Neurological injury is a frequent cause of morbidity and mortality from general anesthesia and related surgical procedures that could be alleviated by development of effective, easy to administer and safe preconditioning treatments. We seek to define the neural immune signaling responsible for cold-preconditioning as means to identify novel targets for therapeutics development to protect brain before injury onset. Low-level pro-inflammatory mediator signaling changes over time are essential for cold-preconditioning neuroprotection. This signaling is consistent with the basic tenets of physiological conditioning hormesis, which require that irritative stimuli reach a threshold magnitude with sufficient time for adaptation to the stimuli for protection to become evident.
Accordingly, delineation of the immune signaling involved in cold-preconditioning neuroprotection requires that biological systems and experimental manipulations plus technical capacities are highly reproducible and sensitive. Our approach is to use hippocampal slice cultures as an in vitro model that closely reflects their in vivo counterparts with multi-synaptic neural networks influenced by mature and quiescent macroglia / microglia. This glial state is particularly important for microglia since they are the principal source of cytokines, which are operative in the femtomolar range. Also, slice cultures can be maintained in vitro for several weeks, which is sufficient time to evoke activating stimuli and assess adaptive responses. Finally, environmental conditions can be accurately controlled using slice cultures so that cytokine signaling of cold-preconditioning can be measured, mimicked, and modulated to dissect the critical node aspects. Cytokine signaling system analyses require the use of sensitive and reproducible multiplexed techniques. We use quantitative PCR for TNF-α to screen for microglial activation followed by quantitative real-time qPCR array screening to assess tissue-wide cytokine changes. The latter is a most sensitive and reproducible means to measure multiple cytokine system signaling changes simultaneously. Significant changes are confirmed with targeted qPCR and then protein detection. We probe for tissue-based cytokine protein changes using multiplexed microsphere flow cytometric assays using Luminex technology. Cell-specific cytokine production is determined with double-label immunohistochemistry. Taken together, this brain tissue preparation and style of use, coupled to the suggested investigative strategies, may be an optimal approach for identifying potential targets for the development of novel therapeutics that could mimic the advantages of cold-preconditioning.
24 Related JoVE Articles!
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
Generation of Subcutaneous and Intrahepatic Human Hepatocellular Carcinoma Xenografts in Immunodeficient Mice
Institutions: University Health Network, University Health Network, University Health Network.
experimental models of hepatocellular carcinoma (HCC) that recapitulate the human disease provide a valuable platform for research into disease pathophysiology and for the preclinical evaluation of novel therapies. We present a variety of methods to generate subcutaneous or orthotopic human HCC xenografts in immunodeficient mice that could be utilized in a variety of research applications. With a focus on the use of primary tumor tissue from patients undergoing surgical resection as a starting point, we describe the preparation of cell suspensions or tumor fragments for xenografting. We describe specific techniques to xenograft these tissues i) subcutaneously; or ii) intrahepatically, either by direct implantation of tumor cells or fragments into the liver, or indirectly by injection of cells into the mouse spleen. We also describe the use of partial resection of the native mouse liver at the time of xenografting as a strategy to induce a state of active liver regeneration in the recipient mouse that may facilitate the intrahepatic engraftment of primary human tumor cells. The expected results of these techniques are illustrated. The protocols described have been validated using primary human HCC samples and xenografts, which typically perform less robustly than the well-established human HCC cell lines that are widely used and frequently cited in the literature. In comparison with cell lines, we discuss factors which may contribute to the relatively low chance of primary HCC engraftment in xenotransplantation models and comment on technical issues that may influence the kinetics of xenograft growth. We also suggest methods that should be applied to ensure that xenografts obtained accurately resemble parent HCC tissues.
Medicine, Issue 79, Liver Neoplasms, Hepatectomy, animal models, hepatocellular carcinoma, xenograft, cancer, liver, subcutaneous, intrahepatic, orthotopic, mouse, human, immunodeficient
A Rapid Protocol for Integrating Extrachromosomal Arrays With High Transmission Rate into the C. elegans Genome
Institutions: Université Claude Bernard Lyon, CNRS UMR 5534.
Microinjecting DNA into the cytoplasm of the syncytial gonad of Caenorhabditis elegans
is the main technique used to establish transgenic lines that exhibit partial and variable transmission rates of extrachromosomal arrays to the next generation. In addition, transgenic animals are mosaic and express the transgene in a variable number of cells. Extrachromosomal arrays can be integrated into the C. elegans
genome using UV irradiation to establish nonmosaic transgenic strains with 100% transmission rate of the transgene. To that extent, F1 progenies of UV irradiated transgenic animals are screened for animals carrying a heterozygous integration of the transgene, which leads to a 75% Mendelian transmission rate to the F2 progeny. One of the challenges of this method is to distinguish between the percentage of transgene transmission in a population before (X% transgenic animals) and after integration (≥75% transgenic F2 animals). Thus, this method requires choosing a nonintegrated transgenic line with a percentage of transgenic animals that is significantly lower than the Mendelian segregation of 75%. Consequently, nonintegrated transgenic lines with an extrachromosomal array transmission rate to the next generation ≤60% are usually preferred for integration, and transgene integration in highly transmitting strains is difficult. Here we show that the efficiency of extrachromosomal arrays integration into the genome is increased when using highly transmitting transgenic lines (≥80%). The described protocol allows for easy selection of several independent lines with homozygous transgene integration into the genome after UV irradiation of transgenic worms exhibiting a high rate of extrachromosomal array transmission. Furthermore, this method is quite fast and low material consuming. The possibility of rapidly generating different lines that express a particular integrated transgene is of great interest for studies focusing on gene expression pattern and regulation, protein localization, and overexpression, as well as for the development of subcellular markers.
