Endothelial Cell Transcription Modulation in Cerebral Aneurysms After Endovascular Flow Diversion

Flow diverting stents (FDS) are used to treat cerebral aneurysms, by promoting thrombosis and occlusion of the aneurysm sac. However, retreatment is required in some cases, and the biologic basis behind treatment outcome is not known. The goal of this study was to understand how changes in hemodynamic flow after FDS placement affect aneurysmal endothelial cell (EC) activity.

Three-dimensional models of patient-specific aneurysms were created to quantify the EC response to FDS placement. Computational fluid dynamic simulations were used to determine the hemodynamic impact of FDS. Two identical models were created for each patient; into one a FDS was inserted. Each model was then populated with human carotid ECs and subjected to patient-specific pulsatile flow for 24 h. ECs were isolated from aneurysm dome from each model and bulk RNA sequencing was performed.

Paired untreated and treated models were created for four patients. Aneurysm dome EC analysis revealed 366 (2.6%) significant gene changes between the untreated and FDS conditions, out of 13909 total expressed genes. Gene set enrichment analysis of the untreated models demonstrated enriched gene ontology terms related to cell adhesion, growth/tensile activity, cytoskeletal organization, and calcium ion binding. In the FDS models, enriched terms were related to cellular proliferation, ribosomal activity, RNA splicing, and protein folding.

Treatment of cerebral aneurysms with FDS induces significant EC gene transcription changes related to aneurysm hemodynamics in patient-specific in vitro 3D-printed models subjected to pulsatile flow. Further investigation is needed into the relationship between transcriptional change and treatment outcome.