MicroRNA-21/PDCD4 proapoptotic signaling from circulating CD34+ cells to vascular endothelial cells: a potential contributor to adverse cardiovascular outcomes in patients with critical limb ischemia

<b>Objective</b>. In patients with type 2 diabetes (T2D) and critical limb ischemia (CLI), migration of circulating CD34⁺ cells predicted cardiovascular mortality at 18 months post-revascularization. This study aimed to provide long-term validation and mechanistic understanding of the biomarker. <p><b>Research Design and Methods</b>. The association between CD34⁺ cell migration and cardiovascular mortality was reassessed at 6 years post-revascularization. In a new series of T2D-CLI and control subjects, immuno-sorted bone marrow (BM)-CD34⁺ cells were profiled for microRNA expression and assessed for apoptosis and angiogenesis activity. The differentially regulated microRNA-21, and its pro-apoptotic target PDCD4, were titrated to verify their contribution in transferring damaging signals from CD34⁺ cells to endothelial cells.</p> <p><b>Results</b>.<b> </b>Multivariable regression analysis confirmed CD34⁺ cell migration forecasts long-term cardiovascular mortality. <a>CD34⁺ cells from T2D-CLI patients were more apoptotic and less proangiogenic than controls and featured microRNA-21 downregulation, modulation of several long non-coding RNAs acting as microRNA-21 sponges, and upregulation of the microRNA-21 proapoptotic target PDCD4. Silencing miR-21 in control CD34⁺ cells phenocopied the T2D-CLI cell behavior. In coculture, T2D-CLI CD34⁺ cells imprinted naïve endothelial cells, increasing apoptosis, reducing network formation, and modulating the TUG1 sponge/microRNA-21/PDCD4 axis. Silencing PDCD4 or scavenging ROS protected endothelial cells from the negative influence of T2D-CLI CD34⁺ cells</a></p> <p><b>Conclusions</b>.<b> </b>Migration of CD34⁺ cells predicts long-term cardiovascular mortality in T2D-CLI patients. An altered paracrine signalling conveys anti-angiogenic and pro-apoptotic features from CD34⁺ cells to the endothelium. This damaging interaction may increase the risk for life-threatening complications.</p>