Name: glaucoma-inducing procedure in an in vivo rat model and whole-mount retina preparation
Uploaded: 2016-03-12T14:00:00
Description: Watch this Scientific Journal Video about Glaucoma-inducing Procedure in an In Vivo Rat Model and Whole-mount Retina Preparation at JoVE.com

C. Linn is supported by an NIH grant (NIH NEI EY022795).

All procedures using animal subjects have been in accordance with the standards of the Institute of Animal Care and Use Committee (IACUC) at Western Michigan University.
1. Animals
<ol>
	<li>Use male and female rats 3 months of age in this study.</li>
	<li>Keep animals in a 12 hr light/dark cycle with free access to food and water.</li>
</ol>
2. Preparation of KAX Cocktail for Animal Anesthesia
<ol>
	<li>Dissolve 50 mg of xylazine (20 mg/ml) in 5 ml ketamine (100 mg...

This protocol describes a method of inducing glaucoma-like conditions in an in vivo rat model. This procedure uses an injection of hypertonic saline to induce scarring in the trabecular meshwork 29, 32. Developing scar tissue occludes the outflow of aqueous humor which increases pressure in the anterior chamber. With decreased outflow and pressure build up, the lens suspended by elastic ligaments pushes back into the vitreous chamber. Vitreous humor then applies pressure onto the retina damaging the f...

Glaucoma is a group of eye diseases affecting neurons in the retina, specifically, the retinal ganglion cells1-2. The axons of these cells converge to become the optic nerve carrying visual information to the brain where vision is perceived. Damage to RGCs and their axons therefore causes visual defects.
The primary characteristics associated with glaucoma disorders are RGC degeneration and death, increased intraocular pressure (IOP), and optic disk cupping and atrophy. These features lead to visual field loss or complete, irreversible blindness. Currently, glaucoma has caused blindness in 70 million people worldwide 3. As such, it is the world&#39;s third largest cause of blindness 4.
The exact mechanism of RGC death in glaucoma remains unknown. Much research has been done to unlock the mystery. It is known, however, that the primary risk factor of glaucoma is an increase in intraocular pressure due to irregular circulation of aqueous humor (AH) in the anterior chamber of the eye. AH acts as a transparent and colorless replacement for blood in the avascular anterior chamber of the eye. It nourishes the surrounding cells, removes secreted waste products from metabolic processes, transports neurotransmitters, and permits the circulation of drugs and inflammatory cells within the eye during pathological states 1.
The maintenance of aqueous humor circulation involves the ciliary body and the trabecular meshwork. Aqueous humor is produced by the ciliary body. It then flows into the anterior chamber to maintain the overall health of the ocular tissue. 75 - 80% of aqueous humor outflow is actively secreted through non-pigmentary ciliary epithelium when the fluid is filtered through three layers of spongy tissue in the ciliary muscle. The fluid exits through the trabecular meshwork and through Schlemm&#39;s Canal which empties into the blood system 5.The remaining 20 - 25% of outflow bypasses the trabecular meshwork and is passively secreted by ultrafiltration and diffusion through the uveo-scleral pathway. This pathway appears to be relatively independent of intraocular pressure 1.
When aqueous humor production and outflow are out of balance, pressure builds within the eye. As stated, this increase in intraocular pressure is the primary risk factor in the development of glaucoma. Such pressure causes damage to the intricate layers of neurons in the retina at the back of the eye. Damage to the retinal ganglion cell axons of the optic nerve causes the brain to no longer receive accurate visual information. As a result, the perception of vision is lost and complete blindness can occur.
To date, there is no cure for glaucoma. Different treatment methods exist that primarily aim to reduce intraocular pressure. These include topical medication classes such as beta1-adrenergic receptor blockers, or topical prostaglandin analogues. Beta blockers reduce the intraocular pressure by decreasing the production of aqueous humor 7. Prostaglandins function to reduce IOP by increasing the outflow of aqueous humor 8-14. Alpha adrenergic agonists and carbonic anhydrase inhibitors are also used as secondary methods of treatment. Alpha adrenergic agonists increase outflow through the uveoscleral pathway 15-17. Carbonic anhydrase inhibitors reduce the production of AH by enzymatic inhibition 18. Much more invasive procedures are also being used to treat glaucoma. Laser trabeculoplasty is used to increase the outflow of aqueous humor 19. Another surgical therapy, called trabeculectomy, creates an alternative drainage site to filter AH when the traditional trabecular pathway is blocked 20-21.
These treatment options have been known to effectively reduce IOP. However, up to 40% of glaucoma patients show normal IOP levels indicating a need for more complete therapeutic methods.22,23 Additionally, retinal ganglion cell death seen in glaucoma is irreversible once it begins and current treatments do not stop the progression of the disease 24-28. This has highlighted the need for effective neuroprotective therapies that target the survival of the neurons themselves. Development of glaucoma models is crucial for this development.
In this study we are demonstrating a method of inducing glaucoma-like effects in adult Long Evans rats using a modified procedure originally outlined by Morrison29. In this procedure, injections of 2 M hypertonic saline into the episcleral venous plexus induces glaucoma-like conditions by scarring tissue to reduce aqueous humor outflow in the trabecular meshwork leading to an increase in intraocular pressure and a significant loss of RGCs within one month of the procedure 30-31. Glaucoma-inducing procedures, such as the one described here, may be the key to unlocking new developments in glaucoma treatments.

