This study was supported by a grant from the German Research Foundation (DFG, AR 1092/2-1).

All methods were conducted according to the National Institutes of Health Guide for the Care and Use of Laboratory Animals and the German law for the welfare of animals, and they were approved by local authorities (Regierungspr&#228;sidium T&#252;bingen).
1. Induction of Experimental Nephrotic Syndrome by Doxorubicin Injection to the Retrobulbar Sinus
<ol>
	<li>Prepare a 0.5 mL syringe with a mounted 30G cannula by marking the stop position of the piston.</li>
	<li>Calculate injection volume of doxorubicin for male (7.25 &#181;L/g body weight (bw) equal to 14.5 &#181;g/g bw doxorubicin) and female mice (6.9 &#181;L/g bw equal to 13.8 &#181;g/g bw doxorubicin) according to the body weight from the morning. 
	NOTE: The given dose is appropriate for induction of nephrotic syndrome. Minor changes in dosage lead to a crucial different course of nephropathy reaching from mild chronic kidney disease with only small changes in glomerular filtration rate (12.6 &#181;g/g bw doxorubicin) to acute kidney failure (15.4 &#181;g/g bw doxorubicin)7,15.</li>
	<li>Warm the calculated amount of doxorubicin solution (2 &#181;g/&#181;L) in a 37 &#176;C warm chamber. 
	Caution: Doxorubicin is harmful if swallowed and can cause cancer. Always wear gloves if working with doxorubicin and avoid any skin contact.</li>
	<li>Prefill the syringe with doxorubicin solution until the marking point and set the balance to zero. Fill the syringe with the injection volume and check the volume by weighing the syringe.</li>
	<li>Narcotize the mouse deeply with 5 vol% isoflurane using a vaporizer and oxygen flow of 2 L/min.
	<ol>
		<li>Do not use ointment on the eyes prior to the injection. The operator needs a clear view of the orbital cavity for performing a safe and successful retrobulbar injection.</li>
		<li>Assess the level of anesthesia by pedal reflex and adjust anesthetic delivery if necessary before starting injection.</li>
	</ol>
	</li>
	<li>Place the mouse at a right lateral recumbency with its back facing to the operator&#39;s body and its head facing to the operator&#39;s injection hand. 
	NOTE: The procedure is described for a right-handed person, for left-handed persons performing the injection with the left hand it is easier to do the position and injection reversed right to left.</li>
	<li>Carefully protrude the mouse&#39;s left eyeball from the eye socket by applying gentle pressure to the skin, dorsal and ventral to the eye.</li>
	<li>Puncture the left retrobulbar sinus from the inner eye angle (medial palpebral commissure). Avoid any contact with the mouse&#180;s eyeball.</li>
	<li>Slightly tilt the syringe and inject entire volume in one go. Make sure that the volume is injected without any resistance and without any signs of extravasation such as exopthalmus or leakage from the injection site.</li>
	<li>Since doxorubicin is a highly toxic substance, check well-being at least once a day by using a score-sheet according to Morton and Griffiths et al.16 and pay special attention to the injection site. If any signs of extravasation like exopthalmus, impaired eyelid closure or any signs of necrosis like swelling or skin lesions occure after injection or in the following days, the mouse should be euthanized.</li>
</ol>
2. Implantation of Sustained-Release Pellets Containing Aprotinin
<ol>
	<li>Order pellets with the desired dose per day and release duration in advance. In case of aprotinin, choose a dose of 1 mg per day to be released over 10 days. 
	NOTE: In this study, the aprotinin pellets contain a dose of 10 mg.
	<ol>
		<li>Store the pellets under dry conditions and avoid any exposure to humidity.</li>
	</ol>
	</li>
	<li>Prepare required items for the surgery, including a pair of hair scissors, a pair of skin preparation scissors, a scalpel, surgical tweezers, two pairs of tissue tweezers, a needle holder, and 15 cm monofile suture non resorbable.
	<ol>
		<li>Sterilize the instruments using a heat sterilizer for 5 min at 240 &#176;C. Before using the instruments, wait for 5 min until they reach room temperature.
		<ol>
			<li>Avoid any contact of sterilized instrument tips to nonsterile surfaces.</li>
			<li>Avoid skin burn by hot instruments.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Narcotize mouse with isoflurane 5 vol% followed by 1.5 vol% using a vaporizer and oxygen flow of 2 L/min.</li>
