Convection-Enhanced Delivery of Antibodies into a Mouse Brain

Secure an anesthetized mouse that has a cranial midline incision to a stereotactic frame.

Detect the bregma, a reference point on the skull, and determine the injection location.

Create a burr hole at the location, avoiding damage to the dura mater covering the brain.

Take a step catheter loaded with antibodies, mounted on a stereotactic robot, and connected to an infusion pump.

The catheter comprises a fused silica capillary protruding from a metal needle, creating a stepped outer diameter at the fusion point.

Insert the catheter into the brain parenchyma. Start the infusion pump to create a pressure gradient at the catheter opening and deliver the antibodies at a controlled rate, a technique known as convection-enhanced delivery.

The stepped diameter compresses the tissue, creating a seal.

The seal prevents fluid reflux and enables the distribution of large antibody volumes while lowering the risk of tissue damage.

For antibody injection into the murine striatum, confirm a lack of response to skin pinch in an anesthetized mouse, and shave the head with a hair trimmer. Disinfect the skin with cotton swabs soaked in iodine solution.

Use a scalpel to make a 10-millimeter skin incision along the cranial midline finishing at the eye level. Fix the mouse in the stereotactic frame using the nose clamp and ear bars, taking care that the skull surface is horizontal and tightly secured.

Place the syringe in the stereotactic robot, and synchronize the drill bit with the tip of the catheter on a reference point. Use forceps to retract the skin, and localize bregma on the skull surface. Reference bregma in the software using the tip of the drill bit, and move the drill to a 1-millimeter frontal and 2-millimeter lateral from bregma position.

Drill a burr hole, taking care not to damage the dura mater, and move the syringe over the burr hole. Dispense 0.5 to 1 microliter from the syringe to ensure that no air bubbles are left in the catheter. Start the convection-enhanced delivery as demonstrated, observing the skull surface for any traces of fluid backflow from the injection spot.

At the end of the delivery and catheter removal, start the injection pump at 0.2 microliters per minute to check for evidence of catheter clogging during the injection. If no clogging occurred, a droplet of injection mix should immediately be observed coming from the catheter tip.