Name: urethral stricture induction followed by buccal mucosa graft urethroplasty in a rat model
Uploaded: 2023-04-28T13:00:00
Description: Watch this Scientific Journal Video about Urethral Stricture Induction Followed by Buccal Mucosa Graft Urethroplasty in a Rat Model at JoVE.com

We thank Jo&#227;o Leit&#227;o, head of the Radiology department of Centro Hospitalar Universit&#225;rio Lisboa Norte, and Catia Fernandes, technician of the Radiology department of Centro Hospitalar Universit&#225;rio Lisboa Norte, for their cooperation in the realization of urethrograms.

All animal procedures were performed according to Directive 2010/63/EU. The procedures were approved by the institutional Animal Welfare Body, licensed by DGAV, the Portuguese competent authority for animal protection (license number 0421/000/000/2021). Male Wistar Han IGS (Crl:WI(Han) rats (400-500 g) at 12-14 weeks of age were used for the present study. The animals were obtained from a commercial source (see Table of Materials).
1. Preparation of solutions</p...

<ol>
	<li>Souza, G. F., Calado, A. A., Delcelo, R., Ortiz, V., Macedo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histopathological+evaluation+of+urethroplasty+with+dorsal+buccal+mucosa:+an+experimental+study+in+rabbits.">Histopathological evaluation of urethroplasty with dorsal buccal mucosa: an experimental study in rabbits.</a> International Brazilian Journal of Urology. 34 (3), 345-354 (2008).</li><li>Andrich, D. E., Mundy, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urethral+strictures+and+their+surgical+treatment.">Urethral strictures and their surgical treatment.</a> BJU International. 86 (5), 571-580 (2000).</li><li>Bhargava, S., Chapple, C. R., Bullock, A. J., Layton, C., MacNeil, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-engineered+buccal+mucosa+for+substitution+urethroplasty.">Tissue-engineered buccal mucosa for substitution urethroplasty.</a> BJU International. 93 (6), 807-811 (2004).</li><li>Fu, Q., 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=Substitution+urethroplasty+for+anterior+urethral+stricture+repair:+comparison+between+lingual+mucosa+graft+and+pedicled+skin+flap.">Substitution urethroplasty for anterior urethral stricture repair: comparison between lingual mucosa graft and pedicled skin flap.</a> Scandinavian Journal of Urology. 51 (6), 479-483 (2017).</li><li>Blain, B., 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=Vascular+grafts+in+the+rat+model:+an+anatomic+study.">Vascular grafts in the rat model: an anatomic study.</a> Microsurgery. 21 (3), 80-83 (2001).</li><li>Schmauss, D., Weinzierl, A., Schmauss, V., Harder, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Common+rodent+flap+models+in+experimental+surgery.">Common rodent flap models in experimental surgery.</a> European Surgical Research. 59 (3-4), 255-264 (2018).</li><li>You, H., 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+rat+orthotopic+renal+transplantation+model+for+renal+allograft+rejection.">A rat orthotopic renal transplantation model for renal allograft rejection.</a> Journal of Visualized Experiments. (180), e63464 (2022).</li><li>Park, J. H., 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=Balloon-expandable+biodegradable+stents+versus+self-expandable+metallic+stents:+a+comparison+study+of+stent-induced+tissue+hyperplasia+in+the+rat+urethra.">Balloon-expandable biodegradable stents versus self-expandable metallic stents: a comparison study of stent-induced tissue hyperplasia in the rat urethra.</a> Cardiovascular and Interventional Radiology. 42 (9), 1343-1351 (2019).</li><li>Mart&#237;n-Cano, 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=Histological+and+immunohistochemical+changes+in+the+rat+oral+mucosa+used+as+an+autologous+urethral+graft.">Histological and immunohistochemical changes in the rat oral mucosa used as an autologous urethral graft.</a> Journal of Pediatric Surgery. 48 (7), 1557-1564 (2013).</li><li>Hofer, M. 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=Analysis+of+primary+urethral+wound+healing+in+the+rat.">Analysis of primary urethral wound healing in the rat.</a> Urology. 84 (1), e1-7 (2014).</li><li>Tavukcu, H. H., 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=Protective+effect+of+platelet-rich+plasma+on+urethral+injury+model+of+male+rats.">Protective effect of platelet-rich plasma on urethral injury model of male rats.</a> Neurourology and Urodynamics. 37 (4), 1286-1293 (2018).</li></ol>

