The present study was supported by grants from Kidney Research UK (ST4/2011), the Cunningham Trust (CT11/14), the Mrs AE Hogg Charitable Trust for Kidney Research and the Renal Endowment Fund of the Royal Infirmary of Edinburgh.

General Guidance: Animal experiments were performed in accordance with the guidelines and regulations imposed by the Animals (Scientific Procedures) Act 1986. This protocol and the accompanying video protocol are for both a standard UUO and a R-UUO, which can be performed on many mouse strains. In the accompanying video, both procedures are performed on male C57BL/6 mice aged 8 weeks. The data presented in the representative results section were obtained from male FVB/n mice.
NOTE: This protocol and accompanying video details how to perform a standard UUO and R-UUO utilizing the left ureter, however the same techniques can easily be applied to the right ureter.
1. Animal Preparation and Laparotomy
<ol>
	<li>Perform all procedures with sterile (autoclaved) instruments and consumables.</li>
	<li>Inject ketamine hydrochloride (70mg/kg) and medetomidine hydrochloride (1mg/kg) intraperitoneally to anesthetize the mouse. Note: The duration of the resulting anesthetic plane is 4 hr and no supplemental anesthesia is required.</li>
	<li>Confirm the depth of anesthesia by loss of reflexes e.g., toe pinch.</li>
	<li>Remove all hair surrounding the incision area and prepare the abdominal skin for surgery via application of a dilute chlorhexidine solution.</li>
	<li>Place the mouse on a heated surgical pad in a supine position and fix the limbs to the pad using low-tack adhesive tape.</li>
	<li>During the procedure, monitor the mouse for signs of thermal burns as a result of the heated surgical pad. If possible use a non-electric heat source.</li>
	<li>Administer analgesic by a subcutaneous injection of buprenorphine hydrochloride (0.06mg/kg) and apply eye lubricant to prevent corneal drying.</li>
	<li>Make a midline laparotomy and an incision of the avascular linea alba using tissue separating scissors to gain access to the peritoneal cavity.</li>
	<li>Drape the mouse and insert a colibri retractor into the incision.</li>
</ol>
2. Unilateral Ureteric Obstruction
<ol>
	<li>Using sterilized cotton buds expose the left ureter by displacing the intestines towards the right side of the abdominal cavity and cover them with moistened drapes.</li>
	<li>Using angled forceps isolate and lift the left ureter.</li>
	<li>To create a ureteric obstruction, ligate the left ureter twice with 6/O black braided silk suture anywhere between the bladder and renal pelvis. For long term experiments, use absorbable suture for all abdominal surgeries. Alternatively, a ligating clip can be applied to the ureter.</li>
	<li>To isolate the bladder from the ureter, divide the ureter between the two sutures.</li>
	<li>Carefully replace the intestines into the peritoneal cavity.</li>
	<li>Follow the steps listed in Section 4 &#8211; Post-Operative Recovery and Care to close the incision and reverse the anesthesia.</li>
</ol>
3. Preparation for Reversible Unilateral Ureteric Obstruction
<ol>
	<li>Prepare a mouse for surgery and isolate the left ureter as detailed in Steps 1.1 to 2.2 above.</li>
	<li>To create a ureteric obstruction that can be reversed, ligate the left ureter twice with 6/O black braided silk suture close to the bladder. Leave one end of the upper suture long as this will be used to anchor the soft walled plastic tubing in place around the ureter.</li>
	<li>Make a longitudinal slit in a 5mm length of soft walled plastic tubing such that it can be splayed open to allow it to be applied to the ureter. Any soft walled silicone plastic tubing, with an internal diameter of 1mm and external diameter of 2mm, can be used.</li>
	<li>Place the soft walled plastic tubing gently around the ureter. Ensure that the long suture emerges from the center of the slit in the tubing once it is closed around the ureter.</li>
	<li>Place a length of 6/O black braided silk suture around the soft walled tubing enclosing the ureter and tie once. Now place the long end of the suture, emerging from the center of the slit in the tubing, longitudinally across the tubing such that it lies on top of the previously tied suture.</li>
	<li>Tie the suture located around the tubing twice to anchor the tubing and the long suture end in place around the ureter. 
	Note: To prevent adhesion formation on the ureter and the soft walled plastic tubing, an adhesion reduction solution can be applied to the area around the tubing.</li>
	<li>Carefully replace the intestines into the peritoneal cavity.</li>
</ol>
4. Post-Operative Recovery and Care
<ol>
	<li>Close the peritoneum with blanket stitch using 5/O black braided silk suture and approximate the skin using metallic skin clips.</li>
	<li>To minimize the risk of post-operative infection, apply an antiseptic such as iodine/alcohol solution to the abdominal skin.</li>
	<li>Partially reverse anesthesia with atipamezole hydrochloride (2mg/kg) subcutaneously.</li>
	<li>Administer fluids by a subcutaneous injection of 1 ml&#160;warmed saline.</li>
	<li>Monitor the mouse until it has recovered consciousness.</li>
