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

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.