Cost-Effective and Functional Alternatives to Thermanox Cover Rings for Tumor Xenotransplantation on Fertilized Chicken Eggs

Abstract Tumor xenotransplantation to the chorioallantois membrane (CAM) of fertilized chicken eggs is excellently suited to short-time analysis of xenograft growth and can reduce mouse experiments. However, the limiting factor with egg xenograft experiments is the high price and limited availability of Thermanox plastic cell culture coverslips, which are often sold out and unavailable for weeks. According to the regular protocol, rings are punched from Thermanox plastic cell culture coverslips 13 mm ø and sticked to the CAM. The xenografts are then sown into these rings in order to prevent that they slide around on the CAM. Thermanox rings are well tolerated and do not interfere with the development of chicken embryos. Here we present a method for preparation of comparable, cheaper and always available alternative rings. We evaluated self-made rings from agar and PVC tube and compared their suitability to Thermanox rings. We found that rings of agar and PVC tube achieved the same xenograft sizes and had no side effects on chick embryonal growth, and therefore seem to be as as good as Thermanox rings.