<table border="0" cellpadding="0" cellspacing="0" width="982">
	<tbody>
		<tr height="20">
			<td height="20" style="height:21px;width:299px;">Xylazine hydrochloride, Minimum 99%</td>
			<td style="width:156px;">Sigma, Life Science</td>
			<td style="width:200px;">X1251-1G</td>
			<td style="width:327px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Ketamine hydrochloride injection, USP, 100mg/mL&#160;</td>
			<td>Putney, Inc</td>
			<td>NDC 26637-411-01</td>
			<td>10 mL bottle</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Acepromazine Maleate, 10mg/mL</td>
			<td>Phoenix Pharmaceutical, Inc</td>
			<td>NDC 57319-447-04, 670008L-03-0408</td>
			<td>50 mL bottle</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Serum bottle, 10 mL</td>
			<td>VWR</td>
			<td>16171319</td>
			<td>Borosilicate glass</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">1 mL insulin syringe&#160;</td>
			<td>VWR</td>
			<td>BD329410</td>
			<td>28 gauge needle&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Sodium chloride</td>
			<td>Sigma&#160;</td>
			<td>S7653</td>
			<td>2 M Solution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Microelectrode Puller&#160;</td>
			<td>Narishige Group</td>
			<td>PP-830</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Heavy Polished Standard and Thin Walled Borosilicate Tubing&#160;</td>
			<td>Sutter Instruments</td>
			<td>B150-86-10HP</td>
			<td>without filament, 0.86 mm</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Microfil syringe needle for filling micropipettes</td>
			<td>World Precision Instruments, Inc</td>
			<td>MF28G</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">18 gauge Luer-Lock needle</td>
			<td>Fisher Scientific</td>
			<td>1130421</td>
			<td>Syringe needle</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Flexible Polyethylene Tubing</td>
			<td>Fisher Scientific</td>
			<td>22046941</td>
			<td>0.034 inch diameter, approximately 10 inches&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Proparacaine Hydrochloride Opthalmic Solution, USP, 0.5%</td>
			<td>Akorn, Inc</td>
			<td>NDC 17478-263-12</td>
			<td>15 mL&#160; sterile bottle&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Curved Scissors</td>
			<td>Fine Science Tools</td>
			<td>14061-11</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Microscope</td>
			<td>Leica&#160;</td>
			<td>StereoZoom 4</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Hemostat Clamp&#160;</td>
			<td>Fine Science Tools</td>
			<td>1310912</td>
			<td>curved edge</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Triple Antibiotic Ointment&#160;</td>
			<td>Fisher Scientific</td>
			<td>NC0664481</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Scalpel handle</td>
			<td>Fine Science Tools&#160;</td>
			<td>10004-13</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Scalpel blade # 11</td>
			<td>Fine Science Tools&#160;</td>
			<td>10011-00</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">60 mm x 15 mm Disposable Petri Dish</td>
			<td>VWR</td>
			<td>351007</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Phosphate Buffered Saline 10x Concentrate</td>
			<td>Sigma, Life Science&#160;</td>
			<td>P7059-1L</td>
			<td>1x dilution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Spring Scissors</td>
			<td>Fine Science Tools&#160;</td>
			<td>15009-08</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Forceps (2), Dumont # 5</td>
			<td>Fine Science Tools</td>
			<td>11251-30</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">3 mL Transfer Pipets, polyethylene, non sterile</td>
			<td>BD Biosciences</td>
			<td>357524 or 52947-948</td>
			<td>1 and 2 mL graduations</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">35 mm x 10 mm Easy Grip Petri Dish&#160;</td>
			<td>BD Biosciences</td>
			<td>351008</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Sylgard 184</td>
			<td>VWR</td>
			<td>102092-312</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Cactus Needles</td>
			<td>N/A</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Paraformaldehyde</td>
			<td>EMD Millipore&#160;</td>
			<td>PX0055-3 or 818715.0100</td>
			<td>Made into a 4% solution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Triton X-100</td>
			<td>Sigma&#160;</td>
			<td>T9284-100 mL</td>
			<td>Made into both a 1% and 0.1% solution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Fetal Bovine Serum&#160;</td>
			<td>Atlanta Biological</td>
			<td>S11150</td>
			<td>500 ml</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Purified Mouse Anti-Rat CD90/mouse CD90.1</td>
			<td>BD Pharmingen</td>
			<td>Cat 554892</td>
			<td>1:300 dilution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Alexa Fluor 594 goat anti-mouse&#160;</td>
			<td>Life Technologies&#160;</td>
			<td>A11005</td>
			<td>1:300 dilution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Microscope Slides</td>
			<td>Corning&#160;</td>
			<td>2948-75x25</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Glycerol&#160;</td>
			<td>Sigma&#160;</td>
			<td>G5516-100 mL&#160;</td>
			<td>50% glycerol to 50% PBS, by weight&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Coverglass&#160;</td>
			<td>Corning&#160;</td>
			<td>2975-225</td>
			<td>Thickness 1 22 x 50 mm&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;">Confocal Microscope</td>
			<td>Nikon&#160;</td>
			<td>C2 Eclipse Ti</td>
			<td></td>
		</tr>
	</tbody>
</table>

