Assessment of the developing Chick Embryo as an in vivo pharmacology model for undergraduate teaching

Pharmacology is the study of the use, effect and mechanism of action of drugs in living organisms. Thus, it is important for undergraduate pharmacology students to gain experience of the action of drugs in vitro but also in vivo. However, only 2% of students are taught in vivo skills. This lack of practical in vivo experimental laboratories at undergraduate level is mainly due to the cost of rodents, the requirement for a Home Office animal licence and also public concern regarding the use of animals in experimentation.

In the pharmaceutical industry and scientific research, the chick embryo model has gained increased interest as a cheaper in vivo replacement model than rodent models to study the pharmacokinetics, biodistribution, efficacy and toxicology of drugs. During the development of fertilised eggs, a rich vascular network is generated between the double layers of the chorrioallantoic membrane (CAM). This vascular network fuses closely underneath the eggshell and is connected to the embryonic circulation via the allantoic stalk. The CAM system have been widely reported to be a good in vivo model system for studying the effect of pharmacological agents on angiogenesis and human tumour growth. Experimentally the chick embryo can be used for pharmacology studies for up to 14 days (2/3 of the embryonic development period) without an animal licence. Using White Leghorn Chick Embryos, we have developed the model for assessment of cancer tumour growth, toxicology of a range of cancer drugs and nanoparticles as well as assessment of drug and DNA delivery vehicles such as liposomes and gold nanoparticles.

We now aim to use the model within a teaching environment for the demonstration of fundamental pharmacologic principles and techniques. The CAM is low-cost and exempt from much of the regulation and ethical challenges associated with conventional in vivo models. The use of the model is accessible as it is technically simple and students can learn the appropriate techniques quickly and thus can then apply the model to a range of pharmacological experimentation and gain robust experimental data in a relatively short time frame. We have already trialled the model with Master’s students, and now propose to scale this up for inclusion in undergraduate Pharmacology Laboratories.