Surgical Cisterna Magna Injection: A Method for Administering Tumor Cells Directly into Central Nervous System of Murine Model

Begin by injecting the mouse subcutaneously with 1 milligram per kilogram sustained-release buprenorphine. After anesthetizing the mouse, prepare it for surgery. Clip the surgical site with enough border area to keep fur from contaminating the incision site.

Shave the fur of the entire surface of the head and prepare the skin using sterile technique. Then, saturate the site with germicidal skin antiseptic, working from the center of the site to the periphery, and allow it to dry.

Position the body to ensure the spine is kept level with the cisterna magna. While applying slight traction to the tail, place tape at the tail base to secure it.

Apply either a sterile drape or a sterile adhesive-backed plastic drape material to protect the surgical site from contamination. With the neck in full extension, run the surgical scissor tips downward with slight pressure across the occipital bone beginning just between the pinnae.

Make a small 3- to 5-millimeter midline incision slightly above the palpated concavity. Draw 5 microliters of the cell suspension into a 30G Hamilton syringe. Use blunt-tipped forceps with a 1- to 2-millimeter tip to gently press down on the cisterna magna.

Introduce the tips in a closed position and open them while applying downward pressure on the dura. Repeat the blunt dissection until the dural membrane is easily identified and the associated blood vessels are visible in the exposed area.

While holding the forceps, open to retract surrounding musculature. Introduce a 30G non-coring needle under the dura to visualize the bevel, making sure that the needle is only introduced just beyond the bevel itself.

Slowly deploy a syringe plunger and deliver cells just below the dura. If leakage at the injection site is noted, apply gentle pressure with a cotton-tipped applicator. Close the skin by applying a wound clip or a microdrop of skin adhesive.

Monitor the mice daily after the surgery for the first week. If a mouse appears to be in pain or distress, treat it with a subcutaneous injection of 10 milligrams per kilogram carprofen, once every 12 to 24 hours for up to 5 days based on veterinary consultation and directive.