Extensive Vascular Remodeling Without Widespread Blood-Brain Barrier Disruption in a Murine Model of ZFTA-RELA Ependymoma

The aim of this study was to examine vascular architecture and BBB status of a ZFTA-RELA EPN murine model (mZRFUS-EPN).

Methods

We performed immunostaining for endothelial and BBB associated markers, transmission electron microscopy of tight junctions, in vivo vascular leakage assays, and single cell RNA-sequencing of isolated endothelial cells to compare cells from normal brain and mZRFUS-EPN. Results: mZRFUS-EPN exhibit a dense, highly branched vascular network consistent with extensive angiogenic remodeling. Despite these vascular alterations, ultrastructural analysis, BBB marker expression, and in-vivo permeability assays demonstrated that most tumor-associated vessels retained substantial BBB integrity.

Single-cell RNA sequencing identified endothelial cell-state remodeling characterized by inflammatory activation across arterial, venous, and capillary endothelial populations. mZRFUS-EPN capillary endothelial cells were enriched in cell-cycle and angiogenic tip-cell genes, consistent with proliferative and angiogenic remodeling in these tumors. Core BBB-associated transcriptional programs, including tight junction genes, transcytosis regulators, efflux transporters, and BBB specification transcription factors, remained largely preserved within tumor-associated endothelial cells.

Conclusions: These findings identify a distinct neurovascular phenotype in mZRFUS-EPN characterized by inflammatory and angiogenic endothelial remodeling with substantial preservation of BBB-associated programs. Improved understanding of BBB biology in pediatric EPN may inform future therapeutic delivery strategies.