Endothelial sampling in situ enables genetic characterization of vein of Galen Malformation

Background and Objectives: Vein of Galen malformation (VOGM) is the result of arteriovenous shunting between choroidal and/or subependymal arteries and the embryologic prosencephalic vein and is among the most severe cerebrovascular disorders of childhood. While endovascular treatments have improved outcomes, morbidity and mortality remain high. We hypothesized that in situ analysis of the VOGM lesion using endoluminal tissue sampling (ETS) is feasible and may identify somatic mutations and transcriptional aberrations. A mechanistic understanding of VOGM genetics, pathogenesis, and maintenance will guide future therapeutic efforts. Methods: We performed ETS under conditions where clinical factors alone determined vessel selection and access route. Coils were only placed in vessel locations desired for treatment. After a coil was deployed, we allowed 1 minute of endoluminal contact time before the coil was resheathed through the microcatheter, protecting it from contact with other vessel segments. Once the coil was removed, it was rinsed in PBS and dissociated with trypsin before flow cytometry was used to isolate experimental endothelial cells (EC), defined as CD31+ and CD45-. Single-cell RNA sequencing (scRNA-seq) of VOGM ECs was performed using autologous peripheral femoral access ECs as a control to demonstrate feasibility of downstream genomic analyses from ETS. Results: Our cohort contains 6 patients who underwent 10 ETS procedures from arterial and/or venous access during routine VOGM treatment (range: 12 days to ~6 years). No periprocedural complications attributable to ETS occurred. Six unique coil types were used. ETS captured 98 +/- 88 (mean +/- SD; range 17-256) experimental endothelial cells (CD31+ and CD45-). There was no discernable correlation between cell yield and coil type or route of access. Single cell RNA sequencing demonstrated hierarchical clustering and unique cell populations within the VOGM lesion compared to autologous femoral control ECs. Conclusion: We report the first successful utilization of ETS for VOGM. ETS appears safe and may supplement investigations aimed at development of a molecular-genetic taxonomic classification scheme. Moreover, results may eventually inform the selection of personalized pharmacologic or genetic therapies for VOGM and cerebrovascular disorders more broadly. ### Competing Interest Statement Conflict of Interest: A.T.H. and J.G.J. received material support (i.e. coils) from Balt for the purposes of this study. Balt played no role in designing, collecting, interpreting, or reporting the data presented in this manuscript. This paper has been submitted for presentation consideration at the American Association of Neurological Surgeons (AANS) and Congress of Neurological Surgeons (CNS) joint section for Pediatric Neurosurgery in Oklahoma City, OK (USA) in December 2023. ### Funding Statement Disclosure of Funding: The Aneurysm and AVM Foundation (TAAF), Joe Niekro Foundation (JNF), Robert J. Dempsy, MD Research Award from the American Association of Neurological Surgeons (AANS) and Congress of Neurological Surgeons (CNS) joint section for Cerebrovascular Neurosurgery, Kaul Pediatric Research Institute (KPRI) of Childrens of Alabama, and the Center for Clinical and Translational Sciences (CCTS) at University of Alabama at Birmingham provided funding for this study. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of University of Alabama at Birmingham gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.