	<li>Allow the mouse to recover in a heated box kept at 29 &#176;C for 24 hr. Moistened food can also be provided to encourage fluid and nutrition intake.</li>
	<li>Leave the mouse to recover to induce a desired level of obstruction, typically 7 days.</li>
	<li>For long-term recovery experiments, provide ongoing analgesics. If the mouse is to be recovered for longer than 7 days, remove the skin clips 7 days following surgery.</li>
	<li>Once the desired level of obstruction has been induced, either reverse the UUO, as described below, or euthanize the mouse by cervical dislocation and collect the kidneys for histopathology analysis.</li>
</ol>
5. Reversible Unilateral Ureteric Obstruction
<ol>
	<li>To perform a R-UUO prepare a mouse, which has undergone preparation for R-UUO, for surgery as described in steps 1.1 to 1.7.</li>
	<li>If present, remove the skin clips and divide or remove the sutures in the peritoneum to gain access to the abdominal cavity. Note: If the ureter has been obstructed for a long-term experiment skin clips should have been removed 7 days following application.</li>
	<li>Prepare the mouse and isolate the left ureter as described in steps 1.8 to 2.2.</li>
	<li>Using angled forceps, free the soft walled plastic tubing from any granulomatous tissue which may have formed.</li>
	<li>Cut the suture holding the plastic tubing around the obstructed ureter with a scalpel and remove the tubing.</li>
	<li>Confirm successful UUO by assessing for the presence of hydronephrosis in the left kidney, the kidney should also appear pale.</li>
	<li>Divide the ureter between the sutures.</li>
	<li>Place the remaining length of ureter, attached to the kidney, on a small piece of sterile gauze. This will be used to collect the urinary sediment and dead cells that will drain from the ureter and renal pelvis once the suture is removed.</li>
	<li>Divide the ureter above, but near, the suture and allow the kidney to drain onto the gauze. Leave the lower suture, closest to the bladder, intact. This is to ensure that no urine will leak from the bladder and into the peritoneal cavity.</li>
	<li>Once the ureter and renal pelvis have been drained, apply a long 6/O black braided silk suture to the end of the remaining length of ureter. This will be used to aid the ureter to bladder anastomosis performed later.</li>
	<li>Follow the steps below to anastomose the remaining length of ureter into the bladder:
	<ol>
		<li>Turn the ureter such that it lies anterior to its original position and lies over the kidney.</li>
		<li>Place a single 9/O polyamide monofilament tacking suture 2 mm from the end of the ureter such that it emerges in the direction of the bladder. Take care to ensure that the suture remains in the muscular coat and does not enter the ureter lumen. The tacking suture will be used to anchor the ureter in the bladder.</li>
		<li>To create a channel through the bladder, pass a 21G needle diagonally through the bladder such that it exits towards the frontal (ventral) wall of the bladder.</li>
		<li>Rest an eyed needle in the bevel of the 21G needle. Use the 21G needle to guide the eyed needle through the bladder. The eyed needle will be used to take the ureter through the bladder.</li>
		<li>Pass the 9/O tacking suture, applied to the ureter in step 5.11.2, through the first incision in the bladder and out through the bladder wall adjacent to the entry point. Once the ureter is passed through the bladder this will be tied to anchor the ureter to the bladder.</li>
		<li>Place the long 6/O black braided silk suture applied to the end of the ureter in step 5.10 through the eyed needle.</li>
		<li>Carefully withdraw the eyed needle out of the bladder whilst ensuring that the ureter is also pulled through the bladder.</li>
		<li>Once the ureter emerges from the bladder remove the eyed needle and apply a clamp to the long suture at the end of the ureter to prevent retraction back into the bladder.</li>
		<li>To anchor the ureter within place in the bladder, tie the 9/O polyamide monofilament tack suture, applied in step 5.11.5.</li>
		<li>Apply additional single 9/O polyamide monofilament tie sutures as described in steps 5.11.2 and 5.11.5 at two locations around the entry point to firmly anchor the ureter within the bladder.</li>
		<li>Using the back of opened scissors, push the bladder wall back slightly to expose more of the emergent ureter.</li>
		<li>Divide the ureter above the long suture located at the end of the ureter. The ureter should retract into the body of the bladder. It is usual to observe urine flowing out of the opening in the bladder, confirming the open lumen of the ureter.</li>
		<li>Close the exit wound in the bladder with a 9/O polyamide monofilament suture.</li>
	</ol>
	</li>
	<li>Carefully replace the intestines into the peritoneal cavity.</li>
	<li>Provide post-operative care as detailed in steps 4.1 to 4.8.</li>
	<li>Allow the mouse to recover until the kidney is decompressed, typically 7 days.</li>
	<li>At the experimental end point, euthanize the mouse by cervical dislocation and collect the kidneys for histopathological analysis.</li>
</ol>

