We thank R. Heintzmann for fruitful discussions during the development of the striped-illumination approach, K. Rajewsky and A. Haberman for providing C57BL/6 B1-8 GFP transgenic mice. We acknowledge the Deutsche Forschungsgemeinschaft under grant NI1167/3-1 (to R.N.), HA5354/4-1 and SFB633, project A15 (to A.E.H.), the Charit&#233; under grant Rahel-Hirsch fellowship (to R.N.) for financial support. We particularly acknowledge the network JIMI for fruitful discussions and infrastructural support

Multi-beam Setup for Striped-illumination TPLSM
The setup used here is a specialized multi-beam two-photon laser-scanning microscope, as described previously6,20. The system is illustrated in Figure 1. The approach can be applied to other two-photon laser-scanning microscopes, which are able to synchronize camera acquisition with the movement of the galvoscanner mirrors, even if they are only capable to perform single-beam scanning. In this case, the disadvantage will...

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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Supraresolution+imaging+in+brain+slices+using+stimulated-emission+depletion+two-photon+laser+scanning+microscopy.">Supraresolution imaging in brain slices using stimulated-emission depletion two-photon laser scanning microscopy.</a> Neuron. 63 (4), 429-437 (2009).</li><li>Bianchini, P., 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=Single-wavelength+two-photon+excitation+-+stimulated+emission+depletion+(SW2PE-STED)+super-resolution+imaging.">Single-wavelength two-photon excitation - stimulated emission depletion (SW2PE-STED) super-resolution imaging.</a> Proc. Natl. Acad. Sci. U.S.A. 109 (17), 6390-6393 (2012).</li><li>Berning, S., 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=Nanoscopy+in+a+living+mouse+brain.">Nanoscopy in a living mouse brain.</a> Science. 335 (6068), 551 (2012).</li><li>York, A. G., 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=Resolution+doubling+in+live,+multicellular+organisms+via+multifocal+structured+illumination+microscopy.">Resolution doubling in live, multicellular organisms via multifocal structured illumination microscopy.</a> Nat. Methods. 9, 749-754 (2012).</li><li>Gu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Advanced optical imaging. , (2001).</li><li>Cha, J. W., Ballesta, J., So, P. T. 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The aim of intravital optical imaging is to dynamically and functionally visualize cellular motility and interactions in order to understand tissue and organ function in health and disease5. The most powerful technology to achieve this, multi-photon laser-scanning microscopy, still has to overcome limitations related to wave front distortions, scattering, slow acquisition, photobleaching and photodamage, which limit its spatial resolution, contrast as well as its time-resolution.
Th...

