Murine Vertical Sleeve Gastrectomy: A Surgical Procedure to Downsize Stomach in Experimental Mouse Models

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

1. Vertical Sleeve Gastrectomy and Sham Procedures

1. On the day of surgery, weigh mice to obtain a baseline weight measurement.
2. Equip the surgical room with an anesthesia system, heated water bath, and heating pad. Set the water bath to 37 °C and use it to warm 0.9% saline solution for irrigation. Clean the surgical field with 70% ethanol and use sterile technique to open autoclaved surgery pack and tools.
   NOTE: The heating pad is used to keep the animal warm during surgery and recovery from anesthesia.
3. Using an induction chamber, anesthetize the mouse with 5% isoflurane and O₂ flow rate of 1 L/min. Confirm that the mouse is in the appropriate plane of anesthesia by performing a toe pinch. Maintain the mouse with 1-3% isoflurane and an O₂ flow rate of 0.6 L/min once a consistent plane of anesthesia has been achieved.
4. Once the mouse is anesthetized, place eye ointment (see Table of Materials) on its eyes to keep them moist during surgery. At this time, also administer an analgesic, such as meloxicam (2 mg/kg subcutaneously). Clip the hair from the umbilicus to the axilla holding the skin down gently to provide tension.
   1. As the mouse's skin is thin and delicate, take care to not cause skin lesions when clipping the hair. Clean the skin with povidone-iodine and alcohol.
   2. Don sterile gloves and prepare the sterile surgical field and instruments. Perform the rest of the procedure using sterile technique. Prepare sterile surgical field by placing sterile surgical drapes on either side of the mouse. Use autoclaved tin foil to create a surgical drape for the mouse.
   3. Cut a small hole in the tin foil to allow access to the mouse's abdomen.
5. Make an incision of the skin from the mid-abdomen (umbilicus) to the level of the xiphoid cartilage using an iris scissor. Identify the linea alba and use iris scissors to cut through the body wall along the linea alba. Use CTAs to gently elevate the stomach out of the abdomen and then bluntly dissect the greater omentum off of the greater curvature of the stomach.
6. Ligate the short gastric artery that runs between the fundus of the stomach and the spleen by placing two ligatures using 7-0 monofilament absorbable suture. Use spring scissors to cut between the two ligatures. Once the artery is transected, fully exteriorize the stomach from the abdominal cavity. Place gauze under the stomach and wet with saline to keep the tissue moist.
7. For the VSG procedure, ligate the prominent branches of the gastric artery and vein with 7-0 monofilament absorbable suture with a taper needle using 3 throws for each knot. Place the ligatures just below (i.e., towards the lesser curvature of the stomach) the intended line of transection.
   NOTE: The intended line of transection starts at ~2 mm above (meaning towards the greater curvature of the stomach) the cardiac notch of the stomach and at least 2 mm below the margo pilcatus and extends to the proximal end of the right lobe of the pancreas. Typically, there are 4 vessels per gastric wall that need to be ligated; however, this may vary between mice.
   1. To prevent spillage of gastric contents during the gastrectomy, place a simple continuous line of suture passing through both gastric walls just below the intended line of transection using a 6-0 monofilament absorbable suture with a taper needle. Begin the suture line to the surgeon's right of the esophagus and below the margo pilcatus and end just above the pancreas.
   2. Place thin-tipped hemostats above the suture line and use spring scissors to cut between the suture line and hemostats. Remove the transected gastric tissue from the sterile surgical field. Use CTAs to clean blood and digesta off of the stomach.
   3. Reinforce apposition of the gastric walls using 6-0 monofilament absorbable suture with a taper needle using a simple discontinuous pattern.
      NOTE: A simple discontinuous suture pattern is recommended since this provides more secure closure than the simple continuous suture pattern.
   4. Flush the gastric remnant with saline throughout the procedure in order to keep the tissue moist and clean. Use a 20G gavage needle attached to a 20 mL syringe to perform gastric lavage with saline. Use this size to ensure adequate pressure is provided without risking gastric tissue damage from excessive pressure or accidental gastric tissue damage from the use of a regular pointed needle.
   5. Use a minimum of 20 knots to securely close the stomach; pay attention to closure along the esophageal side, as this side is more difficult to access and therefore is often a site of dehiscence.
   6. Ensure that there are no leaks by gently pressing on the stomach with CTAs. If leaks are identified, place additional simple discontinuous knots on the areas of leakage and then leak test again. Leak test until no leakage is detected.
   7. Do a final thorough lavage of the stomach using at least 60 mL of saline to ensure that no infectious particulate matter has been left behind.
8. Place the stomach back into the abdominal cavity under the liver using a CTA. Place CTAs along the dorsal aspect of the abdominal cavity to absorb all excess fluid. Using a blunt 18G needle, inject lactated Ringer's solution (LRS) with or without antibiotics (0.5 mL LRS +/- 20 mg/kg Enrofloxacin) directly into the abdominal cavity, just prior to closure.
   NOTE: This replaces fluid loss experienced during surgery and provides a method for direct application of antibiotics to the surgical site to assist with recovery.
9. Close the abdominal muscle layer using a 6-0 monofilament absorbable suture with a taper needle in a simple discontinuous pattern. Then, close the skin layer with 6-0 monofilament absorbable suture in a simple continuous pattern.
10. Place tissue adhesive on the skin and fold the skin over the suture line to bury the suture so that the mouse cannot disrupt the wound closure post-operatively.
11. Turn the isoflurane off and let the mouse recover on the heating pad for 10-15 min before returning it to its home cage. Do not leave the animal unattended until it has regained consciousness and is able to move.
12. Keep animals housed singly until fully recovered from surgery.
    NOTE: If accurate food intake measurements are to be obtained throughout the study, mice should continue to be singly housed throughout the study. There is a risk of foreign body obstruction from eating home cage bedding. Animals should be housed in cages free of bedding except for nesting material to provide enrichment (see Table of Materials).