Preclinical therapeutics ex ovo quail eggs as a biomimetic automation-ready xenograft platform

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.

CAM Model: Intriguing Natural Bioreactor for Sustainable Research and Reliable/Versatile Testing

We are witnessing the revival of the CAM model, which has already used been in the past by several researchers studying angiogenesis and anti-cancer drugs and now offers a refined model to fill, in the translational meaning, the gap between in vitro and in vivo studies. It can be used for a wide range of purposes, from testing cytotoxicity, pharmacokinetics, tumorigenesis, and invasion to the action mechanisms of molecules and validation of new materials from tissue engineering research. The CAM model is easy to use, with a fast outcome, and makes experimental research more sustainable since it allows us to replace, reduce, and refine pre-clinical experimentation ("3Rs" rules). This review aims to highlight some unique potential that the CAM-assay presents; in particular, the authors intend to use the CAM model in the future to verify, in a microenvironment comparable to in vivo conditions, albeit simplified, the angiogenic ability of functionalized 3D constructs to be used in regenerative medicine strategies in the recovery of skeletal injuries of critical size (CSD) that do not repair spontaneously. For this purpose, organotypic cultures will be planned on several CAMs set up in temporal sequences, and a sort of organ model for assessing CSD will be utilized in the CAM bioreactor rather than in vivo.

A Novel Breast Cancer Xenograft Model Using the Ostrich Chorioallantoic Membrane-A Proof of Concept

The avian chorioallantoic membrane (CAM) assay has attracted scientific attention in cancer research as an alternative or complementary method for in vivo animal models. Here, we present a xenograft model based on the ostrich (struthio camelus) CAM assay for the first time. The engraftment of 2 × 10⁶ breast cancer carcinoma MDA-MB-231 cells successfully lead to tumor formation. Tumor growth monitoring was evaluated in eight fertilized eggs after xenotransplantation. Cancer cells were injected directly onto the CAM surface, close to a well-vascularized area. Histological analysis confirmed the epithelial origin of tumors. The CAM of ostrich embryos provides a large experimental surface for the xenograft, while the comparably long developmental period allows for a long experimental window for tumor growth and treatment. These advantages could make the ostrich CAM assay an attractive alternative to the well-established chick embryo model. Additionally, the large size of ostrich embryos compared to mice and rats could help overcome the limitations of small animal models. The suggested ostrich model is promising for future applications, for example, in radiopharmaceutical research, the size of the embryonal organs may compensate for the loss in image resolution caused by physical limitations in small animal positron emission tomography (PET) imaging.

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.

Chorioallantoic Membrane Assay at the Cross-Roads of Adipose-Tissue-Derived Stem Cell Research

With a history of more than 100 years of different applications in various scientific fields, the chicken chorioallantoic membrane (CAM) assay has proven itself to be an exceptional scientific model that meets the requirements of the replacement, reduction, and refinement principle (3R principle). As one of three extraembryonic avian membranes, the CAM is responsible for fetal respiration, metabolism, and protection. The model provides a unique constellation of immunological, vascular, and extracellular properties while being affordable and reliable at the same time. It can be utilized for research purposes in cancer biology, angiogenesis, virology, and toxicology and has recently been used for biochemistry, pharmaceutical research, and stem cell biology. Stem cells and, in particular, mesenchymal stem cells derived from adipose tissue (ADSCs) are emerging subjects for novel therapeutic strategies in the fields of tissue regeneration and personalized medicine. Because of their easy accessibility, differentiation profile, immunomodulatory properties, and cytokine repertoire, ADSCs have already been established for different preclinical applications in the files mentioned above. In this review, we aim to highlight and identify some of the cross-sections for the potential utilization of the CAM model for ADSC studies with a focus on wound healing and tissue engineering, as well as oncological research, e.g., sarcomas. Hereby, the focus lies on the combination of existing evidence and experience of such intersections with a potential utilization of the CAM model for further research on ADSCs.