New "Egg Tumor Model” Developed to Study Cancer

Researchers say they have developed a versatile, powerful, and convenient model to analyze human cancer. They put together an “egg tumor model” in which cultured ovarian cancer cells are transplanted on top of the membrane that surrounds a 10-day-old chicken embryo. An ovarian tumor forms on top of the membrane within three days of transplantation.

The scientists had similar results when they used ovarian tumor samples taken directly from patients, showing that their chicken egg model provides a system for replicating human cancer. Fuyuhiko Tamanoi, Ph.D., of Kyoto University’s Institute for Integrated Cell-Material Sciences (iCeMS), says this conclusion is supported by their detailed characterization of the tumor, demonstrating that it possesses all major cancer features. Dr. Tamanoi’s team, in collaboration with colleagues in the U.S., France, and Saudi Arabia, published their study (“Chick Chorioallantoic Membrane Assay as an In Vivo Model to Study the Effect of Nanoparticle-Based Anticancer Drugs in Ovarian Cancer”) in Scientific Reports.

“New therapy development is critically needed for ovarian cancer. We used the chicken egg CAM [chorioallantoic membrane] assay to evaluate efficacy of anticancer drug delivery using recently developed biodegradable PMO (periodic mesoporous organosilica) nanoparticles. Human ovarian cancer cells were transplanted onto the CAM membrane of fertilized eggs, resulting in rapid tumor formation. The tumor closely resembles cancer patient tumor and contains extracellular matrix as well as stromal cells and extensive vasculature. PMO nanoparticles loaded with doxorubicin were injected intravenously into the chicken egg resulting in elimination of the tumor. No significant damage to various organs in the chicken embryo occurred. In contrast, injection of free doxorubicin caused widespread organ damage, even when less amount was administered,” write the investigators.

“The lack of toxic effect of nanoparticle loaded doxorubicin was associated with specific delivery of doxorubicin to the tumor. Furthermore, we observed excellent tumor accumulation of the nanoparticles. Lastly, a tumor could be established in the egg using tumor samples from ovarian cancer patients and that our nanoparticles were effective in eliminating the tumor. These results point to the remarkable efficacy of our nanoparticle based drug delivery system and suggests the value of the chicken egg tumor model for testing novel therapies for ovarian cancer.”

“We were surprised when the tumor was formed in three days,” notes Dr. Tamanoi. “This is very rapid considering that it takes weeks to do the same with mice. We can start using this model to test for anticancer drugs tailored to each cancer patient’s needs. The process can be completed within one week.” He calls it a major step toward individualized medicine for cancer patients.

The chicken egg model has several advantages over existing models, such as mouse models, for testing anticancer therapies, continues Dr. Tamanoi. The tumors form much more rapidly on the chicken embryonic membranes than in mice due to the rich nutrient environment and the incomplete immune system at this stage of embryonic development. Fertilized chicken eggs are also less expensive to use than immune-compromised mice making the model suitable for high-throughput experiments.