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

Abstract

In patients with type 2 diabetes (T2D) and critical limb ischemia (CLI), migration of circulating CD34 1 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 1 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 1 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 1 cells to endothelial cells. RESULTS Multivariable regression analysis confirmed that CD34 1 cell migration forecasts long-term cardiovascular mortality. CD34 1 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 1 cells phenocopied the T2D-CLI cell behavior. In coculture, T2D-CLI CD34 1 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 1 cells. CONCLUSIONS Migration of CD34 1 cells predicts long-term cardiovascular mortality in T2D-CLI patients. An altered paracrine signaling conveys antiangiogenic and proapoptotic features from CD34 1 cells to the endothelium. This damaging interaction may increase the risk for life-threatening complications.

Cell Therapy for Critical Limb Ischemia: Advantages, Limitations, and New Perspectives for Treatment of Patients with Critical Diabetic Vasculopathy

“…In line with this, recent evidence reports an inhibition of mitophagy (mitochondria-specific autophagy) in PB-MNCs from patients with T2D [ 81 ]. Moreover, tumour suppressor-programmed cell death-4 ( PDCD4 ) overexpression was demonstrated in diabetic PB-MNCs [ 82 •]. These results mirror the recent observation that the inhibition of autophagy associates with an increased expression of PDCD4 in a human cancer cell line [ 83 ].…”

“…Several lncRNAs participate in the regulation of stem cell properties including their potential for self-renewal and differentiation, which help in maintenance of normal cell and tissue homeostasis. We have recently reported a T2D-dependent mechanism involving miR-21 downregulation CD34 + MNCs and induction of its inhibitory target PDCD4, a tumor suppressor protein involved in programmed cell death [ 82 •]. We also found that several lncRNAs that act as sponges for miR-21 were overexpressed in CD34 + MNCs and PB of patients with T2D.…”

“…In addition to causing an altered progenitor cell mobilization, T2D was shown to drastically alter the cellular composition of BM in favour of adipose tissue accumulation; this transformation can hinder the intrinsic regenerative potential of resident mesenchymal and hematopoietic cells and compromise their utility for therapeutic transplantation purposes [ 98 ]. Moreover, our group has discovered that the in vitro migratory activity of CD34 + MNCs positively correlated with cardiovascular death, independently from other predictive factors, such as age, coronary artery disease, serum C-reactive protein, and glomerular filtration rate [ 82 •]. At a first glimpse, these findings may appear counterintuitive, considering that migration is instrumental to BM-derived cells to reach damaged tissues, unless these cells have turned into deleterious elements because of T2D.…”

“…We also found that several lncRNAs that act as sponges for miR-21 were overexpressed in CD34 + MNCs and PB of patients with T2D. We proposed that this altered paracrine signalling may convey antiangiogenic and proapoptotic features from CD34 + cells to the endothelium [ 82 •]. The study has important implications for cell therapy, calling for caution in using CD34 + cells that carry a proapoptotic and antiangiogenic molecular signature, e.g., low miR-21/high PDCD4.…”

“…Moreover, its knockdown was associated to an amelioration of ED [ 134 ]. Interestingly, MALAT-1 is also upregulated in CD34 + cells from patients with T2D, suggesting a general implication in vascular dysfunction and cell-related repair processes [ 82 •]. Another lncRNA, MEG-3, was associated with a protective effect towards high glucose (HG)-treated HUVECs [ 135 ].…”