Establishing Experimental Metastases Mouse Model: Implanting GFP Expressing CRC Organoid Cells in PDX Model to Detect Micrometastases

- Micrometastases are a small group of cancer cells that shed from a primary tumor and spread to different parts of the body via blood or lymph nodes. To detect micrometastases, suspend colorectal cancer organoid cells in PBS to maintain pH and load the cell suspension into a syringe. Next, place an anesthetized mouse in a prone position on a surgical bed. Make a small incision using scissors on the lower part of the left flank and expose the spleen. Gently pull the spleen out using tweezers and slowly inject the cell suspension into the spleen. Close the incision using sutures and return the animal to its cage. Monitor it until it recovers.

After the desired period of injection, sacrifice the mouse to dissect primary tumors and different tissues. Observe dissected tissues under a fluorescence microscope. GFP-expressing cancer cells develop a primary tumor at the injected site in the spleen. A few cancer cells from the primary tumor move to a different organ, usually the liver, to form micrometastatic colonies. In the following protocol, we will establish an experimental metastases mouse model of GFP-expressing colorectal cancer organoid cells.

- To establish an experimental metast