The avian chorioallantoic membrane as an alternative tool to study medullary thyroid cancer

The chicken chorioallantoic membrane assay revisited - A face-lifted approach for new perspectives in placenta research

The study of very early human placentation is largely limited due to ethical restrictions on the use of embryonic tissue and the fact that the placental anatomy of common laboratory animal models varies considerably from that of humans. In recent years several promising models, including trophoblast stem cell-derived organoids, have been developed that have also proven useful for the study of important trophoblast differentiation processes. However, the consideration of maternal blood flow in trophoblast invasion models currently appears to be limited to animal models. An almost forgotten model to study the invasive behavior of trophoblasts is to culture them in vitro on the chicken chorioallantoic membrane (CAM), showing an extraembryonic vascular network in its mesenchymal stroma that is continuously perfused by the chicken embryonic blood circulation. Here, we present an extension of the previously described ex ovo CAM assay and describe the use of cavity-bearing trophoblast spheroids obtained from the first trimester cell line ACH-3P. We demonstrate how spheroids penetrated the CAM and that erosion of CAM vessels by trophoblasts led to filling of the spheroid cavities with chicken blood, mimicking initial steps of intervillous space blood perfusion. Moreover, we prove that this model is useful for state-of-the-art techniques including immunofluorescence and in situ padlock probe hybridization, making it a versatile tool to study aspects of trophoblast invasion in presence of blood flow.

Experimental Tumor Induction and Evaluation of Its Treatment in the Chicken Embryo Chorioallantoic Membrane Model: A Systematic Review

The chorioallantoic membrane (CAM) model, generated during avian development, can be used in cancer research as an alternative in vivo model to perform tumorigenesis in ovo due to advantages such as simplicity, low cost, rapid growth, and being naturally immunodeficient. The aim of this systematic review has been to compile and analyze all studies that use the CAM assay as a tumor induction model. For that, a systematic search was carried out in four different databases: PubMed, Scopus, Cochrane, and WOS. After eliminating duplicates and following the established inclusion and exclusion criteria, a total of 74 articles were included. Of these, 62% use the in ovo technique, 13% use the ex ovo technique, 9% study the formation of metastasis, and 16% induce tumors from patient biopsies. Regarding the methodology followed, the main species used is chicken (95%), although some studies use quail eggs (4%), and one article uses ostrich eggs. Therefore, the CAM assay is a revolutionary technique that allows a simple and effective way to induce tumors, test the effectiveness of treatments, carry out metastasis studies, perform biopsy grafts of patients, and carry out personalized medicine. However, unification of the methodology used is necessary.

Gold Nanoparticles Inhibit Extravasation of Canine Osteosarcoma Cells in the Ex Ovo Chicken Embryo Chorioallantoic Membrane Model

Canine osteosarcoma (OS) is an aggressive bone tumor with high metastatic potential and poor prognosis, mainly due to metastatic disease. Nanomedicine-based agents can be used to improve both primary and metastatic tumor treatment. Recently, gold nanoparticles were shown to inhibit different stages of the metastatic cascade in various human cancers. Here, we assessed the potential inhibitory effect of the glutathione-stabilized gold nanoparticles (Au-GSH NPs) on canine OS cells extravasation, utilizing the ex ovo chick embryo chorioallantoic membrane (CAM) model. The calculation of cells extravasation rates was performed using wide-field fluorescent microscopy. Transmission electron microscopy and Microwave Plasma Atomic Emission Spectroscopy revealed Au-GSH NPs absorption by OS cells. We demonstrated that Au-GSH NPs are non-toxic and significantly inhibit canine OS cells extravasation rates, regardless of their aggressiveness phenotype. The results indicate that Au-GSH NPs can act as a possible anti metastatic agent for OS treatment. Furthermore, the implemented CAM model may be used as a valuable preclinical platform in veterinary medicine, such as testing anti-metastatic agents.

In ovo chorioallantoic membrane assay as a xenograft model for pediatric rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common highly malignant pediatric soft tissue sarcoma. While recent multidisciplinary treatments have improved the 5‑year survival rate of low/intermediate‑risk patients to 70‑90%, there are various complications that arise due to treatment‑related toxicities. Immunodeficient mice‑derived xenograft models have been widely used in cancer drug research; however, these models have some limitations, including i) they are time‑consuming and expensive, ii) their use needs to be approved by animal experimental ethics committees, and iii) the inability to visualize where tumor cells or tissues were engrafted. The present study performed a chorioallantoic membrane (CAM) assay in fertilized chicken eggs, which is time‑saving, simple, and easy to standardize and handle because of the high vascularization and the immature immune system of the fertilized eggs. The present study aimed to examine the usability of the CAM assay as a novel therapeutic model for the development of precision medicine for pediatric cancer. A protocol was developed for constructing cell line‑derived xenograft (CDX) models using a CAM assay by transplanting RMS cells on the CAM. It was then examined as to whether these CDX models could be used as therapeutic drug evaluation models using vincristine (VCR) and human RMS cell lines. After grafting and culturing the RMS cell suspension on the CAM, three‑dimensional proliferation over time was observed visually and by comparing volumes. VCR reduced the size of the RMS tumor on the CAM in a dose‑dependent manner. Currently, treatment strategies based on patient‑specific oncogenic backgrounds have not been adequately developed in the field of pediatric cancer. The establishment of a CDX model with the CAM assay may lead to the advancement of precision medicine and help formulate novel therapeutic strategies for intractable pediatric cancer.

