In-Ovo Imaging Using Embryonated Eggs of Large Ratite Birds - Evaluation of an Alternative to Classic Animal Research

• Applicants: Professor Dr. Martin Freesmeyer; Dr. Thomas Winkens
• Subject Area: Medical Physics, Biomedical Technology ; Nuclear Medicine, Radiotherapy, Radiobiology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 436834475

In-Ovo Imaging Using Embryonated Eggs of Large Ratite Birds - Evaluation of an Alternative to Classic Animal ResearchPreclinical imaging represents a cornerstone in research, predominately using small mammals , e.g. rats and mice. As an alternative in-ovo imaging using embryonated chicken eggs has been described before.According to national and international animal protection laws, research with embryonated eggs is not considered animal research if all experiments are performed before hatching. Thus, in-ovo imaging represents an alternative to classic animal research, meeting the requirements of reduction and replacement of animal research. Additionally, artificial incubation of eggs is less elaborate than keeping of small mammals for classic animal research.Due to the small size of previously used embryonated chicken eggs, dedicated small animal imaging devices (CT, MRI, PET, SPECT; or the combination) are necessary to depict the very small embryonal structures. However, considering PET imaging, these devices exhibit disadvantages, especially regarding the use of widely-used radionuclides as Ga-68 and I-124 with high photon energy. Furthermore, the initial costs of small animal imaging devices, premises, maintenance and adequate personnel limit their accessibility. A potential solution for the abovementioned problems might be the use of embryonated eggs of large ratite birds.Our research group has developed an in-ovo imaging concept using ostrich eggs (Struthio camelus), bypassing the need for small animal imaging devices. These eggs have been investigated with regular scanners used for humans in clinical routine. Ostrich eggs are as large as 20 x 15cm and the embryonal structures can be visualized with CT, MRI, PET and SPECT.First experiments using a regular PET/CT scanner have shown that established and newly designed radiopharmaceuticals are distributed within embryonal structures and visualization of distribution patterns is feasible. However, numerous limitations have been identified requiring methodological refinement. Furthermore, it is necessary to investigate reproducibility of PET measurements to evaluate the potential of in-ovo imaging as an alternative to classic animal research. The goals of the project are 1) methodological optimization regarding embryonal immobilization during imaging, 2) non-invasive investigation of embryonal development to assess the success of artificial incubation and 3) refinement of data acquisition and reconstruction parameters of a PET/CT-scanner and evaluation of measurement reproducibility using established radiopharmaceuticals. A fourth goal is the validation of newly-designed liver-directed radiopharmaceuticals.

• DFG Programme: Research Grants