Technical Implications of the Chicken Embryo Chorioallantoic Membrane Assay to Elucidate Neuroblastoma Biology

Abstract

The chorioallantoic membrane (CAM) can be used as a valuable research tool to examine tumors. The CAM can be used to investigate processes such as migration, invasion, and angiogenesis and to assess novel antitumor drugs. The CAM can be used to establish tumors in a straightforward, rapid, and cost-effective manner via xenotransplantation of cells or tumor tissues with reproducible results; furthermore, the use of the CAM adheres to the three "R" principle, i.e., replace, reduce, and refine. To achieve successful tumor establishment and survival, several technical aspects should be taken into consideration. The complexity and heterogeneity of diseases including neuroblastoma and cancers in general and their impact on human health highlight the importance of preclinical models that help us describe tumor-specific biological processes. These models will not only help in understanding tumor biology, but also allow clinicians to explore therapeutic alternatives that will improve current treatment strategies. In this review, we summarize the technical characteristics as well as the main findings regarding the use of this model to study neuroblastoma for angiogenesis, metastasis, drug sensitivity, and drug resistance.

Keywords: CAM; cancer; neuroblastoma; tumors.

Figure 1

General procedure for in ovo tumor induction in chorioallantoic membrane (CAM). The numbers inside the boxes represent the days of incubation that the chick embryo requires to develop until hatching; the blue color indicates the days from the formation of the CAM until it is fully functional. Fertilized hen eggs in a dynamic incubator: on day 4, open window in eggshell and expose the CAM; tumor cells are inoculated on day 8; the inoculated eggs are placed in an incubator without movement for the time required for the experiment; the tumor is observable after three days of incubation.

Figure 2

The CAM model for the study of neuroblastoma. The CAM assay has shown to be a useful tool for the study of different aspects of neuroblastoma, namely tumorigenicity, metastasis, angiogenesis, drug sensitivity, and drug resistance.