Name: in vivo imaging of reactive oxygen species in a murine wound model
Uploaded: 2018-11-17T13:00:00
Description: Watch this Scientific Journal Video about In Vivo Imaging of Reactive Oxygen Species in a Murine Wound Model at JoVE.com

We are grateful to the Preclinical Imaging Core at the NYU School of Medicine, with special thanks to Orlando Aristizabal and Youssef Zaim Wadghiri. The core is a shared resource partially supported by the Laura and Isaac Perlmutter Cancer Center Support Grant NIH/NCI 5P30CA016087 and NIBIB Biomedical Technology Resource Center Grant NIH P41 EB017183. This work was supported by the American Diabetes Association &#34;Pathway to Stop Diabetes&#34; to D.C. [grant number 1-16-ACE-08] and the NYU Applied Research Support Fund to P.R.

All methods described here have been approved by the Institutional Animal Care and Use Committee of New York University School of Medicine. All mice are housed behind a barrier and all personnel wear appropriate personal protective equipment.
1. Day 0: Preparation of Murine Model of Excisional Wound Healing
<ol>
	<li>Anesthetize diabetic (Leprdb/db) mice, aged 8&#8211;12 weeks, with inhalational 2% isoflurane. Confirm that each mouse has been properly anesthetized using the foot p...

<ol>
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Y., Gloe, T., Keller, M., Schoenafinger, K., Pohl, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitive+superoxide+detection+in+vascular+cells+by+the+new+chemiluminescence+dye+L-012.">Sensitive superoxide detection in vascular cells by the new chemiluminescence dye L-012.</a> Journal of Vascular Research. 36 (6), 456-464 (1999).</li><li>Fuchs, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+Hypoxia+PET+Imaging+Quantifies+the+Severity+of+Arthritic+Joint+Inflammation+in+Line+with+Overexpression+of+Hypoxia-Inducible+Factor+and+Enhanced+Reactive+Oxygen+Species+Generation.">In vivo Hypoxia PET Imaging Quantifies the Severity of Arthritic Joint Inflammation in Line with Overexpression of Hypoxia-Inducible Factor and Enhanced Reactive Oxygen Species Generation.</a> The Journal of Nuclear Medicine. 58 (5), 853-860 (2017).</li><li>Asghar, M. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+imaging+of+reactive+oxygen+and+nitrogen+species+in+murine+colitis.">In vivo imaging of reactive oxygen and nitrogen species in murine colitis.</a> Inflammatory Bowel Diseases. 20 (8), 1435-1447 (2014).</li><li>Galiano, R. D., Michaels, J. t., Dobryansky, M., Levine, J. P., Gurtner, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+and+reproducible+murine+model+of+excisional+wound+healing.">Quantitative and reproducible murine model of excisional wound healing.</a> Wound Repair and Regeneration. 12 (4), 485-492 (2004).</li><li>Soares, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Restoration+of+Nrf2+Signaling+Normalizes+the+Regenerative+Niche.">Restoration of Nrf2 Signaling Normalizes the Regenerative Niche.</a> Diabetes. 65 (3), 633-646 (2016).</li><li>Wang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+ROS+signaling+in+cells+and+animals.">Imaging ROS signaling in cells and animals.</a> Journal of Molecular Medicine. 91 (8), 917-927 (2013).</li><li>Kielland, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+imaging+of+reactive+oxygen+and+nitrogen+species+in+inflammation+using+the+luminescent+probe+L-012.">In vivo imaging of reactive oxygen and nitrogen species in inflammation using the luminescent probe L-012.</a> Free Radical Biology and Medicine. 47 (6), 760-766 (2009).</li><li>Balke, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+Oxidative+Cellular+Stress+Induced+by+Nanoparticles+in+the+Subcytotoxic+Range+Using+Fluorescence+Lifetime+Imaging.">Visualizing Oxidative Cellular Stress Induced by Nanoparticles in the Subcytotoxic Range Using Fluorescence Lifetime Imaging.</a> Small. , (2018).</li><li>Zielonka, J., Lambeth, J. 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Common techniques for measuring ROS have been limited by complex protocols requiring tissue extraction or similarly invasive techniques. In recent years, measurements of oxidative stress have been reported on the basis of innovative imaging modalities, thereby allowing for spatiotemporal assessments9,10,11. L-012 has several advantages as a chemiluminescent probe relative to luminol, lucigenin, and MCLA1<...

