Introduction

Brain tumor treatments are hindered by the blood-brain barrier (BBB), which shelters neoplastic cells. High-frequency irreversible electroporation (H-FIRE) is a minimally-invasive, nonthermal ablative therapeutic in clinical trials for canine primary brain tumors. H-FIRE precisely ablates brain tumors while transiently disrupting peritumoral BBB, enhancing therapeutic delivery to infiltrative margins. H-FIRE-induced cell death and BBB disruption mechanisms remain incompletely characterized. We hypothesize that H-FIRE-induced tumor cell death induces BBB disruption.

Methods

F98 glioma, LL/2 Lewis lung carcinoma, and bEnd.3 cerebral endothelial cell lines modeled primary and metastatic brain cancer and BBB endothelium, respectively. Cell membrane permeability and chromatin condensation of cancer cells were temporally measured via flow cytometry. Endothelial cells were exposed to H-FIRE-treated cancer cell supernatants, and endothelial response was assessed via flow cytometry and RT-qPCR of tight junction genes.

Results

Cancer cells exhibited dose-escalating permeabilization and chromatin condensation, with recovery occurring at lower voltages. Endothelial cell exposure to H-FIRE-ablated cancer cell supernatants resulted in rapid detachment and morphologic changes with no endothelial tight junction gene expression changes induced by immediate-post-treatment supernatants. 24 h-post-treatment F98 supernatants induced downregulation of claudin-3 and upregulation of claudin-5, while 24 h-post-treatment LL/2 supernatants induced downregulation of MPP6, SPTB, and VAPA genes.

Conclusion

Chromatin condensation implicates apoptosis in H-FIRE-induced cell death. Cerebral endothelial cell changes induced by H-FIRE tumor cell ablation suggest an indirect BBB disruption mechanism involving tight junction-associated genes.

Funding Information

Grayton Friedlander Memorial Fund