Basic Protocol, Issue 82, Caenorhabditis elegans, UV-mediated transgene integration, transgenic worms, irradiation, extrachromosomal, fluorescent
Methods for the Modulation and Analysis of NF-κB-dependent Adult Neurogenesis
Institutions: University of Bielefeld, University of Bielefeld.
The hippocampus plays a pivotal role in the formation and consolidation of episodic memories, and in spatial orientation. Historically, the adult hippocampus has been viewed as a very static anatomical region of the mammalian brain. However, recent findings have demonstrated that the dentate gyrus of the hippocampus is an area of tremendous plasticity in adults, involving not only modifications of existing neuronal circuits, but also adult neurogenesis. This plasticity is regulated by complex transcriptional networks, in which the transcription factor NF-κB plays a prominent role. To study and manipulate adult neurogenesis, a transgenic mouse model for forebrain-specific neuronal inhibition of NF-κB activity can be used.
In this study, methods are described for the analysis of NF-κB-dependent neurogenesis, including its structural aspects, neuronal apoptosis and progenitor proliferation, and cognitive significance, which was specifically assessed via a dentate gyrus (DG)-dependent behavioral test, the spatial pattern separation-Barnes maze (SPS-BM). The SPS-BM protocol could be simply adapted for use with other transgenic animal models designed to assess the influence of particular genes on adult hippocampal neurogenesis. Furthermore, SPS-BM could be used in other experimental settings aimed at investigating and manipulating DG-dependent learning, for example, using pharmacological agents.
Neuroscience, Issue 84, NF-κB, hippocampus, Adult neurogenesis, spatial pattern separation-Barnes maze, dentate gyrus, p65 knock-out mice
In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice
Institutions: Jena University Hospital, Fritz Lipmann Institute, Jena, Jena University Hospital.
The rodent visual system encompasses retinal ganglion cells and their axons that form the optic nerve to enter thalamic and midbrain centers, and postsynaptic projections to the visual cortex. Based on its distinct anatomical structure and convenient accessibility, it has become the favored structure for studies on neuronal survival, axonal regeneration, and synaptic plasticity. Recent advancements in MR imaging have enabled the in vivo
visualization of the retino-tectal part of this projection using manganese mediated contrast enhancement (MEMRI). Here, we present a MEMRI protocol for illustration of the visual projection in mice, by which resolutions of (200 µm)3
can be achieved using common 3 Tesla scanners. We demonstrate how intravitreal injection of a single dosage of 15 nmol MnCl2
leads to a saturated enhancement of the intact projection within 24 hr. With exception of the retina, changes in signal intensity are independent of coincided visual stimulation or physiological aging. We further apply this technique to longitudinally monitor axonal degeneration in response to acute optic nerve injury, a paradigm by which Mn2+
transport completely arrests at the lesion site. Conversely, active Mn2+
transport is quantitatively proportionate to the viability, number, and electrical activity of axon fibers. For such an analysis, we exemplify Mn2+
transport kinetics along the visual path in a transgenic mouse model (NF-κB p50KO
) displaying spontaneous atrophy of sensory, including visual, projections. In these mice, MEMRI indicates reduced but not delayed Mn2+
transport as compared to wild type mice, thus revealing signs of structural and/or functional impairments by NF-κB mutations.
In summary, MEMRI conveniently bridges in vivo
assays and post mortem
histology for the characterization of nerve fiber integrity and activity. It is highly useful for longitudinal studies on axonal degeneration and regeneration, and investigations of mutant mice for genuine or inducible phenotypes.
Neuroscience, Issue 89, manganese-enhanced MRI, mouse retino-tectal projection, visual system, neurodegeneration, optic nerve injury, NF-κB
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),
Technique of Subnormothermic Ex Vivo Liver Perfusion for the Storage, Assessment, and Repair of Marginal Liver Grafts
Institutions: Toronto General Hospital, Toronto General Hospital, Toronto General Hospital.
The success of liver transplantation has resulted in a dramatic organ shortage. In most transplant regions 20-30% of patients on the waiting list for liver transplantation die without receiving an organ transplant or are delisted for disease progression. One strategy to increase the donor pool is the utilization of marginal grafts, such as fatty livers, grafts from older donors, or donation after cardiac death (DCD). The current preservation technique of cold static storage is only poorly tolerated by marginal livers resulting in significant organ damage. In addition, cold static organ storage does not allow graft assessment or repair prior to transplantation.
These shortcomings of cold static preservation have triggered an interest in warm perfused organ preservation to reduce cold ischemic injury, assess liver grafts during preservation, and explore the opportunity to repair marginal livers prior to transplantation. The optimal pressure and flow conditions, perfusion temperature, composition of the perfusion solution and the need for an oxygen carrier has been controversial in the past.
In spite of promising results in several animal studies, the complexity and the costs have prevented a broader clinical application so far. Recently, with enhanced technology and a better understanding of liver physiology during ex vivo
perfusion the outcome of warm liver perfusion has improved and consistently good results can be achieved.
This paper will provide information about liver retrieval, storage techniques, and isolated liver perfusion in pigs. We will illustrate a) the requirements to ensure sufficient oxygen supply to the organ, b) technical considerations about the perfusion machine and the perfusion solution, and c) biochemical aspects of isolated organs.
Medicine, Issue 90, ex vivo liver perfusion, marginal grafts, DCD
Intrastriatal Injection of Autologous Blood or Clostridial Collagenase as Murine Models of Intracerebral Hemorrhage
Institutions: Duke University, Duke University, Duke University, Duke University.