Oxygen metabolites generated through inflammatory processes contribute to various signaling cascades as well as destructive alteration of cellular components1. Utilizing sensitive and specific techniques to measure ROS is critical for studying inflammatory processes and characterizing the effects of oxidative stress. In vivo imaging is valuable because of its ability to provide dynamic spatial and temporal data in living tissue. L-012 is a synthetic chemiluminescent probe that is highly sensitive for superoxide anions and produces a higher light intensity than other fluorescent probes in cells, tissues, and whole blood1,2,3,4. It has been successfully employed for in vivo imaging in murine models to study several inflammatory diseases, including arthritis and colitis5,6. It has yet to be employed in an established cutaneous wound healing model. Measurement of ROS generated is equally relevant to assess the progression of wound healing under different conditions. The sensitivity and noninvasive nature of this method makes it a promising technique for studying wound healing across murine models.
Nrf2 is a major driver of the antioxidant response and a transcriptional factor with specificity for the antioxidant response element (ARE) common to the promoter regions of several antioxidant enzymes8. In the absence of oxidative stress, Nrf2 is sequestered in the cytoplasm by Keap1, which subsequently causes its ubiquitination and degradation. Imbalance of the Nrf2/Keap1 pathway has been implicated in inappropriate redox homeostasis and delayed wound healing in the setting of increased oxidative stress9. We have previously shown that suppression of Keap1 stimulates increased Nrf2 activity and promotes rescue of pathologic cutaneous wound healing in diabetic wounds9.
Here we describe a protocol that utilizes L-012-assisted bioluminescence imaging to measure ROS levels in an excisional cutaneous wound healing model, which is critical for highlighting the association between ROS and wound healing. This technique demonstrates real-time changes in oxidative burden within wounds and immediate periphery. Furthermore, this method allows for rapid assessment of interventions and mechanisms that affect redox handling. Here we use a model of Keap1 knockdown for the restoration of redox homeostasis to evaluate the applicability of our strategy. Because our technique is non-invasive and wounds are undisturbed, the same animal can be used for further confirmatory analyses on the basis of histology or cell lysates.

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			<td height="20" style="height:20px;width:265px;">BKS.Cg-Dock7m+/+ Leprdb/J mice</td>
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			<td height="20" style="height:20px;">13 cm x 18 cm Silicone sheet (0.6 mm)</td>
			<td>Sigma Aldrich&#160;</td>
			<td>665581</td>
			<td></td>
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			<td height="20" style="height:20px;">3M Tegaderm Transparent Film Dressings</td>
			<td>3M</td>
			<td>88-1626W</td>
			<td></td>
		</tr>
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			<td height="20" style="height:20px;">Lipofectamine 2000 Transfection Reagent</td>
			<td>Life Technologies&#160;</td>
			<td>11668027</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Keap1 Stealth siRNA</td>
			<td>Thermofisher Scientific</td>
			<td>1299001</td>
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			<td height="20" style="height:20px;">Silencer negative control&#160;</td>
			<td>Thermofisher Scientific&#160;</td>
			<td>AM4635</td>
			<td></td>
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			<td height="20" style="height:20px;">Opti-MEM Reduced Serum</td>
			<td>ThermoFisher Scientific</td>
			<td>11058021</td>
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			<td height="20" style="height:20px;">DPBS</td>
			<td>ThermoFisher Scientific</td>
			<td>14040133</td>
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			<td height="20" style="height:20px;">Methyl-cellulose&#160;</td>
			<td>Sigma Aldrich</td>
			<td>9004-67-5</td>
			<td></td>
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		<tr height="20">
			<td height="20" style="height:20px;">L-012</td>
			<td>Wako Chemicals</td>
			<td>120-04891</td>
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			<td height="20" style="height:20px;">IVIS Lumina III XR In Vivo Imaging System&#160;</td>
			<td>PerkinElmer</td>
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in vivo imaging of reactive oxygen species in a murine wound model

