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

The murine brain is lined by three meningeal layers - the outermost dural membrane,  the middle arachnoid membrane, and the innermost pia membrane.

In the posterior region of the brain, the arachnoid and pia membrane are intervened by a cerebrospinal or CSF-filled subarachnoid space, called the cisterna magna.

To perform intracisternal injection of the tumor cells, begin by taking an anesthetized mouse model. Prep the mouse by removing the hair from the ventral surface of the head.

Now, place the mouse in the prone position and attach its head to a stereotaxic frame. Position the nose of the mouse, pointing it slightly downwards to level the spine with the cisterna magna.

Using scissors, make a small midline incision on the posterior end of the brain, at the ears level.

Carefully pull aside the superficial muscle layer. The cisterna magna can be visualized as an inverted triangle covered by the transparent dural membrane.

Next, take a syringe containing circulating tumor cell suspension.

Keeping the surrounding musculature retracted, insert the syringe under the dura membrane, piercing through the arachnoid membrane. This step allows the injection of tumor cells directly into the CSF present in the cisterna magna.

Finally, close the incision site by applying wound clips, and allow the mouse to recover.