Abstract

The potential of immunotherapy for brain cancer remains limited due to the presence of a restrictive blood-brain barrier and suppressive tumor microenvironment. Therefore, developing strategies to improve the efficacy of molecular and cellular immunotherapy is in urgent need. In this thesis, I explore the potential of therapeutic ultrasound under fluid flow conditions to enhance endothelial cell permeabilization and immunobiology for improving immunotherapy. Here, fluidic systems were employed to cultivate and treat two human endothelial cell types, either umbilical vein (HUVEC) or brain endothelial cells (HBEC-5i), under flow conditions. The findings demonstrated a direct correlation between microbubble flow velocity and ultrasound-assisted cell permeabilization. The velocity of microbubble perfusion also substantially influenced the dynamics of Ca2+ influx in endothelial cells. Additionally, shear-flow preconditioning influenced endothelial cells' cytokine profile, significantly enhancing their susceptibility to ultrasound. Furthermore, distinct microbubble flow patterns dramatically influenced the efficiency of cell permeabilization. Building on these findings, I explored the effects of microbubble-induced shear stress on endothelial cell immunobiology. Ultrasound-stimulated microbubbles led to a time-dependent upregulation of cell adhesion molecules involved in immune cell homing. Additionally, ultrasound treatment under identical conditions significantly increased the secretion of 20 cytokines and chemokines 4 hours post-sonication, improving CAR NK-92 cells homing and trafficking. Overall, this thesis highlights the potential of ultrasound-activated microbubbles to overcome the challenges of tumor microenvironments, thereby enhancing the efficacy of cellular immunotherapy.