Go North: Expanding the use of the chick embryo model in cancer research to a multiuser facility at the University of Strathclyde.

Cancer is one of the leading causes of death in the UK. The majority of cancer deaths are caused by aggressive cancer cells, which resist treatment by various mechanisms. Despite advances in targeting cancer, new therapies are urgently needed to increase patient survival, especially in cancer of the brain, head and neck or in children, where treatment therapies are often limited due to their severity. To understand how, when and why cancer cells spread and evaluate novel therapies, mouse or rat models of cancer are most commonly used in research. To study tumour formation and metastasis, adult mice or rats often have to undergo invasive procedures. These can cause pain, suffering and distress to the animal, which could be eliminated by using an immature model. Here, we propose to replace mouse and rat experiments with the chick embryo tumour model. The chick embryo model is classified as non-protected under the Animals Scientific Procedures Act, and so is a useful technique to replace research in live animals. It has many additional advantages over mouse models, including cost effectiveness, accessibility and speed. It is an excellent model to study the growth and spread of tumour cells, as they can be easily engrafted onto the "chorioallantoic membrane". This is an accessible surface, located outside the chick embryo directly beneath the eggshell, with a good supply of blood vessels. Within a few days, a small tumour develops, which can spread across and into the membrane, potentially accessing blood vessels to spread to specific organs. Importantly, new drug treatments can be readily tested in the chick embryo model, and the tumour cells imaged over time to assess their survival and behaviour.

We have successfully developed and used this model during the past 8 years and applied it to a range of cancer types, including cancer of the breast, head and neck and neuroblastoma, a paediatric cancer. We have developed SOPs for its use in observing tumour burden as well as response to therapies. While its uptake locally (Liverpool) has been excellent, other interested parties might see the need of specialised equipment as an obstacle to trail the new 3R complaint method. To overcome this potential hurdle and ensure a wide uptake, we will transfer our skills and knowledge from the CEF in Liverpool to Glasgow. To do this we will train end users as well as a specialised animal technician of the UoS's animal unit in all methods, but also establish a new chick embryo facility in Glasgow that is open to all users. We will enable free trial experiments and assist new users in their experiments, from planning to successful completion and/or novel methodology development. The knowledge pool in Liverpool will also be enhanced as the specialised irradiation therapy protocols developed in this project will be shared with the users there. The strong link between the two CEFs will ensure a constant exchange of protocols and applications ensuring its continued growth. For GBM and NB specifically we will explore this model as a means to test novel radiation therapies alone or in combination with drugs. This will allow us to observe tumour burden in response to treatment and aid the development of novel therapies to treat this deadly disease. It is crucial that apart from the two local communities, the wider cancer research community becomes aware of this model as it would accelerate their research and enable the replacement of a large number of animal experiments. We will therefore advertise it to the research community and share our established standard protocols via a leaflet, website and several joint workshops.

Despite significant advancements in oncology treatments, cancer remains a leading cause of death within the UK, causing more than a quarter of deaths annually (CRUK 2017). As a consequence, current research is focusing on the underlying mechanisms of this disease and the development of new effective therapies. Despite recent advances, in vitro models such as 3D co-culture systems still lack important components crucial for accurately recreating the complex tumour microenvironment. Mammalian animal models are therefore most frequently used for the predictive evaluation of new treatments in cancer. The chick embryo is a unique and powerful alternative with many advantages over rodent models, including its ease of use, portability, nutrition self-sufficiency and low cost. It also negates the need for use of a sentient species. It's main advantage when models for tumour formation are considered is the accessibility of its chorioallantoic membrane (CAM), a highly vascularised extraembryonic membrane that is located directly beneath the eggshell. Thus, tumour cells or biopsies of human or rodent origin can be engrafted easily and non-invasively. Tumour formation occurs within days and we have previously developed multiple protocols for the observation of tumour progression and treatment efficacy in malignancies from the breast, head and neck, lung, colon, pancreas and paediatric malignancies using longitudinal in vivo screening, such as intravital, bioluminescent and magnetic resonance imaging.

Here, we propose to expand the use of a novel 3Rs-compliant in vivo tumour and pre-clinical screening chick embryo model for cancer research by establishing a new chick embryo facility in the BPU of the UoS, which will be used to encourage the reduction and replacement of murine xenograft models in cancer.