Intracerebral hemorrhage (ICH) is a common form of cerebrovascular disease and is associated with significant morbidity and mortality. Lack of effective treatment and failure of large clinical trials aimed at hemostasis and clot removal demonstrate the need for further mechanism-driven investigation of ICH. This research may be performed through the framework provided by preclinical models. Two murine models in popular use include intrastriatal (basal ganglia) injection of either autologous whole blood or clostridial collagenase. Since, each model represents distinctly different pathophysiological features related to ICH, use of a particular model may be selected based on what aspect of the disease is to be studied. For example, autologous blood injection most accurately represents the brain's response to the presence of intraparenchymal blood, and may most closely replicate lobar hemorrhage. Clostridial collagenase injection most accurately represents the small vessel rupture and hematoma evolution characteristic of deep hemorrhages. Thus, each model results in different hematoma formation, neuroinflammatory response, cerebral edema development, and neurobehavioral outcomes. Robustness of a purported therapeutic intervention can be best assessed using both models. In this protocol, induction of ICH using both models, immediate post-operative demonstration of injury, and early post-operative care techniques are demonstrated. Both models result in reproducible injuries, hematoma volumes, and neurobehavioral deficits. Because of the heterogeneity of human ICH, multiple preclinical models are needed to thoroughly explore pathophysiologic mechanisms and test potential therapeutic strategies.
Medicine, Issue 89, intracerebral hemorrhage, mouse, preclinical, autologous blood, collagenase, neuroscience, stroke, brain injury, basal ganglia
Transient Expression of Proteins by Hydrodynamic Gene Delivery in Mice
Institutions: Hunter College, CUNY.
Efficient expression of transgenes in vivo
is of critical importance in studying gene function and developing treatments for diseases. Over the past years, hydrodynamic gene delivery (HGD) has emerged as a simple, fast, safe and effective method for delivering transgenes into rodents. This technique relies on the force generated by the rapid injection of a large volume of physiological solution to increase the permeability of cell membranes of perfused organs and thus deliver DNA into cells. One of the main advantages of HGD is the ability to introduce transgenes into mammalian cells using naked plasmid DNA (pDNA). Introducing an exogenous gene using a plasmid is minimally laborious, highly efficient and, contrary to viral carriers, remarkably safe. HGD was initially used to deliver genes into mice, it is now used to deliver a wide range of substances, including oligonucleotides, artificial chromosomes, RNA, proteins and small molecules into mice, rats and, to a limited degree, other animals. This protocol describes HGD in mice and focuses on three key aspects of the method that are critical to performing the procedure successfully: correct insertion of the needle into the vein, the volume of injection and the speed of delivery. Examples are given to show the application of this method to the transient expression of two genes that encode secreted, primate-specific proteins, apolipoprotein L-I (APOL-I) and haptoglobin-related protein (HPR).
Genetics, Issue 87, hydrodynamic gene delivery, hydrodynamics-based transfection, mouse, gene therapy, plasmid DNA, transient gene expression, tail vein injection
Renal Ischaemia Reperfusion Injury: A Mouse Model of Injury and Regeneration
Institutions: University of Edinburgh.
Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in patients and occlusion of renal blood flow is unavoidable during renal transplantation. Experimental models that accurately and reproducibly recapitulate renal IRI are crucial in dissecting the pathophysiology of AKI and the development of novel therapeutic agents. Presented here is a mouse model of renal IRI that results in reproducible AKI. This is achieved by a midline laparotomy approach for the surgery with one incision allowing both a right nephrectomy that provides control tissue and clamping of the left renal pedicle to induce ischaemia of the left kidney. By careful monitoring of the clamp position and body temperature during the period of ischaemia this model achieves reproducible functional and structural injury. Mice sacrificed 24 hr following surgery demonstrate loss of renal function with elevation of the serum or plasma creatinine level as well as structural kidney damage with acute tubular necrosis evident. Renal function improves and the acute tissue injury resolves during the course of 7 days following renal IRI such that this model may be used to study renal regeneration. This model of renal IRI has been utilized to study the molecular and cellular pathophysiology of AKI as well as analysis of the subsequent renal regeneration.
Medicine, Issue 88, Murine, Acute Kidney Injury, Ischaemia, Reperfusion, Nephrectomy, Regeneration, Laparotomy
In Vivo Imaging Systems (IVIS) Detection of a Neuro-Invasive Encephalitic Virus
Institutions: University of Texas Medical Branch .
Modern advancements in imaging technology encourage further development and refinement in the way viral research is accomplished. Initially proposed by Russel and Burch in Hume's 3Rs (replacement, reduction, refinement), the utilization of animal models in scientific research is under constant pressure to identify new methodologies to reduce animal usage while improving scientific accuracy and speed. A major challenge to Hume's principals however, is how to ensure the studies are statistically accurate while reducing animal disease morbidity and overall numbers. Vaccine efficacy studies currently require a large number of animals in order to be considered statistically significant and often result in high morbidity and mortality endpoints for identification of immune protection. We utilized in vivo
imaging systems (IVIS) in conjunction with a firefly bioluminescent enzyme to progressively track the invasion of the central nervous system (CNS) by an encephalitic virus in a murine model. Typically, the disease progresses relatively slowly, however virus replication is rapid, especially within the CNS, and can lead to an often, lethal outcome. Following intranasal infection of the mice with TC83-Luc, an attenuated Venezuelan equine encephalitis virus strain modified to expresses a luciferase gene; we are able to visualize virus replication within the brain at least three days before the development of clinical disease symptoms. Utilizing CNS invasion as a key encephalitic disease development endpoint we are able to quickly identify therapeutic and vaccine protection against TC83-Luc infection before clinical symptoms develop. With IVIS technology we are able to demonstrate the rapid and accurate testing of drug therapeutics and vaccines while reducing animal numbers and morbidity.