The generation of reactive oxygen species (ROS) is a hallmark of inflammatory processes, but in excess, oxidative stress is widely implicated in various pathologies such as cancer, atherosclerosis and diabetes. We have previously shown that dysfunction of the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/ Kelch-like erythroid cell-derived protein 1 (Keap1) signaling pathway leads to extreme ROS imbalance during cutaneous wound healing in diabetes. Since ROS levels are an important indicator of progression of wound healing, specific and accurate quantification techniques are valuable. Several in vitro assays to measure ROS in cells and tissues have been described; however, they only provide a single cumulative measurement per sample. More recently, the development of protein-based indicators and imaging modalities have allowed for unique spatiotemporal analyses. L-012 (C13H8ClN4NaO2) is a luminol derivative that can be used for both in vivo and in vitro chemiluminescent detection of ROS generated by NAPDH oxidase. L-012 emits a stronger signal than other fluorescent probes and has been shown to be both sensitive and reliable for detecting ROS. The time lapse applicability of L-012-facilitated imaging provides valuable information about inflammatory processes while reducing the need for sacrifice and overall reducing the number of study animals. Here, we describe a protocol utilizing L-012-facilitated in vivo imaging to quantify oxidative stress in a model of excisional wound healing using diabetic mice with locally dysfunctional Nrf2/Keap1.

Three days after creating bilateral wounds according to an established excisional wound model (Figure 1A), diabetic mice are positioned in the imaging chamber. An initial photograph and a measure of bioluminescence are taken before injection of L-012 to account for background signal (Figure 1B). Following intraperitoneal injection with the L-012 solution, the mice are repositioned in the chamber and bioluminescence is visualized ...

Watch this Scientific Journal Video about In Vivo Imaging of Reactive Oxygen Species in a Murine Wound Model at JoVE.com

In Vivo Imaging of Reactive Oxygen Species in a Murine Wound Model

We describe a non-invasive in vivo imaging protocol that is streamlined and cost-effective, utilizing L-012, a chemiluminescent luminol-analog, to visualize and quantify reactive oxygen species (ROS) generated in a mouse excisional wound model.

In Vivo Imaging of Reactive Oxygen Species in a Murine Wound Model

The generation of reactive oxygen species (ROS) is a hallmark of inflammatory processes, but in excess, oxidative stress is widely implicated in various ...