	<li>Place the mouse in a prone position on a warming device covered with a layer of gauze to avoid thermal injuries to the mouse. Surface temperature is about 37 &#176;C.</li>
	<li>Protect the eyes with ointment.</li>
	<li>Remove the hair on the middle back in an area of about 0.5 cm2 using scissors or a hair trimmer and disinfect the hairless skin with a disinfectant suitable for skin disinfection. Remove as less hair as possible so it stays more difficult for the mouse to reach the wound and thread ends later and to keep body temperature.</li>
	<li>Incise the hairless skin with a scalpel in cranio-caudal direction in a length of about 5 mm. Prepare a left lateral pouch of about 1 cm depth in the subcutaneous connective tissue using a blunt preparation.
	<ol>
		<li>Assess the level of anesthesia by pedal reflex and adjust anesthetic delivery if necessary before starting surgery.</li>
	</ol>
	</li>
	<li>Insert one 10-day release pellet into the prepared left lateral pouch using sterile tissue tweezers. Leave the pellet at the bottom of the pouch in a planar position.
	<ol>
		<li>Avoid any contact of the pellet to fluid and humidity till placed in the prepared pouch.</li>
	</ol>
	</li>
	<li>Close the skin with 2-3 sutures. Only leave very short thread ends to make it more difficult for the mouse to open the sutures by gnawing.</li>
	<li>Place the mice individually to reduce postoperative distress and to prevent opening of the sutures by gnawing. Keep the mouse in view until it has regained sufficient consciousness after narcosis. 
	NOTE: There is no need for postoperative pain management since this intervention is well tolerated without any signs of discomfort or pain.&#160;Alternatively we recommend topical analgesics, e.g. a drop of bupivacaine on the incision prior to closure which would provide up to 8 h of analgesia.</li>
</ol>
3. Assessment for Model Induction, Signs of Nephrotic Syndrome and well-being
<ol>
	<li>Collect morning urine (08:00 am) into a reaction cup (1.5 mL) every day from the injection day by massaging the bladder.
	<ol>
		<li>Measure proteinuria by using Bradford protein assay and normalize to creatinine. 
		NOTE: For induction of nephrotic syndrome, proteinuria should reach a threshold of 120 mg/mg creatinine between day 7 and 10 after doxorubicin injection.</li>
	</ol>
	</li>
	<li>Look for the development of ascites. Check for increase of abdominal circumference or overhanging flanks.</li>
	<li>Weigh the mouse, the food pellets and the drinking bottle in the morning (08:00 am) every day.</li>
	<li>Check well-being at least once a day by using a score-sheet according to Morton and Griffiths et al.16</li>
</ol>
4. Measurement of Urinary Serine Protease with a Chromogenic Assay
<ol>
	<li>Prepare substrate working solution by adding 15 mL of sterile phosphate buffered saline (PBS) to a bottle of 25 mg of lyophilised chromogenic substrate S-2251, yielding a concentration of 2 mM. Dissolve aprotinin in PBS to obtain an aprotinin solution with a concentration of 2 mg/mL.
	<ol>
		<li>Store prepared solutions at -20 &#176;C. This significantly slows the auto-degradation of S-2251. Do not use old solutions with a strong shade of yellow.</li>
	</ol>
	</li>
	<li>Use freshly prepared or thawed substrate working solution and warm it in a 37 &#176;C heat chamber.</li>
	<li>Thaw urine samples at room temperature.
	<ol>
		<li>Prevent protease degradation by avoiding repeated thawing and freezing. Store urine samples at -20 &#176;C.</li>
	</ol>
	</li>
	<li>Use a 96 microwell plate suitable for photometric measurement. Add 3 &#181;L of undiluted urine in each of two wells and add 50 &#181;L of substrate working solution with 3 &#181;L of either PBS or aprotinin solution to the wells. Cover the plate with a plate sealer.</li>
	<li>Incubate the covered microwell plate for 60 min in a 37 &#176;C heat chamber.</li>
	<li>Measure the optical density of each well at 450 nm using a microplate reader.</li>
	<li>Take the difference between the OD without aprotinin and with aprotinin as urinary aprotinin-sensitive serine protease activity. 
	NOTE: Measurement of a paired sample with and without aprotinin increases specificity of the assay since the substrate could also be cleaved by other proteases that do not play a pathophysiological role.</li>
</ol>