Virology, Issue 70, Immunology, Medicine, Neuroscience, Molecular Biology, Pathology, IVIS, in vivo modeling, VEE, CNS, Neuroinvasion, Hume’s 3Rs, Encephalitis, bioluminescence, luciferase, virus
Surgical Procedures for a Rat Model of Partial Orthotopic Liver Transplantation with Hepatic Arterial Reconstruction
Institutions: RWTH-Aachen University, Kyoto University .
Orthotopic liver transplantation (OLT) in rats using a whole or partial graft is an indispensable experimental model for transplantation research, such as studies on graft preservation and ischemia-reperfusion injury 1,2
, immunological responses 3,4
, hemodynamics 5,6
, and small-for-size syndrome 7
. The rat OLT is among the most difficult animal models in experimental surgery and demands advanced microsurgical skills that take a long time to learn. Consequently, the use of this model has been limited. Since the reliability and reproducibility of results are key components of the experiments in which such complex animal models are used, it is essential for surgeons who are involved in rat OLT to be trained in well-standardized and sophisticated procedures for this model.
While various techniques and modifications of OLT in rats have been reported 8
since the first model was described by Lee et al. 9
in 1973, the elimination of the hepatic arterial reconstruction 10
and the introduction of the cuff anastomosis technique by Kamada et al. 11
were a major advancement in this model, because they simplified the reconstruction procedures to a great degree. In the model by Kamada et al.
, the hepatic rearterialization was also eliminated. Since rats could survive without hepatic arterial flow after liver transplantation, there was considerable controversy over the value of hepatic arterialization. However, the physiological superiority of the arterialized model has been increasingly acknowledged, especially in terms of preserving the bile duct system 8,12
and the liver integrity 8,13,14
In this article, we present detailed surgical procedures for a rat model of OLT with hepatic arterial reconstruction using a 50% partial graft after ex vivo
liver resection. The reconstruction procedures for each vessel and the bile duct are performed by the following methods: a 7-0 polypropylene continuous suture for the supra- and infrahepatic vena cava; a cuff technique for the portal vein; and a stent technique for the hepatic artery and the bile duct.
Medicine, Issue 73, Biomedical Engineering, Anatomy, Physiology, Immunology, Surgery, liver transplantation, liver, hepatic, partial, orthotopic, split, rat, graft, transplantation, microsurgery, procedure, clinical, technique, artery, arterialization, arterialized, anastomosis, reperfusion, rat, animal model
The Use of Carboxyfluorescein Diacetate Succinimidyl Ester (CFSE) to Monitor Lymphocyte Proliferation
Institutions: John Curtin School of Medical Research, Australian National University.
Carboxyfluorescein succinimidyl ester (CFSE) is an effective and popular means to monitor lymphocyte division1-3
. CFSE covalently labels long-lived intracellular molecules with the fluorescent dye, carboxyfluorescein. Thus, when a CFSE-labeled cell divides, its progeny are endowed with half the number of carboxyfluorescein-tagged molecules and thus each cell division can be assessed by measuring the corresponding decrease in cell fluorescence via Flow cytometry. The capacity of CFSE to label lymphocyte populations with a high fluorescent intensity of exceptionally low variance, coupled with its low cell toxicity, make it an ideal dye to measure cell division. Since it is a fluorescein-based dye it is also compatible with a broad range of other fluorochromes making it applicable to multi-color flow cytometry. This article describes the procedures typically used for labeling mouse lymphocytes for the purpose of monitoring up to 8 cell divisions. These labeled cells can be used both for in vitro
and in vivo
Immunology, Issue 44, carboxyfluorescein diacetate succinimidyl ester (CFSE), labeling, lymphocytes, proliferation.
Passive Administration of Monoclonal Antibodies Against H. capsulatum and Others Fungal Pathogens
Institutions: Albert Einstein College of Medicine.
The purpose of the use of this methodology is 1) to advance our capacity to protect individuals with antibody or vaccine for preventing or treating histoplasmosis caused by the fungus Histoplasma capsulatum
and 2) to examine the role of virulence factors as target for therapy. To generate mAbs, mice are immunized, the immune responses are assessed using a solid phase ELISA system developed in our laboratory, and the best responder mice are selected for isolation of splenocytes for fusion with hybridoma cells. C57BL/6 mice have been extensively used to study H. capsulatum
pathogenesis and provide the best model for obtaining the data required. In order to assess the role of the mAbs in infection, mice are intraperitoneally administered with either mAb to H. capsulatum
or isotype matched control mAb and then infected by either intravenous (i.v.), intraperitoneal (i.p.), or intranasal (i.n.) routes. In the scientific literature, efficacy of mAbs for fungal infections in mice relies on mortality as an end point, in conjunction with colony formin units (CFU) assessments at earlier time points. Survival (time to death) studies are necessary as they best represent human disease. Thus, efficacy of our intervention would not adequately be established without survival curves. This is also true for establishing efficacy of vaccine or testing of mutants for virulence. With histoplasmosis, the mice often go from being energetic to dead over several hours. The capacity of an intervention such as the administration of a mAb may initially protect an animal from disease, but the disease can relapse which would not be realized in short CFU experiments. In addition to survival and fungal burden assays, we examine the inflammatory responses to infection (histology, cellular recruitment, cytokine responses). For survival/time to death experiments, the mice are infected and monitored at least twice daily for signs of morbidity. To assess fungal burden, histopathology, and cytokine responses, the mice are euthanized at various times after infection. Animal experiments are performed according to the guidelines of the Institute for Animal Studies of the Albert Einstein College of Medicine.