Two-photon laser-scanning microscopy (TPLSM), with its advantages for deep-tissue imaging related to infrared ultra-short pulsed excitation1, has revolutionized our view on vital processes on a single-cell level by revealing motility and interaction patterns of various cell subsets in living animals2-5. However, current technology is still insufficient to elucidate the mechanisms of organ function and dysfunction as a prerequisite for developing new therapeutic strategies, since it renders only sparse information about the molecular basis of cellular response within tissues in health and disease. Current technology enables only a spatial window of few hundred microns due to scattering and wave front distortion effects on spatial resolution and signal-to-noise ratio6, which are particularly obvious in the highly compact tissue of adult animals. These scattering and wave front distortion effects are due to a highly heterogeneous and anisotropic distribution of the refractive index in tissue, leading in a first step to a depth dependent deterioration of 3D spatial resolution and finally to the total loss of signal originating from ballistic excitation photons, i.e. loss of signal-to-noise ratio. In terms of bioscientific and biomedical deep-tissue applications, this means that the current technology is unable to unequivocally reveal cellular communication because poor resolution would lead to falsely positive interactions whereas the decrease of signal-to-noise ratio would cause the system to overlook some interactions between dim structures.
In order to unequivocally detect cellular interactions in a dynamic way, a highly improved spatial resolution is needed deep within the tissue. The currently introduced powerful nanoscopy techniques based on special numerical algorithms, e.g. structure-illumination approaches, on depletion of the first excited state, e.g. STED, RESOLFT, or on molecule localization, e.g. dSTORM, PALM, have found many applications in fixed cells as well as in live cell cultures7. However, in order to extend these applications to tissue sections, living tissue and organisms we still need to overcome severe technical difficulties. Two-photon excitation STED with different wavelengths as well as with a single wavelength (sw2PE-STED) for excitation and stimulated emission has been applied to improve lateral resolution in brain slices8 or in artificial matrices with embedded cells9, respectively, at the same axial resolution as standard TPLSM. Using one-photon STED, the dynamics of dendritic spines could be imaged at the surface of the brain cortex (up to 10-15 &#181;m depth) in a living Thy1 EGFP mouse at a resolution of 67 nm10. A versatile tool for developmental biology is provided by the multifocal structured-illumination microscopy, which provides two-fold improved 2D resolution. However, this technique can be used only in organisms with a low propensity of light scattering such as zebra fish embryos11. Still, none of these techniques can be applied in the highly-scattering tissue of adult animals in several hundreds of micrometers, which are crucial models for the biomedical and clinical research of diseases with onset after birth.
Independent of the approximation used to calculate the diffraction-limited wave front shape, i.e. the point spread function (PSF), after focusing through a lens, the width of the PSF along the optical axis (axial resolution) is at least three times larger than the PSF width perpendicular to the optical axis (lateral resolution)12. Wave front distortions of different orders quantified by Zernike&#39;s coefficients considerably modify the wave front shape of focused electromagnetic wave in deep-tissue imaging leading to much larger PSFs, especially along the optical axis13-15. Hence, both the diffraction laws and the wave front distortion effects point to the resolution along the optical axis as the limiting factor in deep-tissue imaging. Whereas nanoscopy techniques focus on counteracting the limits of diffraction only, a technology which improves axial resolution and contrast by counteracting both diffraction and wave-front distortion effects is needed for high-resolution intravital imaging. Ideally, this technique should be also fast enough to allow monitoring of cellular dynamics.
The real-time correction of PSF aberrations and contrast loss using adaptive optics in TPLSM has been extensively studied and improved in the past decade13,14,16-18 and it is therefore the best currently available choice leading to a better management of ballistic excitation photons14. Still, due to the fact that most wave front correction approaches used in adaptive optics are iterative and that they have to be repeated for small areas (few 10 x 10 &#181;m2) due to the high heterogeneity of the refractive index in tissue, the acquisition speed is significantly lower than necessary for imaging cell motility and communication. Moreover, the physical limit in adaptive-optics improved TPLSM is still determined by diffraction.
Spatial modulation of illumination (SPIN) and temporal modulation on the detection side (SPADE) have been theoretically proposed to be applied to laser-scanning microscopy to improve resolution. Their practical application in intravital imaging still remains to be demonstrated19.
Taken together, there is a high demand for the development of technologies, which improve the resolution for deep-tissue imaging in living adult animals. In this work, we achieve spatial modulation of the excitation pattern by controlling the scanning process in multi-beam striped-illumination multi-photon laser-scanning microscopy (MB-SI-MPLSM)20. Contrary to structured illumination approaches, in which the excitation beam cross section is spatially modulated, we use only the scanning process to achieve the spatial modulation of the excitation. By expanding the excitation to a longer wavelength, we are able to improve both spatial resolution and signal-to-noise ratio in deep-tissue of highly scattering tissue (e.g. lymph node, free-scattering path 47 &#181;m6), independently of the optical non-linear signal we detect, e.g. fluorescence, second harmonic generation or other frequency mixing phenomenon. Using this approach at excitation wavelengths up to 900 nm we are able to dynamically image cellular protein structures on the scale of few molecules in germinal centers of mouse lymph nodes. Thus, we can better visualize the interaction between antigen carrying units on the surface of follicular dendritic cells and B cells in the process of probing the antigen during the immune response in secondary lymphoid organs.