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C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Galectin-3+expression+and+secretion+links+macrophages+to+the+promotion+of+renal+fibrosis.">Galectin-3 expression and secretion links macrophages to the promotion of renal fibrosis.</a> Am J Pathol. 172, 288-298 (2008).</li><li>Kitamoto, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+liposome+clodronate+on+renal+leukocyte+populations+and+renal+fibrosis+in+murine+obstructive+nephropathy.">Effects of liposome clodronate on renal leukocyte populations and renal fibrosis in murine obstructive nephropathy.</a> J Pharmacol Sci. 111, 285-292 (2009).</li><li>Tapmeier, T. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reimplantation+of+the+ureter+after+unilateral+ureteral+obstruction+provides+a+model+that+allows+functional+evaluation.">Reimplantation of the ureter after unilateral ureteral obstruction provides a model that allows functional evaluation.</a> Kidney Int. 73, 885-889 (2008).</li><li>Cochrane, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renal+structural+and+functional+repair+in+a+mouse+model+of+reversal+of+ureteral+obstruction.">Renal structural and functional repair in a mouse model of reversal of ureteral obstruction.</a> J Am Soc Nephrol. 16, 3623-3630 (2005).</li><li>Puri, T. 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C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postobstructive+regeneration+of+kidney+is+derailed+when+surge+in+renal+stem+cells+during+course+of+unilateral+ureteral+obstruction+is+halted.">Postobstructive regeneration of kidney is derailed when surge in renal stem cells during course of unilateral ureteral obstruction is halted.</a> Am J Physiol Renal Physiol. 298, F357-F364 (2010).</li><li>Manson, S. R., Niederhoff, R. A., Hruska, K. A., Austin, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endogenous+BMP-7+is+a+critical+molecular+determinant+of+the+reversibility+of+obstruction-induced+renal+injuries.">Endogenous BMP-7 is a critical molecular determinant of the reversibility of obstruction-induced renal injuries.</a> Am J Physiol Renal Physiol. 301, F1293-F1302 (2011).</li><li>Manson, S. R., Niederhoff, R. A., Hruska, K. A., Austin, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+BMP-7-Smad1/5/8+pathway+promotes+kidney+repair+after+obstruction+induced+renal+injury.">The BMP-7-Smad1/5/8 pathway promotes kidney repair after obstruction induced renal injury.</a> J Urol. 185, 2523-2530 (2011).</li><li>Chaves, L. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contrasting+effects+of+systemic+monocyte/macrophage+and+CD4++T+cell+depletion+in+a+reversible+ureteral+obstruction+mouse+model+of+chronic+kidney+disease.">Contrasting effects of systemic monocyte/macrophage and CD4+ T cell depletion in a reversible ureteral obstruction mouse model of chronic kidney disease.</a> Clin Dev Immunol. 2013, 836-989 (2013).</li><li>Haque, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Longitudinal+changes+in+MRI+markers+in+a+reversible+unilateral+ureteral+obstruction+mouse+model:+preliminary+experience.">Longitudinal changes in MRI markers in a reversible unilateral ureteral obstruction mouse model: preliminary experience.</a> J Magn Reson Imaging. 39, 835-841 (2014).</li><li>Bai, Z. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterially+transplanted+mesenchymal+stem+cells+in+a+mouse+reversible+unilateral+ureteral+obstruction+model:+in+vivo+bioluminescence+imaging+and+effects+on+renal+fibrosis.">Arterially transplanted mesenchymal stem cells in a mouse reversible unilateral ureteral obstruction model: in vivo bioluminescence imaging and effects on renal fibrosis.</a> Chinese Med J. 126, 1890-1894 (2013).</li><li>Chaabane, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renal+functional+decline+and+glomerulotubular+injury+are+arrested+but+not+restored+by+release+of+unilateral+ureteral+obstruction+(UUO).">Renal functional decline and glomerulotubular injury are arrested but not restored by release of unilateral ureteral obstruction (UUO).</a> Am J Physiol Renal Physiol. 304, F432-F439 (2013).</li><li>Thornhill, B. A., Burt, L. E., Chen, C., Forbes, M. S., Chevalier, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variable+chronic+partial+ureteral+obstruction+in+the+neonatal+rat:+a+new+model+of+ureteropelvic+junction+obstruction.">Variable chronic partial ureteral obstruction in the neonatal rat: a new model of ureteropelvic junction obstruction.</a> Kidney Int. 67, 42-52 (2005).</li><li>Thornhill, B. A., Chevalier, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variable+partial+unilateral+ureteral+obstruction+and+its+release+in+the+neonatal+and+adult+mouse.">Variable partial unilateral ureteral obstruction and its release in the neonatal and adult mouse.</a> Methods Mol Biol. 886, 381-392 (2012).</li></ol>

The authors have no competing or conflicting interests to disclose.

