Disruption of xenografted human glioblastoma vasculature is provoked by a single 10 nanosecond pulsed electric field in vivo under multiphoton microscopy imaging
Résumé
High-intensity pulsed electric fields with nanosecond durations (3-300ns; nsPEFs) have emerged as a promising tool for tumor ablation [Chen et al, 2012, Nuccitelli et al, 2006]. The physical mechanisms and specific type of cell death that occurs following the application of nsPEFs is under investigation by several groups and initial studies have shown effects on cell signaling through calcium and cell death pathways [Zhang et al, 2008, Morotomi-Yano et al, 2014, Pakhomova et al, 2014], mitochondria [Beebe et al, 2013] and cytoskeleton [Thompson et al, 2014, Rassokhin et al, 2014, Pakhomov et al, 2014]. In order to understand the utility of nsPEF in treating solid and resistant cancer, we developed an in vivoexposure system to apply nsPEF to vascularized 3D tumours, similar to the one used for longer pulse duration (50µm) in canine patient [Garcia et al, 2011]. We used multiphoton microscopy tools and intravital imaging to study early events of nsPEFeffects.Tumor cell physiology and microenvironment were observed by xenografting human glioblastoma cells (U87-MG)into the avian chorioallantoic membrane (CAM), allowing the study of the response at the level of tumor microenvironment in vivo, where tumor cells are vascularized and proliferating in 3 dimensions. We found that a single nsPEF (10ns, 30-50kV/cm) strongly affects the tumour neovascular network, collapsing micro-capillaries irreversibly but transiently affecting the diameter of larger vessels. Our goal has been therefore to contribute to the fundamental understanding of nsPEF effects in complex tissue environments, and ultimately, to deliver human cancer therapeutics (potentially by endoscopic system) that are painless, without side effects and highly targetable in tissue.