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	<tbody>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">ATTO590 &#8211; NSH for coupling</td>
			<td style="width:99px;">ATTO Tec, Germany</td>
			<td style="width:119px;">AD-590-35</td>
			<td style="width:167px;">-</td>
		</tr>
		<tr height="81">
			<td height="81" style="height:81px;width:216px;">CD21/35 &#8211; Fab fragment &#8211; ATTO590</td>
			<td style="width:99px;">DRFZ, Berlin</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">The coupling reaction was performed in the central lab of our institution.</td>
		</tr>
		<tr height="81">
			<td height="81" style="height:81px;width:216px;">B1-8 Jk-/- EGFP+</td>
			<td style="width:99px;">Prof. Anne Habermann, Yale Univ., CA, US</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">Can be also found at Jackson Laboratories (JAX).</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">EasySep Negative Selection Mouse B Cell Enrichment&#160;</td>
			<td style="width:99px;">StemmCell Technologies, Germany</td>
			<td style="width:119px;">19854</td>
			<td style="width:167px;">-</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Polystyren beads (605), 0.2 &#181;m</td>
			<td style="width:99px;">Life Technologies, Germany</td>
			<td style="width:119px;">F8803</td>
			<td style="width:167px;">-</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:99px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Name of Equipment</td>
			<td style="width:99px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="81">
			<td height="81" style="height:81px;width:216px;">TriMScope I</td>
			<td style="width:99px;">LaVision Biotec, Bielefeld, Germany</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">-</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">OPO (manual version)</td>
			<td style="width:99px;">APE, Berlin, Germany</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">-</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Ti:Sa Laser Chameleon Ultra II</td>
			<td style="width:99px;">Coherent, Duisburg, Germany</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">-</td>
		</tr>
		<tr height="81">
			<td height="81" style="height:81px;width:216px;">water-immersion objective lens, 20x, NA 0.95, IR, WD 2 mm</td>
			<td style="width:99px;">Olympus Germany, Hamburg, Germany</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">-</td>
		</tr>
	</tbody>
</table>

highly resolved intravital striped-illumination microscopy of germinal centers

Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick tissue samples and organs in health and disease. By controlling the scanning pattern in multi-photon microscopy and applying appropriate numerical algorithms, we developed a striped-illumination approach, which enabled us to achieve 3-fold better axial resolution and improved signal-to-noise ratio, i.e. contrast, in more than 100 &#181;m tissue depth within highly scattering tissue of lymphoid organs as compared to standard multi-photon microscopy. The acquisition speed as well as photobleaching and photodamage effects were similar to standard photo-multiplier-based technique, whereas the imaging depth was slightly lower due to the use of field detectors. By using the striped-illumination approach, we are able to observe the dynamics of immune complex deposits on secondary follicular dendritic cells &#8211; on the level of a few protein molecules in germinal centers.

Spatial resolution in lymph nodes
The dimensions of the effective point spread function (ePSF) correspond to the spatial resolution of a microscope12. We measured this three dimensional function by acquiring the second harmonics generation signal of collagen fibers in lymph nodes by our MB-SI-TPLSM as compared to established two-photon laser scanning microscopy techniques, i.e. field detection TPLSM (by means of CCD cameras) and point detection TPLSM (by means of PMTs).
<p...

Watch this Scientific Journal Video about Highly Resolved Intravital Striped-illumination Microscopy of Germinal Centers at JoVE.com

Highly Resolved Intravital Striped-illumination Microscopy of Germinal Centers

High-resolution intravital imaging with enhanced contrast up to 120 &#181;m depth in lymph nodes of adult mice is achieved by spatially modulating the excitation pattern of a multi-focal two-photon microscope. In 100 &#181;m depth we measured resolutions of 487 nm (lateral) and 551 nm (axial), thus circumventing scattering and diffraction limits.

Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick ...

highly-resolved-intravital-striped-illumination-microscopy-germinal

Research

JoVE Journal

Immunology and Infection

9.9K vues.  Leibniz Institute.  Haute résolution intravitale imagerie avec un contraste accru jusqu'à 120 um de profondeur dans les ganglions lymphatiques de la souris adulte est obtenue en modulant spatialement le modèle d'excitation d'un multi-focal microscope à deux photons. En 100 profondeur pm nous avons mesuré des résolutions de 487 nm (latéraux) et 551 nm (axial), contournant ainsi les limites de diffusion et de diffraction. 

