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

OBJECTIVE: In patients with type 2 diabetes (T2D) and critical limb ischemia (CLI), migration of circulating CD34(+) cells predicted cardiovascular mortality at 18 months after revascularization. This study aimed to provide long-term validation and mechanistic understanding of the biomarker. RESEARCH DESIGN AND METHODS: The association between CD34(+) cell migration and cardiovascular mortality was reassessed at 6 years after revascularization. In a new series of T2D-CLI and control subjects, immuno-sorted bone marrow CD34(+) cells were profiled for miRNA expression and assessed for apoptosis and angiogenesis activity. The differentially regulated miRNA-21 and its proapoptotic target, PDCD4, were titrated to verify their contribution in transferring damaging signals from CD34(+) cells to endothelial cells. RESULTS: Multivariable regression analysis confirmed that CD34(+) cell migration forecasts long-term cardiovascular mortality. CD34(+) cells from T2D-CLI patients were more apoptotic and less proangiogenic than those from control subjects and featured miRNA-21 downregulation, modulation of several long noncoding RNAs acting as miRNA-21 sponges, and upregulation of the miRNA-21 proapoptotic target PDCD4. Silencing miR-21 in control CD34(+) cells phenocopied the T2D-CLI cell behavior. In coculture, T2D-CLI CD34(+) cells imprinted naive endothelial cells, increasing apoptosis, reducing network formation, and modulating the TUG1 sponge/miRNA-21/PDCD4 axis. Silencing PDCD4 or scavenging reactive oxygen species protected endothelial cells from the negative influence of T2D-CLI CD34(+) cells. CONCLUSIONS: Migration of CD34(+) cells predicts long-term cardiovascular mortality in T2D-CLI patients. An altered paracrine signaling conveys antiangiogenic and proapoptotic features from CD34(+) cells to the endothelium. This damaging interaction may increase the risk for life-threatening complications.