Name: in vivo nanovector delivery of a heart-specific microrna-sponge
Uploaded: 2018-06-15T15:00:00
Description: Watch this Scientific Journal Video about In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge at JoVE.com

We thank Anthony K. L. Leung of the Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University for his technical help with designing the miR-181-sponge construct. We also thank Polina Sysa-Shah and Kathleen Gabrielson of the Department of Molecular and Comparative Pathobiology, Johns Hopkins Medical Institutions for their technical assistance by the in vivo imaging of the miRNA-Sponge delivery.
This work was supported by grants from the NIH, HL39752 (to Charles Steenbergen) and by a Scientist Development Grant from the American Heart Association 14SDG18890049 (to Samarjit Das). The rat cardio-specific promoter was generously provided by Jeffery D. Molkentin at the Cincinnati Children&#39;s Hospital.

All experimental procedures were approved by the Institutional Animal Care and Use Committee of Johns Hopkins University.
1. Sponge Design
<ol>
	<li>MicroRNA binding 3&#8217;UTR 
	Note: A miRNA functions through specific base pairing interactions with partially complementary sites in the 3&#8217; untranslated region (UTR) of its target mRNAs (for a comprehensive review, see Bartel)15.
	<ol>
		<li>Design the inhibitors of miRNA expression as oligo...

<ol>
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This article described the design and synthesis of a miRNA-sponge and demonstrated how the tissue-specific expression of the sponge is a powerful tool to inhibit tissue-specific miRNA family expression.
We have demonstrated that a miR-181 family targeting sponge can be cloned into an expression plasmid with a cardiac-specific promoter. The plasmid can be efficiently packaged into a nanovector particle for delivery both in vitro and in vivo using electroporation or a tail vein...

Over the last two decades, there have been numerous studies that have pointed to the significant role of miRNAs in human disease. Findings from a large body of literature demonstrate the undeniable importance of miRNAs in the pathophysiology of diseases, such as cancer1 and cardiovascular disease2,3,4,5. For example, miR-21 is upregulated in many cancers, resulting in an increased cell cycle and cell proliferation6. In hepatitis C infections, miR-122 plays an important role in the replication of the virus7, and it has been shown that the inhibition of miR-122 decreases the viral load8. In cardiac hypertrophy, miR-212/132 is upregulated in the heart and is involved in the pathological phenotype9. The obvious importance of the downregulation or functional inhibition of an upregulated miRNA suggests opportunities for therapeutically exploiting the miRNA biology in almost all diseases.
The four miR-181 family members, miR-181a/b/c/d, are found in three genomic locations in the human genome. The intronic region of a non-coding RNA host gene (MIR181A1-HG) encodes the cluster of miR-181-a/b-1. The intronic region of the NR6A1 gene encodes the miR-181-a/b-2. The miR-181-c/d cluster is located in an uncharacterized transcript on chromosome 19. All the miR-181 family members share the same &#34;seed&#34; sequence and all four miR-181 family members can potentially regulate the same mRNA targets.
We3,4 and others10 have highlighted the importance of miR-181 family members during the end-stage heart failure. We have also recognized that a miR-181c upregulation occurs under pathological conditions associated with an increased risk of heart disease, such as type II diabetes, obesity, and aging3,4,5. It has been postulated that the overexpression of miR-181c causes oxidative stress which leads to a cardiac-dysfunction4.
Several groups have suggested that miRNA exist in mitochondria11,12,13,14, but we were the first to demonstrate that miR-181c is derived from the nuclear genome, processed, and subsequently translocated to the mitochondria in the RISC3. Furthermore, we have detected a low expression of miR-181a and miR-181b in the mitochondrial compartment of the heart5. Importantly, we have found that miR-181c represses the mt-COX1 mRNA expression, thereby demonstrating that miRNAs participate in the mitochondrial gene regulation and alter mitochondrial function3,4.
This article discusses the methodology required to design a miRNA-sponge to knock down the entire miR-181 family in cardiomyocytes. Moreover, we outline a protocol for the in vivo application of the miR-181-sponge.

