic macrophages during dextran sodium sulfate (DSS)-induced colitis in mice. In addition, polarized macrophages were derived ex vivo
and transferred to mice by intravenous injection. A caveat to this approach is that clodronate-containing liposomes deplete all professional phagocytes, including both dendritic cells and macrophages so to ensure the effect observed by depletion is macrophage-specific, reconstitution of phenotype by adoptive transfer of macrophages is necessary. Systemic macrophage depletion in mice can also be achieved by backcrossing mice onto a CD11b-DTR background, which is an excellent complementary approach. The advantage of clodronate-containing liposome-mediated depletion is that it does not require the time and expense involved in backcrossing mice and it can be used in mice regardless of the background of the mice (C57BL/6, BALB/c, or mixed background).
Immunology, Issue 66, Molecular Biology, macrophages, clodronate-containing liposomes, macrophage depletion, macrophage derivation, macrophage reconstitution
Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Institutions: Texas A&M University, Texas A&M University, Texas A&M University.
The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.
Immunology, Issue 76, Cellular Biology, Molecular Biology, Medicine, Genetics, Biomedical Engineering, biology (general), genetics (animal and plant), immunology, life sciences, Life Sciences (General), macrophage polarization, bone marrow derived macrophage, flow cytometry, PCR, animal model
A Human Ex Vivo Atherosclerotic Plaque Model to Study Lesion Biology
Institutions: University of Heidelberg, University of Heidelberg, SLK Hospital am Plattenwald.
Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic lesions. Mouse models are an important tool to investigate inflammatory processes in atherogenesis, but these models suffer from the phenotypic and functional differences between the murine and human immune system. In vitro
cell experiments are used to specifically evaluate cell type-dependent changes caused by a substance of interest, but culture-dependent variations and the inability to analyze the influence of specific molecules in the context of the inflammatory compound in atherosclerotic lesions limit the impact of the results. In addition, measuring levels of a molecule of interest in human blood helps to further investigate its clinical relevance, but this represents systemic and not local inflammation. Therefore, we here describe a plaque culture model to study human atherosclerotic lesion biology ex vivo
. In short, fresh plaques are obtained from patients undergoing endarterectomy or coronary artery bypass grafting and stored in RPMI medium on ice until usage. The specimens are cut into small pieces followed by random distribution into a 48-well plate, containing RPMI medium in addition to a substance of interest such as cytokines or chemokines alone or in combination for defined periods of time. After incubation, the plaque pieces can be shock frozen for mRNA isolation, embedded in Paraffin or OCT for immunohistochemistry staining or smashed and lysed for western blotting. Furthermore, cells may be isolated from the plaque for flow cytometry analysis. In addition, supernatants can be collected for protein measurement by ELISA. In conclusion, the presented ex vivo
model opens the possibility to further study inflammatory lesional biology, which may result in identification of novel disease mechanisms and therapeutic targets.
Medicine, Issue 87, ex vivo model, human, tissue culture, atherosclerosis, immune response, inflammation, chronic inflammatory disease
Generation and 3-Dimensional Quantitation of Arterial Lesions in Mice Using Optical Projection Tomography
Institutions: The Queen's Medical Research Institute.
The generation and analysis of vascular lesions in appropriate animal models is a cornerstone of research into cardiovascular disease, generating important information on the pathogenesis of lesion formation and the action of novel therapies. Use of atherosclerosis-prone mice, surgical methods of lesion induction, and dietary modification has dramatically improved understanding of the mechanisms that contribute to disease development and the potential of new treatments.
Classically, analysis of lesions is performed ex vivo
using 2-dimensional histological techniques. This article describes application of optical projection tomography (OPT) to 3-dimensional quantitation of arterial lesions. As this technique is non-destructive, it can be used as an adjunct to standard histological and immunohistochemical analyses.
Neointimal lesions were induced by wire-insertion or ligation of the mouse femoral artery whilst atherosclerotic lesions were generated by administration of an atherogenic diet to apoE-deficient mice.
Lesions were examined using OPT imaging of autofluorescent emission followed by complementary histological and immunohistochemical analysis. OPT clearly distinguished lesions from the underlying vascular wall. Lesion size was calculated in 2-dimensional sections using planimetry, enabling calculation of lesion volume and maximal cross-sectional area. Data generated using OPT were consistent with measurements obtained using histology, confirming the accuracy of the technique and its potential as a complement (rather than alternative) to traditional methods of analysis.
This work demonstrates the potential of OPT for imaging atherosclerotic and neointimal lesions. It provides a rapid, much needed ex vivo
technique for the routine 3-dimensional quantification of vascular remodelling.