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M., Metcoff, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+nephrotic+syndrome+induced+in+rats+by+aminonucleoside;+renal+lesions+and+body+electrolyte+composition.">Experimental nephrotic syndrome induced in rats by aminonucleoside; renal lesions and body electrolyte composition.</a> Proc Soc Exp Biol Med. 89 (3), 424-427 (1955).</li><li>Ichikawa, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+for+intrarenal+mechanisms+in+the+impaired+salt+excretion+of+experimental+nephrotic+syndrome.">Role for intrarenal mechanisms in the impaired salt excretion of experimental nephrotic syndrome.</a> J Clin Invest. 71, (1983).</li><li>Deschenes, G., Wittner, M., Stefano, A., Jounier, S., Doucet, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collecting+duct+is+a+site+of+sodium+retention+in+PAN+nephrosis:+a+rationale+for+amiloride+therapy.">Collecting duct is a site of sodium retention in PAN nephrosis: a rationale for amiloride therapy.</a> J Am Soc Nephrol. 12 (3), 598-601 (2001).</li><li>Lourdel, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperaldosteronemia+and+activation+of+the+epithelial+sodium+channel+are+not+required+for+sodium+retention+in+puromycin-induced+nephrosis.">Hyperaldosteronemia and activation of the epithelial sodium channel are not required for sodium retention in puromycin-induced nephrosis.</a> J Am Soc Nephrol. 16 (12), 3642-3650 (2005).</li><li>Seigneux, S., Kim, S. W., Hemmingsen, S. C., Frokiaer, J., Nielsen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+expression+but+not+targeting+of+ENaC+in+adrenalectomized+rats+with+PAN-induced+nephrotic+syndrome.">Increased expression but not targeting of ENaC in adrenalectomized rats with PAN-induced nephrotic syndrome.</a> Am J Physiol Renal Physiol. 291 (1), F208-F217 (2006).</li><li>Artunc, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum-+and+glucocorticoid-inducible+kinase+1+in+doxorubicin-induced+nephrotic+syndrome.">Serum- and glucocorticoid-inducible kinase 1 in doxorubicin-induced nephrotic syndrome.</a> Am J Physiol Renal Physiol. 295 (6), F1624-F1634 (2008).</li><li>Zheng, Z., 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=A+Mendelian+locus+on+chromosome+16+determines+susceptibility+to+doxorubicin+nephropathy+in+the+mouse.">A Mendelian locus on chromosome 16 determines susceptibility to doxorubicin nephropathy in the mouse.</a> Proc Natl Acad Sci U S A. 102 (7), 2502-2507 (2005).</li><li>Kimura, 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=Interstrain+differences+in+murine+daunomycin-induced+nephrosis.">Interstrain differences in murine daunomycin-induced nephrosis.</a> Nephron. 63 (2), 193-198 (1993).</li><li>Wang, Y., Wang, Y. P., Tay, Y. C., Harris, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progressive+adriamycin+nephropathy+in+mice:+sequence+of+histologic+and+immunohistochemical+events.">Progressive adriamycin nephropathy in mice: sequence of histologic and immunohistochemical events.</a> Kidney Int. 58 (4), 1797-1804 (2000).</li><li>Svenningsen, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmin+in+nephrotic+urine+activates+the+epithelial+sodium+channel.">Plasmin in nephrotic urine activates the epithelial sodium channel.</a> Journal of the American Society of Nephrology : JASN. 20 (2), 299-310 (2009).</li><li>Passero, C. J., Hughey, R. P., Kleyman, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+role+for+plasmin+in+sodium+homeostasis.">New role for plasmin in sodium homeostasis.</a> Curr Opin Nephrol Hypertens. 19 (1), 13-19 (2010).</li><li>Bohnert, B. N., 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=Aprotinin+prevents+proteolytic+epithelial+sodium+channel+(ENaC)+activation+and+volume+retention+in+nephrotic+syndrome.">Aprotinin prevents proteolytic epithelial sodium channel (ENaC) activation and volume retention in nephrotic syndrome.</a> Kidney Int. 93 (1), 159-172 (2018).</li><li>Pippin, J. 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=Inducible+rodent+models+of+acquired+podocyte+diseases.">Inducible rodent models of acquired podocyte diseases.</a> Am J Physiol Renal Physiol. 296 (2), F213-F229 (2009).</li><li>Bohnert, B. N., 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=Impact+of+phosphorus+restriction+and+vitamin+D-substitution+on+secondary+hyperparathyroidism+in+a+proteinuric+mouse+model.">Impact of phosphorus restriction and vitamin D-substitution on secondary hyperparathyroidism in a proteinuric mouse model.</a> Kidney Blood Press Res. 40 (2), 153-165 (2015).</li><li>Morton, D. B., Griffiths, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+on+the+recognition+of+pain,+distress+and+discomfort+in+experimental+animals+and+an+hypothesis+for+assessment.">Guidelines on the recognition of pain, distress and discomfort in experimental animals and an hypothesis for assessment.</a> Vet Rec. 116 (16), 431-436 (1985).</li><li>Beath, S. 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=Plasma+aprotinin+concentrations+during+cardiac+surgery:+full-+versus+half-dose+regimens.">Plasma aprotinin concentrations during cardiac surgery: full- versus half-dose regimens.</a> Anesth Analg. 91 (2), 257-264 (2000).</li><li>Kanter, P. 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=Preclinical+toxicology+study+of+liposome+encapsulated+doxorubicin+(TLC+D-99):+comparison+with+doxorubicin+and+empty+liposomes+in+mice+and+dogs.">Preclinical toxicology study of liposome encapsulated doxorubicin (TLC D-99): comparison with doxorubicin and empty liposomes in mice and dogs.</a> In Vivo. 7 (1), 85-95 (1993).</li><li>Ma, L. J., Fogo, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Model+of+robust+induction+of+glomerulosclerosis+in+mice:+importance+of+genetic+background.">Model of robust induction of glomerulosclerosis in mice: importance of genetic background.</a> Kidney Int. 64 (1), 350-355 (2003).</li><li>Kren, S., Hostetter, T. 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The authors have nothing to disclose.

