Precision opening of the blood brain barrier via ultrasound-mediated disruption
Treating primary tumors (glioblastomas) or metastatic tumors (melanoma, lung cancer, breast cancer) in the brain, proves challenging by virtue of the protective function of the blood-brain barrier (BBB). The tight junction proteins (TJPs) binding the specialized endothelial cells of the BBB largely contribute to the limited permeability of cancer-therapeutic drugs. In both preclinical and clinical models, low intensity focused ultrasound (LIFU) coupled with microbubbles has been proven to safely and transiently open the BBB. Despite this method being established, potential genetic influences on the durability and vulnerability of tight junctions to LIFU have not been elucidated, nor have the determinants of tight junction repair post LIFU been thoroughly investigated. We report the development of an ultrasound transparent organ-on-chip model populated by iPSC-derived endothelial cells (iPSC-EC) co-cultured with astrocytes. We aim to probe the contributions of various tight junction genes to barrier integrity along with the subsequent protein topology involved in reassembly post ultrasound. Thus, this model serves to determine parameters for ultrasound disruption for precision opening of the BBB. The BBB-On-Chip was successfully fabricated and assembled with an optimized technique that has an 80% yield of leak-free devices, with stable cavitation post nanobubble injection. We have also demonstrated by confocal microscopy that vital components of the TJP complex and the vascular endothelium, ZO-1 and CD-31, can be visualized at iPSC-differentiated cell junctions and membrane surface, respectively. Furthermore, western blot reveals claudin-5 expression in our iPSC-differentiated endothelial cells. Expression of key brain EC markers signify successful differentiation to assemble in the BBB-on-Chip to test different parameters of ultrasound disruption. Efforts are underway to characterize the contributions of tight junction genes and their variations to the integrity and disruption of the BBB.