Obstruction of the kidney may affect native or transplanted kidneys and results in kidney injury and scarring. The R-UUO model is of relevance to human disease as patients often present with obstruction of the renal tract secondary to prostatic hypertrophy, posterior urethral valves etc. that requires decompression with patients commonly left with significant residual kidney impairment that has no current treatment options and may eventually lead to end stage kidney disease.8,9 The models detailed here enable ...

The overall aim of the experimental model described here is to induce obstructive nephropathy by unilateral ureteric obstruction (UUO), which can either be irreversible (UUO) or reversible (R-UUO). A simple irreversible model of UUO is presented in which the left ureter is permanently obstructed by ligation with a suture or by the application of a ligating clip. This results in marked dilatation of the ureter together with reduced renal blood flow and glomerular filtration. Renal histology demonstrates tubular dilatation and increasingly severe interstitial renal inflammation and fibrosis. Irreversible UUO is a useful model and has been adopted by many researchers in the study of both renal inflammation and fibrosis.1-4 Although the irreversible model of UUO requires some surgical expertise it is relatively straightforward and is often used to seek insights into the pathogenesis of interstitial renal injury and the ensuing fibrosis. Also presented is a less frequently used R-UUO model using a modification of the method originally described by Tapmeier et al.5 The R-UUO model has much future potential for the study of inflammatory and immune processes, cellular and tissue regeneration as well as the subsequent tissue remodeling following the removal of an injurious stimulus. 
The more challenging R-UUO model has been used by a limited number of investigators with some groups employing a significantly different surgical technique to that described here6,7 though with interesting results. In the R-UUO model presented, the ureter is ligated to induce complete ureteric obstruction for a period of time sufficient to induce the level of injury and fibrosis desired: 7 days of UUO was chosen in the method described here. The ureteric obstruction is reversed and the kidney is allowed to decompress for a period of time determined by the investigator before the mice are culled and the kidney removed for analysis: 7 days of decompression was chosen in the method described here though a longer period would be chosen if the resolution of inflammation and fibrosis was being studied. Although the method described here requires significant surgical expertise, it offers several advantages over other R-UUO models. The application of soft walled plastic tubing to the obstructed ureter prevents excessive ureteric dilation and this facilitates the subsequent manipulation and anastomosis of the ureter. Furthermore, in the described R-UUO model the ureter is divided thereby allowing the removal of any residual urinary sediment and debris. This confirms that the remaining ureter lumen is de-obstructed and patent prior to anastomosis to the bladder. 
Experiments incorporating both the irreversible and reversible UUO models can provide researchers with a powerful insight into the molecular and cellular mechanisms of both injury and subsequent resolution and regeneration. Thus, the model of R-UUO described here would be highly relevant to researchers interested in post-inflammatory tissue remodeling and how this can be modulated.

