Name: in vivo vascular permeability detection in mouse submandibular gland
Uploaded: 2022-08-04T14:00:00
Description: Watch this Scientific Journal Video about In Vivo Vascular Permeability Detection in Mouse Submandibular Gland at JoVE.com

This study was supported by the National Natural Science Foundation of China (grants 31972908, 81991500, 81991502, 81771093, and 81974151) and the Beijing Natural Science Foundation (grant 7202082).

All experimental procedures were approved by the Ethics Committee of Animal Research, Peking University Health Science Center, and complied with the Guide for the Care and Use of Laboratory Animals (NIH Publication No. 85-23, revised 1996). Male wild-type (WT) mice in the age group of 8-10 weeks were used for the present study. The experimental animals were carefully treated to minimize their pain and discomfort.
1. Animal procedures
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	<li>Prepare and administer the anes...

<ol>
	<li>Carpenter, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+secretion,+components,+and+properties+of+saliva.">The secretion, components, and properties of saliva.</a> Annual Review of Food Science and Technology. 4, 267-276 (2013).</li><li>Garrett, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+proper+role+of+nerves+in+salivary+secretion:+A+review.">The proper role of nerves in salivary secretion: A review.</a> Journal of Dental Research. 66 (2), 387-397 (1987).</li><li>Berndt, 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=Tight+junction+proteins+at+the+blood-brain+barrier:+Far+more+than+claudin-5.">Tight junction proteins at the blood-brain barrier: Far more than claudin-5.</a> Cellular and Molecular Life Sciences. 76 (10), 1987-2002 (2019).</li><li>Cong, 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=Disruption+of+endothelial+barrier+function+is+linked+with+hyposecretion+and+lymphocytic+infiltration+in+salivary+glands+of+Sj&#246;gren's+syndrome.">Disruption of endothelial barrier function is linked with hyposecretion and lymphocytic infiltration in salivary glands of Sj&#246;gren's syndrome.</a> Biochimica et Biophysica Acta - Molecular Basis of Disease. 1864 (10), 3154-3163 (2018).</li><li>Helmchen, F., Denk, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deep+tissue+two-photon+microscopy.">Deep tissue two-photon microscopy.</a> Nature Methods. 2 (12), 932-940 (2005).</li><li>Zipfel, W. 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W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonlinear+magic:+Multiphoton+microscopy+in+the+biosciences.">Nonlinear magic: Multiphoton microscopy in the biosciences.</a> Nature Biotechnology. 21 (11), 1369-1377 (2003).</li><li>Masedunskas, A., Sramkova, M., Weigert, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homeostasis+of+the+apical+plasma+membrane+during+regulated+exocytosis+in+the+salivary+glands+of+live+rodents.">Homeostasis of the apical plasma membrane during regulated exocytosis in the salivary glands of live rodents.</a> Bioarchitecture. 1 (5), 225-229 (2011).</li><li>Masedunskas, 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=Role+for+the+actomyosin+complex+in+regulated+exocytosis+revealed+by+intravital+microscopy.">Role for the actomyosin complex in regulated exocytosis revealed by intravital microscopy.</a> Proceedings of the National Academy of Sciences of the United States of America. 108 (33), 13552-13557 (2011).</li><li>Balda, M. 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=Functional+dissociation+of+paracellular+permeability+and+transepithelial+electrical+resistance+and+disruption+of+the+apical-basolateral+intramembrane+diffusion+barrier+by+expression+of+a+mutant+tight+junction+membrane+protein.">Functional dissociation of paracellular permeability and transepithelial electrical resistance and disruption of the apical-basolateral intramembrane diffusion barrier by expression of a mutant tight junction membrane protein.</a> The Journal of Cell Biology. 134 (4), 1031-1049 (1996).</li><li>Enis, D. R., 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=Induction,+differentiation,+and+remodeling+of+blood+vessels+after+transplantation+of+Bcl-2-transduced+endothelial+cells.">Induction, differentiation, and remodeling of blood vessels after transplantation of Bcl-2-transduced endothelial cells.</a> Proceedings of the National Academy of Sciences of the United States of America. 102 (2), 425-430 (2005).</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=Application+of+digital+subtraction+angiography+in+canine+hindlimb+arteriography.">Application of digital subtraction angiography in canine hindlimb arteriography.</a> Vascular. 30 (3), 474-480 (2022).</li><li>Trani, M., Dejana, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+insights+in+the+control+of+vascular+permeability:+vascular+endothelial-cadherin+and+other+players.">New insights in the control of vascular permeability: vascular endothelial-cadherin and other players.</a> Current Opinion in Hematology. 22 (3), 267-272 (2015).</li><li>Viazzi, F., 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=Vascular+permeability,+blood+pressure,+and+organ+damage+in+primary+hypertension.">Vascular permeability, blood pressure, and organ damage in primary hypertension.</a> Hypertension Research. 31 (5), 873-879 (2008).</li><li>Scheppke, L., 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=Retinal+vascular+permeability+suppression+by+topical+application+of+a+novel+VEGFR2/Src+kinase+inhibitor+in+mice+and+rabbits.">Retinal vascular permeability suppression by topical application of a novel VEGFR2/Src kinase inhibitor in mice and rabbits.</a> The Journal of Clinical Investigation. 118 (6), 2337-2346 (2008).</li><li>Blanchet, M. R., 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=Loss+of+CD34+leads+to+exacerbated+autoimmune+arthritis+through+increased+vascular+permeability.">Loss of CD34 leads to exacerbated autoimmune arthritis through increased vascular permeability.</a> Journal of Immunology. 184 (3), 1292-1299 (2010).</li><li>Egawa, G., Ono, S., Kabashima, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravital+Imaging+of+vascular+permeability+by+two-photon+microscopy.">Intravital Imaging of vascular permeability by two-photon microscopy.</a> Methods in Molecular Biology. 2223, 151-157 (2021).</li><li>Vestweber, D., Wessel, F., Nottebaum, A. 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The maintenance and regulation of endothelial barrier function are essential for vascular homeostasis. Endothelial cells and their intercellular junctions play a critical role in maintaining and controlling vascular integrity12. The shear force of blood flow, growth factors, and inflammatory factors can cause changes in vascular permeability and, thus, participate in the occurrence and development of systemic diseases such as hypertension, diabetes, and autoimmune diseases13</sup...