Here, we demonstrate that doxorubicin injection via retrobulbar sinus injection induces experimental nephrotic syndrome in 129S1/SvImJ mice with proteinuria, sodium retention, hypoalbumenia and hyperlipidemia. However, there are two critical issues that have to be taken into account when using this model. Firstly, the model induction is strictly dose dependent and deviations of doxorubicin dose as small as 0.3 &#181;g/g affect the response of the mice15. When injected with a lower dose such as 14 ...

Nephrotic syndrome is characterized by heavy proteinuria, hypoalbuminemia, edema and hyperlipidemia, and can be regarded as the most extreme manifestation of proteinuric kidney disease. In rodents, experimental nephrotic syndrome can be induced by single injection of anthracyclines or puromycin which leads to podocyte damage and resembles human minimal change disease and focal segmental glomerulosclerosis (FSGS)1. After its first description in 1955 by Frenk et al.2, puromycin nucleoside nephrosis (PAN) in rats has become a standard model to investigate the pathophysiology of nephrotic syndrome in numerous studies3,4,5,6. In mice, the corresponding model can be induced by the anthracycline doxorubicin7. However, there is a strong strain-dependency that is genetically determined by at least two genetic loci8. In addition, there are differences in the proteinuric response and course of the nephrotic syndrome9,10. Using 129S1/SvImJ mice and rapid intravenous injection of doxorubicin via the retrobulbar sinus, proteinuria responses reach values that are sufficient to induce the typical features of nephrotic syndrome, particularly volume retention characterized by ascites and nearly sodium-free urine7. Sodium retention in experimental nephrotic syndrome has been presumed to be the result of activation of the epithelial sodium channel (ENaC) in the distal tubule by aberrantly filtered serine proteases such as plasmin causing proteolysis of its &#947;-subunit4,11,12. Recently, this concept was proven in nephrotic mice which were protected from proteolytic ENaC activation and sodium retention by treatment with the serine protease inhibitor aprotinin that was equally effective as the ENaC blocker amiloride13. To ensure continuous delivery to the distal tubule, aprotinin was administered via subcutaneously implanted sustained release pellets. Future studies are required to identify the serine proteases that are responsible for proteolytic ENaC activation in nephrotic syndrome which is thought to parallel the human situation. For this purpose, doxorubicin-induced nephrotic syndrome is a valuable model that can be used in wild-type mice or expanded to genetically engineered mice. Its advantages include low cost of the drug, lower complexity of management and good reproducibility14.
In this article, we demonstrate the induction of experimental nephrotic syndrome by rapid intravenous injection of doxorubicin to the retrobulbar sinus and implantation of sustained-release pellets containing aprotinin to inhibit urinary serine protease activity as measured with a chromogenic assay.

