045-23 – Investigating tumour/host vasculature in a chick embryo CAM model of glioblastoma using advanced in vivo imaging

Introduction: Glioblastoma multiforme (GBM) is an aggressive brain tumour characterized by intense, aberrant vasculature and treatment resistance. The chick chorioallantoic membrane (CAM) is a time- and cost-effective alternative to rodent models and its well-developed vasculature allows engraftment of tumour cells, making it ideal for investigating vascularization. We aim to study tumour/ host vasculature in the GBM-CAM model using advanced in vivo imaging.
Methods: Human GBM U251 cells were xenografted onto the CAM and imaged using brightfield (BF) microscopy and magnetic resonance imaging (MRI). Blood vessel area, mean thickness and number of branching points were determined from BF images and blood vessel volume from 3D MRI.
Results: Vascularized tumour nodules formed with high engraftment rate. BF microscopy revealed distinct differences in CAM vasculature between GBM- and control CAMs. In GBM-CAMs, blood vessel morphology appeared to change from linear branching to a radial “spoke-like” pattern around the tumour. Quantification showed fewer branching points in GBM-CAMs, indicating blood vessels being directed straight to the tumour. MRI revealed vessels penetrating the nodules, not visible by BF microscopy. Control CAM vessels appeared thicker, while GBM-CAMs had more small diameter vessels, suggesting angiogenesis to supply the tumour. These findings suggest significant vascular remodelling in the presence of GBM xenografts.
Conclusion: MRI and BF microscopy enable visualization of intra- and extra-tumoural blood vessels on the CAM surface. MRI provides additional 3D information through the layers of the CAM. In combination these provide comprehensive assessment of tumour/ host vasculature and demonstrate potential of GBM-CAM to study anti-vascular therapies.