The Effect of Proprotein Convertase Subtilisin Kexin Type 9 Inhibitors on Circulating Endothelial Progenitor Cells in Patients with Cardiovascular Disease

Purpose Circulating endothelial progenitor cells (cEPCs) are vital to vascular repair by re-endothelialization. We aimed to explore the effect of proprotein convertase subtilisin kexin type 9 inhibitors (PCSK9i) on cEPCs hypothesizing a possible pleiotropic effect. Methods Patients with cardiovascular disease (CVD) were sampled for cEPCs at baseline and following the initiation of PCSK9i. cEPCs were assessed using flow cytometry by the expression of CD34((+))/CD133((+)) and vascular endothelial growth factor receptor (VEGFR)-2((+)), and by the formation of colony-forming units (CFUs) and production of VEGF. Results Our cohort included 26 patients (median age 68 (IQR 63, 73) years; 69% male). Following 3 months of treatment with PCSK9i and a decline in low-density lipoprotein cholesterol levels (153 (IQR 116, 176) to 56 (IQR 28, 72) mg/dl), p < 0.001), there was an increase in CD34((+))/CD133((+)) and VEGFR-2((+)) cell levels (0.98% (IQR 0.37, 1.55) to 1.43% (IQR 0.90, 4.51), p = 0.002 and 0.66% (IQR 0.22, 0.99) to 1.53% (IQR 0.73, 2.70), p = 0.05, respectively). Functionally, increase in EPCs-CFUs was microscopically evident following treatment with PCSK9i (1 CFUs (IQR 0.0, 1.0) to 2.5 (IQR 1.5, 3), p < 0.001) with a concomitant increase in EPC's viability as demonstrated by an MTT assay (0.15 (IQR 0.11, 0.19) to 0.21 (IQR 0.18, 0.23), p < 0.001). VEGF levels increased following PCSK9i treatment (57 (IQR 18, 24) to 105 (IQR 43, 245), p = 0.006). Conclusions Patients with CVD treated with PCSK9i demonstrate higher levels of active cEPCs, reflecting the promotion of endothelial repair. These findings may represent a novel mechanism of action of PCSK9i.

Automated summary

The study investigated the effect of PCSK9 inhibitors on circulating endothelial progenitor cells (cEPCs) in patients with cardiovascular disease, finding that treatment with PCSK9i resulted in higher levels of active cEPCs, promoting endothelial repair and suggesting a novel mechanism of action for PCSK9i.