Urethroplasty with buccal mucosa grafts is a major cornerstone in urethral reconstruction. However, innovative procedures should be developed to optimize those already described and establish new ones, such as tissue-engineered materials and biological grafts, to reduce complications and morbidity. Several procedures have been published to establish preclinical models and define surgical techniques. Souza et al.1 conducted a study including 12 New Zealand rabbits. A ventral longitudinal skin incis...

Urethral reconstruction is a major challenge for urological surgeons in the management of urethral injury in the setting of strictures, trauma, or congenital defects1. With curative intent, urethroplasty is the treatment of choice for most patients, with long (&gt;2 cm) and anterior urethral defects requiring some form of substitution urethroplasty2. Many tissues have been used as urethral substitutes, including full or split-thickness skin grafts of genital or extragenital areas, bladder wall mucosa, or the widespread buccal mucosa2. Buccal mucosa grafts have several advantages, such as coming from a wet and hairless environment, being easy to harvest, being resistant to infection, a thick epithelium, a reduced likelihood of pseudo-diverticulum formation, and a thin lamina, allowing early imbibition and inosculation3. In contrast with flaps, grafts have no blood supply, depending on the recipient's vascular bed to survive4.
Animal models of grafts or flaps have been used extensively to develop or refine surgical techniques, study and understand tissue physiology, underlying mechanisms, and causes of failure, and evaluate innovative treatment strategies5,6. Although bigger animals facilitate technical execution, rodents, namely rats and mice, are easier to handle and maintain, resistant to diseases, more cost-effective, and, importantly, with the tools to investigate molecular mechanisms, crucial to test innovative therapies5,6. Several models of flaps and grafts have been described in rats using different tissues, namely skin, bone, muscle6, vessels5, and even solid organs7. However, there is scarce investigation in murine models into grafts for urethral reconstruction or tissue engineering. 
Nevertheless, advances in translational science depend on animal models that mimic disease. So far, the local pathophysiology environment has not been addressed, since urethral reconstruction is performed immediately after its stricture. Herein, this study aims to perform a urethral reconstruction using a buccal mucosa graft in a local pathophysiology environment. With this objective, the urethral stricture was induced 1 week before its reconstruction. This experimental model, performed in rats, allows to test innovative therapies and investigate their molecular mechanisms and clinical advantages in the future.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Atipamezole</td>
			<td>OrionPharma</td>
			<td></td>
			<td>ANTISEDAN (atipamezole) is indicated for the reversal of the sedative and analgesic effects.</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>RichterPharma</td>
			<td></td>
			<td>Buprenorphine is a derivative of the opioid alkaloid thebaine that is a more potent (25-40 times) and longer lasting analgesic than morphine.</td>
		</tr>
		<tr>
			<td>Carl Zeiss Opmi-1 FC Surgical Stereo Microscope</td>
			<td>Carl Zeiss Microscopy, Germany</td>
			<td></td>
			<td>OPMI 1 FC from ZEISS symbolizes quality, precision and reliability. The manual system is easy to use and delivers high fidelity images with the legendary ZEISS optics.</td>
		</tr>
		<tr>
			<td>Carprofen</td>
			<td>Zoetis</td>
			<td></td>
			<td>Carprofen is a non-steroidal anti-inflammatory drug (NSAID) of the propionic acid class.</td>
		</tr>
		<tr>
			<td>Catheter 22 G. x 1&#39;&#39;</td>
			<td>B Braun</td>
			<td>Introcan Safety</td>
			<td>IV Catheter of fluorinated ethylene propylene (FEP) with firmer construction for 
			arterial access.</td>
		</tr>
		<tr>
			<td>Enrofloxacin</td>
			<td>Bayer</td>
			<td></td>
			<td>Enrofloxacin is a fluoroquinolone antibiotic.</td>
		</tr>
		<tr>
			<td>Fentanyl</td>
			<td>Braun</td>
			<td>3644960</td>
			<td>Fentanyl is a powerful synthetic opioid analgesic.</td>
		</tr>
		<tr>
			<td>Flumazenil</td>
			<td>Fresenius Kabi</td>