Vidéo: Highly Resolved Intravital Striped-illumination Microscopy of Germinal Centers

Intravital Microscopy of the Inguinal Lymph Node

Lymph nodes (LN's), located throughout the body, are an integral component of the immune system. They serve as a site for induction of adaptive immune response and therefore, the development of effector cells. As such, LNs are key to fighting invading pathogens and maintaining health. The choice of LN to study is dictated by accessibility and the desired model; the inguinal lymph node is well situated and easily supports studies of biologically relevant models of skin and genital mucosal infection.
The inguinal LN, like all LNs, has an extensive microvascular network supplying it with blood. In general, this microvascular network includes the main feed arteriole of the LN that subsequently branches and feeds high endothelial venules (HEVs). HEVs are specialized for facilitating the trafficking of immune cells into the LN during both homeostasis and infection. How HEVs regulate trafficking into the LN under both of these circumstances is an area of intense exploration. The LN feed arteriole, has direct upstream influence on the HEVs and is the main supply of nutrients and cell rich blood into the LN. Furthermore, changes in the feed arteriole are implicated in facilitating induction of adaptive immune response. The LN microvasculature has obvious importance in maintaining an optimal blood supply to the LN and regulating immune cell influx into the LN, which are crucial elements in proper LN function and subsequently immune response. 
The ability to study the LN microvasculature in vivo is key to elucidating how the immune system and the microvasculature interact and influence one another within the LN. Here, we present a method for in vivo imaging of the inguinal lymph node. We focus on imaging of the microvasculature of the LN, paying particular attention to methods that ensure the study of healthy vessels, the ability to maintain imaging of viable vessels over a number of hours, and quantification of vessel magnitude. Methods for perfusion of the microvasculature with vasoactive drugs as well as the potential to trace and quantify cellular traffic are also presented. 
Intravital microscopy of the inguinal LN allows direct evaluation of microvascular functionality and real-time interface of the direct interface between immune cells, the LN, and the microcirculation. This technique potential to be combined with many immunological techniques and fluorescent cell labelling as well as manipulated to study vasculature of other LNs.

A technique for performing intravital microscopy of the inguinal lymph node (LN) is outlined. Such technique allows for real-time, in vivo study of the lymph node microvasculature and structure both during homeostasis and infection. This technique can be adapted to cell trafficking studies and to other lymph node sites.

Lymph nodes (LN's), located throughout the body, are an integral component of the immune system. They serve as a site for induction of adaptive immune ...

Tracking Neutrophil Intraluminal Crawling, Transendothelial Migration and Chemotaxis in Tissue by Intravital Video Microscopy

The recruitment of circulating leukocytes from blood stream to the inflamed tissue is a crucial and complex process of inflammation1,2. In the postcapillary venules of inflamed tissue, leukocytes initially tether and roll on the luminal surface of venular wall. Rolling leukocytes arrest on endothelium and undergo firm adhesion in response to chemokine or other chemoattractants on the venular surface. Many adherent leukocytes relocate from the initial site of adhesion to the junctional extravasation site in endothelium, a process termed intraluminal crawling3. Following crawling, leukocytes move across endothelium (transmigration) and migrate in extravascular tissue toward the source of chemoattractant (chemotaxis)4. Intravital microscopy is a powerful tool for visualizing leukocyte-endothelial cell interactions in vivo and revealing cellular and molecular mechanisms of leukocyte recruitment2,5. In this report, we provide a comprehensive description of using brightfield intravital microscopy to visualize and determine the detailed processes of neutrophil recruitment in mouse cremaster muscle in response to the gradient of a neutrophil chemoattractant. To induce neutrophil recruitment, a small piece of agarose gel (~1-mm3 size) containing neutrophil chemoattractant MIP-2 (CXCL2, a CXC chemokine) or WKYMVm (Trp-Lys-Tyr-Val-D-Met, a synthetic analog of bacterial peptide) is placed on the muscle tissue adjacent to the observed postcapillary venule. With time-lapsed video photography and computer software ImageJ, neutrophil intraluminal crawling on endothelium, neutrophil transendothelial migration and the migration and chemotaxis in tissue are visualized and tracked. This protocol allows reliable and quantitative analysis of many neutrophil recruitment parameters such as intraluminal crawling velocity, transmigration time, detachment time, migration velocity, chemotaxis velocity and chemotaxis index in tissue. We demonstrate that using this protocol, these neutrophil recruitment parameters can be stably determined and the single cell locomotion conveniently tracked in vivo.

We describe a protocol of brightfield intravital microscopy for measuring dynamic neutrophil-endothelial cell interactions during neutrophil recruitment in response to the source of a neutrophil chemoattractant in vivo. Neutrophil intraluminal crawling, transendothelial migration and chemotaxis in mouse cremaster muscle tissue are visualized with time-lapsed video photography and tracked with ImageJ.