Medicine, Issue 99, neointima, mouse femoral artery, atherosclerosis, brachiocephalic trunk, optical projection tomography
Isolation and Th17 Differentiation of Naïve CD4 T Lymphocytes
Institutions: The University of Florida.
Th17 cells are a distinct subset of T cells that have been found to produce interleukin 17 (IL-17), and differ in function from the other T cell subsets including Th1, Th2, and regulatory T cells. Th17 cells have emerged as a central culprit in overzealous inflammatory immune responses associated with many autoimmune disorders. In this method we purify T lymphocytes from the spleen and lymph nodes of C57BL/6 mice, and stimulate purified CD4+ T cells under control and Th17-inducing environments. The Th17-inducing environment includes stimulation in the presence of anti-CD3 and anti-CD28 antibodies, IL-6, and TGF-β. After incubation for at least 72 hours and for up to five days at 37 °C, cells are subsequently analyzed for the capability to produce IL-17 through flow cytometry, qPCR, and ELISAs. Th17 differentiated CD4+CD25- T cells can be utilized to further elucidate the role that Th17 cells play in the onset and progression of autoimmunity and host defense. Moreover, Th17 differentiation of CD4+CD25- lymphocytes from distinct murine knockout/disease models can contribute to our understanding of cell fate plasticity.
Immunology, Issue 79, Cellular Biology, Molecular Biology, Medicine, Infection, Th17 cells, IL-17, Th17 differentiation, T cells, autoimmunity, cell, isolation, culture
Induction of Invasive Transitional Cell Bladder Carcinoma in Immune Intact Human MUC1 Transgenic Mice: A Model for Immunotherapy Development
Institutions: University of California, Davis, University of California, Davis, Merck KGaA, Darmstadt, Germany.
A preclinical model of invasive bladder cancer was developed in human mucin 1 (MUC1) transgenic (MUC1.Tg) mice for the purpose of evaluating immunotherapy and/or cytotoxic chemotherapy. To induce bladder cancer, C57BL/6 mice (MUC1.Tg and wild type) were treated orally with the carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine (OH-BBN) at 3.0 mg/day, 5 days/week for 12 weeks. To assess the effects of OH-BBN on serum cytokine profile during tumor development, whole blood was collected via submandibular bleeds prior to treatment and every four weeks. In addition, a MUC1-targeted peptide vaccine and placebo were administered to groups of mice weekly for eight weeks. Multiplex fluorometric microbead immunoanalyses of serum cytokines during tumor development and following vaccination were performed. At termination, interferon gamma (IFN-γ)/interleukin-4 (IL-4) ELISpot analysis for MUC1 specific T-cell immune response and histopathological evaluations of tumor type and grade were performed. The results showed that: (1) the incidence of bladder cancer in both MUC1.Tg and wild type mice was 67%; (2) transitional cell carcinomas (TCC) developed at a 2:1 ratio compared to squamous cell carcinomas (SCC); (3) inflammatory cytokines increased with time during tumor development; and (4) administration of the peptide vaccine induces a Th1-polarized serum cytokine profile and a MUC1 specific T-cell response. All tumors in MUC1.Tg mice were positive for MUC1 expression, and half of all tumors in MUC1.Tg and wild type mice were invasive. In conclusion, using a team approach through the coordination of the efforts of pharmacologists, immunologists, pathologists and molecular biologists, we have developed an immune intact transgenic mouse model of bladder cancer that expresses hMUC1.
Medicine, Issue 80, Urinary Bladder, Animals, Genetically Modified, Cancer Vaccines, Immunotherapy, Animal Experimentation, Models, Neoplasms Bladder Cancer, C57BL/6 Mouse, MUC1, Immunotherapy, Preclinical Model
Setting-up an In Vitro Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport
Institutions: VECT-HORUS SAS, CNRS, NICN UMR 7259.
The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and characterize a highly reproducible rat syngeneic in vitro
model of the BBB using co-cultures of primary rat brain endothelial cells (RBEC) and astrocytes to study receptors involved in transcytosis across the endothelial cell monolayer. Astrocytes were isolated by mechanical dissection following trypsin digestion and were frozen for later co-culture. RBEC were isolated from 5-week-old rat cortices. The brains were cleaned of meninges and white matter, and mechanically dissociated following enzymatic digestion. Thereafter, the tissue homogenate was centrifuged in bovine serum albumin to separate vessel fragments from nervous tissue. The vessel fragments underwent a second enzymatic digestion to free endothelial cells from their extracellular matrix. The remaining contaminating cells such as pericytes were further eliminated by plating the microvessel fragments in puromycin-containing medium. They were then passaged onto filters for co-culture with astrocytes grown on the bottom of the wells. RBEC expressed high levels of tight junction (TJ) proteins such as occludin, claudin-5 and ZO-1 with a typical localization at the cell borders. The transendothelial electrical resistance (TEER) of brain endothelial monolayers, indicating the tightness of TJs reached 300 ohm·cm2
on average. The endothelial permeability coefficients (Pe) for lucifer yellow (LY) was highly reproducible with an average of 0.26 ± 0.11 x 10-3
cm/min. Brain endothelial cells organized in monolayers expressed the efflux transporter P-glycoprotein (P-gp), showed a polarized transport of rhodamine 123, a ligand for P-gp, and showed specific transport of transferrin-Cy3 and DiILDL across the endothelial cell monolayer. In conclusion, we provide a protocol for setting up an in vitro
BBB model that is highly reproducible due to the quality assurance methods, and that is suitable for research on BBB transporters and receptors.