Infection, Issue 48, Fungal pathogens, monoclonal antibodies, protection, passive administration
Use of a Hanging-weight System for Liver Ischemia in Mice
Institutions: University of Colorado, Denver, University of Colorado, Denver.
Acute liver injury due to ischemia can occur during several clinical procedures e.g. liver transplantation, hepatic tumor resection or trauma repair and can result in liver failure which has a high mortality rate1-2
. Therefore murine studies of hepatic ischemia have become an important field of research by providing the opportunity to utilize pharmacological and genetic studies3-9
. Specifically, conditional mice with tissue specific deletion of a gene (cre, flox system) provide insights into the role of proteins in particular tissues10-13
. Because of the technical difficulty associated with manually clamping the portal triad in mice, we performed a systematic evaluation using a hanging-weight system for portal triad occlusion which has been previously described3
. By using a hanging-weight system we place a suture around the left branch of the portal triad without causing any damage to the hepatic lobes, since also the finest clamps available can cause hepatic tissue damage because of the close location of liver tissue to the vessels. Furthermore, the right branch of the hepatic triad is still perfused thus no intestinal congestion occurs with this technique as blood flow to the right hepatic lobes is preserved. Furthermore, the portal triad is only manipulated once throughout the entire surgical procedure. As a result, procedures like pre-conditioning, with short times of ischemia and reperfusion, can be easily performed. Systematic evaluation of this model by performing different ischemia and reperfusion times revealed a close correlation of hepatic ischemia time with liver damage as measured by alanine (ALT) and aspartate (AST) aminotransferase serum levels3,9
. Taken together, these studies confirm highly reproducible liver injury when using the hanging-weight system for hepatic ischemia and intermittent reperfusion. Thus, this technique might be useful for other investigators interested in liver ischemia studies in mice. Therefore the video clip provides a detailed step-by-step description of this technique.
Medicine, Issue 66, Physiology, Immunology, targeted gene deletion, murine model, liver failure, ischemia, reperfusion, video demonstration
Seven Steps to Stellate Cells
Institutions: Harvard Medical School.
Hepatic stellate cells are liver-resident cells of star-like morphology and are located in the space of Disse between liver sinusoidal endothelial cells and hepatocytes1,2
. Stellate cells are derived from bone marrow precursors and store up to 80% of the total body vitamin A1, 2
. Upon activation, stellate cells differentiate into myofibroblasts to produce extracellular matrix, thus contributing to liver fibrosis3
. Based on their ability to contract, myofibroblastic stellate cells can regulate the vascular tone associated with portal hypertension4
. Recently, we demonstrated that hepatic stellate cells are potent antigen presenting cells and can activate NKT cells as well as conventional T lymphocytes5
Here we present a method for the efficient preparation of hepatic stellate cells from mouse liver. Due to their perisinusoidal localization, the isolation of hepatic stellate cells is a multi-step process. In order to render stellate cells accessible to isolation from the space of Disse, mouse livers are perfused in situ
with the digestive enzymes Pronase E and Collagenase P. Following perfusion, the liver tissue is subjected to additional enzymatic treatment with Pronase E and Collagenase P in vitro
. Subsequently, the method takes advantage of the massive amount of vitamin A-storing lipid droplets in hepatic stellate cells. This feature allows the separation of stellate cells from other hepatic cell types by centrifugation on an 8% Nycodenz gradient. The protocol described here yields a highly pure and homogenous population of stellate cells. Purity of preparations can be assessed by staining for the marker molecule glial fibrillary acidic protein (GFAP), prior to analysis by fluorescence microscopy or flow cytometry. Further, light microscopy reveals the unique appearance of star-shaped hepatic stellate cells that harbor high amounts of lipid droplets.
Taken together, we present a detailed protocol for the efficient isolation of hepatic stellate cells, including representative images of their morphological appearance and GFAP expression that help to define the stellate cell entity.
Immunology, Issue 51, Hepatic Stellate Cell, Ito Cell, Liver Immunology, Retinoic Acid, Cell Isolation
Modeling Neural Immune Signaling of Episodic and Chronic Migraine Using Spreading Depression In Vitro
Institutions: The University of Chicago Medical Center, The University of Chicago Medical Center.
Migraine and its transformation to chronic migraine are healthcare burdens in need of improved treatment options. We seek to define how neural immune signaling modulates the susceptibility to migraine, modeled in vitro
using spreading depression (SD), as a means to develop novel therapeutic targets for episodic and chronic migraine. SD is the likely cause of migraine aura and migraine pain. It is a paroxysmal loss of neuronal function triggered by initially increased neuronal activity, which slowly propagates within susceptible brain regions. Normal brain function is exquisitely sensitive to, and relies on, coincident low-level immune signaling. Thus, neural immune signaling likely affects electrical activity of SD, and therefore migraine. Pain perception studies of SD in whole animals are fraught with difficulties, but whole animals are well suited to examine systems biology aspects of migraine since SD activates trigeminal nociceptive pathways. However, whole animal studies alone cannot be used to decipher the cellular and neural circuit mechanisms of SD. Instead, in vitro
preparations where environmental conditions can be controlled are necessary. Here, it is important to recognize limitations of acute slices and distinct advantages of hippocampal slice cultures. Acute brain slices cannot reveal subtle changes in immune signaling since preparing the slices alone triggers: pro-inflammatory changes that last days, epileptiform behavior due to high levels of oxygen tension needed to vitalize the slices, and irreversible cell injury at anoxic slice centers.
