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.

Automated GMP Production and Preclinical Evaluation of [68Ga]Ga-TEoS-DAZA and [68Ga]Ga-TMoS-DAZA.

[68Ga]Ga-TEoS-DAZA and [68Ga]Ga-TMoS-DAZA are two novel radiotracers suitable for functional PET liver imaging. Due to their specific liver uptake and biliary excretion, the tracers may be applied for segmental liver function quantification, gall tree imaging and the differential diagnosis of liver nodules. The purpose of this study was to investigate problems that occurred initially during the development of the GMP compliant synthesis procedure and to evaluate the tracers in a preclinical model. After low radiolabeling yields were attributed to precursor instability at high temperatures, an optimized radiolabeling procedure was established. Quality controls were in accordance with Ph. Eur. requirements and gave compliant results, although the method for the determination of the 68Ga colloid is partially inhibited due to the presence of a radioactive by-product. The determination of logP revealed [68Ga]Ga-TEoS-DAZA (ethoxy bearing) to be more lipophilic than [68Ga]Ga-TMoS-DAZA (methoxy bearing). Accordingly, biodistribution studies in an in ovo model showed a higher liver uptake for [68Ga]Ga-TEoS-DAZA. In dynamic in ovo PET imaging, rapid tracer accumulation in the liver was observed. Similarly, the activity in the intestines rose steadily within the first hour p.i., indicating biliary excretion. As [68Ga]Ga-TEoS-DAZA and [68Ga]Ga-TMoS-DAZA can be prepared according to GMP guidelines, transition into the early clinical phase is now possible.

In-ovo imaging using ostrich eggs: Biomagnetism for detection of cardiac signals and embryonal motion.

In-ovo imaging using ostrich eggs has been described as a potential alternative to common animal testing. The main advantage is its independence from small animal imaging devices as ostrich eggs provide good image quality on regular CT, MRI, or PET used in examinations of humans. However, embryonal motion during dynamic imaging studies produce artifacts. The aims of this study were (1) to explore the feasibility of biomagnetism to detect cardiac signals and embryonal motion and to use these findings (2) to investigate the effect of isoflurane anesthesia on ostrich embryos. A standard magnetoencephalography developed for brain studies was used to detect embryonal signals of ostrich eggs on developmental day 34. Signals were instantly shown on a screen and data were also postprocessed. For assessing the effects of anesthesia, nine ostrich eggs were investigated using isoflurane 6% for 90 min. Biomagnetic signals were recorded simultaneously. A control group consisting of eight different ostrich eggs was also investigated. Cardiac signals similar to electrocardiography were observed in all eggs. Postprocessing revealed frequent motion of embryos without anesthesia. The exposure to isoflurane led to a significant decrease in motion signals in 9/9 ostrich embryos after 8 min. Motion was significantly reduced in the isoflurane group versus control group. There were no isoflurane-related deaths. This study shows that biomagnetism is feasible to detect cardiac signals and motion of ostrich embryos in-ovo. Application of isoflurane is safe and leads to a rapid decrease in embryonal motion, which is an important prerequisite for the implementation of in-ovo imaging using ostrich eggs.