We present a surgical procedure to catheterize the intestinal lymph trunk in neonatal pigs to collect large quantities of lipid metabolism components from efferent lymph.
Lymphatic catheterization is an important technique used to investigate mechanisms involved in lipid and drug metabolism, cancer metastasis, and immune function and collecting large quantities of lymph from various animal models enables researchers to study these processes. The video demonstrates in detail the surgical procedure employed to catheterize the intestinal lymphatic trunk in neonatal pigs using a ventral mid-line approach. All procedures were approved by the University of Alberta Institutional Animal Care and Use Committee.
To access the lymphatic vessel the abdominal cavity was opened. Electrocautery on the cut setting was used to open the muscle layer. A retractor was placed to hold the abdominal wall open for the duration of the procedure.
Key abdominal organs are identified to aid in localizing the lymphatic vessel. For improved access to the lymphatic vessel segments of the small intestine and colon are exteriorized to the left side of the body. The lymphatic vessel is landmarked by identifying the liver and the right ventral segment of the portal vein.
In neonatal pigs the lymphatic vessels are delicate and easily torn, so meticulous dissection with swabs and blunt instruments is required. Here is the intestinal lymphatic vessel. Now the suture is being passed underneath the lymphatic vessel with blunt forceps.
Now there are three 2-0 silk sutures passed underneath the lymphatic vessel. The caudal most suture is used to dilate the vessel and secure the catheter to the vessel. The cranial sutures are used to secure the catheter within the vessel.
A small incision in the lymphatic vessel allows blunt forceps to dilate the vessel. The catheter is inserted into the vessel. This must be done gently to ensure the lymphatic vessel does not tear.
The catheter needs to be advanced beyond the cranial most suture to ensure it is well seated. The three 2-0 silk sutures secure the catheter into the lymphatic vessel. Importantly the two cranial sutures are first used to secure the catheter into the vessel and the caudal most suture is then used to tether the catheter, adding stability.
It is important to ensure there is good lymph flow prior to closing the abdominal cavity. The catheter is exteriorized on the left mid-flank of the pig. Large forceps are used to pull the catheter from the abdominal cavity to the external surface of the pig's flank.
The muscle layers are closed with 2-0 vicryl suture on a tapered needle in a simple interrupted suture pattern. The skin is closed with 2-0 vicryl suture on a cutting needle in a running subcuticular suture pattern. With the exit incision the catheter passes through the skin and is closed with 2-0 nylon suture on a cutting needle in a purse-string suture pattern.
This closure helps prevent ascending infections tracking inwards along the catheter. The jacket holding the lymph collection bottles is placed on the pig while the pig is still under anesthesia. The catheter is inserted into the collection bottle and good lymph flow is assured prior to waking the pig.
The pigs recover well from the procedure and excellent lymph flow is maintained throughout the experiment. The table displays the components of lymph collected from the lymphatic vessel. These components include Apolipoprotein B48, Triglycerides, and Cholesterol.
The figure of the Western Blot shows the presence of both Apolipoprotein B48 and small amounts of plasma-derived Apolipoprotein B100 within the collected lymph sample. Although lymphatic catheterization in young pigs can be technically challenging, as the lymphatic vessels are both delicate and friable, this video demonstrates that using proper and careful surgical technique in young pigs can provide researchers with an excellent model for collecting intestinal lymph.