			<td></td>
			<td>Benzodiazepine antagonist is used for the complete or partial reversal of the sedative effects caused by benzodiazepines.</td>
		</tr>
		<tr>
			<td>High temperature cautery</td>
			<td>Fiab</td>
			<td>F7244</td>
			<td>Disposable cautery, sterile, high temperature (1200 &#176;C), 28 mm fine tip.</td>
		</tr>
		<tr>
			<td>Instillagel gel</td>
			<td>Farco-pharma</td>
			<td></td>
			<td>Cellulose-based lubricant with local anaesthetic and disinfecting properties.</td>
		</tr>
		<tr>
			<td>Iopromide</td>
			<td>Bayer</td>
			<td></td>
			<td>Non-ionic injectable contrast medium, with iodine.</td>
		</tr>
		<tr>
			<td>Laser Doppler imaging system (perfusion imager moorLDI2-HIR and dedicated software)</td>
			<td>MoorLDI-V6.0, Moor Instruments Ltd, Axminster, UK</td>
			<td>5710</td>
			<td>The angiogenesis models uses Laser Doppler imaging to assess blood perfusion in the hind limbs, one of which is ligated surgically. Dedicated measurement and comparison software allows the definition of regions of interest for blood flow assessment on the ischaemic versus non-ischaemic limb to establish a &#34;reperfusion ratio&#34; which can be assessed as often as needed and over a number of days on the same subject.</td>
		</tr>
		<tr>
			<td>Lubrithal Eye Gel</td>
			<td>Dechra</td>
			<td></td>
			<td>Eye gel used in animals for prevention of dry eyes during anaesthesia. Lubricating and moisturising action on cornea and conjunctiva.</td>
		</tr>
		<tr>
			<td>Male Wistar Han IGS (Crl:WI(Han) rats</td>
			<td>Charles River Laboratories, Spain</td>
			<td></td>
			<td>Twelve to fourteen-week-old</td>
		</tr>
		<tr>
			<td>Metedomidin</td>
			<td>Virbac</td>
			<td>037/01/07RFVPT</td>
			<td>Medetomidine is a synthetic drug used as surgical anesthetic.</td>
		</tr>
		<tr>
			<td>Midazolam</td>
			<td>Labesfal</td>
			<td></td>
			<td>Benzodiazepine medication is used for anesthesia and procedural sedation.</td>
		</tr>
		<tr>
			<td>Monoplan Angiography System</td>
			<td>Philips Medical Systems</td>
			<td>Azurion 7 M20</td>
			<td>A stationary diagnostic fluoroscopic x-ray system specifically designed to optimize the capability of users to visually and quantitatively evaluate the anatomy and function of blood vessels of the heart, brain and other organs, as well as the lymphatic system.</td>
		</tr>
		<tr>
			<td>Mosquito forceps</td>
			<td>Henry Schein</td>
			<td>102-4346</td>
			<td>Hartman-Mosquito Hemostatic Forcep Curved 3-1/2&#34; Stainless Steel</td>
		</tr>
		<tr>
			<td>Needle Holder</td>
			<td>Henry Schein</td>
			<td>100-2570</td>
			<td>Needle holder Mayo-Hegar, stainless steel, 14 cm</td>
		</tr>
		<tr>
			<td>Ophtalmic Needle Holder</td>
			<td>Asico</td>
			<td>AE-6143</td>
			<td>Needle holder barranquer most delicate without lock</td>
		</tr>
		<tr>
			<td>Pentobarbital Sodium</td>
			<td>Ecuphar</td>
			<td></td>
			<td>Pentobarbital Sodium is the sodium salt of pentobarbital used for euthanasia.</td>
		</tr>
		<tr>
			<td>Pointed Forceps</td>
			<td>Aesculap</td>
			<td>BD335R</td>
			<td>Microforceps, 0.30 mm tip</td>
		</tr>
		<tr>
			<td>Polysorb 6.0</td>
			<td>Medtronic (Covidien)</td>
			<td>UL-101</td>
			<td>Coated Synthetic Absorbable Suture aimed to reduce the inflammatory reaction in tissues, followed by gradual encapsulation of the suture by fibrous connective tissue.</td>
		</tr>
		<tr>
			<td>Providone-Iodine</td>
			<td>Mylan</td>
			<td></td>
			<td>Povidone-iodine 10% is an antiseptic drug, used as a disinfectant before and after surgery.</td>
		</tr>
		<tr>
			<td>Scalpel Blade n&#186;11</td>
			<td>B Braun</td>
			<td>BB511</td>
			<td>Carbon steel, sterile</td>
		</tr>
		<tr>
			<td>Spring Scissor</td>
			<td>Henry Schein</td>
			<td>600-4826</td>
			<td>Surgical scissors 31 castroviejo</td>
		</tr>
		<tr>
			<td>Surgical Forceps</td>
			<td>Aesculap</td>
			<td>BD33R</td>
			<td>Microforceps, 0.20mm tip</td>
		</tr>
		<tr>
			<td>Surgical Scissor</td>
			<td>Aesculap</td>
			<td>MA873R</td>
			<td>Micro Iris Scissor, curved shrap tips</td>
		</tr>
		<tr>
			<td>SurgiPro 7.0</td>
			<td>Medtronic (Coviden)</td>
			<td>VP-702-X</td>
			<td>Non-Absorbable Monofilament Polypropylene Suture indicated for use in general soft tissue ligation.</td>
		</tr>
	</tbody>
</table>