This method can help answer key questions in the tissue repair and regeneration field about the associations among the cytoprotective pathways, oxidative stress, and the wound healing response. The main advantage of this powerful technique is that you can measure reactive oxygen species in a wound, in real-time, to determine their impact on tissue regeneration. Demonstrating the procedure with me will be Jennifer Kwong, a research assistant in my laboratory.Use a glucometer to measure the blood glucose of each anesthetized eight to 12 week old diabetic mouse. And use a hair trimmer and depilatory cream to remove the dorsal hair from the first animal. Use alcohol wipes two times to clean the exposed skin and drape the animal so that only the surgical area is exposed.When the alcohol has dried, use sterile 10 millimeter biopsy punches to create two, 10 millimeter full thickness wounds extending through the panniculus carnosus according to a well established excisional wound healing technique. Use a 0.5 millimeter thick silicone sheet with 10 millimeter circular cutouts to splint the wounds open and secure the stints with interrupted 4/0 silk sutures. Then place the mice on a heat pad with monitoring until full recovery, before returning to its individual cage, providing paper towels as additional nesting material for two weeks.The next day, apply either control nonsense small interfering RNA gel or experimental small interfering Keap1 gel to the top of the wound of each animal and wrap each torso with transparent film dressing to keep the gel in place while leaving the limbs free. On day three of the experiment, load a one millimeter syringe equipped with a 27-gauge needle with freshly prepared L-012 solution and wrap the syringe to protect the solution from light. To image the wounds, gently remove the transparent film dressing from each of the mice without disturbing the wounds and place the mice into the imaging chamber of a bioluminescence imaging system.Set the imaging system inflow and the induction chamber oxygen levels to one liter per minute and image the mice by bioluminescence and bright field at baseline. Next, wipe the abdomens with alcohol wipes then inject five milligrams of L-012 solution per 200 grams body weight, IP, into each mouse once the alcohol has dried. Injecting the L-012 solution without disturbing the wounds on the dorsal skin is critical, because any distortion will affect the wound healing trajectory and data interpretation.Ensure that the animal is securely in dorsal recumbency before the injection. Immediately following the injection, place the mice back into their respective locations in the imaging chamber and image the animals for one minute every four minutes over a 60 minute imaging period, defining the 10 millimeter wound as the region of interest for determining the level of reactive oxygen species. Then place the mice on a heat pad with monitoring until full recovery before returning the animals to their individual cages.Three days after creating bilateral wounds according to the established excisional wound model, no bioluminescence is observed prior to L-012 injection. Following intraperintoneal L-012 solution injection, bioluminescence is observed in the areas of the wound where reactive oxygen species are detected. Recording of the bioluminescence for one minute every four to five minutes over the course of 60 minutes demonstrates the bioluminescent saturation of the region of interest over time, with the optimal imaging time to reach complete L-012 saturation observed at about 50 minutes.The bioluminescence in each wound region of interest before and after L-012 injection into nonsense small interfering RNA treated or Keap1 small interfering RNA treated mice can then be calculated by dividing the total counts of light intensity by the area. Analysis of day 10 wound tissue sections to confirm the accuracy of reactive oxygen species level measurement by H&E staining reveals a reduced cellular infiltration into small interfering Keap1 treated wounds compared to small interfering nonsense treated tissues, indicating a reduced inflammatory morphology in the experimental gel-treated animals. Analysis of the immuno-reactivity of F4/80, a protein macrophage marker on wound tissue sections, indicates a reduced number of macrophages in small interfering Keap1 treated wounds compared to small interfering nonsense treated wounds, further underscoring the validity of this method.When attempting this procedure, make sure to confirm the L-012 is not expired and to stir the solution in a place protected from light. Following this procedure, targeted probes and immuno-assay based methods can be used to study the sub-cellular localization of reactive oxygen species and their correlates, enabling a rapid assessment of interventions and mechanisms that affect the redux stats of wounds.

in-vivo-imaging-of-reactive-oxygen-species-in-a-murine-wound-model

Research

JoVE Journal

Immunology and Infection

In vivo Imaging of Transgenic Leishmania Parasites in a Live Host

Distinct species of Leishmania, a protozoan parasite of the family Trypanosomatidae, typically cause different human disease manifestations. The most common forms of disease are visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). Mouse models of leishmaniasis are widely used, but quantification of parasite burdens during murine disease requires mice to be euthanized at various times after infection. Parasite loads are then measured either by microscopy, limiting dilution assay, or qPCR amplification of parasite DNA. The in vivo imaging system (IVIS) has an integrated software package that allows the detection of a bioluminescent signal associated with cells in living organisms. Both to minimize animal usage and to follow infection longitudinally in individuals, in vivo models for imaging Leishmania spp. causing VL or CL were established. Parasites were engineered to express luciferase, and these were introduced into mice either intradermally or intravenously. Quantitative measurements of the luciferase driving bioluminescence of the transgenic Leishmania parasites within the mouse were made using IVIS. Individual mice can be imaged multiple times during longitudinal studies, allowing us to assess the inter-animal variation in the initial experimental parasite inocula, and to assess the multiplication of parasites in mouse tissues. Parasites are detected with high sensitivity in cutaneous locations. Although it is very likely that the signal (photons/second/parasite) is lower in deeper visceral organs than the skin, but quantitative comparisons of signals in superficial versus deep sites have not been done. It is possible that parasite numbers between body sites cannot be directly compared, although parasite loads in the same tissues can be compared between mice. Examples of one visceralizing species (L. infantum chagasi) and one species causing cutaneous leishmaniasis (L. mexicana) are shown. The IVIS procedure can be used for monitoring and analyzing small animal models of a wide variety of Leishmania species causing the different forms of human leishmaniasis.

