Abstract Body: Introduction: Vein of Galen malformations (VOGM) are challenging congenital arteriovenous malformations (AVMs) to treat. During management, for unknown reasons, VOGM may develop fine angiogenic networks of feeding vessels within subarachnoid spaces. This is associated with increased symptom burden and complicates treatment. Here, we temporally characterized the evolution of VOGM during endovascular therapy to investigate changes in gene expression associated with onset and cessation of angiogenesis.

Methods: Whole blood was prospectively collected from femoral access (peripheral) and catheterized intracranial feeding vessels (intralesional) during endovascular embolization of 4 angiogenic and 4 non-angiogenic patients for management of VOGM. Patients were grouped by development of extra-axial angiogenesis during treatment. If angiogenesis developed, whole blood was collected upon onset and cessation of angiogenesis as determined by serial cerebral angiograms. RNA sequencing of 15,730 genes from 23 samples after quality-control was aligned, normalized, and residualized using Rsubread, sva, and limma/voom. Differentially expressed genes were identified between actively angiogenic, formerly angiogenic, and non-angiogenic patients. Gene set enrichment analysis (GSEA) was conducted using Gene Ontology biological processes and cellular components.

Results: 677 genes (349 upregulated, 328 downregulated) were significantly associated with actively angiogenic VOGM versus formerly angiogenic VOGM. These included VEGFR and VEGFR-mediated genes associated with hypoxia-induced angiogenesis (e.g. FLT1, DAAM2), angiogenic non-coding RNAs (ncRNA) (e.g. SBF2-AS1, RP11-430C1.1, ANKRD20A4), and markers suggestive of neurological symptom burden (e.g. MT1F, FAM171B). GSEA highlighted enrichments in aerobic respiration pathways and ncRNA processing. 1349 genes (673 upregulated, 676 downregulated) were differentially expressed in actively angiogenic versus non-angiogenic VOGM with hypoxic and angiogenic roles (e.g. PDC). 274 genes (192 upregulated, 82 downregulated) were expressed in formerly angiogenic versus non-angiogenic VOGM, comprised of pro-coagulation and antiproliferative genes (e.g. PROS1, PROSER2).

Conclusion: Angiogenesis in VOGM is mechanistically driven by local hypoxia-induced VEGFR-mediated responses. VOGMs transiently express an angiogenic ncRNA signature during active angiogenesis, which switches to a pro-coagulatory profile as the VOGM is progressively treated.