<table><tbody><tr><td>&lt;strong&gt;supplies&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>BD Micro FINE + U-40 (0.30 mm x 8 mm)</td><td>BD Deutschland GmbH, Heidelberg, Germany</td><td>PZN: 07468060</td><td>syring</td></tr><tr><td>ETHILON*II (5/0, 16 mm, 3/8c, 45 cm)</td><td>Johnson&amp;amp;Johnson Medical GmbH, Ethicon Deutschland, Norderstedt, Germany)</td><td>EH7823H</td><td>suture</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;reagents&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>aprotinin (6000 KIU/mg)</td><td>LOXO, Heidelberg, Germany</td><td>CAS 9087-70-1</td><td></td></tr><tr><td>Bepanthen, Augen- und Nasensalbe</td><td>Bayer Vital GmbH, Leverkusen, Germany</td><td>PZN: 1578681</td><td>ointment</td></tr><tr><td>Chromogenix S-2251</td><td>HAEMOCHROM DIAGNOSTICA GmbH, Essen, Germany</td><td>82 0332 39</td><td>chromogenic substrate</td></tr><tr><td>doxorubicin (2.0 &amp;micro;g/&amp;micro;L)</td><td>Cell Pharm, Bad Vilbel, Germany</td><td>CAS 25316-40-9</td><td>doxorubicin</td></tr><tr><td>isofluran CP (1 mL/mL)</td><td>CP-Pharma, Burgdorf, Germany</td><td>CAS 26675-46-7</td><td>isofluran</td></tr><tr><td>pellets with matrix-driven sustained release (custom-made)</td><td>Innovative Research of America, Sarasota, FL</td><td>X-999</td><td>pellet</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>ELx808 Absorbance Mikroplate Reader</td><td>BioTek, Bad Friedrichshall, Germany</td><td>ELx808</td><td>microplate reader</td></tr><tr><td>MICROSTERIL - 436</td><td>B.M.S., Trescore Balneario, Italy</td><td>GAL/436</td><td>sterilizer</td></tr><tr><td>Hybridization oven/shaker</td><td>GE Healthcare UK Limited, Amersham LIFE SCIENCE, Little Chalfont, UK</td><td>RPN 2511</td><td>heat chamber</td></tr><tr><td>Thermo MAT Pro 10 W, 15x25 cm, Lucky Reptile</td><td>Import Export Peter Hoch GmbH, Waldkirch, Germany</td><td>61201</td><td>mouse warming device</td></tr></tbody></table>

induction of nephrotic syndrome in mice by retrobulbar injection of doxorubicin and prevention of volume retention by sustained release aprotinin

Nephrotic syndrome is the most extreme manifestation of proteinuric kidney disease and characterized by heavy proteinuria, hypoalbuminemia, and edema due to sodium retention and hyperlipidemia. To study the pathophysiology of this syndrome, rodent models have been developed based on the injection of toxic substances such as doxorubicin causing podocyte damage. In mice, only few strains are susceptible to this model. In wildtype 129S1/SvImJ mice, the administration of doxorubicin by rapid intravenous injection to the retrobulbar sinus induces experimental nephrotic syndrome that features all the symptoms of human disease including sodium retention and edema. After the onset of proteinuria, mice exhibit increased urinary serine protease activity that leads to the activation of the epithelial sodium channel (ENaC) and sodium retention. Pharmacological inhibition of urinary serine proteases by the treatment with sustained release aprotinin abrogates ENaC activation and prevents sodium retention. This model is ideal to study the pathophysiology of proteasuria, i.e., the excretion of active serine proteases that cause ENaC activation by the proteolysis of its &#947;-subunit. This can be regarded as the primary mechanism of ENaC activation and sodium retention in proteinuric kidney disease.

After the induction of isoflurane narcosis, doxorubicin was rapidly injected via the left retrobulbar sinus. The entire volume of 7.25 &#181;L/g bw was injected without any resistance and extravasation proving correct intravenous location of the cannula. The mouse recovered from narcosis rapidly and had no impairment on that day and thereafter. Particularly, there was no sign of damage at the left eye. After doxorubicin injection, food and fluid intake dropped over the first 3 days due to...

Watch this Scientific Journal Video about Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin at JoVE.com

Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin

Here, we describe the induction of experimental nephrotic syndrome in 129S1/SvImJ mice by rapid retrobulbar injection of doxorubicin. We also treat nephrotic mice with sustained release pellets containing aprotinin to inhibit urinary serine protease activity and prevent sodium retention.

Nephrotic syndrome is the most extreme manifestation of proteinuric kidney disease and characterized by heavy proteinuria, hypoalbuminemia, and edema due ...

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Medicine

8.3K Views.  University Hospital Tübingen. Hier beschrijven we de inductie van experimentele nefrotisch syndroom bij 129S1/SvImJ muizen door snelle retrobulbaire injectie van Doxorubicine. Wij behandelen ook nefrotisch muizen met aanhoudende release pellets met aprotinin remmen urine serine protease-activiteit te voorkomen retentie van natrium.

Video: Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin

Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often unreported mortality rates that may confound analyses. Bilateral renal pedicle clamping is commonly used to induce IR-AKI, but differences between effective clamp pressures and/or renal responses to ischemia between kidneys often lead to more variable results. In addition, shorter clamp times are known to induce more variable tubular injury, and while mice undergoing bilateral injury with longer clamp times develop more consistent tubular injury, they often die within the first 3 days after injury due to severe renal insufficiency. To improve post-injury survival and obtain more consistent and predictable results, we have developed two models of unilateral ischemia-reperfusion injury followed by contralateral nephrectomy. Both surgeries are performed using a dorsal approach, reducing surgical stress resulting from ventral laparotomy, commonly used for mouse IR-AKI surgeries. For induction of moderate injury BALB/c mice undergo unilateral clamping of the renal pedicle for 26 min and also undergo simultaneous contralateral nephrectomy. Using this approach, 50-60% of mice develop moderate AKI 24 hr after injury but 90-100% of mice survive. To induce more severe AKI, BALB/c mice undergo renal pedicle clamping for 30 min followed by contralateral nephrectomy 8 days after injury. This allows functional assessment of renal recovery after injury with 90-100% survival. Early post-injury tubular damage as well as post injury fibrosis are highly consistent using this model.

