Abstract 632: Cell Populations In Pre-access Veins And Arteriovenous Fistulas: A Single Cell Perspective

Objective: A comprehensive picture of the cellular events dictating the transformation of the vein after arteriovenous fistula (AVF) creation has remained elusive so far. This study generated the first granular cellular atlas of pre-access veins and AVF from patients with end-stage kidney disease (ESKD). Methods: Veins (n=5) and AVF (n=7) were obtained from a total of 12 ESKD patients undergoing fistula creation in two stages. 41,000 enzymatically dissociated cells were single cell sequenced using the 10x Chromium system. Monocle3 inferred the trajectory leading to neointimal cells and signaling interactome in the AVF. Results: Cells populated 16 clusters containing canonical and non-canonical vascular markers after integrating the single cell transcriptomic profiles in Seurat v4. The majority of cells in both veins and AVF were smooth muscle cells (6.6 vs. 9.4%), fibroblasts (12.4 vs. 26.7%), neointimal-like cells (11.5% vs, 17.0, endothelial cells (10.5 vs. 10.5%), macrophages (26.1 vs. 19.5%), lymphocytes (16.4 vs.10.3), and neutrophils (0.7vs. 3.8 %). CENPF+ dividing cells were abundant in the AVF (0.2 to 1.2%). For the first time, we have detected a potential transcriptomic neointimal signature defined by the expression of BGN and PRELP genes that was increased in AVFs, but not absent in the pre-access veins, confirming previous histological findings. Neutrophilic infiltration (S100A8/9+ and CSF3R+) was increased in the AVF. Interestingly, lymphocytes and macrophages were decreased in the AVF with respect to the vein. These changes in cell populations in the AVF wall correlated with up-regulation of GO terms such as ECM deposition, neutrophil activation, and blood vessel remodeling in the AVF. Finally, we established a pseudotime cellular trajectory from contractile SMCs to neointimal-like cells, defined by COL8A1, PRELP, and BGN by Cohen’s I. Conclusions: We present a comprehensive single-cell atlas of the AVF transformation and assign identity to the cellular sources and cell trajectories in this remarkable vascular transformation.