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.