In vivo Imaging of Transgenic Leishmania Parasites in a Live Host

An in vivo imaging system is used to generate quantitative measurements of murine infection with the Trypanosomatid protozoan Leishmania. This is a non-invasive and non-lethal method for detecting parasites expressing luciferase within many tissues throughout the course of chronic Leishmania spp. infection.

Distinct species of Leishmania, a protozoan parasite of the family Trypanosomatidae, typically cause different human disease manifestations. The most ...

Non-invasive Imaging of Leukocyte Homing and Migration in vivo

Two-photon (2P) microscopy is a high resolution imaging technique that has been broadly adapted by biologists. The value of 2P microscopy is that it provides rich spatiotemporal information regarding cell behaviors within intact tissues and in live mice. Leukocyte recruitment plays a significant role in host defense against infection and when unchecked, can contribute to inflammatory and autoimmune diseases. Studying leukocyte recruitment in vivo is technically challenging since cells are moving rapidly within vessels located deep within light scattering tissues. To date, most intravital imaging studies require surgical preparation to expose the blood vessels and tissues. To avoid the tissue damage and inflammation induced by surgery itself, here, we describe a non-invasive single-cell imaging approach that can be used to study leukocyte trafficking in the mouse footpad and phalanges. We discuss the technical aspects of our 2P imaging preparation and walk the reader through a typical experiment from initial set up to execution and data collection.

Non-invasive Imaging of Leukocyte Homing and Migration in vivo

Here, we describe a non-invasive two-photon (2P) microscopy approach to study leukocyte homing in the mouse footpad. We discuss the technical aspects of our tissue imaging preparation and walk the reader through a typical experiment from initial set up to execution and data collection.

Two-photon (2P) microscopy is a high resolution imaging technique that has been broadly adapted by biologists.  The value of 2P microscopy is that it ...

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological deficiencies. GVHD is caused by mature alloreactive T cells present in the bone marrow graft that are infused into the recipient and cause damage to host organs. However, in mice, T cells must be added to the bone marrow inoculum to cause GVHD. Although extensive work has been done to characterize T cell responses post transplant, bioluminescent imaging technology is a non-invasive method to monitor T cell trafficking patterns in vivo. 
Following lethal irradiation, recipient mice are transplanted with bone marrow cells and splenocytes from donor mice. T cell subsets from L2G85.B6 (transgenic mice that constitutively express luciferase) are included in the transplant. By only transplanting certain T cell subsets, one is able to track specific T cell subsets in vivo, and based on their location, develop hypotheses regarding the role of specific T cell subsets in promoting GVHD at various time points. At predetermined intervals post transplant, recipient mice are imaged using a Xenogen IVIS CCD camera. Light intensity can be quantified using Living Image software to generate a pseudo-color image based on photon intensity (red = high intensity, violet = low intensity). 
Between 4-7 days post transplant, recipient mice begin to show clinical signs of GVHD. Cooke et al.1 developed a scoring system to quantitate disease progression based on the recipient mice fur texture, skin integrity, activity, weight loss, and posture. Mice are scored daily, and euthanized when they become moribund. Recipient mice generally become moribund 20-30 days post transplant. 
Murine models are valuable tools for studying the immunology of GVHD. Selectively transplanting particular T cell subsets allows for careful identification of the roles each subset plays. Non-invasively tracking T cell responses in vivo adds another layer of value to murine GVHD models.