Various salivary glands produce saliva, which primarily acts as the first line of defense against infections and helps digestion, thereby playing an essential role in oral and overall health1. Blood supply is crucial for salivary gland secretion since it constantly provides water, electrolytes, and molecules that form the primary saliva. Endothelial barrier function, regulated by the tight junction (TJ) complex, strictly and delicately limits the permeation of capillaries, which are highly permeable to water, solutes, proteins, and even cells moving from the circulating blood vessels into the salivary gland tissues2,3. We have previously found that the opening of the endothelial TJs in response to a cholinergic stimulus facilitates saliva secretion, whereas the impairment of the endothelial barrier function is interlinked with hyposecretion and lymphocytic infiltration in the submandibular glands (SMGs) in Sj&#246;gren&#39;s syndrome4. These data suggest that the contribution of endothelial barrier function needs to be paid enough attention regarding a variety of salivary gland diseases.
A two-photon laser-scanning microscope is a powerful tool for observing the dynamics of cells in intact tissue in vivo. One of the advantages of this technique is that near-infrared light (NIR) has deeper tissue penetration than visible or ultraviolet light when specimens are excited by NIR and does not cause obvious light damage to tissues under appropriate conditions5,6. Indeed, the salivary glands are a very homogenous and superficial tissue, in which the surface acinar cells are only around 30 &#181;m away from the gland surface7,8. It has been shown that intravital confocal microscopy can study exocrine secretion and actin cytoskeleton in live mouse salivary glands at subcellular resolution8. Two-photon laser-scanning microscopy, nevertheless, not only has the advantage of conventional confocal microscopy but can also be used to detect deeper tissue and image more clearly. Here, fluorescence-labeled dextrans, which are frequently used as paracellular permeability tracers and have the advantage of different sizes, can be used to test the magnitude of TJ pore9. In the present study, an intravital real-time two-photon laser-scanning microscopy technique is established for in situ evaluation of endothelial barrier function in mouse SMGs. Each work step for in vivo vascular permeability detection in mouse SMGs is described in the current protocol. Here is an example of detecting endothelial barrier function in the mouse SMG duct ligation model.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2-photon microscope (TCS-SP8 DIVE)</td>
			<td>Leica, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4 kDa FITC-labeled dextran</td>
			<td>Sigma Aldrich</td>
			<td>46944</td>
			<td></td>
		</tr>
		<tr>
			<td>70 kDa rhodamine B-labeled dextran</td>
			<td>Sigma Aldrich</td>
			<td>R9379</td>
			<td></td>
		</tr>
		<tr>
			<td>Blunt tissue separation nickel</td>
			<td>Bejinghuabo Company</td>
			<td>NZW28</td>
			<td></td>
		</tr>
		<tr>
			<td>Depilatory cream</td>
			<td>Veet</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable sterile syringe</td>
			<td>Zhiyu Company</td>
			<td></td>
			<td>1 mL</td>
		</tr>
		<tr>
			<td>Image J software</td>
			<td>National Institutes of Health</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin syringe</td>
			<td>Becton, Dickinson and Company</td>
			<td>0253316</td>
			<td>1 mL</td>
		</tr>
		<tr>
			<td>Leica Application Suite X software</td>
			<td>Leica Microsystems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microtubes</td>
			<td>Axygen</td>
			<td>MCT-150-C</td>
			<td>1.5 mL</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline 1x</td>
			<td>Servicebio</td>
			<td>G4207-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue scissors</td>
			<td>Bejinghuabo Company</td>
			<td>M286-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Tribromoethanol</td>
			<td>JITIAN Bio</td>
			<td>JT0781</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vivo vascular permeability detection in mouse submandibular gland

