The use of the chorio-allantoic membrane of the chick embryo as test for anti-inflammatory activity

Multiple variants of soluble CD146 are involved in Systemic Sclerosis: identification of a novel pro-fibrotic factor

OBJECTIVE

Systemic sclerosis (SSc) is an autoimmune disorder characterized by excessive fibrosis, immune dysfunction and vascular damages, in which expression of many growth factors is deregulated. CD146 was recently described as a major actor in SSc. As CD146 also exists as a circulating soluble form (sCD146) acting as a growth factor in numerous angiogenic- and inflammatory-related pathologies, we sought to identify the mechanisms underlying the generation of sCD146 and characterized the regulation and functions of the different identified variants in SSc.

METHODS

To this end, we performed in vitro experiments, including RNA-seq and antibody arrays, and in vivo experiments using animal models of SSc induced by bleomycin and of hindlimb ischemia.

RESULTS

Multiple forms of sCD146, generated by both shedding and alternative splicing of the primary transcript, were discovered. The shed form of sCD146 was generated from the cleavage of both long and short membrane isoforms of membrane CD146 through Adam10 and Tace metalloproteinases, respectively. In addition, two novel sCD146 splice variants, I5-13-sCD146 and I10-sCD146 were identified. Of interest, I5-13-sCD146 was significantly increased in sera of SSc patients, in particular in patients with pulmonary fibrosis, whereas I10-sCD146 was decreased. Further experiments revealed that shed sCD146 and I10-sCD146 displayed pro-angiogenic activity through FAK and PKCε signalling pathways, respectively, whereas I5-13-sCD146 displayed pro-fibrotic effects through wint1/β-catenin/wisp1 pathway.

CONCLUSION

Variants of sCD146, and in particular the novel I5-13-sCD146 splice variant, could thus constitute novel biomarkers and/or molecular targets for the diagnosis and treatment of SSc, but also of other angiogenesis- or fibrosis-related pathologies.

Microvascular Experimentation in the Chick Chorioallantoic Membrane as a Model for Screening Angiogenic Agents including from Gene-Modified Cells

The chick chorioallantoic membrane (CAM) assay model of angiogenesis has been highlighted as a relatively quick, low cost and effective model for the study of pro-angiogenic and anti-angiogenic factors. The chick CAM is a highly vascularised extraembryonic membrane which functions for gas exchange, nutrient exchange and waste removal for the growing chick embryo. It is beneficial as it can function as a treatment screening tool, which bridges the gap between cell based in vitro studies and in vivo animal experimentation. In this review, we explore the benefits and drawbacks of the CAM assay to study microcirculation, by the investigation of each distinct stage of the CAM assay procedure, including cultivation techniques, treatment applications and methods of determining an angiogenic response using this assay. We detail the angiogenic effect of treatments, including drugs, metabolites, genes and cells used in conjunction with the CAM assay, while also highlighting the testing of genetically modified cells. We also present a detailed exploration of the advantages and limitations of different CAM analysis techniques, including visual assessment, histological and molecular analysis along with vascular casting methods and live blood flow observations.

The Chicken Embryo Model: A Novel and Relevant Model for Immune-Based Studies

Dysregulation of the immune system is associated with many pathologies, including cardiovascular diseases, diabetes, and cancer. To date, the most commonly used models in biomedical research are rodents, and despite the various advantages they offer, their use also raises numerous drawbacks. Recently, another in vivo model, the chicken embryo and its chorioallantoic membrane, has re-emerged for various applications. This model has many benefits compared to other classical models, as it is cost-effective, time-efficient, and easier to use. In this review, we explain how the chicken embryo can be used as a model for immune-based studies, as it gradually develops an embryonic immune system, yet which is functionally similar to humans'. We mainly aim to describe the avian immune system, highlighting the differences and similarities with the human immune system, including the repertoire of lymphoid tissues, immune cells, and other key features. We also describe the general in ovo immune ontogeny. In conclusion, we expect that this review will help future studies better tailor their use of the chicken embryo model for testing specific experimental hypotheses or performing preclinical testing.

Utilisation of Chick Embryo Chorioallantoic Membrane as a Model Platform for Imaging-Navigated Biomedical Research

The fertilised chick egg and particularly its chorioallantoic membrane (CAM) have drawn continuing interest in biomedicine and bioengineering fields, especially for research on vascular study, cancer, drug screening and development, cell factors, stem cells, etc. This literature review systemically introduces the CAM's structural evolution, functions, vascular features and the circulation system, and cell regulatory factors. It also presents the major and updated applications of the CAM in assays for pharmacokinetics and biodistribution, drug efficacy and toxicology testing/screening in preclinical pharmacological research. The time course of CAM applications for different assays and their advantages and limitations are summarised. Among these applications, two aspects are emphasised: (1) potential utility of the CAM for preclinical studies on vascular-disrupting agents (VDAs), promising for anti-cancer vascular-targeted therapy, and (2) modern imaging technologies, including modalities and their applications for real-time visualisation, monitoring and evaluation of the changes in CAM vasculature as well as the interactions occurring after introducing the tested medical, pharmaceutical and biological agents into the system. The aim of this article is to help those working in the biomedical field to familiarise themselves with the chick embryo CAM as an alternative platform and to utilise it to design and optimise experimental settings for their specific research topics.