<table>
	<tbody>
		<tr>
			<td>pEGFP-C1 vector</td>
			<td>Addgene</td>
			<td>6084-1</td>
			<td></td>
		</tr>
		<tr>
			<td>In-fusion</td>
			<td>Clontech</td>
			<td>121416</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAprep Miniprep</td>
			<td>Qiagen</td>
			<td>27104</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick Gel Extraction Kit</td>
			<td>Qiagen</td>
			<td>28704</td>
			<td></td>
		</tr>
		<tr>
			<td>miR-181-sponge synthesis</td>
			<td>Introgen GeneArt</td>
			<td>custome made</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR primers</td>
			<td>Integrated DNA Technologies</td>
			<td>custome</td>
			<td></td>
		</tr>
		<tr>
			<td>EcoRI enzymes</td>
			<td>New Endland Biolabs</td>
			<td>R0101S</td>
			<td></td>
		</tr>
		<tr>
			<td>KpnI enzymes</td>
			<td>New Endland Biolabs</td>
			<td>R0142S</td>
			<td></td>
		</tr>
		<tr>
			<td>Rapid DNA Ligation Kit</td>
			<td>Sigma-Aldrich</td>
			<td>11635379001</td>
			<td></td>
		</tr>
		<tr>
			<td>H9c2 cells</td>
			<td>ATCC</td>
			<td>CRL-1446</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM Media</td>
			<td>Thermo Fisher Scientific</td>
			<td>11965092</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Thermo Fisher Scientific</td>
			<td>10082139</td>
			<td></td>
		</tr>
		<tr>
			<td>Nucleofector 2b Device</td>
			<td>Lonza</td>
			<td>AAB-1001</td>
			<td></td>
		</tr>
		<tr>
			<td>Nucleofector Kits for H9c2 (2-1)</td>
			<td>Lonza</td>
			<td>VCA-1005</td>
			<td></td>
		</tr>
		<tr>
			<td>G418, Geneticin</td>
			<td>Thermo Fisher Scientific</td>
			<td>11811023</td>
			<td></td>
		</tr>
		<tr>
			<td>FACSAria II Flow cytometer</td>
			<td>BD Bioscience</td>
			<td>644832</td>
			<td></td>
		</tr>
		<tr>
			<td>Branson 450 sonifier</td>
			<td>Marshall Scientific</td>
			<td>EDP 100-214-239</td>
			<td></td>
		</tr>
		<tr>
			<td>The Xenogen IVIS Spectrum optical imaging device</td>
			<td>Caliper Life Sciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-MTCO1 antibody</td>
			<td>Abcam</td>
			<td>ab14705</td>
			<td></td>
		</tr>
		<tr>
			<td>&#945;-tubulin antibody</td>
			<td>Abcam</td>
			<td>ab7291</td>
			<td></td>
		</tr>
		<tr>
			<td>Sequoia C256 ultrasound system</td>
			<td>Siemens</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

in vivo nanovector delivery of a heart-specific microrna-sponge

MicroRNA (miRNA) is small non-coding RNA which inhibits post-transcriptional messenger RNA (mRNA) expression. Human diseases, such as cancer and cardiovascular disease, have been shown to activate tissue and/or cell-specific miRNA expression associated with disease progression. The inhibition of miRNA expression offers the potential for a therapeutic intervention. However, traditional approaches to inhibit miRNAs, employing antagomir oligonucleotides, affect specific miRNA functions upon global delivery. Herein, we present a protocol for the in vivo cardio-specific inhibition of the miR-181 family in a rat model. A miRNA-sponge construct is designed to include 10 repeated anti-miR-181 binding sequences. The cardio-specific &#945;-MHC promoter is cloned into the pEGFP backbone to drive the cardio-specific miR-181 miRNA-sponge expression. To create a stable cell line expressing the miR-181-sponge, myoblast H9c2 cells are transfected with the &#945;-MHC-EGFP-miR-181-sponge construct and sorted by fluorescence-activated cell sorting (FACs) into GFP positive H9c2 cells which are cultured with neomycin (G418). Following stable growth in neomycin, monoclonal cell populations are established by additional FACs and single cell cloning. The resulting myoblast H9c2-miR-181-sponge-GFP cells exhibit a loss of function of miR-181 family members as assessed through the increased expression of miR-181 target proteins and compared to H9c2 cells expressing a scramble non-functional sponge. In addition, we develop a nanovector for the systemic delivery of the miR-181-sponge construct by complexing positively charged liposomal nanoparticles and negatively charged miR-181-sponge plasmids. In vivo imaging of GFP reveals that multiple tail vein injections of a nanovector over a three-week period are able to promote a significant expression of the miR-181-sponge in a cardio-specific manner. Importantly, a loss of miR-181 function is observed in the heart tissue but not in the kidney or the liver. The miRNA-sponge is a powerful method to inhibit tissue-specific miRNA expression. Driving the miRNA-sponge expression from a tissue-specific promoter provides specificity for the miRNA inhibition, which can be confined to a targeted organ or tissue. Furthermore, combining nanovector and miRNA-sponge technologies permits an effective delivery and tissue-specific miRNA inhibition in vivo.