Saliva plays an important role in oral and overall health. The intact endothelial barrier function of blood vessels enables saliva secretion, whereas the endothelial barrier dysfunction is related to many salivary gland secretory disorders. The present protocol describes an in vivo paracellular permeability detection method to evaluate the function of endothelial tight junctions (TJs) in mouse submandibular glands (SMG). First, fluorescence-labeled dextrans with different molecular weights (4 kDa, 40 kDa, or 70 kDa) were injected into the angular veins of mice. Afterward, the unilateral SMG was dissected and fixed in the customized holder under a two-photon laser-scanning microscope, and then images were captured for blood vessels, acini, and ducts. Utilizing this method, the real-time dynamic leakage of the different-sized tracers from blood vessels into the basal sides of the acini and even across the acinar epithelia into the ducts was monitored to evaluate the alteration of the endothelial barrier function under physiological or pathophysiological conditions.

Following the protocol, the unilateral SMG was attached to a custom-made holder, and the gland was kept as far away from the mouse body as possible to prevent breathing from causing motion artifacts. The rapid flow of the red blood cells (black dots) in blood vessels was observed under the microscope. After finding the tissue field under an ocular lens, one must switch to manipulate the microscope software. In the control group, both the tracers existed in the blood vessels of the mouse SMG. In particular, due to its sma...

Watch this Scientific Journal Video about In Vivo Vascular Permeability Detection in Mouse Submandibular Gland at JoVE.com

In Vivo Vascular Permeability Detection in Mouse Submandibular Gland

In the present protocol, the endothelial barrier function of the submandibular gland (SMG) was evaluated by injecting different molecular weighted fluorescent tracers into the angular veins of test animal models in vivo under a two-photon laser-scanning microscope.

In Vivo Vascular Permeability Detection in Mouse Submandibular Gland

Saliva plays an important role in oral and overall health. The intact endothelial barrier function of blood vessels enables saliva secretion, whereas the ...