The recruitment of circulating leukocytes from blood stream to the inflamed tissue is a crucial and complex process of inflammation1,2. In the ...

Intravital Imaging of the Mouse Thymus using 2-Photon Microscopy

Two-photon Microscopy (TPM) provides image acquisition in deep areas inside tissues and organs. In combination with the development of new stereotactic tools and surgical procedures, TPM becomes a powerful technique to identify "niches" inside organs and to document cellular "behaviors" in live animals. While intravital imaging provides information that best resembles the real cellular behavior inside the organ, it is both more laborious and technically demanding in terms of required equipment/procedures than alternative ex vivo imaging acquisition. Thus, we describe a surgical procedure and novel "stereotactic" organ holder that allows us to follow the movements of Foxp3+ cells within the thymus.
Foxp3 is the master regulator for the generation of regulatory T cells (Tregs). Moreover, these cells can be classified according to their origin: ie. thymus-differentiated Tregs are called "naturally-occurring Tregs" (nTregs), as opposed to peripherally-converted Tregs (pTregs). Although significant amount of research has been reported in the literature concerning the phenotype and physiology of these T cells, very little is known about their in vivo interactions with other cells. This deficiency may be due to the absence of techniques that would permit such observations. The protocol described in this paper provides a remedy for this situation.
Our protocol consists of using nude mice that lack an endogenous thymus since they have a punctual mutation in the DNA sequence that compromises the differentiation of some epithelial cells, including thymic epithelial cells. Nude mice were gamma-irradiated and reconstituted with bone marrows (BM) from Foxp3-KIgfp/gfp mice. After BM recovery (6 weeks), each animal received embryonic thymus transplantation inside the kidney capsule. After thymus acceptance (6 weeks), the animals were anesthetized; the kidney containing the transplanted thymus was exposed, fixed in our organ holder, and kept under physiological conditions for in vivo imaging by TPM. We have been using this approach to study the influence of drugs in the generation of regulatory T cells.

We have developed novel laboratory tools and protocols for intravital imaging acquisition of the thymus. Our technique should help in the identification of &#x201C;niches&#x201D; within the thymus where T cell development occurs.

Two-photon Microscopy (TPM) provides image acquisition in deep areas inside tissues and organs. In combination with the development of new stereotactic ...

Intravital Microscopy of the Spleen: Quantitative Analysis of Parasite Mobility and Blood Flow

The advent of intravital microscopy in experimental rodent malaria models has allowed major advances to the knowledge of parasite-host interactions 1,2. Thus, in vivo imaging of malaria parasites during pre-erythrocytic stages have revealed the active entrance of parasites into skin lymph nodes 3, the complete development of the parasite in the skin 4, and the formation of a hepatocyte-derived merosome to assure migration and release of merozoites into the blood stream 5. Moreover, the development of individual parasites in erythrocytes has been recently documented using 4D imaging and challenged our current view on protein export in malaria 6. Thus, intravital imaging has radically changed our view on key events in Plasmodium development. Unfortunately, studies of the dynamic passage of malaria parasites through the spleen, a major lymphoid organ exquisitely adapted to clear infected red blood cells are lacking due to technical constraints.
Using the murine model of malaria Plasmodium yoelii in Balb/c mice, we have implemented intravital imaging of the spleen and reported a differential remodeling of it and adherence of parasitized red blood cells (pRBCs) to barrier cells of fibroblastic origin in the red pulp during infection with the non-lethal parasite line P.yoelii 17X as opposed to infections with the P.yoelii 17XL lethal parasite line 7. To reach these conclusions, a specific methodology using ImageJ free software was developed to enable characterization of the fast three-dimensional movement of single-pRBCs. Results obtained with this protocol allow determining velocity, directionality and residence time of parasites in the spleen, all parameters addressing adherence in vivo. In addition, we report the methodology for blood flow quantification using intravital microscopy and the use of different colouring agents to gain insight into the complex microcirculatory structure of the spleen. 
Ethics statement
All the animal studies were performed at the animal facilities of University of Barcelona in accordance with guidelines and protocols approved by the Ethics Committee for Animal Experimentation of the University of Barcelona CEEA-UB (Protocol No DMAH: 5429). Female Balb/c mice of 6-8 weeks of age were obtained from Charles River Laboratories.

