Cardiac SGLT2 Expression and Cell-Type-Specific Responses to Empagliflozin in iPSC-Derived Models of Diabetic...

Sodium-glucose co-transporter 2 (SGLT2) inhibitors confer cardioprotection in patients with and without diabetes; however, whether SGLT2 is expressed in cardiac tissue and how these drugs act locally in the heart remains unclear. We investigated SGLT2 expression and the effects of empagliflozin in human iPSC-derived cardiac cells exposed to diabetogenic conditions. SGLT2 expression and the effects of empagliflozin were assessed in iPSC-derived cardiomyocytes, endothelial cells, and cardiac fibroblasts under acute diabetogenic conditions using protein expression and metabolic activity assays, and in a multicellular 3D cardiac microtissue model using metabolic activity and contraction analyses. SGLT2 was detected in all three iPSC-derived cardiac cell types with nuclear and perinuclear localisation; no membrane-bound expression was observed. Endothelial cell SGLT2 expression was elevated under diabetogenic conditions. Diabetogenic stress reduced metabolic activity in both cardiomyocytes and endothelial cells; empagliflozin partially rescued endothelial cell metabolic activity but had no effect in cardiomyocytes. Empagliflozin reversed diabetogenic stress-induced cardiac fibroblast activation. 3D cardiac microtissues under diabetogenic conditions exhibited prolonged relaxation time, reduced beat rate variability, and reduced metabolic activity. Empagliflozin maintained metabolic activity at levels comparable to those of the control but did not rescue relaxation time or beat rate variability. The responsiveness of non-myocytes (endothelial cells and cardiac fibroblasts) to empagliflozin, in the absence of any effect on cardiomyocytes, suggests that non-myocyte-mediated mechanisms may contribute to the clinically observed cardioprotection of SGLT2 inhibitors.