We describe models of moderate and severe ischemia-reperfusion-induced kidney injury in which the mice undergo unilateral renal pedicle clamping followed by simultaneous or delayed contralateral nephrectomy, respectively. These models consistently give rise to renal dysfunction and post-injury fibrosis, but injury severity and survival are dependent on mouse background, age and surgical equipment.

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often ...

Effective Systemic Delivery in Mice Using Retrobulbar Injection Technique

Systemic Treatment for Postnatal, Juvenile, and Runted Adult Mice by Retrobulbar Sinus Injection

While tail vein injections are frequently used as a systemic route of delivery in adult mice, retrobulbar injections are an alternative method for systemic delivery with fewer limitations. First, tail vein injections (TVIs) are limited to adult mice where the size of the tail vein is suitable for access. Being restricted to treating adult mice can be problematic when dealing with mouse models that do not survive to adulthood. Second, TVIs are not feasible for mouse models with growth retardation phenotypes where the mice never achieve the size of adult wildtype mice. Therefore, retrobulbar injections can be successfully used to treat both young and small adult mice. Lastly, retrobulbar injections are performed under anesthesia, which is less stressful on the mice than TVIs that are commonly performed without anesthesia. This article presents a protocol and detailed instructions for retrobulbar injections that can be used for systemic delivery to small and young mice.

This article provides a protocol and an accompanying video for the retrobulbar sinus injection of up to a total volume of 150 &#181;L for postnatal, juvenile, and runted adult mice. This procedure is particularly well suited for the injection of small mice (15 g) when tail vein injection is not feasible.

While tail vein injections are frequently used as a systemic route of delivery in adult mice, retrobulbar injections are an alternative method for ...

Genetics

Assessment of Kidney Function in Mouse Models of Glomerular Disease

The use of murine models to mimic human kidney disease is becoming increasingly common. Our research is focused on the assessment of glomerular function in diabetic nephropathy and podocyte-specific VEGF-A knock-out mice; therefore, this protocol describes the full kidney work-up used in our lab to assess these mouse models of glomerular disease, enabling a vast amount of information regarding kidney and glomerular function to be obtained from a single mouse. In comparison to alternative methods presented in the literature to assess glomerular function, the use of the method outlined in this paper enables the glomerular phenotype to be fully evaluated from multiple aspects. By using this method, the researcher can determine the kidney phenotype of the model and assess the mechanism as to why the phenotype develops. This vital information on the mechanism of disease is required when examining potential therapeutic avenues in these models. The methods allow for detailed functional assessment of the glomerular filtration barrier through measurement of the urinary albumin creatinine ratio and individual glomerular water permeability, as well as both structural and ultra-structural examination using the Periodic Acid Schiff stain and electron microscopy. Furthermore, analysis of the genes dysregulated at the mRNA and protein level enables mechanistic analysis of glomerular function. This protocol outlines the generic but adaptable methods that can be applied to all mouse models of glomerular disease.

This protocol describes a full kidney work-up that should be carried out in mouse models of glomerular disease. The methods allow for detailed functional, structural, and mechanistic analysis of glomerular function, which can be applied to all mouse models of glomerular disease.

The use of murine models to mimic human kidney disease is becoming increasingly common. Our research is focused on the assessment of glomerular function ...

Delivery of Exogenous Artificially Synthesized miRNA Mimic to the Kidney Using Polyethylenimine Nanoparticles in Several Kidney Disease Mouse Models

microRNAs&#160;(miRNAs), small noncoding RNAs (21-25 bases) that are not translated into proteins, inhibit lots of target messenger RNAs (mRNAs) by destabilizing and inhibiting their translation in various kidney diseases. Therefore, alternation of miRNA expression by exogenous artificially synthesized miRNA mimics is a potentially useful treatment option for inhibiting the development of many kidney diseases. However, because serum RNAase immediately degrades systematically administered exogenous miRNA mimics in vivo, delivery of miRNA to the kidney remains a challenge. Therefore, vectors that can protect exogenous miRNA mimics from degradation by RNAase and significantly deliver them to the kidney are necessary. Many studies have used viral vectors to deliver exogenous miRNA mimics or inhibitors to the kidney. However, viral vectors may cause an interferon response and/or genetic instability. Therefore, the development of viral vectors is also a hurdle for the clinical use of exogenous miRNA mimics or inhibitors. To overcome these concerns regarding viral vectors, we developed a nonviral vector method to deliver miRNA mimics to the kidney using tail vein injection of polyethylenimine nanoparticles (PEI-NPs), which led to significant overexpression of target miRNAs in several mouse models of kidney disease.