<table><tbody><tr><td>Blunt Dissecting Scissors</td><td>Fine Science Tools</td><td>14072-10</td><td></td></tr><tr><td>Spring Scissors &amp;ndash; straight</td><td>Fine Science Tools</td><td>15000-10</td><td></td></tr><tr><td>Toothed forceps</td><td>Fine Science Tools</td><td>11021-12</td><td></td></tr><tr><td>Angled forceps x 2</td><td>Fine Science Tools</td><td>00649-11</td><td></td></tr><tr><td>Straight forceps</td><td>Fine Science Tools</td><td>00632-11</td><td></td></tr><tr><td>Colibri 3 cm wire retractor</td><td>Fine Science Tools</td><td>17000-03</td><td></td></tr><tr><td>Castroviejo needle holder with lock</td><td>Fine Science Tools</td><td>12565-14</td><td></td></tr><tr><td>Wound clip applicator</td><td>Fine Science Tools</td><td>12031-07</td><td></td></tr><tr><td>7 mm wound clips</td><td>Fine Science Tools</td><td>12032-07</td><td></td></tr><tr><td>Castroviejo micro needle holder with lock</td><td>Fine Science Tools</td><td>12060-01</td><td></td></tr><tr><td>OPMI pico microscope</td><td>Carl Zeiss</td><td>S100</td><td></td></tr><tr><td>Heat electronic pad</td><td>Cozee Comfort</td><td>n/a</td><td></td></tr><tr><td>6/O silk braided suture</td><td>Harvard Apparatus</td><td>72-3287</td><td></td></tr><tr><td>9/O Dafilon (polyamide) suture</td><td>B-Braun</td><td>G1111434</td><td></td></tr><tr><td>5/O braided silk suture</td><td>Harvard Apparatus</td><td>51-7680</td><td></td></tr><tr><td>Regular bevel needle, 1 inch, 21G</td><td>Becton, Dickinson and Company</td><td>305175</td><td></td></tr><tr><td>1 ml syringe slip tip</td><td>Becton, Dickinson and Company</td><td>300184</td><td></td></tr><tr><td>Wypall paper swabs</td><td>Kimberley-Clark</td><td>L40</td><td>Sterilised (Autoclave)</td></tr><tr><td>Cotton wool buds</td><td>Johnson and Johnson</td><td>n/a</td><td>Sterilised (Autoclave)</td></tr><tr><td>Plain drapes</td><td>Guardian</td><td>CB03</td><td>Sterilised (Autoclave)</td></tr><tr><td>Soft wall silicone rubber tubing</td><td></td><td></td><td>Silicone tubing - internal diameter 1.0 mm; external diameter 2.0 mm; wall thickness 0.6 mm</td></tr><tr><td>(Lacri-Lube) White soft paraffin 57.3%, mineral oil 42.5% and lanolin alcohols 0.2%</td><td>Allergan Ltd</td><td>21956GB10X</td><td></td></tr><tr><td>(Videne) Povidone-iodine 10%</td><td>Ecolab Ltd</td><td>PL 04509/0041</td><td></td></tr><tr><td>(Vetalar V) Ketamine hydrochloride</td><td>Pfizer Animal Health</td><td>Vm 42058/4165</td><td>100mg/ml solution</td></tr><tr><td>(Domitor) Medetomidine hydrochloride</td><td>Orion Pharma</td><td>Vm 06043/4003</td><td>1mg/ml</td></tr><tr><td>(Vetergesic) Bupernorphine hydrochloride</td><td>Alsto Animal Health</td><td>Vm 00063/4002</td><td>0.3mg/ml</td></tr><tr><td>(Antisedan) Atipamezole hydrochoride</td><td>Orion Pharma</td><td>Vm 06043/4004</td><td>5mg/ml</td></tr><tr><td>(Adept) 4% Icodextrin</td><td>Baxter</td><td></td><td>Adhesion reduction solution</td></tr><tr><td>NaCl 0.9%</td><td>Baxter</td><td>FKE1323</td><td></td></tr></tbody></table>

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 appearance of the kidney changes markedly following ureteric obstruction and it becomes paler and tense to palpation with time (Figure 1). There is increasing dilatation of the ureter proximal to the obstruction and the renal pelvis. The kidney becomes increasingly atrophic as the duration of obstructive nephropathy increases with prolonged obstruction resulting in a marked thinning of the renal cortex and medulla. Following the reversal of the ureteric obstruction, the colour of the kidney becomes d...

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A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction

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 ...

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Medicine

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Video: A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction

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 ...

A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of spinal cord injury (SCI) in which the thoracic spinal cord is injured. Additionally, because most human cord injuries occur as the result of blunt, non-penetrating trauma (e.g. motor vehicle accident, sporting injury) where the spinal cord is violently struck by displaced bone or soft tissues, the majority of SCI researchers are of the opinion that the most clinically relevant injury models are those in which the spinal cord is rapidly contused.1 Therefore, an important step in the preclinical evaluation of novel treatments on their way to human translation is an assessment of their efficacy in a model of contusion SCI within the cervical spinal cord. Here, we describe the technical aspects and resultant anatomical and behavioral outcomes of an unilateral contusive model of cervical SCI that employs the Infinite Horizon spinal cord injury impactor.
Sprague Dawley rats underwent a left-sided unilateral laminectomy at C5. To optimize the reproducibility of the biomechanical, functional, and histological outcomes of the injury model, we contused the spinal cords using an impact force of 150 kdyn, an impact trajectory of 22.5&deg; (animals rotated at 22.5&deg;), and an impact location off of midline of 1.4 mm. Functional recovery was assessed using the cylinder rearing test, horizontal ladder test, grooming test and modified Montoya's staircase test for up to 6 weeks, after which the spinal cords were evaluated histologically for white and grey matter sparing.
The injury model presented here imparts consistent and reproducible biomechanical forces to the spinal cord, an important feature of any experimental SCI model. This results in discrete histological damage to the lateral half of the spinal cord which is largely contained to the ipsilateral side of injury. The injury is well tolerated by the animals, but does result in functional deficits of the forelimb that are significant and sustained in the weeks following injury. The cervical unilateral injury model presented here may be a resource to researchers who wish to evaluate potentially promising therapies prior to human translation.