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Murine bone marrow transplantation is a widely used technique to study immunological mechanisms governing graft-versus-host disease in humans. The ability to monitor T cell trafficking patterns in vivo allows for detailed analysis of the development and perpetuation of T cell responses during graft-versus-host disease.

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological ...

Measurement of Tactile Allodynia in a Murine Model of Bacterial Prostatitis

Uropathogenic Escherichia coli (UPEC) are pathogens that play an important role in urinary tract infections and bacterial prostatitis1. We have recently shown that UPEC have an important role in the initiation of chronic pelvic pain2, a feature of Chronic prostatitis/Chronic pelvic pain syndrome (CP/CPPS)3,4. Infection of the prostate by clinically relevant UPEC can initiate and establish chronic pain through mechanisms that may involve tissue damage and the initiation of mechanisms of autoimmunity5.
A challenge to understanding the pathogenesis of UPEC in the prostate is the relative inaccessibility of the prostate gland to manipulation. We utilized a previously described intraurethral infection method6 to deliver a clinical strain of UPEC into male mice thereby establishing an ascending infection of the prostate. Here, we describe our protocols for standardizing the bacterial inoculum7 as well as the procedure for catheterizing anesthetized male mice for instillation of bacteria.
CP/CPPS is primarily characterized by the presence of tactile allodynia4. Behavior testing was based on the concept of cutaneous hyperalgesia resulting from referred visceral pain8-10. An irritable focus in visceral tissues reduces cutaneous pain thresholds allowing for an exaggerated response to normally non-painful stimuli (allodynia). Application of normal force to the skin result in abnormal responses that tend to increase with the intensity of the underlying visceral pain. We describe methodology in NOD/ShiLtJ mice that utilize von Frey fibers to quantify tactile allodynia over time in response to a single infection with UPEC bacteria.

Infection of the prostate may be a contributing factor in mediating pelvic pain in chronic prostatitis. We describe the procedure for preparation of standardized bacterial inoculum, instillation of bacteria into the urethra of male mice and methodology for measuring tactile allodynia in mice over time.

Uropathogenic Escherichia coli (UPEC) are pathogens that play an important role in urinary tract infections and bacterial prostatitis1. We have recently ...

Total Protein Extraction and 2-D Gel Electrophoresis Methods for Burkholderia Species

The investigation of the intracellular protein levels of bacterial species is of importance to understanding the pathogenic mechanisms of diseases caused by these organisms. Here we describe a procedure for protein extraction from Burkholderia species based on mechanical lysis using glass beads in the presence of ethylenediamine tetraacetic acid and phenylmethylsulfonyl fluoride in phosphate buffered saline. This method can be used for different Burkholderia species, for different growth conditions, and it is likely suitable for the use in proteomic studies of other bacteria. Following protein extraction, a two-dimensional (2-D) gel electrophoresis proteomic technique is described to study global changes in the proteomes of these organisms. This method consists of the separation of proteins according to their isoelectric point by isoelectric focusing in the first dimension, followed by separation on the basis of molecular weight by acrylamide gel electrophoresis in the second dimension. Visualization of separated proteins is carried out by silver staining.

Total Protein Extraction and 2-D Gel Electrophoresis Methods for Burkholderia Species

Members of the Burkholderia genus are pathogens of clinical importance. We describe a method for total bacterial protein extraction, using mechanical disruption, and 2-D gel electrophoresis for subsequent proteomic analysis.

The investigation of  the intracellular protein levels of bacterial species is of importance to  understanding the pathogenic mechanisms of diseases ...

