The chick embryo; a new drug delivery model for neuroblastoma

Neuroblastoma (NB) commonly presents as high risk disease which despite intensive multimodal therapies is often fatal. Preclinical models are required to aid the development of novel therapeutics for this challenging childhood malignancy, however current systems are complex and inherently costly. We aimed to explore the ability of the chick embryo to act as a new tool for NB therapeutic research. "High risk"- MYCN amplified human neuroblastoma cells were xenografted on to the surface of the chick embryo chorioallantoic membrane (CAM) and tumours allowed to form over a 7 day period. qPCR was used to detect the effects of a differentiation agent, retinoic acid (RA), firstly on NB cells in culture, and then on NB tumours in the chick embryo model. Tumours formed in the chick embryo model 4 days after the introduction of NB cells on to the CAM. After 7 days, analysis of fully formed tumours demonstrated active proliferation and vascular recruitment from the surrounding CAM. In culture, RA induced morphological changes consistent with the differentiation of NB cells. RT-qPCR identified reproducible changes in gene expression in response to RA. Increased expression of differentiation markers ROBO2 and STMN4 and decreased expression of the stem cell marker KLF4 was observed in cell culture. Similar changes in the expression of these genes were also seen during in vivo chick embryo experiments. Against expectations, levels of the MYCN transcription factor did not fall significantly following 3 days of RA treatment during in vitro or in vivo experimentation. These results suggest that other targets may also be involved in the RA induced differentiation of these cells. We have observed the ability of the chick embryo to act as an in vivo model system for NB therapeutic research. Reproducible changes in gene expression induced by the administration of retinoic acid have been detected using this model