Abstract Body: Introduction: Biomarkers combining blood-based gene expression and image-based features are an emerging method to detect and stratify intracranial aneurysms (IAs). However, the relationship between vascular hemodynamic insult and aneurysm initiation growth is poorly understood. Here, we sought to use local gene expression levels from spatial sequencing of IA tissue to study this complex interaction.

Methods: We performed bilateral carotid artery ligation on a New Zealand white rabbit to increase blood flow, inducing hemodynamic insult at the basilar terminus (BT). We euthanized the rabbit 24 hours post-surgery. We reconstructed the basilar artery (BA) using 3D angiography images and performed computational fluid dynamics (CFD) to compute pressure and wall shear stress (WSS), gradient (WSSG), and divergence (WSSD). 10-micron frozen sections of BA and BT in the plane of the bifurcation were collected onto Visium Spatial Gene Expression Capture Slide. Illumina sequencing libraries were constructed with unique molecular identifiers (UMI) and reads were aligned to rabbit genome. UMI counts were quantified for each spot using Cell Ranger pipeline. Using histological images and Loupe Browser, we identified spots on intima and media. Considering only genes with expression in greater than or equal to 50% of samples, differentially expressed genes (DEGs) were identified by F-test (p<0.1).

Results: Using CFD, we observed a significant change in WSS along the BA and BT and changes in pressure, WSSG, and WSSD. A representative plot of WSS and WSSD along BT is shown in Fig. 1. When comparing BA to BT, we identified 215 DEGs in media and 155 in intima. DEGs largely reflected organismal injury/abnormalities and tissue development. Violin plots illustrate summarized expression of DEGs across groups of interest.

Conclusion: WSS on BT increased ~4x after ligation. Expression analysis from spatial sequencing revealed ample differential expression between BA and BT for both intima and media.