Tumor grafted - chick chorioallantoic membrane as an alternative model for biological cancer research and conventional/nanomaterial-based theranostics evaluation

Introduction: Advancements in cancer management and treatment are associated with strong preclinical research data, in which reliable cancer models are demanded. Indeed, inconsistent preclinical findings and stringent regulations following the 3Rs principle of reduction, refinement, and replacement of conventional animal models currently pose challenges in the development and translation of efficient technologies. The chick embryo chorioallantoic membrane (CAM) is a system for the evaluation of treatment effects on the vasculature, therefore suitable for studies on angiogenesis. Apart from vascular effects, the model is now increasingly employed as a preclinical cancer model following tumor-grafting procedures.Areas covered: The broad application of CAM tumor model is highlighted along with the methods for analyzing the neoplasm and vascular system. The presented and cited investigations focus on cancer biology and treatment, encompassing both conventional and emerging nanomaterial-based modalities.Expert opinion: The CAM tumor model finds increased significance given the influences of angiogenesis and the tumor microenvironment in cancer behavior, then providing a qualified miniature system for oncological research. Ultimately, the establishment and increased employment of such a model may resolve some of the limitations present in the standard preclinical tumor models, thereby redefining the preclinical research workflow.

Iodixanol as a Contrast Agent in a Fibrin Hydrogel for Endodontic Applications

The application of biomaterials used in regenerative endodontics should be traceable. In this study, we checked some basic effects of rendering a fibrin hydrogel radiopaque using an iodine-based contrast agent (iodixanol) approved for systemic application. Fibrin hydrogels were prepared from a fibrin sealant (Tisseel) using either an isotonic iodixanol solution (Visipaque 320, test) or Tris buffer (control) as a diluent. Gelation kinetics, radiopacity, and swelling of lyophilized hydrogels were tested using standard methods. Hydrogel structure was evaluated using scanning electron microscopy (SEM). Furthermore, iodixanol release from the test gels was assessed using spectrophotometry, and tissue compatibility was compared between test and control hydrogels using the chick chorioallantoic membrane (CAM) assay. Results were compared using pairwise t-test, p < 0.05. Iodixanol caused a 70-fold delay in gelation to 26 min in the test compared to the control hydrogels (22 ± 1 s). Radiopacity of the test gels was 1.9 ± 0.2 mm Al/mm, compared to zero in the control hydrogels. Lyophilized hydrogel swelling was strongly reduced when iodixanol was added to the hydrogel (p < 0.05). Test hydrogels had an altered SEM appearance compared to controls, and exhibited a reduced porosity. Iodixanol release from the test hydrogels reached 14.5 ± 0.5% after 120 h and then ceased. This release did not have any apparent toxic effect and neither affected the viability, nor the physiology or vascularization of the CAM of fertilized chicken eggs. Iodixanol can render a fibrin hydrogel radiopaque and maintains its tissue compatibility, yet impacts gelation kinetics and hydrogel porosity.

Chapter 2. Chick embryo chorioallantoic membrane models to quantify angiogenesis induced by inflammatory and tumor cells or purified effector molecules

Angiogenesis plays a critical role in many normal physiological processes as well as in tumor neovascularization associated with cancer progression. Among various animal model systems designed to study the mechanisms underlying angiogenesis, chick embryo models have been useful tools in analyzing the angiogenic potential of purified factors and intact cells. The chorioallantoic membrane (CAM), a specialized, highly vascularized tissue of the avian embryo, serves as an ideal indicator of the anti- or pro-angiogenic properties of test compounds. In this chapter, we describe a number basic chick embryo CAM models of angiogenesis. A special emphasis is on the model system employing three-dimensional (3D) collagen grafts planted on the CAM, referred herein as onplants. This collagen onplant model allows for unambiguous quantification of angiogenesis and also for in-depth analysis of the cellular and biochemical mechanisms by which specific cells of different origin or purified effector molecules induce or inhibit the angiogenic process.

Enhancement of implantable glucose sensor function in vivo using gene transfer-induced neovascularization

The in vivo failure of implantable glucose sensors is thought to be largely the result of inflammation and fibrosis-induced vessel regression at sites of sensor implantation. To determine whether increased vessel density at sites of sensor implantation would enhance sensor function, cells genetically engineered to over-express the angiogenic factor (AF) vascular endothelial cell growth factor (VEGF) were incorporated into an ex ova chicken embryo chorioallantoic membrane (CAM)-glucose sensor model. The VEGF-producing cells were delivered to sites of glucose sensor implantation on the CAM using a tissue-interactive fibrin bio-hydrogel as a cell support and activation matrix. This VEGF-cell-fibrin system induced significant neovascularization surrounding the implanted sensor, and significantly enhanced the glucose sensor function in vivo. This model system, for the first time, provides the "proof of principle" that increasing vessel density at the sites of implantation can enhance glucose sensor function in vivo, and demonstrates the potential of gene transfer and tissue interactive fibrin bio-hydrogels in the development of successful implants.

Corticosteroids are unable to protect against pseudorabies virus-induced tissue damage in the developing brain

After intraocular injection of the virulent pseudorabies virus (PRV) strain Becker into late-stage chicken embryos, the virus spreads and replicates in the brain, where severe edema and hemorrhaging follow. By contrast, the attenuated Bartha strain does not cause severe brain pathology despite viral replication and spread throughout the brain (B. W. Banfield, G. S. Yap, A. C. Knapp, and L. W. Enquist, J. Virol. 72:4580-4588, 1998). These observations prompted us to explore the mechanism by which the virulent Becker strain mediates pathology in the chicken embryo central nervous system (CNS). To test the hypothesis that Becker infection induced an inflammatory response in the developing CNS, we examined the ability of the anti-inflammatory corticosteroid dexamethasone (Dex) to protect chicken embryos from PRV-induced brain damage. We found that Dex is not sufficient to protect the chicken embryo CNS from damage due to Becker infection. Surprisingly, systemic Dex delivery appeared to potentiate CNS damage, which was preceded by petechial hemorrhaging in the optic lobes. Taken together, these data suggest that the severe pathology elicited during the Becker infection is due not to immunopathology but to damage by the virus itself, possibly through the damage to or destruction of endothelial cells.