Abstract Body: Type 2 diabetes (T2D) is associated with accelerated vascular complications like hypertension and atherosclerosis. “Phenotypic switching” of vascular smooth muscle cells (SMCs) is a major driver of these complications and is enhanced in diabetes. Despite adequate glycemic control, SMC dysfunction can persist due to “metabolic memory” of prior hyperglycemia. However, the mechanisms of hyperglycemic memory associated with persistent SMC dysfunction are unclear. Here, leveraging single-cell (sc) multi-omics, we examined the effect of glucose normalization on transcriptomic and epigenomic changes associated with SMC phenotypic transition in T2D mice.
We treated T2D db/db mice with the antidiabetic drug dapagliflozin (DAPA) (db/db-DAPA) or vehicle (db/db), and non-diabetic control db/+ mice with vehicle for 6 weeks. Dissected aortas were subjected to scRNA-seq, scATAC-seq, and spatial transcriptomics (Xenium) to determine single-cell changes in gene expression and chromatin accessibility. DAPA treatment conferred effective glycemic control in db/db mice, evident by significant reduction in blood glucose/hemoglobin A1c. scRNA and scATAC-seq analysis of aortas identified major cell populations, including SMCs, fibroblasts, endothelial and immune cells. SMCs were further clustered into contractile and fibromyocyte-like cells. Cell composition analysis revealed decreases in contractile SMCs and increases in fibromyocyte-like (pathologic) SMCs in db/db versus db/+ mice. Interestingly, DAPA did not reverse most of the diabetes-induced changes in contractile markers but reversed many fibromyocyte markers in db/db mice. Pseudo-time trajectory analysis revealed increased activity/expression of fibromyocyte-associated transcription factors during contractile SMC to fibromyocyte transition. Spatial transcriptomics analysis further mapped aortic cell types and confirmed that DAPA reversed alterations in key fibromyocyte genes but not contractile genes in db/db mouse aortas. T2D reduced contractile SMC gene expression and related chromatin accessibility and promoted phenotypic transition to fibromyocytes. DAPA partially reversed the transition to fibromyocytes, but not the loss in contractile SMC/genes. These results suggest persistent epigenetic changes may contribute to sustained vascular remodeling in T2D. These changes are only partially reversed by commonly used anti-diabetic drugs, underscoring the need for more effective therapies for hyperglycemic memory.