THE GROWTH OF LEPTOSPIRA ICTEROHEMORRHAGIAE ON THE CHORIOALLANTOIC MEMBRANE OF THE CHICK EMBRYO

Chorioallantoic Membrane Models of Various Avian Species: Differences and Applications

The chorioallantoic membrane model (CAM) of an avian embryo is used as an experimental model in various fields of research, including angiogenesis research and drug testing, xenografting and cancer research, and other scientific and commercial disciplines in microbiology, biochemistry, cosmetics, etc. It is a low-cost, low-maintenance, and well-available in vivo animal model that is non-sentient and can be used as an alternative for other mammal experimental models. It respects the principles of the "3R" rule (Replacement, Reduction, and Refinement)-conditions set out for scientific community providing an essential framework for conducting a more human animal research, which is also in line with constantly raising public awareness of welfare and the ethics related to the use of animal experimental models. In this review, we describe the chorioallantoic membrane of an avian embryo, focusing on its properties and development, its advantages and disadvantages as an experimental model, and the possibilities of its application in various fields of biological research. Since the most common chicken CAM model is already well known and described in many publications, we are particularly focusing on the advantages and application of less known avian species that are used for the CAM model-quail, turkey, and duck.

Chorioallantoic Membrane Assay as Model for Angiogenesis in Tissue Engineering: Focus on Stem Cells

Tissue engineering aims to structurally and functionally regenerate damaged tissues, which requires the formation of new blood vessels that supply oxygen and nutrients by the process of angiogenesis. Stem cells are a promising tool in regenerative medicine due to their combined differentiation and paracrine angiogenic capacities. The study of their proangiogenic properties and associated potential for tissue regeneration requires complex in vivo models comprising all steps of the angiogenic process. The highly vascularized extraembryonic chorioallantoic membrane (CAM) of fertilized chicken eggs offers a simple, easy accessible, and cheap angiogenic screening tool compared to other animal models. Although the CAM assay was initially primarily performed for evaluation of tumor growth and metastasis, stem cell studies using this model are increasing. In this review, a detailed summary of angiogenic observations of different mesenchymal, cardiac, and endothelial stem cell types and derivatives in the CAM model is presented. Moreover, we focus on the variation in experimental setup, including the benefits and limitations of in ovo and ex ovo protocols, diverse biological and synthetic scaffolds, imaging techniques, and outcome measures of neovascularization. Finally, advantages and disadvantages of the CAM assay as a model for angiogenesis in tissue engineering in comparison with alternative in vivo animal models are described. Impact statement The chorioallantoic membrane (CAM) assay is an easy and cheap screening tool for the angiogenic properties of stem cells and their associated potential in the tissue engineering field. This review offers an overview of all published angiogenic studies of stem cells using this model, with emphasis on the variation in used experimental timeline, culture protocol (in ovo vs. ex ovo), stem cell type (derivatives), scaffolds, and outcome measures of vascularization. The purpose of this overview is to aid tissue engineering researchers to determine the ideal CAM experimental setup based on their specific study goals.

Establishment of xenografts of urological cancers on chicken chorioallantoic membrane (CAM) to study metastasis

Cancer of the urological system commonly occurs in the kidney, bladder, and prostate gland. The clear cell subtype of renal cell carcinoma (ccRCC) constitutes the great majority of kidney cancer. Metastatic ccRCC portends a very poor outcome with no effective treatment available. Prostate cancer is the most common cancer in males in the US. Despite recent advances in selective kinase inhibitors and immunotherapies, the rate of developing new treatment from bench to bedside is slow. A time-consuming step is at the animal drug testing stage, in which the mouse model is the gold standard. In the pursuit to streamline the in vivo cancer biology research and drug development, we explored the feasibility of the chicken chorioallantoic membrane (CAM) model to establish xenografts. The CAM model greatly shortens the time of tumor growth and lowers the cost comparing to immunocompromised mice. We generated CAM xenografts from ccRCC, bladder and prostate cancer, with established cancer cell lines and freshly isolated patient-derived tissues, either as primary tumor cells or small pieces of tumors. The successful CAM engraftment rate from the different tumor sources is 70% or above. Using our previously established metastatic ccRCC mouse model, we showed that the CAM xenograft maintains the same tumor growth pattern and metastatic behavior as observed in mice. Taken together, CAM can serve as a valuable platform to establish new patient-derived xenografts (PDXs) to study tumor biology, thus accelerating the development of individualized treatment to halt the deadly metastatic stage of cancer.

The chicken chorioallantoic membrane model in biology, medicine and bioengineering

The chicken chorioallantoic membrane (CAM) is a simple, highly vascularized extraembryonic membrane, which performs multiple functions during embryonic development, including but not restricted to gas exchange. Over the last two decades, interest in the CAM as a robust experimental platform to study blood vessels has been shared by specialists working in bioengineering, development, morphology, biochemistry, transplant biology, cancer research and drug development. The tissue composition and accessibility of the CAM for experimental manipulation, makes it an attractive preclinical in vivo model for drug screening and/or for studies of vascular growth. In this article we provide a detailed review of the use of the CAM to study vascular biology and response of blood vessels to a variety of agonists. We also present distinct cultivation protocols discussing their advantages and limitations and provide a summarized update on the use of the CAM in vascular imaging, drug delivery, pharmacokinetics and toxicology.