urethral stricture induction followed by buccal mucosa graft urethroplasty in a rat model

Urethral reconstruction is an important area of expertise for urologists. The buccal mucosa is considered the best option when urethral grafting is necessary, although in some cases, it is inappropriate or needs to be optimized to repair a given stricture. Therefore, developing innovative procedures and evaluating their putative success in experimental models is crucial to fit the clinical need. With this goal, this study describes a protocol in which urethral stricture was induced by electrocautery in Wistar rats. Urethral reconstruction was performed 1 week later with a buccal mucosa graft, harvested from the lower lip, and placed in a ventral onlay fashion. A retrograde urethrogram showed a significant improvement in urethral diameter after urethroplasty compared to the respective value after stricture induction. Additionally, the graft placement was assessed by blood perfusion analysis using laser Doppler. As expected, a dark blue area corresponded to the non-vascularized buccal mucosa graft. This procedure can successfully simulate the normal pathophysiological process of urethral injury and tissue modulation, as well as urethral reconstruction using a buccal mucosa graft in a reproducible manner, and serve as the basis for future research based on tissue engineering or urethral grafts.

A total of 12 male Wistar rats, weighing 400-500 g and 12-14 weeks old, were used for urethral stricture induction. A retrograde urethrogram (RUG1) was performed 1 week later8, confirming the success of the technique. The urethral diameter was measured in millimeters at the level of the stricture induction. After this, a urethroplasty with a buccal mucosa graft was performed in the ventral face of the rat urethra. The same rats were submitted to a second retrograde urethrogram (RUG2) 14 days after...