A reliable and repeatable way to produce a cervical unilateral spinal cord injury using the Infinite Horizon impactor is described. The method takes advantage of a custom designed frame and clamp to stabilize the spine. The standardized procedure and biomechanical injury parameters result in sufficient and sustained injuries.

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of ...

A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion

Surgical trauma by thoracotomy in open-chest models of coronary ligation induces an immune response which modifies different mechanisms involved in ischemia and reperfusion. Immune response includes cytokine expression and release or secretion of endogenous ligands of innate immune receptors. Activation of innate immunity can potentially modulate infarct size. We have modified an existing murine closed-chest model using hanging weights which could be useful for studying myocardial pre- and postconditioning and the role of innate immunity in myocardial ischemia and reperfusion. This model allows animals to recover from surgical trauma before onset of myocardial ischemia.
Volatile anesthetics have been intensely studied and their preconditioning effect for the ischemic heart is well known. However, this protective effect precludes its use in open chest models of coronary artery ligation. Thus, another advantage could be the use of the well controllable volatile anesthetics for instrumentation in a chronic closed-chest model, since their preconditioning effect lasts up to 72 hours. Chronic heart diseases with intermittent ischemia and multiple hit models are other possible applications of this model.
For the chronic closed-chest model, intubated and ventilated mice undergo a lateral blunt thoracotomy via the 4th intercostal space. Following identification of the left anterior descending a ligature is passed underneath the vessel and both suture ends are threaded through an occluder. Then, both suture ends are passed through the chest wall, knotted to form a loop and left in the subcutaneous tissue. After chest closure and recovery for 5 days, mice are anesthetized again, chest skin is reopened and hanging weights are hooked up to the loop under ECG control.
At the end of the ischemia/reperfusion protocol, hearts can be stained with TTC for infarct size assessment or undergo perfusion fixation to allow morphometric studies in addition to histology and immunohistochemistry.

Surgical trauma induces an inflammatory response. Cytokines and endogenous ligands are known to modulate myocardial infarct size following ischemia and reperfusion. We present a modified closed-chest model of murine ischemia and reperfusion using hanging weights to minimize effects of thoracotomy.

Surgical trauma by thoracotomy in open-chest models of coronary ligation induces an immune response which modifies different mechanisms involved in ...

Quantitative Real-Time PCR Evaluation of microRNA Expressions in Mouse Kidney with Unilateral Ureteral Obstruction

MicroRNAs (miRNAs) are single stranded, non-coding RNA molecules that typically regulate gene expression at the post-transcriptional level by binding to partially complementary target sites in the 3&#39; untranslated region (UTR) of messenger RNA (mRNA), which reduces the mRNA&#39;s translation and stability. The miRNA expression profiles in various organs and tissues of mice have been investigated, but standard methods for the purification and quantification of miRNA in mouse kidney have not been available. We have established an effective and reliable method for extracting and evaluating miRNA expression in mouse kidney with renal interstitial fibrosis by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The protocol required five steps: (1) creation of sham and unilateral ureteral obstruction (UUO) mice; (2) extraction of kidney samples from the UUO mice; (3) extraction of total RNA, which includes miRNA, from the kidney samples; (4) complementary DNA (cDNA) synthesis with reverse transcription from miRNA; and (5) qRT-PCR using the cDNA. Using this protocol, we successfully confirmed that compared to the controls, the expression of miRNA-3070-3p was significantly increased and those of miRNA-7218-5p and miRNA-7219-5p were significantly decreased in the kidneys of a mouse model of renal interstitial fibrosis. This protocol can be used to determine the miRNA expression in the kidneys of mice with UUO.

We describe a method for evaluating the microRNA expression in the kidneys of mice with unilateral ureteral obstruction (UUO) by quantitative reverse-transcription polymerase chain reaction. This protocol is suitable for studying kidney microRNA expression profiles in mice with UUO and in the context of other pathological conditions.

MicroRNAs (miRNAs) are single stranded, non-coding RNA molecules that typically regulate gene expression at the post-transcriptional level by binding to ...