In contrast, we examine immune signaling in mature hippocampal slice cultures since the cultures closely parallel their in vivo
counterpart with mature trisynaptic function; show quiescent astrocytes, microglia, and cytokine levels; and SD is easily induced in an unanesthetized preparation. Furthermore, the slices are long-lived and SD can be induced on consecutive days without injury, making this preparation the sole means to-date capable of modeling the neuroimmune consequences of chronic SD, and thus perhaps chronic migraine. We use electrophysiological techniques and non-invasive imaging to measure
neuronal cell and circuit functions coincident with SD. Neural immune gene expression variables are measured with qPCR screening, qPCR arrays, and, importantly, use of cDNA preamplification for detection of ultra-low level targets such as interferon-gamma using whole, regional, or specific cell enhanced (via laser dissection microscopy) sampling. Cytokine cascade signaling is further assessed with multiplexed phosphoprotein related targets with gene expression and phosphoprotein changes confirmed via cell-specific immunostaining. Pharmacological and siRNA strategies are used to mimic
SD immune signaling.
Neuroscience, Issue 52, innate immunity, hormesis, microglia, T-cells, hippocampus, slice culture, gene expression, laser dissection microscopy, real-time qPCR, interferon-gamma
Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Institutions: The University of Melbourne, The University of Melbourne.
Listeria monocytogenes (Listeria)
is a Gram-positive facultative intracellular pathogen1
. Mouse studies typically employ intravenous injection of Listeria
, which results in systemic infection2
. After injection, Listeria quickly disseminates to the spleen and liver due to uptake by CD8α+
dendritic cells and Kupffer cells3,4
. Once phagocytosed, various bacterial proteins enable Listeria
to escape the phagosome, survive within the cytosol, and infect neighboring cells5
. During the first three days of infection, different innate immune cells (e.g. monocytes, neutrophils, NK cells, dendritic cells) mediate bactericidal mechanisms that minimize Listeria
T cells are subsequently recruited and responsible for the eventual clearance of Listeria
from the host, typically within 10 days of infection6
Successful clearance of Listeria
from infected mice depends on the appropriate onset of host immune responses6
. There is a broad range of sensitivities amongst inbred mouse strains7,8
. Generally, mice with increased susceptibility to Listeria
infection are less able to control bacterial proliferation, demonstrating increased bacterial load and/or delayed clearance compared to resistant mice. Genetic studies, including linkage analyses and knockout mouse strains, have identified various genes for which sequence variation affects host responses to Listeria
. Determination and comparison of infection kinetics between different mouse strains is therefore an important method for identifying host genetic factors that contribute to immune responses against Listeria
. Comparison of host responses to different Listeria
strains is also an effective way to identify bacterial virulence factors that may serve as potential targets for antibiotic therapy or vaccine design.
We describe here a straightforward method for measuring bacterial load (colony forming units [CFU] per tissue) and preparing single-cell suspensions of the liver and spleen for FACS analysis of immune responses in Listeria
-infected mice. This method is particularly useful for initial characterization of Listeria
infection in novel mouse strains, as well as comparison of immune responses between different mouse strains infected with Listeria
. We use the Listeria monocytogenes
that, when cultured on blood agar, exhibits a characteristic halo zone around each colony due to β-hemolysis1
(Figure 1). Bacterial load and immune responses can be determined at any time-point after infection by culturing tissue homogenate on blood agar plates and preparing tissue cell suspensions for FACS analysis using the protocols described below. We would note that individuals who are immunocompromised or pregnant should not handle Listeria
, and the relevant institutional biosafety committee and animal facility management should be consulted before work commences.
Immunology, Issue 54, Listeria, intracellular bacteria, genetic susceptibility, liver, spleen, blood, FACS analysis, T cells
Isolation of CD133+ Liver Stem Cells for Clonal Expansion
Institutions: Pennsylvania State College of Medicine, Pennsylvania State College of Medicine, University of California Los Angeles, School of Medicine.
Liver stem cell, or oval cells, proliferate during chronic liver injury, and are proposed to differentiate into both hepatocytes and cholangiocytes. In addition, liver stem cells are hypothesized to be the precursors for a subset of liver cancer, Hepatocellular carcinoma. One of the primary challenges to stem cell work in any solid organ like the liver is the isolation of a rare population of cells for detailed analysis. For example, the vast majority of cells in the liver are hepatocytes (parenchymal fraction), which are significantly larger than non-parenchymal cells. By enriching the specific cellular compartments of the liver (i.e. parenchymal and non-parenchymal fractions), and selecting for CD45 negative cells, we are able to enrich the starting population of stem cells by over 600-fold.The proceduresdetailed in this report allow for a relatively rare population of cells from a solid organ to be sorted efficiently. This process can be utilized to isolateliver stem cells from normal murine liver as well as chronic liver injury models, which demonstrate increased liver stem cell proliferation. This method has clear advantages over standard immunohistochemistry of frozen or formalin fixed liver as functional studies using live cells can be performed after initial co-localization experiments. To accomplish the procedure outlined in this report, a working relationship with a research based flow-cytometry core is strongly encouraged as the details of FACS isolation are highly dependent on specialized instrumentation and a strong working knowledge of basic flow-cytometry procedures. The specific goal of this process is to isolate a population of liver stem cells that can be clonally expanded in vitro
Developmental Biology, Issue 56, CD133, liver stem cell, oval cell, liver cancer stem cell, stem cell, cell isolation, non-parenchymal fraction of liver, flow cytometry
Efficient Recombinant Parvovirus Production with the Help of Adenovirus-derived Systems
Institutions: German Cancer Research Center (DKFZ), German Cancer Research Center (DKFZ).
