Abstract Background We previously demonstrated that human red blood cells (RBCs) and their extracellular vesicles (EVs) contribute to vascular endothelial dysfunction in type 2 diabetes (T2D). Chronic treatment of sunitinib, a receptor tyrosine kinase inhibitor targeting VEGFR2, significantly attenuates endothelial dysfunction in T2D rats. However, whether activation of VEGFR2 contributes to endothelial dysfunction induced by RBCs in T2D remain poorly understood. Purpose This study aimed to determine whether vascular VEGFR2 activation mediates RBC-induced endothelial dysfunction in T2D. Methods RBCs were isolated using centrifugation from whole blood of individuals with T2D and age-matched healthy controls. EVs were isolated from conditional medium of human RBCs (20% hematocrit) using ExoEasy kit. Endothelium-dependent relaxation (EDR) in response to acetylcholine was assessed using wire myograph in: (1) aortas from T2D Goto-Kakizaki (GK) and Wistar rats; (2) Wistar aortas incubated with human RBCs (45% hematocrit) for 18 h; (3) C57BL/6 mouse aortas incubated with human RBC-EVs for 18 h; and (4) aortas of recipient Wistar rats 4 h after in vivo transfusion with RBCs from GK or Wistar rats (~6% donor RBCs in recipients). The selective VEGFR2 antagonist SU1498 (10 μM) was applied in myograph organ chamber to assess VEGFR2 involvement. Results EDR was significantly impaired in GK versus Wistar aortas (Fig. 1A and 1B). SU1498 markedly restored EDR, which was diminished by endothelial nitric oxide synthase inhibition (Fig. 1B, 1C and 1D). RBCs from patients with T2D impaired EDR in Wistar aortas, an effect attenuated by SU1498 (Fig. 2A and 2B). In contrast, SU1498 had no effect on EDR in aortas incubated with RBCs from healthy controls (Fig. 2B). Transfusion with GK RBCs impaired EDR in aortas from recipient Wistar rats, which was significantly attenuated by SU1498 (Fig. 2C). Interestingly, RBC-EVs from T2D individuals impaired EDR, and SU1498 mitigated this effect (Fig. 2D). Conclusions Our findings highlight that vascular VEGFR2 is a key mediator of RBC- and EV-induced vascular endothelial dysfunction in T2D. Vascular VEGFR2 may represent a therapeutic target to prevent vascular complications in T2D.Figure 1For image description, please refer to the figure legend and surrounding text. Figure 2For image description, please refer to the figure legend and surrounding text.
Jiao et al. (Fri,) studied this question.