glaucoma-inducing procedure in an in vivo rat model and whole-mount retina preparation

Glaucoma is a disease of the central nervous system affecting retinal ganglion cells (RGCs). RGC axons making up the optic nerve carry visual input to the brain for visual perception. Damage to RGCs and their axons leads to vision loss and/or blindness. Although the specific cause of glaucoma is unknown, the primary risk factor for the disease is an elevated intraocular pressure. Glaucoma-inducing procedures in animal models are a valuable tool to researchers studying the mechanism of RGC death. Such information can lead to the development of effective neuroprotective treatments that could aid in the prevention of vision loss. The protocol in this paper describes a method of inducing glaucoma - like conditions in an in vivo rat model where 50 &#181;l of 2 M hypertonic saline is injected into the episcleral venous plexus. Blanching of the vessels indicates successful injection. This procedure causes loss of RGCs to simulate glaucoma. One month following injection, animals are sacrificed and eyes are removed. Next, the cornea, lens, and vitreous are removed to make an eyecup. The retina is then peeled from the back of the eye and pinned onto sylgard dishes using cactus needles. At this point, neurons in the retina can be stained for analysis. Results from this lab show that approximately 25% of RGCs are lost within one month of the procedure when compared to internal controls. This procedure allows for quantitative analysis of retinal ganglion cell death in an in vivo rat glaucoma model.

This section illustrates the apparatus components and procedure used to induce glaucoma-like conditions in an in vivo rat glaucoma model. We show the individual tools and equipment used to perform a hypertonic saline injection which causes an increase in intraocular pressure. We show the injection into the episcleral venous plexus with its characteristic blanching effect and the cloudy appearance of the anterior chamber that results. We also describe the process of retina removal...

Watch this Scientific Journal Video about Glaucoma-inducing Procedure in an In Vivo Rat Model and Whole-mount Retina Preparation at JoVE.com

Glaucoma-inducing Procedure in an In Vivo Rat Model and Whole-mount Retina Preparation

Glaucoma is characterized by damage to retinal ganglion cells. Inducing glaucoma in animal models can provide insight into the study of this disease. Here, we outline a procedure that induces loss of RGCs in an in vivo rat model and demonstrates the preparation of whole-mount retinas for analysis.

Glaucoma-inducing Procedure in an In Vivo Rat Model and Whole-mount Retina Preparation

Glaucoma is a disease of the central nervous system affecting retinal ganglion cells (RGCs). RGC axons making up the optic nerve carry visual input to the ...

The overall goal of this procedure is to create significant loss of retinal ganglion cells in the rat retina by inducing glaucoma-like conditions. This method can help answer key questions in the fields of glaucoma and neural protection. The main advantage of this technique is that it causes a gradual loss of retinal ganglion cells, similar to that seen in human glaucoma.To begin this procedure, pull two finely-tapered glass microneedles from a heavy polished standard thin-walled Borosilicate Tube with a microelectrode puller. Then, backfill one microneedle with two molar saline, using a one milliliter syringe. Tap out the air bubbles from the tip of the electrode.Next, fill a second one milliliter syringe with two molar NaCl. Connect it to an 18 gauge needle, and then attach the needle to 10-inch polyethylene tubing. Use the syringe plunger to fill the polyethylene tubing with saline through the needle.When both the microneedle and tubing are filled with saline, carefully connect the two. Eliminate any air in the connection by tapping out the air bubbles. Then, scrape the microneedle tip lightly against a paper towel to finely bevel it.Check the resistance of the microneedle by gently pushing the plunger on the syringe until a fine stream of liquid can be seen on the paper towel. The stream of liquid should be no wider than 0.5 millimeters to ensure the appropriate integrity of the needle tip. In this procedure, after anesthetizing the animal with KAX cocktail, check the reflexes by giving pinches to its feet or tail to ensure the animal is unconscious.Then, trim the whiskers with scissors. Subsequently, saturate a cotton tip applicator with betadine solution and swab the area around the experimental eye. Under the microscope, use a hemostat to clamp the bottom eyelid, in order to bulge the eye, expose the episcleral vein, and restrict the eye movement.Next, carefully pierce the episcleral vein with the microneedle at an angle between 10 and 20 degrees to the vein. A puncture into the vein is successful when the blood is observed to enter the tip of the microneedle. Slowly inject 50 microliters of saline into the vein.The veins with blanch white as the salt circulates through the vasculature, but some regions may maintain a blood-red appearance. The single most critical step in this procedure occurs during the injection of the two molar saline. It is imperative that blanching in the vasculature occurs to ensure a successful outcome.Maintaining a steady needle and a 20 degree angle are crucial for this procedure. After that, perform a second injection into the vein to ensure thorough damage of the retinal ganglion cell layer. Within minutes, one should see a distinct cloudy appearance through the iris of the eye, as the salt circulates through the vascular system.Now, use a scalpel to cut the connective tissue in the orbital cavity surrounding the eye, being careful not to cut into the eyeball itself. Then, carefully cut the optic nerve and any remaining tissue to extract the intact eyeball with the curved-edge scissors. Place the extracted eyeball in a sterile petri dish containing fresh PBS.Next, make an eye cup from the eyeball by making a small incision with the scalpel just posterior to the border between the iris and the sclera. Continue the incision around the eye circumference to remove the corneal hemisphere from the eyeball. Holding the pigmented layer of the retina with forceps to stabilize the eye cup, use another pair of forceps to gently tease the pinkish-beige whole intact retina off from the back of the eye.Subsequently, cut or pinch off the area where the optic nerve is attached to the retina. Be sure to cut away any residual pigment epithelium or scleral tissue from the retina. Then, gently transfer the isolated retina to a clean Sylgard-coated petri dish containing fresh PBS.Once in the Sylgard dish, pin the retina in place. Keep the retinal ganglion cell layer facing up, and the optic nerve down. Next, cut the retina into four quadrants, making the shape of a four-leaf clover, radiating from the optic nerve head.Then, pin the quadrants of the retina with additional cactus needles to make the retina as flat as possible without stretching. Afterward, fix the pinned retina in the Sylgard dish with three milliliters of 4%paraformaldehyde over night at room temperature before conducting the standard staining procedures. Here is a comparison of the control untreated eye and the experimental eye, one month after receiving glaucoma-inducing saline injection.The retinal ganglion cells are labeled with an antibody against Thy 1.1. The procedure leads to a reduction in the number of RGCs, defasciculation of the axons off the main axon bundles, and distortion to the circularity of the remaining RGCs. These are the characteristic defasciculating axons resulting from the saline injection.A blood vessel is shown within the retina, and these are the axon bundles. Once mastered, this technique can be done in 30 minutes, if it is performed properly. While attempting this procedure, it's important to remember to always use a fresh, sharp, beveled microneedle.Following this procedure, other methods like immunocytochemistry, Western Blots, in situ hybridization, mRNA sequencing, or behavioral analysis can be performed in order to answer additional questions associated with glaucoma, such as how the loss of retinal ganglion cells affects animals'visual acuity. After its development, this technique paved the way for researchers in the field of glaucoma to explore neural protective strategies in rats. After watching this video, you should have a good understanding of how to induce a significant loss of retinal ganglion cells in the rat, using a hypertonic saline injection to the episcleral vein.

glaucoma-inducing-procedure-an-vivo-rat-model-whole-mount-retina

Research

JoVE Journal

Medicine

Multi-modal Imaging of Angiogenesis in a Nude Rat Model of Breast Cancer Bone Metastasis Using Magnetic Resonance Imaging, Volumetric Computed Tomography and Ultrasound

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell proliferation in the bone marrow cavity as well as for interaction of tumor and bone cells resulting in local bone destruction. Our aim was to develop a model of experimental bone metastasis that allows in vivo assessment of angiogenesis in skeletal lesions using non-invasive imaging techniques.
For this purpose, we injected 105 MDA-MB-231 human breast cancer cells into the superficial epigastric artery, which precludes the growth of metastases in body areas other than the respective hind leg1. Following 25-30 days after tumor cell inoculation, site-specific bone metastases develop, restricted to the distal femur, proximal tibia and proximal fibula1. Morphological and functional aspects of angiogenesis can be investigated longitudinally in bone metastases using magnetic resonance imaging (MRI), volumetric computed tomography (VCT) and ultrasound (US).
MRI displays morphologic information on the soft tissue part of bone metastases that is initially confined to the bone marrow cavity and subsequently exceeds cortical bone while progressing. Using dynamic contrast-enhanced MRI (DCE-MRI) functional data including regional blood volume, perfusion and vessel permeability can be obtained and quantified2-4. Bone destruction is captured in high resolution using morphological VCT imaging. Complementary to MRI findings, osteolytic lesions can be located adjacent to sites of intramedullary tumor growth. After contrast agent application, VCT angiography reveals the macrovessel architecture in bone metastases in high resolution, and DCE-VCT enables insight in the microcirculation of these lesions5,6. US is applicable to assess morphological and functional features from skeletal lesions due to local osteolysis of cortical bone. Using B-mode and Doppler techniques, structure and perfusion of the soft tissue metastases can be evaluated, respectively. DCE-US allows for real-time imaging of vascularization in bone metastases after injection of microbubbles7.
In conclusion, in a model of site-specific breast cancer bone metastases multi-modal imaging techniques including MRI, VCT and US offer complementary information on morphology and functional parameters of angiogenesis in these skeletal lesions.

In the pathogenesis of bone metastasis, angiogenesis is a crucial process and therefore represents a target for imaging and therapy. Here, we present a rat model of site-specific breast cancer bone metastasis and describe strategies to non-invasively image angiogenesis in vivo using magnetic resonance imaging, volumetric computed tomography and ultrasound.

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell ...

Retinal Detachment Model in Rodents by Subretinal Injection of Sodium Hyaluronate

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the occurrence of subretinal hemorrhage can affect photoreceptor cell death in the detached retina. Hence, it is advantageous to create reproducible RDs without subretinal hemorrhage for evaluating photoreceptor cell death. We modified a previously reported method to create bullous and persistent RDs in a reproducible location with rare occurrence of subretinal hemorrhage. The critical step of this modified method is the creation of a self-sealing scleral incision, which can prevent leakage of sodium hyaluronate after injection into the subretinal space. To make the self-sealing scleral incision, a scleral tunnel is created, followed by scleral penetration into the choroid with a 30 G needle. Although choroidal hemorrhage may occur during this step, astriction with a surgical spear reduces the rate of choroidal hemorrhage. This method allows a more reproducible and reliable model of photoreceptor death in diseases that involve RD such as rhegmatogenous RD, retinopathy of prematurity, diabetic retinopathy, central serous chorioretinopathy, and age-related macular degeneration (AMD).

Creating experimental retinal detachments with a reproducible and sustained height of detachment, and without subretinal hemorrhage, is important for studying the pathophysiology of photoreceptor cell loss in retinal disease and evaluating potential therapeutic interventions. Here, we report such a method in detail.

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the ...

In vivo 19F MRI for Cell Tracking

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing. The technique is applicable to various cell types and animal models, although here we focus on a typical mouse model for tracking murine immune cells. The most important issues for cell labeling are described, as these are relevant to all models. Similarly, key imaging parameters are listed, although the details will vary depending on the MRI system and the individual setup. Finally, we include an image processing protocol for quantification. Variations for this, and other parts of the protocol, are assessed in the Discussion section. Based on the detailed procedure described here, the user will need to adapt the protocol for each specific cell type, cell label, animal model, and imaging setup. Note that the protocol can also be adapted for human use, as long as clinical restrictions are met.

In vivo 19F MRI for Cell Tracking

We describe a general protocol for in vivo cell tracking using MRI in a mouse model with ex vivo labeled cells. A typical protocol for cell labeling, image acquisition processing and quantification is included.

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. ...

Slow-release Drug Delivery through Elvax 40W to the Rat Retina: Implications for the Treatment of Chronic Conditions

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these diseases. Chronic retinal diseases such as retinal oedema or neovascularization usually require multiple intraocular injections to effectively treat the condition. However, the risks associated with these injections increase with repeated delivery of the drug. Therefore, alternative delivery methods need to be established in order to minimize the risks of reinjection. Several other investigations have developed methods to deliver drugs over extended time, through materials capable of releasing chemicals slowly into the eye. In this investigation, we outline the use of Elvax 40W, a copolymer resin, to act as a vehicle for drug delivery to the adult rat retina. The resin is made and loaded with the drug. The drug-resin complex is then implanted into the vitreous cavity, where it will slowly release the drug over time. This method was tested using 2-amino-4-phosphonobutyrate (APB), a glutamate analogue that blocks the light response of the retina. It was demonstrated that the APB was slowly released from the resin, and was able to block the retinal response by 7 days after implantation. This indicates that slow-release drug delivery using this copolymer resin is effective for treating the retina, and could be used therapeutically with further testing.

This paper details how Elvax 40W can be used as a slow-release method for drug delivery to the adult rat retina. The protocol for preparing, loading, and delivering the drug-resin complex to the eye is described.

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic patient tumors in different assays1. Human tumor xenografts represent the gold standard with respect to tumor biology, drug discovery, and metastasis research 2-4. Tumor xenografts can be derived from different types of material like tumor cell lines, tumor tissue from primary patient tumors4 or serially transplanted tumors. When propagated in vivo, xenografted tissue is infiltrated and vascularized by cells of mouse origin. Multiple factors such as the tumor entity, the origin of xenografted material, growth rate and region of transplantation influence the composition and the amount of mouse cells present in tumor xenografts. However, even when these factors are kept constant, the degree of mouse cell contamination is highly variable.
Contaminating mouse cells significantly impair downstream analyses of human tumor xenografts. As mouse fibroblasts show high plating efficacies and proliferation rates, they tend to overgrow cultures of human tumor cells, especially slowly proliferating subpopulations. Mouse cell derived DNA, mRNA, and protein components can bias downstream gene expression analysis, next-generation sequencing, as well as proteome analysis 5. To overcome these limitations, we have developed a fast and easy method to isolate untouched human tumor cells from xenografted tumor tissue. This procedure is based on the comprehensive depletion of cells of mouse origin by combining automated tissue dissociation with the benchtop tissue dissociator and magnetic cell sorting. Here, we demonstrate that human target cells can be can be obtained with purities higher than 96% within less than 20 min independent of the tumor type.

Human tumor xenografts are vascularized and infiltrated by cells of mouse origin during the growth phase in vivo. To circumvent the bias caused by these contaminating cells during downstream analysis, we developed a method allowing for comprehensive depletion of all mouse cells by magnetic cell sorting.

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...

Re-Arterialized Rat Partial Liver Transplantation with an in vivo Vessel-Oriented 70% Hepatectomy

Split liver transplantation and living liver donor liver transplantation were developed in the clinic to utilize liver organs in a more efficient manner. To better understand the mechanism behind these surgical procedures, a rat partial liver transplantation (PLTx) model was established for relevant surgical studies. Because of the complexity of the rat PLTx model, a protocol with detailed descriptions is required. An article published previously reported a protocol in which ex vivo hepatectomy was used to achieve 50% rat PLTx. In contrast to this protocol, we introduced a re-arterialized PLTx with an in vivo 70% hepatectomy. An updated vessel-oriented hepatectomy was incorporated into the rat PLTx to refine the microsurgical procedure. The portal veins and hepatic arteries of the left lateral lobe and the median lobe were individually dissected and ligated before removal of the liver parenchyma, thereby decreasing the probability of bleeding in the remnant liver stump. Furthermore, an end-to-side vessel anastomosis between the common hepatic artery and the enlarged proper hepatic artery was introduced to re-arterialize the hepatic artery. By using this end-to-side vessel anastomosis technique, the diameter of the anastomosis was enlarged, thereby decreasing the difficulty of hand suture and maintaining a high rate of anastomotic patency. Moreover, the cuff anastomosis of the infrahepatic vena cava was slightly modified. A section of circumferential liver parenchyma around the vena cava of a recipient was preserved during cuff anastomosis to maintain the three-dimensional shape of the vascular lumen. This section of liver parenchyma was removed after completing the anastomosis. With this modification, the step involving placement of stay sutures was omitted, thereby further shortening the cuff anastomosis time. By using this protocol of rat PLTx, a low liver enzyme level, an intact liver lobular architecture and a high survival rate were achieved after microsurgery.

Re-Arterialized Rat Partial Liver Transplantation with an in vivo Vessel-Oriented 70% Hepatectomy

Here, a protocol involving re-arterialized rat partial liver transplantation is presented. Specifically, 70% liver was resected in vivo by using an updated technique of vessel-oriented hepatectomy. The hepatic artery was reconstructed in an end-to-side manner. The cuff technique was modified to shorten the anastomosis time of the infrahepatic vena cava.

Split liver transplantation and living liver donor liver transplantation were developed in the clinic to utilize liver organs in a more efficient manner. ...

An Ex Vivo Tissue Culture Model for Fibrovascular Complications in Proliferative Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and one of the leading causes of blindness in working-age adults. No current animal models of diabetes and oxygen-induced retinopathy develop the full-range progressive changes manifested in human proliferative diabetic retinopathy (PDR). Therefore, understanding of the disease pathogenesis and pathophysiology has relied largely on the use of histological sections and vitreous samples in approaches that only provide steady-state information on the involved pathogenic factors. Increasing evidence indicates that dynamic cell-cell and cell-extracellular matrix (ECM) interactions in the context of three-dimensional (3D) microenvironments are essential for the mechanistic and functional studies towards the development of new treatment strategies. Therefore, we hypothesized that the pathological fibrovascular tissue surgically excised from eyes with PDR could be utilized to reliably unravel the cellular and molecular mechanisms of this devastating disease and to test the potential for novel clinical interventions. Towards this end, we developed a novel method for 3D ex vivo culture of surgically-excised patient-derived fibrovascular tissue (FT), which will serve as a relevant model of human PDR pathophysiology. The FTs are dissected into explants and embedded in fibrin matrix for ex vivo culture and 3D characterization. Whole-mount immunofluorescence of the native FTs and end-point cultures allows thorough investigation of tissue composition and multicellular processes, highlighting the importance of 3D tissue-level characterization for uncovering relevant features of PDR pathophysiology. This model will allow the simultaneous assessment of molecular mechanisms, cellular/tissue processes and treatment responses in the complex context of dynamic biochemical and physical interactions within the PDR tissue architecture and microenvironment. Since this model recapitulates PDR pathophysiology, it will also be amenable for testing or developing new treatments.

Here, we present a protocol to study the pathophysiology of proliferative diabetic retinopathy by using patient-derived, surgically-excised, fibrovascular tissues for three-dimensional native tissue characterization and ex vivo culture. This ex vivo culture model is also amenable for testing or developing new treatments.

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and one of the leading causes of blindness in working-age adults. No ...

Murine Precision-Cut Liver Slices as an Ex Vivo Model of Liver Biology

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic fatty liver disease, metabolic liver disease, and liver cancer) requires experimental manipulation of animal models and in vitro cell cultures. Both techniques have limitations, such as the requirement of large numbers of animals for in vivo manipulation. However, in vitro cell cultures do not reproduce the structure and function of the multicellular hepatic environment. The use of precision-cut liver slices is a technique in which uniform slices of viable mouse liver are maintained in laboratory tissue culture for experimental manipulation. This technique occupies an experimental niche that exists between animal studies and in vitro cell culture methods. The presented protocol describes a straightforward and reliable method to isolate and culture precision-cut liver slices from mice. As an application of this technique, ex vivo liver slices are treated with bile acids to simulate cholestatic liver injury and ultimately assess the mechanisms of hepatic fibrogenesis.

This protocol provides a simple and reliable method for the production of viable precision-cut liver slices from mice. The ex vivo tissue samples can be maintained under laboratory tissue culture conditions for multiple days, providing a flexible model to examine liver pathobiology.

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic ...

Whole-Mount Immunofluorescence Staining, Confocal Imaging and 3D Reconstruction of the Sinoatrial and Atrioventricular Node in the Mouse

The electrical signal physiologically generated by pacemaker cells in the sinoatrial node (SAN) is conducted through the conduction system, which includes the atrioventricular node (AVN), to allow excitation and contraction of the whole heart. Any dysfunction of either SAN or AVN results in arrhythmias, indicating their fundamental role in electrophysiology and arrhythmogenesis. Mouse models are widely used in arrhythmia research, but the specific investigation of SAN and AVN remains challenging.
The SAN is located at the junction of the crista terminalis with the superior vena cava and AVN is located at the apex of the triangle of Koch, formed by the orifice of the coronary sinus, the tricuspid annulus, and the tendon of Todaro. However, due to the small size, visualization by conventional histology remains challenging and it does not allow the study of SAN and AVN within their 3D environment.
Here we describe a whole-mount immunofluorescence approach that allows the local visualization of labelled mouse SAN and AVN. Whole-mount immunofluorescence staining is intended for smaller sections of tissue without the need for manual sectioning. To this purpose, the mouse heart is dissected, with unwanted tissue removed, followed by fixation, permeabilization and blocking. Cells of the conduction system within SAN and AVN are then stained with an anti-HCN4 antibody. Confocal laser scanning microscopy and image processing allow differentiation between nodal cells and working cardiomyocytes, and to clearly localize SAN and AVN. Furthermore, additional antibodies can be combined to label other cell types as well, such as nerve fibers.
Compared to conventional immunohistology, whole-mount immunofluorescence staining preserves the anatomical integrity of the cardiac conduction system, thus allowing the investigation of AVN; especially so into their anatomy and interactions with the surrounding working myocardium and non-myocyte cells.

We provide a step-by-step protocol for whole-mount immunofluorescence staining of the sinoatrial node (SAN) and atrioventricular node (AVN) in murine hearts.

The electrical signal physiologically generated by pacemaker cells in the sinoatrial node (SAN) is conducted through the conduction system, which includes ...