Rodent parvoviruses (PV) such as rat H-1PV and MVM, are small icosahedral, single stranded, DNA viruses. Their genome includes two promoters P4 and P38 which regulate the expression of non-structural (NS1 and NS2) and capsid proteins (VP1 and VP2) respectively1
. They attract high interest as anticancer agents for their oncolytic and oncosuppressive abilities while being non-pathogenic for humans2
. NS1 is the major effector of viral cytotoxicity3
. In order to further enhance their natural antineoplastic activities, derivatives from these vectors have been generated by replacing the gene encoding for the capsid proteins with a therapeutic transgene (e.g.
a cytotoxic polypeptide, cytokine, chemokine, tumour suppressor gene etc.)4
. The recombinant parvoviruses (recPVs) vector retains the NS1/2 coding sequences and the PV genome telomeres which are necessary for viral DNA amplification and packaging. Production of recPVs occurs only in the producer cells (generally HEK293T), by co-transfecting the cells with a second vector (pCMV-VP) expressing the gene encoding for the VP proteins (Fig. 1
. The recPV vectors generated in this way are replication defective. Although recPVs proved to possess enhanced oncotoxic activities with respect to the parental viruses from which they have been generated, their production remains a major challenge and strongly hampers the use of these agents in anti-cancer clinical applications.
We found that introduction of an Ad-5 derived vector containing the E2a, E4(orf6
) and the VA RNA
pXX6 plasmid) into HEK293T improved the production of recPVs by more than 10 fold in comparison to other protocols in use. Based on this finding, we have constructed a novel Ad-VP-helper that contains the genomic adenoviral elements necessary to enhance recPVs production as well as the parvovirus VP gene unit5
. The use of Ad-VP-helper, allows production of rec-PVs using a protocol that relies entirely on viral infection steps (as opposed to plasmid transfection), making possible the use of cell lines that are difficult to transfect (e.g.
NB324K) (Fig. 2
). We present a method that greatly improves the amount of recombinant virus produced, reducing both the production time and costs, without affecting the quality of the final product5
. In addition, large scale production of recPV (in suspension cells and bioreactors) is now conceivable.
Immunology, Issue 62, Recombinant parvovirus, adenovirus, virus production, pXX6, virus helper, virology, oncology
A Cre-Lox P Recombination Approach for the Detection of Cell Fusion In Vivo
Institutions: University of Wisconsin-Madison, University of Wisconsin-Madison.
The ability of two or more cells of the same type to fuse has been utilized in metazoans throughout evolution to form many complex organs, including skeletal muscle, bone and placenta. Contemporary studies demonstrate fusion of cells of the same type confers enhanced function. For example, when the trophoblast cells of the placenta fuse to form the syncytiotrophoblast, the syncytiotrophoblast is better able to transport nutrients and hormones across the maternal-fetal barrier than unfused trophoblasts1-4
. More recent studies demonstrate fusion of cells of different types can direct cell fate. The "reversion" or modification of cell fate by fusion was once thought to be limited to cell culture systems. But the advent of stem cell transplantation led to the discovery by us and others that stem cells can fuse with somatic cells in vivo
and that fusion facilitates stem cell differentiation5-7
. Thus, cell fusion is a regulated process capable of promoting cell survival and differentiation and thus could be of central importance for development, repair of tissues and even the pathogenesis of disease.
Limiting the study of cell fusion, is lack of appropriate technology to 1) accurately identify fusion products and to 2) track fusion products over time. Here we present a novel approach to address both limitations via induction of bioluminescence upon fusion (Figure 1
); bioluminescence can be detected with high sensitivity in vivo8-15
. We utilize a construct encoding the firefly luciferase (Photinus pyralis) gene placed adjacent to a stop codon flanked by LoxP sequences. When cells expressing this gene fuse with cells expressing the Cre recombinase protein, the LoxP sites are cleaved and the stop signal is excised allowing transcription of luciferase.
Because the signal is inducible, the incidence of false-positive signals is very low. Unlike existing methods which utilize the Cre/LoxP
, we have incorporated a "living" detection signal and thereby afford for the first time the opportunity to track the kinetics of cell fusion in vivo
To demonstrate the approach, mice ubiquitously expressing Cre recombinase served as recipients of stem cells transfected with a construct to express luciferase downstream of a floxed stop codon.
Stem cells were transplanted via intramyocardial injection and after transplantation intravital image analysis was conducted to track the presence of fusion products in the heart and surrounding tissues over time. This approach could be adapted to analyze cell fusion in any tissue type at any stage of development, disease or adult tissue repair.
Bioengineering, Issue 59, Cell fusion, stem cell, fusogen, cre recombinase, biophotonic imaging, cellular transplantation
Intraductal Injection of LPS as a Mouse Model of Mastitis: Signaling Visualized via an NF-κB Reporter Transgenic
Institutions: Vanderbilt University Medical Center, Vanderbilt University Medical Center, University of Hawaii at Hilo College of Pharmacy.