Here, we deliver exogenous artificially synthesized miRNA mimics to the kidney via tail vein injection of a nonviral vector and polyethylenimine nanoparticles in several kidney disease mouse models. This led to significant overexpression of target miRNA in the kidney, resulting in inhibited progression of kidney disease in several mouse models.

microRNAs&#160;(miRNAs), small noncoding RNAs (21-25 bases) that are not translated into proteins, inhibit lots of target messenger RNAs (mRNAs) by ...

Improved Renal Denervation Mitigated Hypertension Induced by Angiotensin II Infusion

The benefits of renal sympathetic denervation (RDN) on blood pressure have been proved in a large number of clinical trials in recent years. However, the regulatory mechanism of RDN on hypertension remains elusive. Thus, it&#39;s essential to establish a simpler RDN model in mice. In this study, osmotic mini pumps filled with Angiotensin II were implanted in 14-week-old C57BL/6 mice. One week after the implantation of the mini-osmotic pump, a modified RDN procedure was performed on bilateral renal arteries of the mice using phenol. Age-sex-matched mice were given saline and served as sham group. Blood pressure was measured at baseline and every week subsequently for 21 days. Then, renal artery, abdominal aorta and heart were collected for histological examination using H&#38;E and Masson staining. In this study, we present a simple, practical, repeatable, and standardized RDN model, which can control hypertension and alleviate cardiac hypertrophy. The technique can denervate peripheral renal sympathetic nerves without renal artery damage. Compared to previous models, the modified RDN facilitates the study of the pathobiology and pathophysiology of hypertension.

Here, we present a protocol for renal sympathetic denervation (RDN) in mice with hypertension induced by Angiotensin II infusion. The procedure is repeatable, convenient and allows to study the regulatory mechanisms of RDN on hypertension and cardiac hypertrophy.

The benefits of renal sympathetic denervation (RDN) on blood pressure have been proved in a large number of clinical trials in recent years. However, the ...

A Murine Model of Hemodialysis Access-Related Hand Dysfunction

Chronic kidney disease is a major public health problem, and the prevalence of end-stage renal disease (ESRD) requiring chronic renal replacement therapies such as hemodialysis continues to increase. Autogenous arteriovenous fistula (AVF) placement remains a primary vascular access option for ESRD patients. Unfortunately, approximately half of the hemodialysis patients experience dialysis access-related hand dysfunction (ARHD), ranging from subtle paresthesia to digital gangrene. Notably, the underlying biologic drivers responsible for ARHD are poorly understood, and no adequate animal model exists to elucidate the mechanisms and/or develop novel therapeutics for the prevention/treatment of ARHD. Herein, we describe a new mouse model in which an AVF is created between the left common iliac artery and vein, thereby facilitating the assessment of limb pathophysiology. The microsurgery includes vessel isolation, longitudinal venotomy, creation of arteriovenous anastomosis, and venous reconstruction. Sham surgeries include all the critical steps except for AVF creation. Iliac AVF placement results in clinically relevant alterations in central hemodynamics, peripheral ischemia, and impairments in hindlimb neuromotor performance. This novel preclinical AVF model provides a useful platform that recapitulates common neuromotor perturbations reported by hemodialysis patients, allowing researchers to investigate the mechanisms of ARHD pathophysiology and test potential therapeutics.

This protocol details the surgical steps of murine common iliac arteriovenous fistula creation. We developed this model to study hemodialysis access-related limb pathophysiology.

Chronic kidney disease is a major public health problem, and the prevalence of end-stage renal disease (ESRD) requiring chronic renal replacement ...

Drug Treatment by Central Venous Catheter in a Mouse Model of Angiotensin II Induced Abdominal Aortic Aneurysm and Monitoring by 3D Ultrasound

Since pharmaceutical treatment options are lacking in the clinical management of abdominal aortic aneurysm (AAA), animal models, in particular mouse models, are applied to advance the understanding of the disease pathogenesis and to identify potential therapeutic targets. Testing novel drug candidates to block AAA growth in these models generally requires repeated drug administration during the time course of the experiment. Here, we describe a compiled protocol for AAA induction, insertion of an intravenous catheter to facilitate prolonged therapy, and serial AAA monitoring by 3D ultrasound. Aneurysms are induced in apolipoprotein E (ApoE) deficient mice by angiotensin II release over 28 days from osmotic mini-pumps implanted subcutaneously into the mouse back. Subsequently, the surgical procedure for external jugular vein catheterization is conducted to allow for daily intravenous drug treatment or repeated blood sampling via a subcutaneous vascular access button. Despite the two dorsal implants, the monitoring of AAA development is readily facilitated by sequential semi-automated 3D ultrasound analysis, which yields comprehensive information on the expansion of aortic diameter and volume and on aneurysm morphology, as illustrated by experimental examples.