In the stably transfected pEGFP-miR-181-sponge-expressing H9c2 cells (from step 4.2), the expression of the entire miR-181 family (miR-181a, miR-181b, miR-181c, and miR-181d) was moderately decreased relative to pEGFP-scrambled-expressing H9c2 cells. MiR-181-sponge serves as a competitive inhibitor of the entire miR-181 family, so we anticipated that the expression of the miR-181c mitochondrial target gene, mt-COX1, would increase. Western blot data suggest that the mt-COX1 expression was...

Watch this Scientific Journal Video about In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge at JoVE.com

In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge

Tissue-specific microRNA inhibition is a technology that is underdeveloped in the microRNA field. Herein, we describe a protocol to successfully inhibit the miR-181 microRNA family in myoblast cells from the heart. Nanovector technology is used to deliver a microRNA sponge that demonstrates significant in vivo cardio-specific miR-181 family inhibition.

In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge

MicroRNA (miRNA) is small non-coding RNA which inhibits post-transcriptional messenger RNA (mRNA) expression. Human diseases, such as cancer and ...

So for the last couple of decades, the importance of microRNA has been recognized in human disease conditions, but the problem is that, therapy-wise, it did not go to the primetime. One of the problem is, one microRNA can have different targets in different tissues. So one microRNA can be protected in one organ but detrimental to the others.So this method can help to eliminate tissue-specific microRNA knockdown strategy. The main advantage of this technology is we will use a microRNA sponge delivery and can be performed a tissue-specific manner. Begin this procedure with sponge design as described in the text protocol.To remove the CMV promoter from the commercially-available EGFR plasmid, first perform a digestion reaction. Following digestion, add five times the reaction volume of column binding buffer. Purify the digested linearized plasmid with a DNA purification column as described by the manufacturer.Elute with 25 microliters of elution buffer added carefully to the center column. Gel-purify the digested plasmid on a 0.5%agarose gel by first adding five microliters of loading buffer to the eluded plasmid. Load the entire sample into one well on a 0.5%agarose gel.Include a separate lane with 500 nanograms of uncut vector. Run it for 30 to 40 minutes, until an adequate separation of cut and uncut plasmids is achieved. After cloning the cardio-specific promoter alpha-myosin heavy chain as subscribed in the text protocol, add five times the reaction volume of the column binding buffer to the PCR reaction and purify it with a DNA purification column as described by the manufacturer.Elute the mixture with 25 microliters of elution buffer added carefully to the center of the column. Add five microliters of loading buffer to the eluded plasmid and load the entire sample into one well of a 1%agarose gel. Run the gel for 30 to 40 minutes before excising the PCR product as before.Ligate the alpha-myocin heavy chain promoter with the EGFP plasmid at 50 degrees Celsius for 15 minutes before cooling the reaction on ice. Perform a bacterial transformation by transfecting 50 microliters of competent cells with 2.5 microliters of infusion ligation mix. Rest the Eppendorf tube on ice for 20 minutes.Then, incubate the reaction in a 42 degree Celsius water bath for 40 seconds and place the tube on ice for two minutes. Following the transformation, add 350 microliters of SOC media and grow the cells at 37 degrees Celsius for 45 minutes. Plate 200 microliters of the outgrowth solution on LB plates with Kanamycin.Perform a colony PCR to identify Kanamycin-resistant cells, which contain the alpha-myosin heavy chain promoter ligation. Ligate the microRNA 181 sponge into the alpha-myosin heavy chain expressed EGFP vector by setting up a 21 microliter ligation reaction as detailed in the text protocol. Perform the ligation at room temperature for five minutes and then place it on ice.Transform 50 microliters of XL1-Blue competent cells with two microliters of ligation mix as before. Perform a colony PCR to identify Kanamycin-resistant bacteria, which contain the correct plasmid cloned with the first alpha-myacin heavy chain followed by the microRNA 181 sponge construct sequence. Design screening primers to PCR across the ligation junction.Expand the PCR positive clones in LB Kanamycin broth and in plasmids purified using standard mini-prep plasmid purification protocols. Perform DNA sequencing to verify that the plasmid is expressing the desired DNA sequences. Using an electroporator, transfect rat myoblasts with either a scramble sponge as a control, or the plasmid cloned with the first alpha-myocin heavy chain, followed by the microRNA 181 sponge construct.Briefly, transfect 0.4 million cells with two microgams of plasmid