We show the method for performing intravital microscopy of the spleen using GFP transgenic malaria parasites and the quantification of parasite mobility and blood flow within this organ.

The advent of intravital microscopy in experimental rodent malaria models has allowed major advances to the knowledge of parasite-host interactions 1,2. ...

Intravital Microscopy Imaging of the Liver following Leishmania Infection: An Assessment of Hepatic Hemodynamics

Intravital microscopy (IVM) is a powerful optical imaging technique that has made possible the visualization, monitoring and quantification of various biological events in real time and in live animals. This technology has greatly advanced our understanding of physiological processes and pathogen-mediated phenomena in specific organs.
In this study, IVM is applied to the mouse liver and protocols are designed to image in vivo the circulatory system of the liver and measure red blood cell (RBC) velocity in individual hepatic vessels. To visualize the different vessel subtypes that characterize the hepatic organ and perform blood flow speed measurements, C57Bl/6 mice are intravenously injected with a fluorescent plasma reagent that labels the liver-associated vasculature. IVM enables in vivo, real time, measurement of RBC velocity in a specific vessel of interest. Establishing this methodology will make it possible to investigate liver hemodynamics under physiological and pathological conditions. Ultimately, this imaging-based methodology will be important for studying the influence of L. donovani infection&#160;on hepatic hemodynamics.
This method can be applied to other infectious models and mouse organs and might be further extended to pre-clinical testing of a drug&#8217;s effect on inflammation by quantifying its effect on blood flow.

Intravital Microscopy Imaging of the Liver following Leishmania Infection: An Assessment of Hepatic Hemodynamics

This article reports on a detailed method for the dynamic measurement and quantification of blood flow velocity within individual blood vessels of the mouse liver vasculature using intravital microscopy imaging in combination with a specific methodology for image acquisition and analysis.

Intravital microscopy (IVM) is a powerful optical imaging technique that has made possible the visualization, monitoring and quantification of various ...

Intravital Microscopy of Leukocyte-endothelial and Platelet-leukocyte Interactions in Mesenterial Veins in Mice

Intravital microscopy is a method that can be used to investigate different processes in different regions and vessels in living animals. In this protocol, we describe intravital microscopy of mesentery veins. This can be performed in a short period of time with reproducible results showing leukocyte-endothelial interactions in vivo. We describe an inflammatory setting after LPS challenge of the endothelium. But in this model one can apply many different types of inflammatory conditions, like bacterial, chemical or biological and investigate the administration of drugs and their direct effects on the living animal and its impact on leukocyte recruitment. This protocol has been applied successfully to a number of different treatments of mice and their effects on inflammatory response in vessels. Herein, we describe the visualization of leukocytes and platelets by fluorescently labeling these with rhodamine 6G. Additionally, any specific imaging can be performed using targeted fluorescently labeled molecules.

This simplified application of intravital microscopy of mesentery veins in mice can be used in different models of inflammation to observe leukocyte-endothelial and platelet-leukocyte interactions.

Intravital microscopy is a method that can be used to investigate different processes in different regions and vessels in living animals. In this ...

Imaging Neutrophils and Monocytes in Mesenteric Veins by Intravital Microscopy on Anaesthetized Mice in Real Time

Efficient immune response is dependent on rapid mobilization of blood leukocytes to the site of infection or injury. Investigating leukocyte migration in vivo is crucial for understanding the molecular basis of leukocyte transendothelial migration and interaction with vascular endothelium. One powerful approach involves intravital microscopy on transgenic mice expressing fluorescent proteins in cells of interest.
Here we present a protocol for imaging monocytes and neutrophils in the CX3CR1gfp/wt mouse i.v. injected with orange dye-labeled neutrophils with an inverted confocal microscope. Time-lapse movies gathered from 30 min&#160;to several hours of imaging allow the analysis of leukocyte behavior in mesenteric veins under both steady state and inflammatory conditions. We also describe the steps to locally induce blood vessel inflammation with TLR2/TLR1 agonist Pam3SK4 and monitor the subsequent recruitment of neutrophils and monocytes.
The presented technique can also be used to monitor other populations of leukocytes and investigate molecules implicated in leukocyte recruitment or trafficking using other stimuli or transgenic mice.

We detail a protocol to monitor the behavior of neutrophils and monocytes in mesenteric veins under steady state and inflammatory conditions using intravital confocal microscopy on anaesthetized mice.