This protocol describes the consecutive implantation of an osmotic pump to induce abdominal aortic aneurysm by angiotensin II release in apolipoprotein E (ApoE) deficient mice and of a vascular access port with a jugular vein catheter for repeated drug treatment. Monitoring of aneurysm development by 3D ultrasound is effectively conducted despite dorsal implants.

Since pharmaceutical treatment options are lacking in the clinical management of abdominal aortic aneurysm (AAA), animal models, in particular mouse ...

A Mouse 5/6th Nephrectomy Model That Induces Experimental Uremic Cardiomyopathy

Chronic kidney disease (CKD) is a great risk factor for cardiovascular disease events and mortality, and progressively develops to the clinical phenotype called "uremic cardiomyopathy". We describe here an experimental CKD mouse model, named 5/6th partial nephrectomy (PNx) with pole ligation, which developed uremic cardiomyopathy at four weeks post-surgery. This PNx model was performed by a two-step surgery. In step-one surgery, both poles of the left kidney were ligated. In step-two surgery, which was performed 7 days after the step-one surgery, the right kidney was removed. For the sham surgery, the same surgery procedures were performed but without pole ligation of the left kidney or removal of the right kidney. The surgical procedures are easier and less time-consuming, compared to other methods. However, the remnant functional renal mass is not as easily controlled as the renal artery ligation. Four weeks after surgery, in comparison with the sham-operated mice, the PNx mice developed impaired renal function, anemia, cardiac hypertrophy, cardiac fibrosis, and decreased heart systolic and diastolic function.

A Mouse 5/6th Nephrectomy Model That Induces Experimental Uremic Cardiomyopathy

This manuscript provides a detailed two-step surgical procedure to perform mouse 5/6th partial nephrectomy (PNx) with pole ligation. Four weeks after surgery, in comparison with sham-operated mice, the PNx mice developed impaired renal function, anemia, cardiac hypertrophy, cardiac fibrosis, and decreased heart systolic and diastolic function.

Chronic kidney disease (CKD) is a great risk factor for cardiovascular disease events and mortality, and progressively develops to the clinical phenotype ...

Biology

Traditional Medicine and PI3K/AKT Pathway Activation in Membranous Nephropathy

Mechanism of Kemeng Fang's Inhibition of Podocyte Apoptosis in Rats with Membranous Nephropathy through the PI3K/AKT Signaling Pathway

Membranous nephropathy (MN) is a common pathological type of adult nephrotic syndrome. Up to 20% of patients with MN develop end-stage renal disease (ESRD). Podocytes have an important function in maintaining the glomerular filtration barrier and play a crucial role in the occurrence and development of proteinuria and MN. PI3K/AKT signaling pathway is involved in the entire process of podocyte growth, differentiation, and apoptosis. Kemeng Fang (KMF) is a traditional Chinese medicine formula that has been used to delay kidney injury. However, the therapeutic mechanism of KMF in MN is unclear. Here, the MN rat model was established by axillary, inguinal, and tail vein injections of cationized bovine serum albumin (C-BSA), and then KMF and PI3K inhibitor (LY294002) were administered. The data of liver function, kidney function, blood lipid, renal pathology, podocyte function, expression level of PI3K/AKT signaling pathway, and transcriptomics of rats demonstrated that KMF has a protective effect on the podocytes of MN rats by activating the PI3K/AKT signaling pathway, and it can effectively prevent the progression of MN.

The present protocol describes the establishment of a membranous nephropathy (MN) animal model, and how Kemeng Fang's inhibition reduces MN rat podocyte apoptosis by activating the PI3K/AKT signaling pathway.

Membranous nephropathy (MN) is a common pathological type of adult nephrotic syndrome. Up to 20% of patients with MN develop end-stage renal disease ...

Sympathetic Denervation of Renal Arteries in an Angiotensin II-Induced Hypertension Mouse Model

Source: Wang, M., et al., <a href="https://app.jove.com/v/63719">Improved Renal Denervation Mitigated Hypertension Induced by Angiotensin II Infusion.</a> J. Vis. Exp. (2022)
This video demonstrates a procedure for renal artery sympathetic denervation in an angiotensin II-induced hypertensive mouse model, using phenol to disrupt sympathetic nerve function and reduce blood pressure.

Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin

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