DNA and 100 microliters of a solution compatible with the electroporation device. Use an appropriate program to transfect the H9C2 cells. Plate only the GFP-expressed cells into a six-well plate with an addition of neomycin to the complete growth media.After seeding five to 10 cells in each well of a 96-well plate, followed by flow sorting, expand the monoclonal cells from the 96-well plate to 24-well plates over several passages. Prepare the liposomal nanoparticles by dissolving the components listed in the text protocol in a mixture of chloroform and methanol in a glass vial. Prepare the mixture by adding 5%glucose to the vacuum-dried lipid film before leaving it overnight to allow this mixture to hydrate the film.Gently rock the vial for two to three minutes at room temperature in order to produce multilamellar vesicles. Then, incubate the vesicles with occasional shaking in a 45 degree Celsius incubator. Sonicate the multilamellar vesicles to prepare small unilamellar vesicles in an ice bath for three to four minutes, until clarity can be observed.Add a 100%duty cycle and 25 watts of output power. Mix either a scramble sequence or a microRNA 181 sponge sequence cloned into the alpha-myocin heavy chain expressed EGFP plasmid with liposome on a one-to-three charge ratio basis to form the nanovector. The results of optimized three-week treatment protocols with six intravenous injections through the tail vein are shown here.The yellow colorization in the epifluorescence image demonstrates expression of the EGFP vector. The maximum intensity of yellow colorization is observed at the week three time point. The alpha-myosin heavy chain promoter sequence in the EGFP vector selectively expresses either microRNA 181 sponge or scrambled sequence in the heart at Day 21 as revealed by the yellow fluorescence.The Western blot and band densitometry showed a significant increase in the mt-COX1 expression in the microRNA 181 sponge nanovector injected rats as compared to the scramble nanovector groups, with alpha-Tubulin as the normalization control. One of the major challenges in this particular protocol is to keep the orientation of the sequencing, you need directional. Once a bacterial preparation is made, with a proper orientation of the microRNA sponge, this technique can be done with a two or three minute tail vein injection time.While attempting this procedure, it is important to sequence your bacterial colony multiple times, multiple batches, to make sure the microRNA response sequence is in the correct order. After watching this video, you should have a good understanding of how to design a microRNA sponge to knock down the expression of any microRNA family and prepare an in vivo application of microRNA sponge. Following this procedure, other methods, such as in vivo antagomir treatment can be performed to answer additional questions like whether a specific microRNA can be knocked down in all the organ at the same time.After its development, this particular technology paved the way for researcher in the field of microRNA to explore tissue-specific knockdown of a microRNA in the pathophysiology of multiple-disease conditions. Tissue-specific microRNA inhibition is currently an undeveloped technique in the microRNA field. The importance of mat-down regulation of functional inhibition of up-regulated microRNAs in human disease suggest exploring microRNA biology to create a cellular vulnerability for therapeutic intervention.

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Research

JoVE Journal

Biology

Construction and Implantation of a Microinfusion System for Sustained Delivery of Neuroactive Agents.

Sustained delivery of neuroactive agents is widely used in neuroscience, but poses many technical challenges. It is necessary to deliver the agent with high precision while minimizing localized trauma and inflammation. Also, the ability to customize the system to accommodate animals of different species and sizes is desirable. This video presentation demonstrates the construction of an infusion system that can be fitted to any particular research animal. The delivery microcannula diameter is approximately 10-fold smaller than most infusion cannulas presently used. This translates into enhanced accuracy and reduced trauma to the brain region under study. The delivery cannula can also be sculpted to fit the contour of the surface of the animal's skull, thereby allowing closure of the scalp incision neatly over the infusion system, precluding the need for a skull-mounted pedestal, reducing risk of infection, and ensuring a greater level of comfort to the animal. The system is assembled in an air-free environment and requires the researcher to fashion glass micropipettes with a heat source. These construction methods require special skills that are best acquired, if not in person, using video instruction.  (This article is based on work first reported in J Neurosci Methods. 2008 Jan 30;167(2):213-20. Epub 2007 Aug 28.).