The present protocol describes an in vivo paracellular permeability detection measure to evaluate the function of tight endothelial junctions in mouse submandibular glands. Two photon laser scanning microscopy, nevertheless, not only has the advantage of conventional confocal microscopy but can also be used to detect deeper tissue and image more clearly. This experiment provides a good method measure for assessing the vascular permeability of different tissues especially the surface tissues and organs of animals.Begin by choosing appropriate tracers such as fluorescein, isothiocyanate, labeled dextran and Rhodamine B, labeled dextran with distinct excitation emissions spectra, to minimize the interference between fluorescence signals for the permeability assay. Dilute the traces into sterile phosphate buffered saline into 100 milligrams per milliliter stocks and store the aliquots protected from light at minus 20 degrees Celsius. After anesthetizing the 8 to 10 weeks old male wild type mouse, gently hold the head and neck of the mouse to make one side of the eyeball protrude slightly.Insert an insulin syringe containing 100 microliters of fluorescent tracer solution mixture along the corner of the eye at a right angle to the eye. After the injection, quickly place the mouse on the cardboard in a supine position with its limbs and head taped. For submandibular gland or SMG isolation, under a stereoscopic microscope, cut the epidermis of the neck with general tissue scissors to expose both sides of the SMGs.Next, use a blunt tissue separation needle to gently separate the capsule from the gland surface without damaging the gland tissue, blood vessels, and glandular structure. Connect the customized holder to the negative pressure device and check whether the negative pressure effect is properly achieved in advance. Gently place the exposed SMG on the customized holder and suck up the tissue by negative pressure suction, as far away from the mouse body as possible, to reduce motion artifacts caused by respiration and other conditions.Commence imaging soon after the site of the gland is chosen. Acquire sequential images along the Z axis stepped two micron apart from the gland's surface up to 70 to 140 microns into the tissue to generate a three-dimensional construction. Next, acquire time lapse imaging of the vessels to measure vascular permeability in the SMG.In the Explorer dialogue box, click on Add New Folder"and change the file name. Then, go back to the acquisition column. In XY, the format is 512 by 512, and the speed is 400 hertz.Turn Bidirectional X"on, set the zoom factor to 0.75 and 1.5 for zoom. Next, select XYT under Acquisition Mode"to acquire time lapse imaging. Set duration to 20 seconds, 30 minutes or longer according to the experimental need.After setting the conditions, click on Live"to observe the vascular imaging of two channels and overlapping channels in the photo forming frame and choose the areas of interest. Click on Start"to begin imaging. In vivo vascular permeability assay, and three dimensional images of blood vessels in mice.Submandibular glands are shown here. In the control group, both the tracers existed in the blood vessels of the SMG. Due to its small molecular weight, FD4 was able to leak out of the blood vessels to the basal sides of acini and ducts, thereby clearly depicting the shape of the acini and ducts.The RD70 was distributed in large sized blood vessels and micro vessels. In the duct ligation group, both FD4 and RD70 were extravasated to the basal sides of acini, which indicated that duct ligation could disrupt the endothelial barrier function and increase the permeability to large molecules. Further, the semi-quantitative FD4 and RD70 fluorescence intensity results confirmed these observations.The three dimensional images showed much more obscured fluorescence of FD4 and RD70 around blood vessels in the ligation group compared to the control group. Careful SMG isolation and appropriate placement and the microscope are essential prerequisites for successful detection. Following the procedures, the blood flow rate can be calculated by marrying the movement of red blood cells and the infiltration of the fluorescence labeled blood cells can be chased.