Genetics

Nerve-sparing Mid-urethral Obstruction (NeMO) in Female Small Rodents

Partial bladder outlet obstruction (pBOO) has a high prevalence, causes significant patient burden, and immense health care costs. The most common animal model to investigate bladder remodeling in pBOO are female rodents undergoing partial obstruction at the proximal urethra. Variability in the degree of obstruction and animal mortality are major concerns with proximal obstruction. Furthermore, dissecting around the proximal urethra and bladder neck jeopardizes bladder innervation.
We developed a nerve-sparing mid-urethral obstruction (NeMO) model for pBOO avoiding the disadvantages of the traditional model. We approached the urethra just inferior to the pubic symphysis, which obviated the need for laparotomy as well as for dissection in this area; also, the striated urethral sphincter remained untouched. We performed NeMO in female Sprague-Dawley rats (12 obstructions, 6 sham animals) as well as in female C57/bl6 mice (20 obstructions, 18 sham animals). After two weeks, we evaluated bladder function, bladder mass, and body mass.
We had no mortalities among obstructed- or sham-operated female rats; as described for the traditional proximal pBOO-method, we tied the suture around the proximal urethra and a temporarily placed 0.9 mm metal rod. NeMO induced an 85% increase in bladder mass after two weeks, average residual urine volume was 0.4 mL in partially obstructed rats while only 0.03 mL in sham animals. In mice, we tested 3 sizes of cannulas that we placed along the urethra when tying the suture. We found that using a 27-gauge cannula resulted in over 50% animal mortality; placing the 25-gauge cannula did not yield the desired response in increasing bladder mass; utilizing a 26-gauge cannula yielded favorable results with minimal animal mortality (1/8) yet a significant 2-fold increase in bladder mass.

Nerve-sparing Mid-urethral Obstruction NeMO in Female Small Rodents

Traditional modeling of partial bladder outlet obstruction in rodents is fraught with animal mortality. A denervation injury from dissection around the proximal urethra and bladder neck is also of major concern. We developed and evaluated a safe and reliable mid-urethral obstruction model, avoiding the shortcomings of the traditional model.

Partial bladder outlet obstruction (pBOO) has a high prevalence, causes significant patient burden, and immense health care costs. The most common animal ...

Detrusor Underactivity Model in Rats by Conus Medullaris Transection

The goal of the presented protocol was to establish a detrusor underactivity (DU) model in the rat through conus medullaris transection. Laminectomy was performed in a total of 40 female Wistar rats (control group: 10 rats; test group: 30 rats) weighing 200&#8211;220 g, and the conus medullaris was transected at the L4&#8210;L5 level in the test group. All the rats were housed and fed under the same environmental conditions for six weeks. In the test group, urine voiding was performed twice daily for six weeks, and mean residual urine volume was recorded. A cystometrogram was performed in both groups. Maximum cystometric capacity (MCC), detrusor opening pressure (DOP), and compliance of the bladder were recorded and calculated. The test group showed significant urinary retention after the surgery, both during and after the spinal shock. However, no abnormality was observed in the control group. When compared to the control group, the MCC and compliance of bladder in the test group was significantly higher than that of the test group (3.24 &#177; 2.261 mL versus 1.04 &#177; 0.571 mL; 0.43 &#177; 0.578 mL/cmH2O versus 0.032 &#177; 0.016 mL/cmH2O), whereas DOP in the test group was lower than control (20.28 &#177; 14.022 cmH2O versus 35 &#177; 13.258 cmH2O). This method of establishing an animal model of DU by the conus medullaris transection offers an excellent opportunity to understand DU&#8217;s pathophysiology in a better manner.

We present a method for establishing a detrusor underactivity model by conus medullaris transection in rats. Detrusor underactivity was successfully stimulated in these animals. The model can be used for studying urinary tract function.

The goal of the presented protocol was to establish a detrusor underactivity (DU) model in the rat through conus medullaris transection. Laminectomy was ...

Neuroscience

Using 2-Photon Microscopy to Quantify the Effects of Chronic Unilateral Ureteral Obstruction on Glomerular Processes

Applying novel microscopy methods to suitable animal disease models to explore the dynamic physiology of the kidney remains a challenge. Rats with surface glomeruli provide a unique opportunity to investigate physiological and pathophysiological processes using intravital 2-photon microscopy. Quantification of glomerular capillary blood flow and vasoconstriction and dilatation in response to drugs, permeability, and inflammation are just some of the processes that can be studied. In addition, transgenic rats, i.e., podocytes labeled with fluorescent dyes and other molecular biomarker approaches, provide increased resolution to directly monitor and quantify protein-protein interactions and the effects of specific molecular alterations.
In mice, which lack surface glomeruli after four weeks of age, unilateral ureteral obstruction (UUO) for several weeks has been used to induce surface glomeruli. As this induction model does not allow for baseline studies, we quantified the effects of UUO on glomerular processes in the UUO model in Munich Wistar Fr&#246;mter (MWF) rats, which have surface glomeruli under physiologic conditions. The UUO model for five weeks or more induced significant alterations to gross renal morphology, the peritubular and glomerular microvasculature, as well as the structure and function of tubular epithelia. Glomerular and peritubular red blood cell (RBC) flow decreased significantly (p &#60; 0.01), probably due to the significant increase in the adherence of white blood cells (WBCs) within glomerular and peritubular capillaries. The glomerular sieving coefficient of albumin increased from 0.015 &#177; 0.002 in untreated MWFs to 0.045 &#177; 0.05 in 5-week-old UUO MWF rats. Twelve weeks of UUO resulted in further increases in surface glomerular density and glomerular sieving coefficient (GSC) for albumin. Fluorescent albumin filtered across the glomeruli was not reabsorbed by the proximal tubules. These data suggest that using UUO to induce surface glomeruli limits the ability to study and interpret normal glomerular processes and disease alterations.