As neuroscience inquiry becomes more sophisticated, investigation of brain structures and circuitry requires improved levels of accuracy and higher resolution. We have developed a method for the preparation and implantation of a chronic infusion system within the brain utilizing a borosilicate microcannula with a tip diameter of 50 microns.

Sustained delivery of neuroactive agents is widely used in neuroscience, but poses many technical challenges. It is necessary to deliver the agent with ...

In vivo Imaging of Deep Cortical Layers using a Microprism

We present a protocol for in vivo imaging of cortical tissue using a deep-brain imaging probe in the shape of a microprism.  Microprisms are 1-mm in size and have a reflective coating on the hypotenuse to allow internal reflection of excitation and emission light.  The microprism probe simultaneously images multiple cortical layers with a perspective typically seen only in slice preparations.  Images are collected with a large field-of-view (~900 &mu;m).  In addition, we provide details on the non-survival surgical procedure and microscope setup.  Representative results include images of layer V pyramidal neurons from Thy-1 YFP-H mice showing their apical dendrites extending through the superficial cortical layer and extending into tufts.  Resolution was sufficient to image dendritic spines near the soma of layer V neurons.  A tail-vein injection of fluorescent dye reveals the intricate network of blood vessels in the cortex.  Line-scanning of red blood cells (RBCs) flowing through the capillaries reveals RBC velocity and flux rates can be obtained. This novel microprism probe is an elegant, yet powerful new method of visualizing deep cellular structures and cortical function in vivo.

In vivo Imaging of Deep Cortical Layers using a Microprism

Right-angle microprisms inserted into the mouse neocortex allows for deep imaging of multiple cortical layers with a viewpoint typically found in slice. One-millimeter microprisms offer a wide field-of-view (~900 &mu;m) and spatial resolutions sufficient to resolve dendritic spines. We demonstrate layer V neuronal imaging and neocortical vascular imaging using microprisms.

We present a protocol for in vivo imaging of cortical tissue using a deep-brain imaging probe in the shape of a microprism.  Microprisms are 1-mm in size ...

In-vivo Centrifugation of Drosophila Embryos

A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in buoyant density. However, when cells are disrupted prior to centrifugation, proteins and organelles in this non-native environment often inappropriately stick to each other. Here we describe a method to separate organelles by density in intact, living Drosophila embryos. Early embryos before cellularization are harvested from population cages, and their outer egg shells are removed by treatment with 50% bleach. Embryos are then transferred to a small agar plate and inserted, posterior end first, into small vertical holes in the agar. The plates containing embedded embryos are centrifuged for 30 min at 3000g. The agar supports the embryos and keeps them in a defined orientation. Afterwards, the embryos are dug out of the agar with a blunt needle. Centrifugation separates major organelles into distinct layers, a stratification easily visible by bright-field microscopy. A number of fluorescent markers are available to confirm successful stratification in living embryos. Proteins associated with certain organelles will be enriched in a particular layer, demonstrating colocalization. Individual layers can be recovered for biochemical analysis or transplantation into donor eggs. This technique is applicable for organelle separation in other large cells, including the eggs and oocytes of diverse species.

In-vivo Centrifugation of Drosophila Embryos

We describe a method to separate organelles by density in living Drosophila embryos. Embryos are embedded in agar and centrifuged. This technique yields reproducible separation of major organelles along the anterior-posterior embryo axis. This method facilitates colocalization experiments and yields organelle fractions for biochemical analysis and transplantation experiments.

A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in ...

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa

Spermatozoa are quite unique amongst cell types. Although produced in the testis, both nuclear gene transcription and translation are switched off once the pre-cursor round cell begins to elongate and differentiate into what is morphologically recognized as a spermatozoon. However, the spermatozoon is very immature, having no ability for motility or egg recognition. Both of these events occur once the spermatozoa transit a secondary organ known as the epididymis. During the ~12 day passage that it takes for a sperm cell to pass through the epididymis, post-translational modifications of existing proteins play a pivotal role in the maturation of the cell. One major facet of such is protein phosphorylation. In order to characterize phosphorylation events taking place during sperm maturation, both pure sperm cell populations and pre-fractionation of phosphopeptides must be established. Using back flushing techniques, a method for the isolation of pure spermatozoa of high quality and yield from the distal or caudal epididymides is outlined. The steps for solubilization, digestion, and pre-fractionation of sperm phosphopeptides through TiO2 affinity chromatography are explained. Once isolated, phosphopeptides can be injected into MS to identify both protein phosphorylation events on specific amino acid residues and quantify the levels of phosphorylation taking place during the sperm maturation processes.

