New, Innovative, Three-Dimensional In Vivo Model for High-Level Microsurgical and Supermicrosurgical Training: A Replacement for Animal Models.

SUMMARY: Microsurgery and supermicrosurgery are surgical subdomains necessary for a large variety of surgical disciplines. So far, there is no training model for lymphatic surgery or perforator flap surgery, and the most commonly used microsurgical training models are living animals. However, the ethical principles of replacement, refinement, and reduction (the three Rs) of living animals for training purposes were implemented, highlighting the necessity of an animal-sparing microsurgical training model. Formed during embryogenesis, the chick chorioallantoic membrane resembles a highly vascularized, noninnervated membrane within fertilized chicken eggs. The aim of this study was to utilize the chorioallantoic membrane model as an innovative and versatile training model for supermicrosurgery and microsurgery that can reduce the number of animals used for these purposes. The variety of different sized vessels for the implementation of an anastomosis proved the chorioallantoic membrane model as a well-functioning supermicrosurgical and microsurgical training model. The circulatory system is resilient enough to withstand the mechanical stress applied to the tissue, and the patency of the implemented anastomosis can be tested for the verification of the procedures. In summary, the integration of the chorioallantoic membrane model into a surgical training program can benefit its quality by representing a realistic anatomical and physiological model with a high variety of vascular structures. Moreover, the chorioallantoic membrane model satisfies the principles of replacement, refinement, and reduction as an animal-sparing model, indicating the potential of this model as an innovative microsurgical training model for the improvement of surgical skills.

Extended analysis of intratumoral heterogeneity of primary osteosarcoma tissue using 3D-in-vivo-tumor-model.

BACKGROUND: Osteosarcomas are a rare, heterogeneous and malignant group of bone tumors that have a high potential for metastasis and aggressive growth patterns. Treatment of metastasized osteosarcoma is often insufficient and research is compromised by problems encountered when culturing cells or analyzing genetic alterations due to the high level of intratumoral and intertumoral heterogeneity. The chick chorioallantoic membrane (CAM) model, a 3D-in-vivo-tumor-model, could potentially facilitate the investigation of osteosarcoma heterogeneity at an individual and highly specified level. OBJECTIVE: Objective was to establish the grafting and transplantation of different primary osteosarcoma tissue parts onto several consecutive CAMs for tumor profiling and investigation of osteosarcoma heterogeneity. METHODS: Various parts of primary osteosarcoma tissue were grafted onto CAMs and were transplanted onto another CAM for five to seven consecutive times, enabling further experimental analyzes. RESULTS: Primary osteosarcoma tissue parts exhibited satisfactory growth patterns and displayed angiogenic development on the CAM. It was possible to graft and transplant different tumor parts several times while the tissue viability was still high and tumor profiling was performed. CONCLUSIONS: Primary osteosarcoma tissue grew on several different CAMs for an extended time period and neovascularization of serial transplanted tumor parts was observed, improving the versatility of the 3D-in-vivo-tumor-model.

3D monitoring of tumor volume in an in vivo model.

BACKGROUND: The ability to evaluate tumor development within experimental oncology is of upmost importance. However, determining tumor volumes in 3D in vivo tumor models is challenging. The chick chorioallantoic membrane (CAM) model represents an optimized xenograft model that surpasses many disadvantages that are inherent to rodent models and provides the opportunity of real-time monitoring of tumor growth. OBJECTIVE: The objective of this study was to introduce a new method that enables monitoring of tumor growth within the CAM model throughout the course of the experiment. METHODS: Sarcoma cell lines and sarcoma primary tumors were grafted onto the CAM of fertilized chicken eggs. A digital microscope (Keyence VHX-6000) was used for 3D volume monitoring before and after tumor excision and compared it to tumor weight. RESULTS: Accuracy of tumor volumes was validated through correlation with tumor weight. In and ex ovo tumor volumes correlated significantly with tumor weight values. CONCLUSIONS: The described method can be used to assess the effects of chemotherapeutic agents on the growth of tumors that have been grafted onto the CAM and further advance personalized cancer therapy. In summary, we established a promising protocol that enables in vivo real-time tracking of tumor growth in the CAM model using a digital microscope.