Renal Capsule Tumor Xenografting: A Technique to Generate an Experimental Animal Model to Evaluate Prostate Carcinogenesis

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Surgical Procedure: Renal Capsule Xenografting

1. Prior to induction of anesthesia, observe the mouse to ensure health and wellbeing.
2. Place the mouse into the chamber for induction of isoflurane anesthesia at 3-5%. When the animal has stopped moving and the respiratory rate has decreased, transfer to the nose cone in the prone position, and maintain anesthesia at 1-3%.
3. If necessary, use clippers to shave the back of the mouse. This is not needed when utilizing athymic nude (nu/nu) mice.
4. Apply firm pressure to the webbing of the extended hindfoot to evaluate the adequacy of anesthesia. If the mouse responds to pressure, more time is needed for the anesthesia to take effect. If necessary, adjust anesthesia flow slightly to achieve adequate anesthesia.
5. When the mouse is adequately anesthetized, disinfect the surgical site with surgical iodine (Betadine) solution followed by 70% alcohol.
6. Don sterile gloves and gowns; apply sterile drapes to the surgical site. Lift the back skin with a pair of toothed forceps, and using the coarse scissors, make a 2-3 cm dorsal midline incision.
7. Using blunt scissors or a probe, separate the underlying dermis from the body wall (on both sides of the incision for bilateral grafting or on one side for unilateral grafting).
8. Reposition the mouse into lateral position and identify the location of the kidney by viewing the renal profile through the muscle wall. Applying gentle manual pressure with the thumb and index finger on the abdomen may assist with visualizing internal organs.
9. Using fine iris scissors and taking care to avoid major vessels and spinal nerves, make a 1 cm incision in the body wall parallel to the spine. Widen this incision to 1.5-2.0 cm (slightly longer than the long axis of the kidney) by gently opening the scissors wider after placing them in the initial incision.
10. Exteriorize the kidney by applying gentle pressure outside the muscle wall on either side of the kidney using the index finger and thumb. Tuck the skin edges below the exteriorized kidney, which will rest on the body wall. While the kidney is exteriorized, maintain hydration of the renal capsule by applying sterile saline.
11. Using fine #5 forceps, gently lift the kidney capsule from the parenchyma of the kidney, and with a fine scalpel, make a 2-4 mm incision in the capsule. The size of the incision is determined by the size of the graft but should be minimized to maintain the integrity of the capsule.
12. Manipulate a glass Pasteur pipette that has been drawn thin and fire-polished with a rounded closed end under the capsule tangential to the surface of the kidney. Gently open a small capsule pocket for the grafts, using great care not to damage the kidney parenchyma.
13. The cut edge of the kidney capsule is lifted with the fine forceps, and the graft is inserted into the pocket under the capsule using the fire-polished glass pipette. Several grafts can be placed under the kidney capsule and evenly spaced on the kidney surface.
14. If during the course of grafting the capsule becomes dehydrated, it should be moistened by applying sterile saline.
15. When grafting is complete, gently lift the sides of the muscle wall incision to replace the kidney back into the body cavity. Observe that the grafts do not slip out from under the capsule.
16. Close the muscle wall with a single suture (4-0, FS-2 vicryl suture). The surgical procedure can be repeated on the contralateral kidney by repositioning the mouse.
17. Using toothed forceps, align the skin incision edges and apply 2-3 surgical wound clips to close the incision. Administer analgesia (we use 5-10 mg/kg carprofen using a subcutaneous injection) and place the mouse in the lateral recumbent position in the recovery cage. Ensure maintenance of body temperature with heat from a lamp or heating pad. Observe for full recovery of the mouse, which should occur in less than 15 minutes.
18. Mice should be observed for the next 24 hr for signs of post-operative pain, bleeding, and/or other complications. Regularly inspect surgical incisions for signs of infection.
19. Remove wound clips with surgical wound clip removal device 7-14 days after surgery.