Proteomic analysis of any cell type is highly dependent on both purity and pre-fractionation of the starting material in order to de-complexify the sample prior to liquid chromatography mass spectrometry (MS). By using back-flushing techniques, pure spermatozoa can be obtained from rodents. Following digestion, phosphopeptides can be enriched using TiO2.

Spermatozoa are quite unique amongst cell types. Although produced in the testis, both nuclear gene transcription and translation are switched off once ...

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, is expressed in neurons in response to various stimuli. The protein product can be readily detected with immunohistochemical techniques leading to the use of c-FOS detection to map groups of neurons that display changes in their activity. In this article, we focused on the identification of brainstem neuronal populations involved in the ventilatory adaptation to hypoxia or hypercapnia. Two approaches were described to identify involved neuronal populations in vivo in animals and ex vivo in deafferented brainstem preparations. In vivo, animals were exposed to hypercapnic or hypoxic gas mixtures. Ex vivo, deafferented preparations were superfused with hypoxic or hypercapnic artificial cerebrospinal fluid. In both cases, either control in vivo animals or ex vivo preparations were maintained under normoxic and normocapnic conditions. The comparison of these two approaches allows the determination of the origin of the neuronal activation i.e., peripheral and/or central. In vivo and ex vivo, brainstems were collected, fixed, and sliced into sections. Once sections were prepared, immunohistochemical detection of the c-FOS protein was made in order to identify the brainstem groups of cells activated by hypoxic or hypercapnic stimulations. Labeled cells were counted in brainstem respiratory structures. In comparison to the control condition, hypoxia or hypercapnia increased the number of c-FOS labeled cells in several specific brainstem sites that are thus constitutive of the neuronal pathways involved in the adaptation of the central respiratory drive.

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Here, we present a protocol based on c-FOS protein immunohistological detection, a classical technique used for the identification of neuronal populations involved in specific physiological responses in vivo and ex vivo.

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, ...

RNAi Trigger Delivery into Anopheles gambiae Pupae

RNA interference (RNAi), a naturally occurring phenomenon in eukaryotic organisms, is an extremely valuable tool that can be utilized in the laboratory for functional genomic studies. The ability to knockdown individual genes selectively via this reverse genetic technique has allowed many researchers to rapidly uncover the biological roles of numerous genes within many organisms, by evaluation of loss-of-function phenotypes. In the major human malaria vector Anopheles gambiae, the predominant method used to reduce the function of targeted genes involves injection of double-stranded (dsRNA) into the hemocoel of the adult mosquito. While this method has been successful, gene knockdown in adults excludes the functional assessment of genes that are expressed and potentially play roles during pre-adult stages, as well as genes that are expressed in limited numbers of cells in adult mosquitoes. We describe a method for the injection of Serine Protease Inhibitor 2 (SRPN2) dsRNA during the early pupal stage and validate SRPN2 protein knockdown by observing decreased target protein levels and the formation of melanotic pseudo-tumors in SRPN2 knockdown adult mosquitoes. This evident phenotype has been described previously for adult stage knockdown of SRPN2 function, and we have recapitulated this adult phenotype by SRPN2 knockdown initiated during pupal development. When used in conjunction with a dye-labeled dsRNA solution, this technique enables easy visualization by simple light microscopy of injection quality and distribution of dsRNA in the hemocoel.

RNAi Trigger Delivery into Anopheles gambiae Pupae

RNA interference (RNAi) is an extremely valuable tool for uncovering gene function. However, the ability to target genes using RNAi during pre-adult stages is limited in the major human malaria vector Anopheles gambiae. We describe an RNAi protocol to reduce gene function via direct injection during pupal development.

RNA interference (RNAi), a naturally occurring phenomenon in eukaryotic organisms, is an extremely valuable tool that can be utilized in the laboratory ...

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 ...