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Biology

Single-cell Suction Recordings from Mouse Cone Photoreceptors

Rod and cone photoreceptors in the retina are responsible for light detection. In darkness, cyclic nucleotide-gated (CNG) channels in the outer segment are open and allow cations to flow steadily inwards across the membrane, depolarizing the cell. Light exposure triggers the closure of the CNG channels, blocks the inward cation current flow, and thus results in cell hyperpolarization. Based on the polarity of photoreceptors, a suction recording method was developed in 1970s that, unlike the classic patch-clamp technique, does not require penetrating the plasma membrane 1. Drawing the outer segment into a tightly-fitting glass pipette filled with extracellular solution allows recording the current changes in individual cells upon test-flash exposure. However, this well-established "outer-segment-in (OS-in)" suction recording is not suitable for mouse cone recordings, because of the low percentage of cones in the mouse retina (3%) and the difficulties in identifying the cone outer segments. Recently, an inner-segment-in (IS-in) recording configuration was developed to draw the inner segment/nuclear region of the photoreceptor into the recording pipette 2,3. In this video, we will show how to record from individual mouse cone photoresponses using single-cell suction electrode.

We will show how to record flash responses from single mouse cones using a suction electrode.

Rod and cone photoreceptors in the retina are responsible for light detection. In darkness, cyclic nucleotide-gated (CNG) channels in the outer segment ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

Evaluation of Mammary Gland Development and Function in Mouse Models

The human mammary gland is composed of 15-20 lobes that secrete milk into a branching duct system opening at the nipple. Those lobes are themselves composed of a number of terminal duct lobular units made of secretory alveoli and converging ducts1. In mice, a similar architecture is observed at pregnancy in which ducts and alveoli are interspersed within the connective tissue stroma. The mouse mammary gland epithelium is a tree like system of ducts composed of two layers of cells, an inner layer of luminal cells surrounded by an outer layer of myoepithelial cells denoted by the confines of a basement membrane2. At birth, only a rudimental ductal tree is present, composed of a primary duct and 15-20 branches. Branch elongation and amplification start at the beginning of puberty, around 4 weeks old, under the influence of hormones3,4,5. At 10 weeks, most of the stroma is invaded by a complex system of ducts that will undergo cycles of branching and regression in each estrous cycle until pregnancy2. At the onset of pregnancy, a second phase of development begins, with the proliferation and differentiation of the epithelium to form grape-shaped milk secretory structures called alveoli6,7. Following parturition and throughout lactation, milk is produced by luminal secretory cells and stored within the lumen of alveoli. Oxytocin release, stimulated by a neural reflex induced by suckling of pups, induces synchronized contractions of the myoepithelial cells around the alveoli and along the ducts, allowing milk to be transported through the ducts to the nipple where it becomes available to the pups 8. Mammary gland development, differentiation and function are tightly orchestrated and require, not only interactions between the stroma and the epithelium, but also between myoepithelial and luminal cells within the epithelium9,10,11. Thereby, mutations in many genes implicated in these interactions may impair either ductal elongation during puberty or alveoli formation during early pregnancy, differentiation during late pregnancy and secretory activation leading to lactation12,13. In this article, we describe how to dissect mouse mammary glands and assess their development using whole mounts. We also demonstrate how to evaluate myoepithelial contractions and milk ejection using an ex-vivo oxytocin-based functional assay. The effect of a gene mutation on mammary gland development and function can thus be determined in situ by performing these two techniques in mutant and wild-type control mice.

This method describes how to dissect and assess mammary gland development and function from mice. Excised mammary glands are assessed for the degree of development using whole mount while milk ejection is evaluated using an oxytocin-based myoepithelial cell contraction assay.

The human mammary gland is composed of 15-20 lobes that secrete milk into a branching duct system opening at the nipple. Those lobes are themselves ...

Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria

The mitochondrial permeability transition pore (mtPTP) is a non specific channel that forms in the inner mitochondrial membrane to transport solutes with a molecular mass smaller than 1.5 kDa. Although the definitive molecular identity of the pore is still under debate, proteins such as cyclophilin D, VDAC and ANT contribute to mtPTP formation. While the involvement of mtPTP opening in cell death is well established1, accumulating evidence indicates that the mtPTP serves a physiologic role during mitochondrial Ca2+ homeostasis2, bioenergetics and redox signaling 3.
mtPTP opening is triggered by matrix Ca2+ but its activity can be modulated by several other factors such as oxidative stress, adenine nucleotide depletion, high concentrations of Pi, mitochondrial membrane depolarization or uncoupling, and long chain fatty acids4. In vitro, mtPTP opening can be achieved by increasing Ca2+ concentration inside the mitochondrial matrix through exogenous additions of Ca2+ (calcium retention capacity). When Ca2+ levels inside mitochondria reach a certain threshold, the mtPTP opens and facilitates Ca2+ release, dissipation of the proton motive force, membrane potential collapse and an increase in mitochondrial matrix volume (swelling) that ultimately leads to the rupture of the outer mitochondrial membrane and irreversible loss of organelle function.
Here we describe a fluorometric assay that allows for a comprehensive characterization of mtPTP opening in isolated mouse heart mitochondria. The assay involves the simultaneous measurement of 3 mitochondrial parameters that are altered when mtPTP opening occurs: mitochondrial Ca2+ handling (uptake and release, as measured by Ca2+ concentration in the assay medium), mitochondrial membrane potential, and mitochondrial volume. The dyes employed for Ca2+ measurement in the assay medium and mitochondrial membrane potential are Fura FF, a membrane impermeant, ratiometric indicator which undergoes a shift in the excitation wavelength in the presence of Ca2+, and JC-1, a cationic, ratiometric indicator which forms green monomers or red aggregates at low and high membrane potential, respectively. Changes in mitochondrial volume are measured by recording light scattering by the mitochondrial suspension. Since high-quality, functional mitochondria are required for the mtPTP opening assay, we also describe the steps necessary to obtain intact, highly coupled and functional isolated heart mitochondria.

A spectrofluorometric protocol for the measurement of the mitochondrial permeability transition pore opening in isolated mouse heart mitochondria is presented here. The assay involves the simultaneous measurement of mitochondria Ca2+ handling, mitochondrial membrane potential and mitochondrial volume. The procedure for obtaining high-quality and functional heart mitochondria is also described.

The mitochondrial permeability transition pore (mtPTP) is a non specific channel that forms in the inner mitochondrial membrane to transport solutes with ...

Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of genes within the mammary epithelium has been difficult to achieve due to the lack of appropriate targeting molecules that are independent of developmental stages such as pregnancy and lactation. Herein, we describe a technique for localized delivery of reagents to the mammary gland at any stage in adulthood via intraductal injection into the nipples of mice. The injections can be performed on live mice, under anesthesia, and allow for a non-invasive and localized drug delivery to the mammary gland. Furthermore, the injections can be repeated over several months without damaging the nipple. Vital dyes such as Evans Blue are very helpful to learn the technique. Upon intraductal injection of the blue dye, the entire ductal tree becomes visible to the eye. Furthermore, fluorescently labeled reagents also allow for visualization and distribution within the mammary gland. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents, and small molecules.

A protocol for the non-invasive intraductal delivery of aqueous reagents to the mouse mammary gland is described. The method takes advantage of localized injection into the nipples of mammary glands targeting mammary ducts specifically. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents and small molecules.

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of ...

Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is a simple and very efficient method for the determination of the osmotic water permeability coefficient (Pf) in plant protoplasts, applicable in principle also to other spherical cells such as frog oocytes. The first step of the assay is the isolation of protoplasts from the plant tissue of interest by enzymatic digestion into a chamber with an appropriate isotonic solution. The second step consists of an osmotic challenge assay: protoplasts immobilized on the bottom of the chamber are submitted to a constant perfusion starting with an isotonic solution and followed by a hypotonic solution. The cell swelling is video recorded. In the third step, the images are processed offline to yield volume changes, and the time course of the volume changes is correlated with the time course of the change in osmolarity of the chamber perfusion medium, using a curve fitting procedure written in Matlab (the &#8216;PfFit&#8217;), to yield Pf.

Measuring the Osmotic Water Permeability Coefficient Pf of Spherical Cells: Isolated Plant Protoplasts as an Example

Measuring the osmotic water permeability coefficient (Pf) of cells can help understand the regulatory mechanisms of aquaporins (AQPs). Pf determination in spherical plant cell protoplasts presented here involves protoplasts isolation and numerical analysis of their initial rate of volume change as a result of an osmotic challenge during constant bath perfusion.

