Development and validation of the chick embryo tumour model for assessment of cancer combination therapies

Introduction:
The Chorioallantoic Membrane (CAM), also known as the chorioallantois, is a highly vascularized membrane found in the eggs of certain amniotes like birds and reptiles. It is formed by the fusion of the mesodermal layers of two extra-embryonic membranes – the chorion and the allantois and it is the avian homologue of the mammalian placenta. It is the outermost extra-embryonic membrane which lines the nonvascular egg shell membrane. Given the characteristics of this membrane, researchers have been investigating the use of the CAM for as a cheaper in vivo model replacement for Murine models which can reduce and replace procedures in rodents.
Material and Methods:
Procedures were undertaken using white leg horn chicken eggs which were grown in humidified rotating incubators for 3 days before undergo windowing, tumour cell implantation and treatment with drugs or irradiation or nanoparticles on specific days of gestation. A variety of cells were used to grow tumours on the CAM including; Pancreatic, Triple Negative Breast Cancer and Glioblastoma cells. The development of these tumours are monitored from implantation until the end point by visual inspection and imaging under microscope.
Results and Discussions:
The CAM model has successfully produced tumours from a variety of different cancers that have been transfected with GFP, to allow clear distinction between cancer cells and cells belonging to the embryo. We were able to track metastasis through the membrane and measure the volume of tumour growth on the CAM. It was established that the dose of chemotherapeutic drugs and irradiation that are used to treat developing tumours do not kill the embryos.
Conclusion:
We have successfully developed the methodology from the CAM tumour models, and established the replicability of the model. Including which cell type established the more desirable tumours and allows for investigation of metastasis. our next stage of the investigation will be to develop and adapt irradiation methodologies in the developed tumours of the chick embryo model for single or combination treatment and to validate the model by comparison to our existing mouse xenograft data. Finally, we will screen for the efficacy of drugs or nanomaterials alone or in combination.