Femur Window Chamber Model for In Vivo Cell Tracking in the Murine Bone Marrow

Bone marrow is a complex organ that contains various hematopoietic and non-hematopoietic cells. These cells are involved in many biological processes, including hematopoiesis, immune regulation and tumor regulation. Commonly used methods for understanding cellular actions in the bone marrow, such as histology and blood counts, provide static information rather than capturing the dynamic action of multiple cellular components in vivo. To complement the standard methods, a window chamber (WC)-based model was developed to enable serial in vivo imaging of cells and structures in the murine bone marrow. This protocol describes a surgical procedure for installing the WC in the femur, in order to facilitate long-term optical access to the femoral bone marrow. In particular, to demonstrate its experimental utility, this WC approach was used to image and track neutrophils within the vascular network of the femur, thereby providing a novel method to visualize and quantify immune cell trafficking and regulation in the bone marrow. This method can be applied to study various biological processes in the murine bone marrow, such as hematopoiesis, stem cell transplantation, and immune responses in pathological conditions, including cancer.

Femur Window Chamber Model for In Vivo Cell Tracking in the Murine Bone Marrow

The protocol describes a novel murine femur window chamber model that can be used to track movement of cells in the femoral bone marrow in vivo. Intravital multiphoton fluorescence microscopy is used to image three components of the femoral bone marrow (vasculature, collagen matrix, and neutrophils) over time.

Bone marrow is a complex organ that contains various hematopoietic and non-hematopoietic cells. These cells are involved in many biological processes, ...

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo Cell Trafficking by PET/CT

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte cell culture and 64Cu-antibody receptor targeting of the cells. In vitro evaluation of the radiolabel and non-invasive in vivo cell tracking in an animal model of an airway delayed-type hypersensitivity reaction (DTHR) by PET/CT are described.
In detail, the conjugation of a mAb with the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is shown. Following the production of radioactive 64Cu, radiolabeling of the DOTA-conjugated mAb is described. Next, the expansion of chicken ovalbumin (cOVA)-specific CD4+ interferon (IFN)-&#947;-producing T helper cells (cOVA-TH1) and the subsequent radiolabeling of the cOVA-TH1 cells are depicted. Various in vitro techniques are presented to evaluate the effects of 64Cu-radiolabeling on the cells, such as the determination of cell viability by trypan blue exclusion, the staining for apoptosis with Annexin V for flow cytometry, and the assessment of functionality by IFN-&#947; enzyme-linked immunosorbent assay (ELISA). Furthermore, the determination of the radioactive uptake into the cells and the labeling stability are described in detail. This protocol further describes how to perform cell tracking studies in an animal model for an airway DTHR and, therefore, the induction of cOVA-induced acute airway DHTR in BALB/c mice is included. Finally, a robust PET/CT workflow including image acquisition, reconstruction, and analysis is presented.
The 64Cu-antibody receptor targeting approach with subsequent receptor internalization provides high specificity and stability, reduced cellular toxicity, and low efflux rates compared to common PET-tracers for cell labeling, e.g.64Cu-pyruvaldehyde bis(N4-methylthiosemicarbazone) (64Cu-PTSM). Finally, our approach enables non-invasive in vivo cell tracking by PET/CT with an optimal signal-to-background ratio for 48 h. This experimental approach can be transferred to different animal models and cell types with membrane-bound receptors that are internalized.

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo  Cell Trafficking by PET/CT

Following the preparation of a 64Cu-modified monoclonal antibody binding to a transgenic murine T cell receptor, T cells are radiolabeled in vivo, analyzed for viability, functionality, labeling stability and apoptosis, and adoptively transferred into mice with an airway delayed-type hypersensitivity reaction for non-invasive imaging by positron emission tomography/computed tomography (PET/CT).

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte ...