Disease Animal Models for Cancer Research

Despite nonanimal methods (NAMs) are more and more exploited and new NAMs are developed and validated, animal models are still used in cancer research. Animals are used at multiple levels, from understanding molecular traits and pathways, to mimicking clinical aspects of tumor progression, to drug testing. In vivo approaches are not trivial and involve cross-disciplinary knowledge: animal biology and physiology, genetics, pathology, and animal welfare.The aim of this chapter is not to list and address all animal models used in cancer research. Instead, the authors would like to guide experimenters in the strategies to adopt in both planning and performing in vivo experimental procedures, including the choice of cancer animal models.

In ovo model in cancer research and tumor immunology

Considering cancer not only as malignant cells on their own but as a complex disease in which tumor cells interact and communicate with their microenvironment has motivated the establishment of clinically relevant 3D models in past years. Technological advances gave rise to novel bioengineered models, improved organoid systems, and microfabrication approaches, increasing scientific importance in preclinical research. Notwithstanding, mammalian in vivo models remain closest to mimic the patient’s situation but are limited by cost, time, and ethical constraints. Herein, the in ovo model bridges the gap as an advanced model for basic and translational cancer research without the need for ethical approval. With the avian embryo being a naturally immunodeficient host, tumor cells and primary tissues can be engrafted on the vascularized chorioallantoic membrane (CAM) with high efficiencies regardless of species-specific restrictions. The extraembryonic membranes are connected to the embryo through a continuous circulatory system, readily accessible for manipulation or longitudinal monitoring of tumor growth, metastasis, angiogenesis, and matrix remodeling. However, its applicability in immunoncological research is largely underexplored. Dual engrafting of malignant and immune cells could provide a platform to study tumor-immune cell interactions in a complex, heterogenic and dynamic microenvironment with high reproducibility. With some caveats to keep in mind, versatile methods for in and ex ovo monitoring of cellular and molecular dynamics already established in ovo are applicable alike. In this view, the present review aims to emphasize and discuss opportunities and limitations of the chicken embryo model for pre-clinical research in cancer and cancer immunology.

The chorioallantoic membrane as a bio-barrier model for the evaluation of nanoscale drug delivery systems for tumour therapy

In 2010, the European Parliament and the European Union adopted a directive on the protection of animals used for scientific purposes. The directive aims to protect animals in scientific research, with the final goal of complete replacement of procedures on live animals for scientific and educational purposes as soon as it is scientifically viable. Furthermore, the directive announces the implementation of the 3Rs principle: "When choosing methods, the principles of replacement, reduction and refinement should be implemented through a strict hierarchy of the requirement to use alternative methods." The visibility, accessibility, and the rapid growth of the chorioallantoic membrane (CAM) offers a clear advantage for various manipulations and for the simulation of different Bio-Barriers according to the 3R principle. The extensive vascularisation on the CAM provides an excellent substrate for the cultivation of tumour cells or tumour xenografts which could be used for the therapeutic evaluation of nanoscale drug delivery systems. The tumour can be targeted either by topical application, intratumoural injection or i.v. injection. Different application sites and biological barriers can be examined within a single model.

Applications of the Chick Chorioallantoic Membrane as an Alternative Model for Cancer Studies

A variety of in vivo experimental models have been established for the studies of human cancer using both cancer cell lines and patient-derived xenografts (PDXs). In order to meet the aspiration of precision medicine, the in vivomurine models have been widely adopted. However, common constraints such as high cost, long duration of experiments, and low engraftment efficiency remained to be resolved. The chick embryo chorioallantoic membrane (CAM) is an alternative model to overcome some of these limitations. Here, we provide an overview of the applications of the chick CAM model in the study of oncology. The CAM model has shown significant retention of tumor heterogeneity alongside increased xenograft take rates in several PDX studies. Various imaging techniques and data analysis have been applied to study tumor metastasis, angiogenesis, and therapeutic response to novel agents. Lastly, to practically illustrate the feasibility of utilizing the CAM model, we summarize the general protocol used in a case study utilizing an ovarian cancer PDX.

Melanoma xenotransplant on the chicken chorioallantoic membrane: a complex biological model for the study of cancer cell behaviour

The globally increasing incidence of cancer, including melanoma, requires novel therapeutic strategies. Development of successful novel drugs is based on clear identification of the target mechanisms responsible for the disease progression. The specific cancer microenvironment represents a critically important aspect of cancer biology, which cannot be properly studied in simplistic cell culture conditions. Among other traditional options, the study of melanoma cell growth on the chicken chorioallantoic membrane offers several significant advantages. This model offers increased complexity compared to usual in silico culture models and still remains financially affordable. Using this model, we studied the growth of three established human melanoma cell lines: A2058, BLM, G361. The combination of histology, immunohistochemistry with the application of human-specific antibodies, intravascular injection of contrast material such as filtered Indian ink, Mercox solution and phosphotungstic acid, and X-ray micro-CT and live-cell monitoring was employed. Melanoma cells spread well on the chicken chorioallantoic membrane. However, invasion into the stroma of the chorioallantoic membrane and the limb primordium graft was rare. The melanoma cells also significantly influenced the architecture of the blood vessel network, resulting in the orientation of the vessels to the site of the tumour cell inoculation. The system of melanoma cell culture on the chorioallantoic membrane is suitable for the study of melanoma cell growth, particularly of rearrangement of the host vascular pattern after cancer cell implantation. The system also has promising potential for further development.