The Chick Chorioallantoic Membrane (CAM) as a Multi‐Purpose Preclinical Model in Oncology

Abstract

The chorioallantoic membrane (CAM) of fertilized chick eggs is a preclinical in vivo model and an alternative or pretest for animal studies in rodents. Although the CAM xenotransplantation model is a reproducible, reliable and efficient model conforming to the 3R principle to reduce mammalian animal experiments, and the United States Food and Drug Administration recommended the CAM for in vivo studies on angiogenesis, the method is not very common so far. Undoubtedly, the CAM assay has its limitations: The experimental window of about 10 days is a limiting factor hampering the establishment of the model in oncology. Here we show the implementation of the CAM model in oncological research on modern diagnostics and therapeutics. Tumor cells were xenotransplanted onto the chorioallantoic membrane, which serves as nutritious natural substrate for their growth and allows the three‐dimensional formation of solid tumors in an in vivo microenvironment. We successfully transplanted cancer cells stably expressing firefly luciferase, e.g. breast and lung cancer cells, and established methods for direct in ovo monitoring after the topical or intravenous administration of diagnostics or therapeutics. Upon administration of doxorubicin, a commonly used chemotherapeutic, the growth of cancer xenografts on the CAM was monitored by bioluminescence imaging using an IVIS in vivo Imaging System after the application of D‐luciferin for up to 3 days after treatment. The obtained results were quantified and validated by immunohistochemical analysis of proliferation and apoptosis (Ki‐67, Tdt) upon tumor tissue extraction. After labelling of compounds with gadolinium (Gd) as a contrast agent, high‐resolution magnetic resonance (MR) imaging at several time‐points enabled the evaluation of the compound's bio‐distribution and accumulation in tumor tissue. To confirm the MR findings, organs were extracted and analyzed for the Gd contents by inductively coupled plasma optical emission spectrometry (ICP‐OES).These methods facilitate the straightforward and non‐invasive assessment of a compound's therapeutic efficacy and biodistribution and therefore possess implications for the development of new pharmacological substances.The studies were conducted in conformance with the FASEB Statement of Principles for the use of Animals in Research and Education.Support or Funding InformationThis work was supported by the Volkswagen Foundation.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.