Here, we present a protocol using 2-photon microscopy in Munich Wistar Fromter rats with surface glomeruli to quantifythe effects of prolonged ureteral obstruction on glomerular dynamics and function.

Applying novel microscopy methods to suitable animal disease models to explore the dynamic physiology of the kidney remains a challenge. Rats with surface ...

An Immature Murine Model of Reversible Unilateral Ureteral Obstruction

Unilateral ureteral obstruction (UUO) is a common cause of chronic kidney disease (CKD), leading to the progression of renal interstitial fibrosis and ultimately resulting in irreversible kidney damage. The alleviation of UUO is crucial. Several animal models of reversible unilateral ureteral obstruction (RUUO) have been established in the literature, enabling the observation of structural changes and functional damage while also simulating physiological and pathophysiological changes following the relief of ureteral obstruction. In this study, a reversible obstruction model was established in the unilateral murine ureter using a silicone tube. Significant renal damage was observed prior to obstruction relief, with partial recovery noted afterward. Unlike UUO, this model prevents progressive hydronephrosis, leading to distinct pathological outcomes. This simple surgical procedure demonstrates a high success rate and holds promise as a classical model for investigating reversible obstructive nephropathy and potential treatments for renal interstitial fibrosis. Furthermore, it provides a practical platform for studying the mechanisms of recovery from obstructive nephropathy, renal cell regeneration, and tissue remodeling.

The present protocol describes a step-by-step, reproducible model of unilateral ureteral obstruction.

Unilateral ureteral obstruction (UUO) is a common cause of chronic kidney disease (CKD), leading to the progression of renal interstitial fibrosis and ...

Unilateral Ureteral Obstruction Model for Investigating Kidney Interstitial Fibrosis

Kidney fibrosis is the final pathological outcome of progressive chronic kidney disease (CKD). The unilateral ureteral obstruction (UUO) model is widely used to elucidate the molecular and cellular mechanisms underlying kidney interstitial fibrosis and to identify potential therapeutic targets. This model is established in mice through surgical ligation of a unilateral ureter, a procedure that is relatively straightforward and easy to perform. However, the UUO mouse model is known to exhibit significant variability and inconsistency, influenced by factors such as mouse strain, age, sex, anesthesia type, duration of surgery, body temperature during the procedure, the operator's surgical skills, feeding conditions, and the overall health status of the mice. Variations in surgical techniques, suture placement, and the duration of obstruction contribute to the variability in outcomes. Additionally, inconsistent sampling of obstructed kidneys further increases variability in the assessment of kidney fibrosis. This study outlines the process of developing the UUO mouse model and evaluating interstitial fibrosis, discusses the technical challenges contributing to the model's unpredictability, and proposes potential solutions. These insights aim to establish a more standardized and universally applicable approach for investigating kidney fibrosis.

This protocol describes a method for inducing unilateral ureteral obstruction (UUO) in mice to study the progression of tissue fibrosis in obstructive nephropathy. It includes surgical procedures, post-operative care, and methods for fibrosis assessment.

Kidney fibrosis is the final pathological outcome of progressive chronic kidney disease (CKD). The unilateral ureteral obstruction (UUO) model is widely ...

Unilateral Ureteral Obstruction Murine Model: A Surgical Procedure to Obstruct the Urinary Flow from a Kidney in Mouse Models

Source: Yanai, K. et al. <a href="https://www.jove.com/video/61383" target="_blank">Quantitative real-time PCR evaluation of microRNA expressions in mouse kidney with unilateral ureteral obstruction.</a> J. Vis. Exp. (2020)
This video demonstrates the procedure to generate a unilateral ureteral obstruction mouse model. The procedure involves cutting one of the ureters of the mouse to obstruct urine flow.

Source: Yanai, K. et al. Quantitative real-time PCR evaluation of microRNA expressions in mouse kidney with unilateral ureteral obstruction. J. Vis. Exp. ...