Medicine, Issue 88, rat brain endothelial cells (RBEC), mouse, spinal cord, tight junction (TJ), receptor-mediated transport (RMT), low density lipoprotein (LDL), LDLR, transferrin, TfR, P-glycoprotein (P-gp), transendothelial electrical resistance (TEER),
Inducing Myointimal Hyperplasia Versus Atherosclerosis in Mice: An Introduction of Two Valid Models
Institutions: University Hospital Hamburg, Cardiovascular Research Center (CVRC) and DZHK University Hamburg, University Heart Center Hamburg, Columbia University, Cardiovascular Research Foundation, New York, Karolinska Institute, Stockholm, Stanford University School of Medicine, Falk Cardiovascular Research Center.
Various in vivo
laboratory rodent models for the induction of artery stenosis have been established to mimic diseases that include arterial plaque formation and stenosis, as observed for example in ischemic heart disease. Two highly reproducible mouse models – both resulting in artery stenosis but each underlying a different pathway of development – are introduced here. The models represent the two most common causes of artery stenosis; namely one mouse model for each myointimal hyperplasia, and atherosclerosis are shown. To induce myointimal hyperplasia, a balloon catheter injury of the abdominal aorta is performed. For the development of atherosclerotic plaque, the ApoE -/- mouse model in combination with western fatty diet is used. Different model-adapted options for the measurement and evaluation of the results are named and described in this manuscript. The introduction and comparison of these two models provides information for scientists to choose the appropriate artery stenosis model in accordance to the scientific question asked.
Medicine, Issue 87, vascular diseases, atherosclerosis, coronary stenosis, neointima, myointimal hyperplasia, mice, denudation model, ApoE -/-, balloon injury, western diet, analysis
Isolation and Characterization of Neutrophils with Anti-Tumor Properties
Institutions: Hebrew University Medical School, Hadassah-Hebrew University Medical Center.
Neutrophils, the most abundant of all white blood cells in the human circulation, play an important role in the host defense against invading microorganisms. In addition, neutrophils play a central role in the immune surveillance of tumor cells. They have the ability to recognize tumor cells and induce tumor cell death either through a cell contact-dependent mechanism involving hydrogen peroxide or through antibody-dependent cell-mediated cytotoxicity (ADCC). Neutrophils with anti-tumor activity can be isolated from peripheral blood of cancer patients and of tumor-bearing mice. These neutrophils are termed tumor-entrained neutrophils (TEN) to distinguish them from neutrophils of healthy subjects or naïve mice that show no significant tumor cytotoxic activity. Compared with other white blood cells, neutrophils show different buoyancy making it feasible to obtain a > 98% pure neutrophil population when subjected to a density gradient. However, in addition to the normal high-density neutrophil population (HDN), in cancer patients, in tumor-bearing mice, as well as under chronic inflammatory conditions, distinct low-density neutrophil populations (LDN) appear in the circulation. LDN co-purify with the mononuclear fraction and can be separated from mononuclear cells using either positive or negative selection strategies. Once the purity of the isolated neutrophils is determined by flow cytometry, they can be used for in vitro
and in vivo
functional assays. We describe techniques for monitoring the anti-tumor activity of neutrophils, their ability to migrate and to produce reactive oxygen species, as well as monitoring their phagocytic capacity ex vivo
. We further describe techniques to label the neutrophils for in vivo
tracking, and to determine their anti-metastatic capacity in vivo
. All these techniques are essential for understanding how to obtain and characterize neutrophils with anti-tumor function.
Immunology, Issue 100, Neutrophil isolation, tumor-entrained neutrophils, high-density neutrophils, low-density neutrophils, anti-tumor cytotoxicity, BrdU labeling, CFSE labeling, luciferase assay, neutrophil depletion, anti-metastatic activity, lung metastatic seeding assay, neutrophil adoptive transfer.