Caudal artery injection

The caudal artery (CA) injection is a safe and reliable method for constructing bone metastasis model mice with much less burden on mice than conventional methods.

Reference: Kuchimaru T, Kataoka N, Nakagawa K, Isozaki T, Miyabara H, Minegishi M, Kadonosono T, Kizaka-Kondoh S*. An easy and reliable model of bone metastasis by injecting cancer cells through caudal arteries. Nature Communications, 9(1):2981 (2018). doi: 10.1038/s41467-018-05366-3.

1. Anesthetize mice (usually 6-8 week old) with common intraperitoneally injectable anesthetics such as pentobarbital sodium /medetomidine-midazolam-butrphanol combination /ketamine-xylazine combination (* see below for detailed dose).

Do not use gas anesthetics such as isoflurane.

Removal of black hair greatly increased the sensitivity of bioluminescence imaging for post-injection analysis.

2. Prepare a single-cell suspension and pipette several times to dissociate aggregated cells just before filling into a 29G needle syringe. Adjust the volume to be injected into one mice to 100 uL and prepare syringes one by one. The number of cells that can be injected at a time varies from cell to cell and must be examined. Cells that tend to form aggregates need to reduce the number of cells. If the cells are difficult to aggregate, up to 5 million can be injected.

3. Place an anesthetized mouse with the abdomen up on a mouse restraint commonly used for tail vein injection.

4. Disinfect the injection site with 70% ethanol. The injection site can be anywhere within the range shown in Figure 1. If the injection fails, it can be injected again, so it is recommended to start as close to the end as possible.

5. Insert a needle slowly under the skin in a similar way of tail vein injection. When the tip of the needle no longer feels resistance, it has successfully accessed the tail artery.

6. Quickly push the cell suspension out of the syringe within seconds.

7. Stop bleeding for 1 min immediately after removing the needle from the injection site.

See Movie 1 & Movie 2. These movies were shot at the same time from a side view (Movie 1) and top view (Movie 2) of CA injection.

* 50 mg/kg pentobarbital sodium

0.3 mg/kg medetomidine + 4 mg/kg midazolam + 5 mg/kg butrphanol

100 mg/kg ketamin + 10 mg/kg midazolam