Watch this Scientific Journal Video about Urethral Stricture Induction Followed by Buccal Mucosa Graft Urethroplasty in a Rat Model at JoVE.com

Urethral Stricture Induction Followed by Buccal Mucosa Graft Urethroplasty in a Rat Model

In the present protocol, a urethral stricture induction was developed in Wistar rats, followed by urethral reconstruction with a buccal mucosa graft. A retrograde urethrogram and laser Doppler assessment were performed, validating urethral reconstruction (after stricture formation) and graft placement.

Urethral reconstruction is an important area of expertise for urologists. The buccal mucosa is considered the best option when urethral grafting is ...

In this protocol, urethral reconstruction using a buccal mucosa graft is developed for the first time in a local pathophysiological environment, which is crucial to mimic disease. This technique allow us to develop innovative therapies and to study their molecular mechanisms and clinical advantages in a translational way. To begin, apply protective eye gel to both eyes of the anesthetized rat.Place the animal in the dorsal decubitus position on a heat pad and position a dissection microscope over the rat for the surgical procedure. After retracting the foreskin of the penis, dorsally place a superficial seven-zero suture on the penile glands. Leave a needle holder in place to keep the penis retracted.Place a 22 gauge venous catheter into the urethra for catheterization using lubricant gel. Make a one-centimeter-long ventral incision in the penile skin with a surgical scalpel blade. Dissect the penile tissue layers with forceps and spring scissors until the urethra is exposed to mid-shaft level.Apply current with an electrocautery device on one lateral side of the urethra and ventrally at the penis mid-shaft. Close the incision with a six-zero absorbable running suture. Remove the urethral catheter and the penile traction suture.Place the rat in a ventral decubitus position and administer a subcutaneous injection of the anti-sedative solution. Clean the lower lip, buccal mucosa, penis, and abdominal skin of an anesthetized rat with povidone iodine. Place three seven-zero sutures on both sides and the middle of the lower lip.Place a mosquito in each one to retract the lip and expose the inner mucosa. Using spring scissors and pointed forceps, harvest a four-millimeter graft from the inner buccal mucosa of the lower lip. Place the graft in a small recipient with sterile 0.9%saline.Compress the donor area with a sponge. Remove the previously placed stay sutures of the lower lip and expose the penis. Place a 22 gauge venous catheter into the urethra for cauterization using a lubricant gel.Using spring scissors, make a circumferential subcoronal incision and deglove the penis to the base. Dissect the remaining layers to expose the urethra. Make a four-millimeter longitudinal ventral incision about three millimeters distal to the coronal sulcus, spatulating the urethra at the level of the stricture.Place two seven-zero stay sutures at each side of the spatulation. Leave a mosquito in each one to retract the urethra. Place two non-absorbable seven-oh sutures at each end of the spatulation.Place the buccal mucosa graft in a ventral onlay fashion with the mucosa side facing the urethral lumen. Pass one of the sutures through the graft and perform a half ellipse with a running suture. Remove the urethral catheter and reposition the penile skin.Close the circumferential subcoronal incision with a six-zero absorbable interrupted suture. Remove the penile traction suture, then administer the anti-sedative solution as demonstrated previously. The rat subjected to stricture induction showed a ureter diameter of 0.92 millimeters, which improved to 1.59 millimeters two weeks after graft urethroplasty.The mean blood flow was significantly reduced post-urethroplasty compared to pre-urethroplasty animals. Too much current can lead to a risk of urethral closure. The graft must be placed with the mucosa facing the urethral lumen with a watertight running suture to avoid fistulas.Any kind of urethroplasties with grafts can be performed, different types of grafts can be evaluated. This experimental model allow us to optimize the use of grafts and explore new therapeutic strategies, such as tissue-engineered materials with an impact on translational research to fit clinical needs.

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