Animal models of human disease are necessary in order to rigorously study stages of disease progression and associated mechanisms, and ultimately, as pre-clinical models to test interventions. In these methods, we describe a technique in which lipopolysaccharide (LPS) is injected into the lactating mouse mammary gland via the nipple, effectively modeling mastitis, or inflammation, of the gland. This simulated infection results in increased nuclear factor kappa B (NF-κB) signaling, as visualized through bioluminescent imaging of an NF-κB luciferase reporter mouse1
Our ultimate goal in developing these methods was to study the inflammation associated with mastitis in the lactating gland, which often includes redness, swelling, and immune cell infiltration2,3
. Therefore, we were keenly aware that incision or any type of wounding of the skin, the nipple, or the gland in order to introduce the LPS could not be utilized in our methods since the approach would likely confound the read-out of inflammation. We also desired a straight-forward method that did not require specially made hand-drawn pipettes or the use of micromanipulators to hold these specialized tools in place. Thus, we determined to use a commercially available insulin syringe and to inject the agent into the mammary duct of an intact nipple. This method was successful and allowed us to study the inflammation associated with LPS injection without any additional effects overlaid by the process of injection. In addition, this method also utilized an NF-κB luciferase reporter transgenic mouse and bioluminescent imaging technology to visually and quantitatively show increased NF-κB signaling within the LPS-injected gland4
These methods are of interest to researchers of many disciplines who wish to model disease within the lactating mammary gland, as ultimately, the technique described here could be utilized for injection of a number of substances, and is not limited to only LPS.
Medicine, Issue 67, mastitis, intraductal injection, NF-kappaB, reporter transgenic, LPS, bioluminescent imaging, lactation
Ischemic Tissue Injury in the Dorsal Skinfold Chamber of the Mouse: A Skin Flap Model to Investigate Acute Persistent Ischemia
Institutions: Technische Universität München, University Hospital of Basel, University of Saarland, University Hospital Zurich.
Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are still occurring, particularly in reconstructive flap surgery. Multiple experimental flap models have been developed to analyze underlying causes and mechanisms and to investigate treatment strategies to prevent ischemic complications. The limiting factor of most models is the lacking possibility to directly and repetitively visualize microvascular architecture and hemodynamics. The goal of the protocol was to present a well-established mouse model affiliating these before mentioned lacking elements. Harder et al.
have developed a model of a musculocutaneous flap with a random perfusion pattern that undergoes acute persistent ischemia and results in ~50% necrosis after 10 days if kept untreated. With the aid of intravital epi-fluorescence microscopy, this chamber model allows repetitive visualization of morphology and hemodynamics in different regions of interest over time. Associated processes such as apoptosis, inflammation, microvascular leakage and angiogenesis can be investigated and correlated to immunohistochemical and molecular protein assays. To date, the model has proven feasibility and reproducibility in several published experimental studies investigating the effect of pre-, peri- and postconditioning of ischemically challenged tissue.
Medicine, Issue 93, flap, ischemia, microcirculation, angiogenesis, skin, necrosis, inflammation, apoptosis, preconditioning, persistent ischemia, in vivo model, muscle.
Protein Transfection of Mouse Lung
Institutions: St. Luke's Roosevelt Medical Center.
Increasing protein expression enables researchers to better understand the functional role of that protein in regulating key biological processes1
. In the lung, this has been achieved typically through genetic approaches that utilize transgenic mice2,3
or viral or non-viral vectors that elevate protein levels via increased gene expression4
. Transgenic mice are costly and time-consuming to generate and the random insertion of a transgene or chronic gene expression can alter normal lung development and thus limit the utility of the model5
. While conditional transgenics avert problems associated with chronic gene expression6
, the reverse tetracycline-controlled transactivator (rtTA) mice, which are used to generate conditional expression, develop spontaneous air space enlargement7
. As with transgenics, the use of viral and non-viral vectors is expensive8
and can provoke dose-dependent inflammatory responses that confound results9
and hinder expression10
. Moreover, the efficacy of repeated doses are limited by enhanced immune responses to the vector11,12
. Researchers are developing adeno-associated viral (AAV) vectors that provoke less inflammation and have longer expression within the lung13
Using β-galactosidase, we present a method for rapidly and effectively increasing protein expression within the lung using a direct protein transfection technique. This protocol mixes a fixed amount of purified protein with 20 μl of a lipid-based transfection reagent (Pro-Ject, Pierce Bio) to allow penetration into the lung tissue itself. The liposomal protein mixture is then injected into the lungs of the mice via the trachea using a microsprayer (Penn Century, Philadelphia, PA). The microsprayer generates a fine plume of liquid aerosol throughout the lungs. Using the technique we have demonstrated uniform deposition of the injected protein throughout the airways and the alveoli of mice14
. The lipid transfection technique allows the use of a small amount of protein to achieve effect. This limits the inflammatory response that otherwise would be provoked by high protein administration. Indeed, using this technique we published that we were able to significantly increase PP2A activity in the lung without affecting lung lavage cellularity15
. Lung lavage cellularity taken 24 hr after challenge was comparable to controls (27±4 control vs. 31±5 albumin transfected; N=6 per group). Moreover, it increases protein levels without inducing lung developmental changes or architectural changes that can occur in transgenic models. However, the need for repeated administrations may make this technique less favorable for studies examining the effects of long-term increases in protein expression. This would be particularly true for proteins with short half-lives.
Molecular Biology, Issue 75, Medicine, Biomedical Engineering, Bioengineering, Biochemistry, Genetics, Cellular Biology, Anatomy, Physiology, Proteins, Torso, Tissues, Cells, Animal Structures, Respiratory System, Eukaryota, Immune System Diseases, Respiratory Tract Diseases, Natural Science Disciplines, Life Sciences (General), transfection, lung, protein, mice, inflammation, animal model