Novel Method of Plasmid DNA Delivery to Mouse Bladder Urothelium by Electroporation

Genetically engineered mouse models (GEMMs) are extremely valuable in revealing novel biological insights into the initiation and progression mechanisms of human diseases such as cancer. Transgenic and conditional knockout mice have been frequently used for gene overexpression or ablation in specific tissues or cell types in vivo. However, generating germline mouse models can be time-consuming and costly. Recent advancements in gene editing technologies and the feasibility of delivering DNA plasmids by viral infection have enabled rapid generation of non-germline autochthonous mouse cancer models for several organs. The bladder is an organ that has been difficult for viral vectors to access, due to the presence of a glycosaminoglycan layer covering the urothelium. Here, we describe a novel method developed in lab for efficient delivery of DNA plasmids into the mouse bladder urothelium in vivo. Through intravesical instillation of pCAG-GFP DNA plasmid and electroporation of surgically exposed bladder, we show that the DNA plasmid can be delivered specifically into the bladder urothelial cells for transient expression. Our method provides a fast and convenient way for overexpression and knockdown of genes in the mouse bladder, and can be applied to building GEMMs of bladder cancer and other urological diseases.

We describe a novel method for the delivery of DNA plasmid into the urothelial cells of mouse bladder in vivo through urethra catheterization and electroporation. It offers a fast and convenient way for generating autochthonous mouse models of bladder diseases.

Genetically engineered mouse models (GEMMs) are extremely valuable in revealing novel biological insights into the initiation and progression mechanisms ...

An Ex Vivo Tissue Culture Model of Cartilage Remodeling in Bovine Knee Explants

Ex vivo culture systems cover a broad range of experiments dedicated to studying tissue and cellular function in a native setting. Cartilage is a unique tissue important for proper function of the synovial joint and is constituted by a dense extracellular matrix (ECM), rich in proteoglycan and type II collagen. Chondrocytes are the only cell type present within cartilage and are widespread and relatively low in number. Altered external stimuli and cellular signalling can lead to changes in ECM composition and deterioration, which are important pathological hallmarks in diseases such as osteoarthritis (OA) and rheumatoid arthritis.
Ex vivo cartilage models allow 1) profiling of chondrocyte mediated alterations of cartilage tissue turnover, 2) visualizing the cartilage ECM composition, and 3) chondrocyte rearrangement directly in the tissue. Profiling these alterations in response to stimuli or treatments are of high importance in various aspects of cartilage biology, and complement in vitro experiments in isolated chondrocytes, or more complex models in live animals where experimental conditions are more difficult to control.
Cartilage explants present a translational and easily accessible method for assessing tissue remodeling in the cartilage ECM in controllable settings. Here, we describe a protocol for isolating and culturing live bovine cartilage explants. The method uses tissue from the bovine knee, which is easily accessible from the local butchery. Both explants and conditioned culture medium can be analyzed to investigate tissue turnover, ECM composition, and chondrocyte function, thus profiling ECM modulation.

Here, we present a protocol describing isolation and culturing of cartilage explants from bovine knees. This method provides an easy and accessible tool to describe tissue changes in response to biological stimuli or novel therapeutics targeting the joint.

Ex vivo culture systems cover a broad range of experiments dedicated to studying tissue and cellular function in a native setting. Cartilage is a unique ...

In Vivo Surface Electrocardiography for Adult Zebrafish

The electrocardiogram waveforms of adult zebrafish and those of humans are remarkably similar. These electrocardiogram similarities enhance the value of zebrafish not only as a research model for human cardiac electrophysiology and myopathies but also as a surrogate model in high throughput pharmaceutical screening for potential cardiotoxicities to humans, such as QT prolongation. As such, in vivo electrocardiography for adult zebrafish is an electrical phenotyping tool that is necessary, if not indispensable, for cross-sectional or longitudinal in vivo electrophysiological characterizations. However, too often, the lack of a reliable, practical, and cost-effective recording method remains a major challenge preventing this in vivo diagnostic tool from becoming more readily accessible. Here, we describe a practical, straightforward approach to in vivo electrocardiography for adult zebrafish using a low-maintenance, cost-effective, and comprehensive system that yields consistent, reliable recordings. We illustrate our protocol using healthy adult male zebrafish of 12-18 months of age. We also introduce a rapid real-time interpretation strategy for quality validation to ensure data accuracy and robustness early in the electrocardiogram recording process.

Here, we present a reliable, minimally invasive, and cost-effective method to record and interpret electrocardiograms in live anesthetized adult zebrafish.

The electrocardiogram waveforms of adult zebrafish and those of humans are remarkably similar. These electrocardiogram similarities enhance the value of ...