Come to the Light Side: In Vivo Monitoring of Pseudomonas aeruginosa Biofilm Infections in Chronic Wounds in a Diabetic Hairless Murine Model

The presence of bacteria as structured biofilms in chronic wounds, especially in diabetic patients, is thought to prevent wound healing and resolution. Chronic mouse wounds models have been used to understand the underlying interactions between the microorganisms and the host. The models developed to date rely on the use of haired animals and terminal collection of wound tissue for determination of viable bacteria. While significant insight has been gained with these models, this experimental procedure requires a large number of animals and sampling is time consuming. We have developed a novel murine model that incorporates several optimal innovations to evaluate biofilm progression in chronic wounds: a) it utilizes hairless mice, eliminating the need for hair removal; b) applies pre-formed biofilms to the wounds allowing for the immediate evaluation of persistence and effect of these communities on host; c) monitors biofilm progression by quantifying light production by a genetically engineered bioluminescent strain of Pseudomonas aeruginosa, allowing real-time monitoring of the infection thus reducing the number of animals required per study. In this model, a single full-depth wound is produced on the back of STZ-induced diabetic hairless mice and inoculated with biofilms of the P. aeruginosa bioluminescent strain Xen 41. Light output from the wounds is recorded daily in an in vivo imaging system, allowing for in vivo and in situ rapid biofilm visualization and localization of biofilm bacteria within the wounds. This novel method is flexible as it can be used to study other microorganisms, including genetically engineered species and multi-species biofilms, and may be of special value in testing anti-biofilm strategies including antimicrobial occlusive dressings.

Come to the Light Side: In Vivo Monitoring of Pseudomonas aeruginosa Biofilm Infections in Chronic Wounds in a Diabetic Hairless Murine Model

Here we describe a novel diabetic murine model utilizing hairless mice for real-time, non-invasive, monitoring of biofilm wound infections of bioluminescent Pseudomonas aeruginosa. This method can be adapted to evaluate infection of other bacterial species and genetically modified microorganisms, including multi-species biofilms, and test the efficacy of antibiofilm strategies.

The presence of bacteria as structured biofilms in chronic wounds, especially in diabetic patients, is thought to prevent wound healing and resolution. ...

Live Imaging of Chemokine Receptors in Zebrafish Neutrophils During Wound Responses

Leukocyte guidance by chemical gradients is essential for immune responses. Neutrophils are the first cells to be recruited to sites of tissue damage where they execute crucial antimicrobial functions. Their trafficking to these loci is orchestrated by several inflammatory chemoattractants, including chemokines. At the molecular level, chemoattractant signaling is regulated by the intracellular trafficking of the corresponding receptors. However, it remains unclear how subcellular changes in chemokine receptors affect leukocyte migration dynamics at the cell and tissue level. Here we describe a methodology for live imaging and quantitative analysis of chemokine receptor dynamics in neutrophils during inflammatory responses to tissue damage. These tools have revealed that differential chemokine receptor trafficking in zebrafish neutrophils coordinates neutrophil clustering and dispersal at sites of tissue damage. This has implications for our understanding of how inflammatory responses are self-resolved. The described tools could be used to understand neutrophil migration patterns in a variety of physiological and pathological settings and the methodology could be expanded to other signaling receptors.

Here we describe protocols to perform live imaging and quantitative analysis of chemoattractant receptor dynamics in zebrafish neutrophils

Leukocyte guidance by chemical gradients is essential for immune responses. Neutrophils are the first cells to be recruited to sites of tissue damage ...

Real-Time Quantification of Reactive Oxygen Species in Neutrophils Infected with Meningitic Escherichia Coli

Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration through the blood-brain barrier are indispensable steps for the development of E. coli meningitis. Reactive oxygen species (ROS) represent the major bactericidal mechanisms of neutrophils to destroy the invaded pathogens. In this protocol, the time-dependent intracellular ROS production in neutrophils infected with meningitic E. coli was quantified using fluorescent ROS probes detected by a real-time fluorescence microplate reader. This method may also be applied to the assessment of ROS production in mammalian cells during pathogen-host interactions.

Real-Time Quantification of Reactive Oxygen Species in Neutrophils Infected with Meningitic Escherichia Coli

Escherichia coli is the leading cause of neonatal Gram-negative bacterial meningitis. During the bacterial infection, reactive oxygen species produced by neutrophils play a major bactericidal role. Here we introduce a method to detect the reactive oxygen species in neutrophils in response to meningitis E. coli.

Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration ...