This work is supported by NIH grants EY024932, EY023295, and EY028106 to YH.

All procedures have been approved by the Institutional Animal Care and Use Committee (IACUC) of Stanford University.
1. Ocular hypertension induction by intracameral injection of SO
<ol>
	<li>Prepare a glass micropipette for intracameral SO injection by pulling a glass capillary with a pipette puller to generate a micropipette. Cut an opening at the tip of the micropipette and further sharpen the tip with a microgrinder-beveling machine to make a 35&#176;&#8722;40&#176; bevel.</li>
	<li>Polish the edges of the bevel and remove all debris by washing with water. Autoclave the micropipette before use.</li>
	<li>Prepare the paracentesis needle for the corneal entry. To do so, attach a 32 G needle to a 5 mL syringe on a Luer lock, and further secure it with tape. Bend the needle bevel tip face up at 30&#176;.</li>
	<li>Prepare the SO injector by attaching and securing a blunt end 18 G needle on a 10 mL syringe first. Then attach a plastic tube with the 18 G needle on one end and fill up with SO as needed through the other end.</li>
	<li>Attach the sterilized micropipette to the plastic tube and push the syringe plunger to fill the entire micropipette with SO.</li>
</ol>
2. Intracameral SO injection for one eye
<ol>
	<li>Place a 9&#8722;10-week-old male C57B6/J mouse into an induction chamber with 3% isoflurane mixed with oxygen at 2 L/min for 3 min.</li>
	<li>Intraperitoneally inject 2,2,2-tribromoethanol at 0.3 mg/g body weight. 
	NOTE: Unlike ketamine/xylazine, 2,2,2-tribromoethanol does not cause obvious pupil dilation.</li>
	<li>Check for the lack of response to a toe pinch and the lack of movement of the whiskers or the tail to determine the anesthetic strength.</li>
	<li>Place the mouse in a lateral position on a surgery platform. To reduce its sensitivity during the procedure, apply one drop of 0.5% proparacaine hydrochloride to the cornea before the injection.</li>
	<li>Make an entry incision with the 32 G paracentesis needle at the superotemporal quadrant, about 0.5 mm from the limbus.</li>
	<li>Tunnel through the layers of the cornea for about 0.3 mm before piercing into the anterior chamber. Be careful not to touch the lens or iris.</li>
	<li>Withdraw the needle slowly to release some aqueous humor (about 1&#8722;2 &#181;L) from the anterior chamber through the tunnel (paracentesis).</li>
	<li>Wait ~8 min to further decrease the IOP. This can be determined by measuring the contralateral, control eye.</li>
	<li>Insert the glass micropipette preloaded with SO through the corneal tunnel into the anterior chamber, with the bevel facing down to the iris surface.</li>
	<li>Push the syringe plunger slowly to inject SO into the anterior chamber until the SO droplet covers most of the iris surface, ~2.3&#8722;2.4 mm in diameter.</li>
	<li>Leave the micropipette in the anterior chamber for 10 s more before withdrawing it slowly.</li>
	<li>Gently push the upper eyelid to close the cornea incision to minimize SO leakage.</li>
	<li>Apply antibiotic ointment (bacitracin-neomycin-polymyxin) to the eye surface.</li>
	<li>Throughout the procedure, frequently moisten the cornea with artificial tears.</li>
	<li>Keep the mouse on the heating pad until fully recovered from anesthesia.</li>
</ol>
3. SO removal
<ol>
	<li>Prepare the irrigation system.
	<ol>
		<li>Prepare the irrigating solution according to the manufacturer&#8217;s instructions and place it in the irrigation bottle. Elevate the irrigating solution bottle to 110&#8722;120 cm (81&#8722;88 mmHg) above the surgery platform.</li>
		<li>Attach an IV administration set to the irrigating solution bottle. Remove air bubbles from the IV tubing. Connect a 33 G needle bent to 20&#176; face up to the IV tubing.</li>
	</ol>
	</li>
	<li>To prepare the drainage system, remove the plunger from a 1 mL syringe. Attach a 33 G needle to the syringe and bend the needle to 20&#176;.</li>
	<li>Remove SO from the anterior chamber.
	<ol>
		<li>Intraperitoneally inject 2,2,2-tribromoethanol (0.3 mg/g body weight). Check for the lack of response to the toe pinch to determine the anesthetic strength and the lack of movement of the whiskers or the tail.</li>
		<li>Place the mouse on a surgery platform and secure it in the lateral position with tape. Apply one drop of 0.5% proparacaine hydrochloride to the cornea to reduce its sensitivity.</li>
		<li>Make two incisions in the temporal quadrant of the cornea between ~2 and 5 o&#8217;clock at the edge of the SO droplet using the premade 32 G paracentesis needle.</li>
		<li>Insert a 33 G irrigation needle connected to irrigating solution through one corneal incision, maximum speed.</li>
		<li>Insert another 33 G drainage needle attached to the syringe without a plunger through the other corneal incision to allow the SO droplet to exit the anterior chamber while irrigating with irrigating solution.</li>
		<li>Withdraw the drainage needle, then the irrigation needle.</li>
		<li>Inject an air bubble into the anterior chamber to maintain its normal depth and press to close the corneal incision.</li>
		<li>Apply antibiotic ointment to both eyes.</li>
		<li>Keep the mouse on the heating recovery pad until fully recovered from the anesthesia.</li>
	</ol>
	</li>
</ol>
4. IOP measurement once a week
<ol>
	<li>Place the mouse into an induction chamber perfused with 3% isoflurane mixed with oxygen at 2L/min for 3 min.</li>
	<li>Intraperitoneally inject xylazine and ketamine (0.01 mg xylazine/g, 0.08 mg ketamine/g).</li>
	<li>Keep the cornea moist by applying artificial tears throughout the procedure.</li>
	<li>Wait about 15 min to allow the pupil to fully dilate.</li>
	<li>Measure the IOP of both eyes using a tonometer according to product instructions. Bring the tonometer near the mouse eye. Keep the distance from the tip of the probe to the mouse cornea at about 3&#8722;4 mm. Press the measuring button 6x to generate one reading. Three machine-generated readings are obtained from each eye to acquire the mean IOP.</li>
	<li>Sacrifice the animals at 8 weeks after SO injection and perform immunohistochemistry of whole-mount retina, RGC counting, optic nerve (ON) semi-thin sections, and quantification of surviving axons, which have been described before13.</li>
</ol>

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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+models+for+glaucoma+retinopathy+and+optic+neuropathy.">Rodent models for glaucoma retinopathy and optic neuropathy.</a> Journal of Glaucoma. 16 (5), 483-505 (2007).</li><li>Morrison, J. C., Johnson, E., Cepurna, W. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+models+for+glaucoma+research.">Rat models for glaucoma research.</a> Progress in Brain Research. 173, 285-301 (2008).</li><li>McKinnon, S. J., Schlamp, C. L., Nickells, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+retinal+ganglion+cell+death+and+glaucoma.">Mouse models of retinal ganglion cell death and glaucoma.</a> Experimental Eye Research. 88 (4), 816-824 (2009).</li><li>Chen, S., Zhang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Rodent+Model+of+Glaucoma+and+Its+Implications.">The Rodent Model of Glaucoma and Its Implications.</a> Asia Pacific Journal of Ophthalmology (Philadelphia). 4 (4), 236-241 (2015).</li><li>Sappington, R. M., Carlson, B. J., Crish, S. D., Calkins, D. 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The authors have nothing to disclose.

Here we demonstrate a simple but effective procedure for inducing sustained IOP elevation in the mouse eye by intracameral injection of SO. This procedure can be learned quickly by anyone with experience in microdissection under a microscope. The primary potential risk of failure is the leakage of SO from the corneal incision. However, one of the advantages of using SO is that because the oil droplet is visible and measurable, we can easily identify mice that received droplets too small to induce stable ocular hypertensi...

The progressive loss of retinal ganglion cells (RGCs) and their axons is the hallmark of glaucoma, a common neurodegenerative disease in the retina1. It will affect more than 100 million individuals 40&#8722;80 years old by 20402. IOP remains the only modifiable risk factor in the development and progression of glaucoma. In order to explore the pathogenesis, progression, and potential treatments of glaucoma, a reliable, reproducible, and inducible experimental ocular hypertension/glaucoma model that replicates key features of human patients is imperative.
IOP depends on aqueous humor inflow to the anterior chamber from the ciliary body in the posterior chamber and outflow through the trabecular meshwork (TM) at the angle of the anterior chamber. Upon reaching a steady state, IOP is maintained. When the inflow exceeds or is less than the outflow, IOP rises or falls respectively. By decreasing the aqueous outflow either by occluding the angle of the anterior chamber or by damaging the TM, several glaucoma models have been established3,4,5,6,7,8,9,10. These models are normally associated with irreversible ocular tissue damage, and the high IOP in the anterior chamber also causes unwanted complications such as corneal edema and intraocular inflammation, which make retinal imaging and visual function assays difficult to perform and interpret.
To develop a model that overcomes these shortcomings, we focused on the well-sudocumented secondary glaucoma caused by silicone oil (SO) that occurs as a postoperative complication of human vitreoretinal surgery11,12. SO is used as a tamponade in retinal surgeries because of its high surface tension. However, SO can physically occlude the pupil because it is lighter than the aqueous and vitreous fluids, which prevents aqueous flow into the anterior chamber. The obstruction causes IOP elevation in the posterior chamber due to the aqueous humor accumulation. This motivated us to develop and characterize a novel ocular hypertension mouse model based on intracameral SO injection and pupillary block13, with key features of the secondary glaucoma: effective pupillary block, significant IOP elevation that can return to normal after SO removal, and glaucomatous neurodegeneration.
Here we present a detailed protocol for SO-induced ocular hypertension in the mouse eye, including SO injection and removal and IOP measurement.

<table border="0" cellpadding="0" cellspacing="0" style="width:915px;" width="915">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">0.5% proparacaine hydrochloride</td>
			<td style="width:232px;">Akorn, Somerset</td>
			<td style="width:147px;"></td>
			<td style="width:279px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">10mL syinge</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;"></td>
			<td>Luer-Lok Tip</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:26px;">18G needle</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;"></td>
			<td>with Regular Bevel, Needle Length:25.4 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">2,2,2-Tribromoethanol (Avertin)</td>
			<td style="width:232px;">Fisher Scientific</td>
			<td style="width:147px;">CAS# 75-80-9</td>
			<td>50g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">32G nano</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;">320122</td>
			<td>BD Nano Ultra Fine Pen Needle-32G 4mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">33G ophalmology needle</td>
			<td style="width:232px;">TSK/ VWR</td>
			<td style="width:147px;">TSK3313/ 10147-200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">5mL syinge</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;"></td>
			<td>Luer-Lok Tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">AnaSed Injection (xylazine)</td>
			<td style="width:232px;">Butler Schein</td>
			<td style="width:147px;"></td>
			<td>100 mg/ml, 50 ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">artificial tears</td>
			<td style="width:232px;">Alcon Laboratories</td>
			<td style="width:147px;">300651431414</td>
			<td>Systane Ultra Lubricant Eye Drops</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">BSS PLUS Irrigating solution</td>
			<td style="width:232px;">Alcon Laboratories</td>
			<td style="width:147px;">65080050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dual-Stage Glass Micropipette Puller</td>
			<td style="width:232px;">NARISHIGE</td>
			<td style="width:147px;">PC-10</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:257px;">EZ-7000 Classic System</td>
			<td style="width:232px;">EZ system</td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">Isoflurane</td>
			<td style="width:232px;">VetOne</td>
			<td style="width:147px;">502017</td>
			<td>isoflurane, USP, 250ml/bottle</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">IV Administration sets</td>
			<td style="width:232px;">EXELint/ Fisher</td>
			<td style="width:147px;">29081</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">KETAMINE HYDROCHLORIDE INJECTION</td>
			<td style="width:232px;">VEDCO</td>
			<td style="width:147px;">50989-996-06</td>
			<td>KETAVED 100mg/ml * 10ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">microgrind bevelling machine</td>
			<td style="width:232px;">NARISHIGE</td>
			<td style="width:147px;">EG-401</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">Miniature EVA Tubing</td>
			<td style="width:232px;">McMaster-Carr</td>
			<td style="width:147px;">1883T4</td>
			<td>0.05&#34; ID, 0.09&#34; OD, 10 ft. Length</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">silicon oil (SILIKON)</td>
			<td style="width:232px;">Alcon Laboratories</td>
			<td style="width:147px;">8065601185</td>
			<td>1,000 mPa.s</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">Standard Glass Capillaries</td>
			<td style="width:232px;">WPI/ Fisher</td>
			<td style="width:147px;">1B150-4</td>
			<td>4 in. (100mm) OD 1.5mm ID 0.84mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TonoLab tonometer</td>
			<td style="width:232px;">Colonial Medical Supply, Finland</td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">veterinary antibiotic ointment</td>
			<td style="width:232px;">Dechra Veterinary</td>
			<td style="width:147px;">1223RX</td>
			<td>BNP ophthalmic ointment, Vetropolycin</td>
		</tr>
	</tbody>
</table>

a reversible silicon oil-induced ocular hypertension model in mice

Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing stable IOP elevation in mice that mimics the post-operative complication of using silicone oil (SO) as a tamponade agent in human vitreoretinal surgery. In this protocol, SO is injected into the anterior chamber of the mouse eye to block the pupil and prevent inflow of aqueous humor. The posterior chamber accumulates aqueous humor and this in turn increases the IOP of the posterior segment. A single SO injection produces reliable, sufficient, and stable IOP elevation, which induces significant glaucomatous neurodegeneration. This model is a true replicate of secondary glaucoma in the eye clinic. To further mimic the clinical setting, SO can be removed from the anterior chamber to reopen the drainage pathway and allow inflow of aqueous humor, which is drained through the trabecular meshwork (TM) at the angle of the anterior chamber. Because IOP quickly returns to normal, the model can be used to test the effect of lowering IOP on glaucomatous retinal ganglion cells. This method is straightforward, does not require special equipment or repeat procedures, closely simulates clinical situations, and may be applicable to diverse animal species. However, minor modifications may be required.

Soon after the injection we can easily identify mice that do not produce stable ocular hypertension because of the SO droplets being too small (&#8804;1.5 mm)13. These animals are excluded from subsequent experiments. Following the injection procedures, more than 80% of SO injected mice end up with droplets larger than 1.6 mm. We measured the IOP of these mouse eyes once a week for 8 weeks after a single SO injection. The IOP of the eye receiving SO remained high, generally double the IOP of the c...

Watch this Scientific Journal Video about A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice at JoVE.com

A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice

Here, we present a protocol to induce ocular hypertension and glaucomatous neurodegeneration in mouse eyes by intracameral injection of silicone oil and the procedure for silicone oil removal from the anterior chamber to return elevated intraocular pressure to normal.

Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing ...

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9.6K Views.  Stanford University School of Medicine. Here, we present a protocol to induce ocular hypertension and glaucomatous neurodegeneration in mouse eyes by intracameral injection of silicone oil and the procedure for silicone oil removal from the anterior chamber to return elevated intraocular pressure to normal.

Video: A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice

Creation of Reversible Cholestatic Rat Model

Cholestasis is a clinical condition commonly encountered by both surgeons and gastroenterologists. Cholestasis can cause various physiological changes and affect the nutritional status and surgical outcomes. Study of the pathophysiological changes occurring in the liver and other organs is of importance. Various studies have been done in cholestatic rat models.
We used a reversible cholestatic rat model in our recent study looking at the role of methylprednisolone in the ischemia reperfusion injury. Various techniques for creation of a reversible cholestatic model have been described. Creation of a reversible cholestatic rat model can be challenging in view of the smaller size and unique hepatopancreatobiliary anatomy in rats. This video article demonstrates the creation of a reversible cholestatic model.
This model can be used in various studies, such as looking at the changes in nutritional, physiological, pathological, histological and immunological changes in the gastrointestinal tract. This model can also be used to see the effects of cholestasis and various therapeutic interventions on major hepatic surgeries.

Cholestasis is a clinical condition commonly encountered by both surgeons and gastroenterologists. Creation of a reversible cholestatic rat model can be challenging in view of the smaller size and unique hepatopancreatobiliary anatomy in rats. This video article demonstrates the creation of a reversible cholestatic model.

Cholestasis is a clinical condition commonly encountered by both surgeons and gastroenterologists. Cholestasis can cause various physiological changes and ...

5/6th Nephrectomy in Combination with High Salt Diet and Nitric Oxide Synthase Inhibition to Induce Chronic Kidney Disease in the Lewis Rat

Chronic kidney disease (CKD) is a global problem. Slowing CKD progression is a major health priority. Since CKD is characterized by complex derangements of homeostasis, integrative animal models are necessary to study development and progression of CKD. To study development of CKD and novel therapeutic interventions in CKD, we use the 5/6th nephrectomy ablation model, a well known experimental model of progressive renal disease, resembling several aspects of human CKD. The gross reduction in renal mass causes progressive glomerular and tubulo-interstitial injury, loss of remnant nephrons and development of systemic and glomerular hypertension. It is also associated with progressive intrarenal capillary loss, inflammation and glomerulosclerosis. Risk factors for CKD invariably impact on endothelial function. To mimic this, we combine removal of 5/6th of renal mass with nitric oxide (NO) depletion and a high salt diet. After arrival and acclimatization, animals receive a NO synthase inhibitor (NG-nitro-L-Arginine) (L-NNA) supplemented to drinking water (20 mg/L) for a period of 4 weeks, followed by right sided uninephrectomy. One week later, a subtotal nephrectomy (SNX) is performed on the left side. After SNX, animals are allowed to recover for two days followed by LNNA in drinking water (20 mg/L) for a further period of 4 weeks. A high salt diet (6%), supplemented in ground chow (see time line Figure 1), is continued throughout the experiment. Progression of renal failure is followed over time by measuring plasma urea, systolic blood pressure and proteinuria. By six weeks after SNX, renal failure has developed. Renal function is measured using 'gold standard' inulin and para-amino hippuric acid (PAH) clearance technology. This model of CKD is characterized by a reduction in glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), hypertension (systolic blood pressure&gt;150 mmHg), proteinuria (&gt; 50 mg/24 hr) and mild uremia (&gt;10 mM). Histological features include tubulo-interstitial damage reflected by inflammation, tubular atrophy and fibrosis and focal glomerulosclerosis leading to massive reduction of healthy glomeruli within the remnant population (&lt;10%). Follow-up until 12 weeks after SNX shows further progression of CKD.

A two-stage method to establish chronic kidney disease (CKD) in the Lewis rat by surgically removing 5/6th of renal mass is described. Combination of the surgical procedure, NOS-inhibition and a high-salt diet leads to a model resembling human CKD, allowing study of causal mechanisms and development of novel therapeutic interventions.

Chronic kidney disease (CKD) is a global problem. Slowing CKD progression is a major health priority. Since CKD is characterized by complex derangements ...

A Laser-induced Mouse Model of Chronic Ocular Hypertension to Characterize Visual Defects

Glaucoma, frequently associated with elevated intraocular pressure (IOP), is one of the leading causes of blindness. We sought to establish a mouse model of ocular hypertension to mimic human high-tension glaucoma. Here laser illumination is applied to the corneal limbus to photocoagulate the aqueous outflow, inducing angle closure. The changes of IOP are monitored using a rebound tonometer before and after the laser treatment. An optomotor behavioral test is used to measure corresponding changes in visual capacity. The representative result from one mouse which developed sustained IOP elevation after laser illumination is shown. A decreased visual acuity and contrast sensitivity is observed in this ocular hypertensive mouse. Together, our study introduces a valuable model system to investigate neuronal degeneration and the underlying molecular mechanisms in glaucomatous mice.

Chronic ocular hypertension is induced using laser photocoagulation of the trabecular meshwork in mouse eyes. The intraocular pressure (IOP) is elevated for several months after laser treatment. The decrease of visual acuity and contrast sensitivity of experimental animals are monitored using the optomotor test.

Glaucoma, frequently associated with elevated intraocular pressure (IOP), is one of the leading causes of blindness. We sought to establish a mouse model ...

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction

Obstruction of the kidney may affect native or transplanted kidneys and results in kidney injury and scarring. Presented here is a model of obstructive nephropathy induced by unilateral ureteric obstruction (UUO), which can either be irreversible (UUO) or reversible (R-UUO). In the irreversible UUO model, the ureter may be obstructed for variable periods of time in order to induce increasingly severe renal inflammation and interstitial fibrotic scarring. In the reversible R-UUO model the ureter is obstructed to induce hydronephrosis, tubular dilation and inflammation. After a suitable period of time the ureteric obstruction is then surgically reversed by anastomosis of the severed previously obstructed ureter to the bladder in order to allow complete decompression of the kidney and restoration of urinary flow to the bladder. The irreversible UUO model has been used to investigate various aspects of renal inflammation and scarring including the pathogenesis of disease and the testing of potential anti-inflammatory or anti-fibrotic therapies. The more challenging model of R-UUO has been used by some investigators and does offer significant research potential as it allows the study of inflammatory and immune processes and tissue remodeling in an injured and scarred kidney following the removal of the injurious stimulus. As a result, the R-UUO model offers investigators the opportunity to explore the resolution of kidney inflammation together with key aspects of tissue repair. These experimental models are of relevance to human disease as patients often present with obstruction of the renal tract that requires decompression and are commonly left with significant residual kidney impairment that has no current treatment options and may lead to eventual end stage kidney failure.

The murine model of irreversible unilateral ureteric obstruction (UUO) is presented together with the model of reversible UUO in which the ureteric obstruction is relieved by anastomosis of the severed ureter into the bladder. These models enable the study of renal inflammation and scarring as well as tissue remodeling.

Obstruction of the kidney may affect native or transplanted kidneys and results in kidney injury and scarring. Presented here is a model of obstructive ...

A Magnetic Microbead Occlusion Model to Induce Ocular Hypertension-Dependent Glaucoma in Mice

The use of rodent models of glaucoma has been essential to understand the molecular mechanisms that underlie the pathophysiology of this multifactorial neurodegenerative disease. With the advent of numerous transgenic mouse lines, there is increasing interest in inducible murine models of ocular hypertension. Here, we present an occlusion model of glaucoma based on the injection of magnetic microbeads into the anterior chamber of the eye using a modified microneedle with a facetted bevel. The magnetic microbeads are attracted to the iridocorneal angle using a handheld magnet to block the drainage of aqueous humour from the anterior chamber. This disruption in aqueous dynamics results in a steady elevation of intraocular pressure, which subsequently leads to the loss of retinal ganglion cells, as observed in human glaucoma patients. The microbead occlusion model presented in this manuscript is simple compared to other inducible models of glaucoma and also highly effective and reproducible. Importantly, the modifications presented here minimize common issues that often arise in occlusion models. First, the use of a bevelled glass microneedle prevents backflow of microbeads and ensures that minimal damage occurs to the cornea during the injection, thus reducing injury-related effects. Second, the use of magnetic microbeads ensures the ability to attract most beads to the iridocorneal angle, effectively reducing the number of beads floating in the anterior chamber avoiding contact with other structures (e.g., iris, lens). Lastly, the use of a handheld magnet allows flexibility when handling the small mouse eye to efficiently direct the magnetic microbeads and ensure that there is little reflux of the microbeads from the eye when the microneedle is withdrawn. In summary, the microbead occlusion mouse model presented here is a powerful investigative tool to study neurodegenerative changes that occur during the onset and progression of glaucoma.

Here, we present a protocol to induce ocular hypertension in the murine eye that results in the loss of retinal ganglion cells as observed in glaucoma. Magnetic microbeads are injected into the anterior chamber and attracted to the iridocorneal angle using a magnet to block the outflow of aqueous humour.

The use of rodent models of glaucoma has been essential to understand the molecular mechanisms that underlie the pathophysiology of this multifactorial ...

A Repetitive Concussive Head Injury Model in Mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of ...

Shunt Surgery, Right Heart Catheterization, and Vascular Morphometry in a Rat Model for Flow-induced Pulmonary Arterial Hypertension

In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt (MCT+Flow). The shunt is created by inserting an 18-G needle from the abdominal aorta into the adjacent caval vein. Increased pulmonary flow has been demonstrated as an essential trigger for a severe form of PAH with distinct phases of disease progression, characterized by early medial hypertrophy followed by neointimal lesions and the progressive occlusion of the small pulmonary vessels. To measure the right heart and pulmonary hemodynamics in this model, right heart catheterization is performed by inserting a rigid cannula containing a flexible ball-tip catheter via the right jugular vein into the right ventricle. The catheter is then advanced into the main and the more distal pulmonary arteries. The histopathology of the pulmonary vasculature is assessed qualitatively, by scoring the pre- and intra-acinar vessels on the degree of muscularization and the presence of a neointima, and quantitatively, by measuring the wall thickness, the wall-lumen ratios, and the occlusion score.

This protocol describes a surgical procedure to create a model for flow-induced pulmonary arterial hypertension (PAH) in rats and the procedures to analyze the principle hemodynamic and histological end-points in this model.

In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt ...

Corneal Epithelial Abrasion with Ocular Burr As a Model for Cornea Wound Healing

The murine cornea provides an excellent model to study wound healing. The cornea is the outermost layer of the eye, and thus is the first defense to injury. In fact, the most common type of eye injury found in clinic is a corneal abrasion. Here, we utilize an ocular burr to induce an abrasion resulting in removal of the corneal epithelium in vivo on anesthetized mice. This method allows for targeted and reproducible epithelial disruption, leaving other areas intact. In addition, we describe the visualization of the abraded epithelium with fluorescein staining and provide concrete advice on how to visualize the abraded cornea. Then, we follow the timeline of wound healing 0, 18, and 72 h after abrasion, until the wound is re-epithelialized. The epithelial abrasion model of corneal injury is ideal for studies on epithelial cell proliferation, migration and re-epithelialization of the corneal layers. However, this method is not optimal to study stromal activation during wound healing, because the ocular burr does not penetrate to the stromal cell layers. This method is also suitable for clinical applications, for example, pre-clinical test of drug effectiveness.

This protocol describes a method to inflict an abrasion to the ocular surface of the mouse, and to follow the wound healing process thereafter. The protocol takes advantage of an ocular burr to partially remove the surface epithelium of the eye in anaesthetized mice.

The murine cornea provides an excellent model to study wound healing. The cornea is the outermost layer of the eye, and thus is the first defense to ...

The Left Pneumonectomy Combined with Monocrotaline or Sugen as a Model of Pulmonary Hypertension in Rats

In this protocol, we detail the correct procedural steps and necessary precautions to successfully perform a left pneumonectomy and induce PAH in rats with the additional administration of monocrotaline (MCT) or SU5416 (Sugen). We also compare these two models to other PAH models commonly used in research. In the last few years, the focus of animal PAH models has moved towards studying the mechanism of angioproliferation of plexiform lesions, in which the role of increased pulmonary blood flow is considered as an important trigger in the development of severe pulmonary vascular remodeling. One of the most promising rodent models of increased pulmonary flow is the unilateral left pneumonectomy combined with a "second hit" of MCT or Sugen. The removal of the left lung leads to increased and turbulent pulmonary blood flow and vascular remodeling. Currently, there is no detailed procedure of the pneumonectomy surgery in rats. This article details a step-by-step protocol of the pneumonectomy surgical procedure and post-operative care in male Sprague-Dawley rats. Briefly, the animal is anesthetized and the chest is opened. Once the left pulmonary artery, pulmonary vein, and bronchus are visualized, they are ligated and the left lung is removed. The chest then closed and the animal recovered. Blood is forced to circulate only on the right lung. This increased vascular pressure leads to a progressive remodeling and occlusion of small pulmonary arteries. The second hit of MCT or Sugen is used one week post-surgery to induce endothelial dysfunction. The combination of increased blood flow in the lung and endothelial dysfunction produces severe PAH. The primary limitation of this procedure is that it requires general surgical skills.

The rodent left pneumonectomy is a valuable technique in pulmonary hypertension research. Here, we present a protocol to describe the rat pneumonectomy procedure and postoperative care to ensure minimal morbidity and mortality.

In this protocol, we detail the correct procedural steps and necessary precautions to successfully perform a left pneumonectomy and induce PAH in rats ...