Efficient immune response is dependent on rapid mobilization of blood leukocytes to the site of infection or injury. Investigating leukocyte migration in ...

Swab Sampling Method for the Detection of Human Norovirus on Surfaces

Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the person-to-person route or indirectly through environmental surfaces or food, contaminated fomites and inanimate surfaces are important vehicles for the spread of the virus during norovirus outbreaks.
We developed and evaluated a protocol using macrofoam swabs for the detection and typing of human noroviruses from hard surfaces. Compared with fiber-tipped swabs or antistatic wipes, macrofoam swabs allow virus recovery (range 1.2-33.6%) from toilet seat surfaces of up to 700 cm2. The protocol includes steps for the extraction of the virus from the swabs and further concentration of the viral RNA using spin columns. In total, 127 (58.5%) of 217 swab samples that had been collected from surfaces in cruise ships and long-term care facilities where norovirus gastroenteritis had been reported tested positive for GII norovirus by RT-qPCR. Of these 29 (22.8%) could be successfully genotyped. In conclusion, detection of norovirus on environmental surfaces using the protocol we developed may assist in determining the level of environmental contamination during outbreaks as well as detection of virus when clinical samples are not available; it may also facilitate monitoring of effectiveness of remediation strategies.

A macrofoam based sampling methodology was developed and evaluated for the detection and quantification of norovirus on environmental hard surfaces.

Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the ...

Preparation of Murine Submandibular Salivary Gland for Upright Intravital Microscopy

The submandibular salivary gland (SMG) is one of the three major salivary glands, and is of interest for many different fields of biological research, including cell biology, oncology, dentistry, and immunology. The SMG is an exocrine gland comprised of secretory epithelial cells, myofibroblasts, endothelial cells, nerves, and extracellular matrix. Dynamic cellular processes in the rat and mouse SMG have previously been imaged, mostly using inverted multi-photon microscope systems. Here, we describe a straightforward protocol for the surgical preparation and stabilization of the murine SMG in anesthetized mice for in vivo imaging with upright multi-photon microscope systems. We present representative intravital image sets of endogenous and adoptively transferred fluorescent cells, including the labeling of blood vessels or salivary ducts and second harmonic generation to visualize fibrillar collagen. In sum, our protocol allows for surgical preparation of mouse salivary glands in upright microscopy systems, which are commonly used for intravital imaging in the field of immunology.

We describe a protocol to surgically expose and stabilize the murine submandibular salivary gland for intravital imaging using upright intravital microscopy. This protocol is easily adaptable to other exocrine glands of the head and neck region of mice and other small rodents.

The submandibular salivary gland (SMG) is one of the three major salivary glands, and is of interest for many different fields of biological research, ...

Imaging Cell Interaction in Tracheal Mucosa During Influenza Virus Infection Using Two-photon Intravital Microscopy

The analysis of cell-cell or cell-pathogen interaction in vivo is an important tool to understand the dynamics of the immune response to infection. Two-photon intravital microscopy (2P-IVM) allows the observation of cell interactions in deep tissue in living animals, while minimizing the photobleaching generated during image acquisition. To date, different models for 2P-IVM of lymphoid and non-lymphoid organs have been described. However, imaging of respiratory organs remains a challenge due to the movement associated with the breathing cycle of the animal.
Here, we describe a protocol to visualize in vivo immune cell interactions in the trachea of mice infected with influenza virus using 2P-IVM. To this purpose, we developed a custom imaging platform, which included the surgical exposure and intubation of the trachea, followed by the acquisition of dynamic images of neutrophils and dendritic cells (DC) in the mucosal epithelium. Additionally, we detailed the steps needed to perform influenza intranasal infection and flow cytometric analysis of immune cells in the trachea. Finally, we analyzed neutrophil and DC motility as well as their interactions during the course of a movie. This protocol allows for the generation of stable and bright 4D images necessary for the assessment of cell-cell interactions in the trachea.

In this study, we present a protocol to perform two-photon intravital imaging and cell interaction analysis in the murine tracheal mucosa after infection with influenza virus. This protocol will be relevant for researchers studying immune cell dynamics during respiratory infections.

The analysis of cell-cell or cell-pathogen interaction in vivo is an important tool to understand the dynamics of the immune response to infection. ...