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The chorioallantoic membrane (CAM) of the avian embryo is a very useful and applicable tool for various areas of research. A special ex ovo model of Japanese quail CAM is suitable for photodynamic treatment investigation.
The chorioallantoic membrane (CAM) of an avian embryo is a thin, extraembryonic membrane that functions as a primary respiratory organ. Its properties make it an excellent in vivo experimental model to study angiogenesis, tumor growth, drug delivery systems, or photodynamic diagnosis (PDD) and photodynamic therapy (PDT). At the same time, this model addresses the requirement for the replacement of experimental animals with a suitable alternative. Ex ovo cultivated embryo allows easy substance application, access, monitoring, and documentation. The most frequently used is chick CAM; however, this article describes the advantages of the Japanese quail CAM as a low-cost and high-throughput model. Another advantage is the shorter embryonic development, which allows higher experimental turnover. The suitability of quail CAM for PDD and PDT of cancer and microbial infections is explored here. As an example, the use of the photosensitizer hypericin in combination with lipoproteins or nanoparticles as a delivery system is described. The damage score from images in white light and changes in fluorescence intensity of the CAM tissue under violet light (405 nm) was determined, together with analysis of histological sections. The quail CAM clearly showed the effect of PDT on the vasculature and tissue. Moreover, changes like capillary hemorrhage, thrombosis, lysis of small vessels, and bleeding of larger vessels could be observed. Japanese quail CAM is a promising in vivo model for photodynamic diagnosis and therapy research, with applications in studies of tumor angiogenesis, as well as antivascular and antimicrobial therapy.
The chicken chorioallantoic membrane (CAM) model is well known and widely used in various areas of research. It is a richly vascularized extraembryonic organ that provides gas exchange and mineral transport1. Due to the transparency and accessibility of this membrane, individual blood vessels and their structural changes can be observed in real time2. Despite the advantages, chick CAM also has some limitations (e.g., larger breeding facilities, egg production, and feed consumption) that could be avoided by using other avian species. In this protocol, an alternative ex ovo CAM model using Japanese quail (Cotu....
The research was performed in compliance with institutional guidelines. All equipment and reagents must be autoclaved or sterilized with 70% ethanol or UV light.
1. Egg incubation
The localization of the tumor on the CAM surface is difficult in white light. Photosensitizer (here, hypericin) used in PDD is expected to be taken up selectively by the tumor and helps visualize the tumor. The addition of hypericin and the use of fluorescent light (e.g., 405 nm) showed the tumor (squamous cell carcinoma TE1) position very well (Figure 6A). Histological analysis showed vital tumor cells invading healthy tissues. Concentric structures of abnormal squamous cells, often de.......
For successful ex ovo cultivation, it is important to follow the protocol above. Moreover, if the eggs are not opened carefully enough or there is insufficient humidity during the cultivation, the yolk sack sticks to the shell and often ruptures. The start of an ex ovo cultivation at the time of about 60 h of egg incubation ensures the high survival rate of the embryos, as they are already large enough to survive the handling. At the later developmental stages, the CAM becomes thinner and adheres to the.......
The work was supported by VEGA 2/0042/21 and APVV 20-0129. The contribution of V. Huntošová is the result of the project implementation: Open scientific community for modern interdisciplinary research in medicine (Acronym: OPENMED), ITMS2014+: 313011V455 supported by the Operational Program Integrated Infrastructure, funded by the ERDF.
....Name | Company | Catalog Number | Comments |
6-Well Cell Culture Plate | Sarstedt | 83.392 | Transparent polystyrene, sterile |
CO2 Incubator ESCO CCL-0508 | ESCO, Singapore | CCL-050B-8 | CO2 cell culture incubator |
cryocut Leica CM 1800 | Reichert-Jung, USA | ||
digital camera Canon EOS 6D II | Canon, Japan | ||
diode laser 405 nm | Ocean Optics, USA | ||
DMSO | Sigma-Aldrich | 67-68-5 | dimethyl sulfoxid |
eosin | Sigma-Aldrich | 15086-94-9 | |
ethanol | Sigma-Aldrich | 64-17-5 | |
fine brush size 2 | Faber-Castell | 281802 | brush for CAM separation and manipulation |
glutaraldehyde | Sigma-Aldrich | 111-30-8 | |
hematoxylin | Sigma-Aldrich | 517-28-2 | |
hypericin | Sigma-Aldrich | 84082-80-4 | |
incubator Bios Midi | Bios Sedlany, Czech Republic | Forced draught incubator for initial incubation | |
incubator Memmert IF160 | Memmert, Germany | Forced air circulation incubator for CAM incubation | |
Kaiser slimlite plano, LED light box | Kaiser, Germany | 2453 | Transilluminator |
LED light 405 nm | custom made circular LED light | ||
macro lens Canon MP- E 65 mm f/2.8 | Canon, Japan | ||
microscope Kapa 2000 | Kvant, Slovakia | optical microscope | |
microtome Auxilab 508 | Auxilab, Spain | manual rotary microtome | |
paraformaldehyde | Sigma-Aldrich | 30525-89-4 | |
Paraplast Plus | Sigma-Aldrich | P3683 | parafin medium for tissue embedding |
PBS | Sigma-Aldrich | P4417 | Phosphate saline buffer |
scissors Castroviejo | Orimed | OR66-108 | micro scissors for CAM separation |
software ImageJ 1.53 | public domain | image processing and analysis program | |
stock solution HDL | Sigma-Aldrich | 437641-10MG | high density lipoproteins |
stock solution LDL | Sigma-Aldrich | 437644-10MG | low density lipoproteins |
Tissue-Tek O.C.T. Compound | Sakura Finetek | 4583 | Optimal Cutting Temperature Compound 118 mL squeeze bottles |
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