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

The Mouse Isolated Perfused Kidney Technique

The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. This is a prerequisite for studying the physiology of the isolated organ and for many innovative applications that may be possible in the future, including perfusion decellularization for kidney bioengineering or the administration of anti-rejection or genome-editing drugs in high doses to prime the kidney for transplantation. During the time of the perfusion, the kidney can be manipulated, renal function can be assessed, and various pharmaceuticals administered. After the procedure, the kidney can be transplanted or processed for molecular biology, biochemical analysis, or microscopy.
This paper describes the perfusate and the surgical technique needed for the ex vivo perfusion of mouse kidneys. Details of the perfusion apparatus are given and data are presented showing the viability of the kidney&#39;s preparation: renal blood flow, vascular resistance, and urine data as functional, transmission electron micrographs of different nephron segments as morphological readouts, and western blots of transport proteins of different nephron segments as molecular readout.

The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. The buffers and surgical technique are described in detail.

The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. This is a ...

In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells

The post-translational modifications of proteins are critical for the proper regulation of intracellular signal transduction. Among these modifications, small ubiquitin-related modifier (SUMO) is a ubiquitin-like protein that is covalently attached to the lysine residues of a variety of target proteins to regulate cellular processes, such as gene transcription, DNA repair, protein interaction and degradation, subcellular transport, and signal transduction. The most common approach to detecting protein SUMOylation is based on the expression and purification of recombinant tagged proteins in bacteria, allowing for an in vitro biochemical reaction which is simple and suitable for addressing mechanistic questions. However, due to the complexity of the process of SUMOylation in vivo, it is more challenging to detect and analyze protein SUMOylation in cells, especially when under endogenous conditions. A recent study by the authors of this paper revealed that endogenous retinoblastoma (Rb) protein, a tumor suppressor that is vital to the negative regulation of the cell cycle progression, is specifically SUMOylated at the early G1 phase. This paper describes a protocol for the detection and analysis of Rb SUMOylation under both endogenous and exogenous conditions in human cells. This protocol is appropriate for the phenotypical and functional investigation of the SUMO-modification of Rb, as well as many other SUMO-targeted proteins, in human cells.

In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells

Small ubiquitin-related modifier (SUMO) family proteins are conjugated to the lysine residues of target proteins to regulate various cellular processes. This paper describes a protocol for the detection of retinoblastoma (Rb) protein SUMOylation under endogenous and exogenous conditions in human cells.

The post-translational modifications of proteins are critical for the proper regulation of intracellular signal transduction. Among these modifications, ...

In Vitro and In Vivo Approaches to Determine Intestinal Epithelial Cell Permeability

The intestinal barrier defends against pathogenic microorganism and microbial toxin. Its function is regulated by tight junction permeability and epithelial cell integrity, and disruption of the intestinal barrier function contributes to progression of gastrointestinal and systemic disease. Two simple methods are described here to measure the permeability of intestinal epithelium. In vitro, Caco-2BBe cells are plated in tissue culture wells as a monolayer and transepithelial electrical resistance (TER) can be measured by an epithelial (volt/ohm) meter. This method is convincing because of its user-friendly operation and repeatability. In vivo, mice are gavaged with 4 kDa fluorescein isothiocyanate (FITC)-dextran, and the FITC-dextran concentrations are measured in collected serum samples from mice to determine the epithelial permeability. Oral gavage provides an accurate dose, and therefore is the preferred method to measure the intestinal permeability in vivo. Taken together, these two methods can measure the permeability of the intestinal epithelium in vitro and in vivo, and hence be used to study the connection between diseases and barrier function.

In Vitro and In Vivo Approaches to Determine Intestinal Epithelial Cell Permeability

Two methods are presented here to determine intestinal barrier function. An epithelial meter (volt/ohm) is used for measurements of transepithelial electrical resistance of cultured epithelia directly in tissue culture wells. In mice, the FITC-dextran gavage method is used to determine the intestinal permeability in vivo.