MicroRNA-146a Induces Lineage-Negative Bone Marrow Cell Apoptosis and Senescence by Targeting Polo-Like Kinase 2 Expression.

Objective: Lineage-negative bone marrow cells (lin- BMCs) are enriched in endothelial progenitor cells and mediate vascular repair. Aging-associated senescence and apoptosis result in reduced number and functionality of lin- BMCs, impairing their prorepair capacity. The molecular mechanisms underlying lin- BMC senescence and apoptosis are poorly understood.

Synergistic induction of miR-126 by hypoxia and HDAC inhibitors in cardiac myocytes.

HDAC inhibitors are under clinical development for the treatment of hypertrophic cardiomyopathy and heart failure although the mechanisms of protection are incompletely understood. Micro-RNA 126, an endothelium-specific miR has been assigned essential developmental roles in the heart by activating survival kinases ERK1/2 and Akt and increasing pro-angiogenic signaling. Here we provide the first evidence that hypoxia and HDAC inhibitors selectively and synergistically stimulate expression of miR-126 in cardiac myocytes.

MicroRNA-10A* and MicroRNA-21 modulate endothelial progenitor cell senescence via suppressing high-mobility group A2.

Rationale: Endothelial progenitor cells (EPCs) contribute to the regeneration of endothelium. Aging-associated senescence results in reduced number and function of EPCs, potentially contributing to increased cardiac risk, reduced angiogenic capacity, and impaired cardiac repair effectiveness. The mechanisms underlying EPC senescence are unknown.

Human umbilical cord blood endothelial progenitor cells decrease vein graft neointimal hyperplasia in SCID mice.

Aims: Vein graft endothelial damage is a key step in the development of neointimal hyperplasia, leading to vein graft failure. We sought to determine whether exogenous endothelial progenitor cells could promote vein graft re-endothelialization, and thereby ameliorate neointimal hyperplasia.

Methods And Results: Carotid artery interposition grafting was performed with syngeneic inferior vena cavae in mice with severe combined immunodeficiency (SCID).

Antitumorigenesis of antioxidants in a transgenic Rac1 model of Kaposi's sarcoma.

Kaposi's sarcoma (KS) is the major AIDS-associated malignancy. It is characterized by the proliferation of spindle cells, inflammatory infiltrate, and aberrant angiogenesis caused by Kaposi's sarcoma herpesvirus (KSHV) infection. Small GTPase Rac1, an inflammatory signaling mediator triggering reactive oxygen species (ROS) production by NADPH-oxidases, is implicated in carcinogenesis and tumor angiogenesis.

Transcriptional regulation of Bim by FOXO3a and Akt mediates scleroderma serum-induced apoptosis in endothelial progenitor cells.

Background: Endothelial progenitor cells (EPCs) contribute to vascular regeneration/repair and thus may protect against scleroderma vasculopathy. We aimed to determine whether circulating EPCs were reduced in scleroderma, whether scleroderma sera could induce EPC apoptosis, and, if so, what the underlying apoptotic signaling pathway was.

Methods And Results: Circulating EPC levels were quantified in 54 patients with scleroderma and 18 healthy control subjects by colony-forming unit assay and flow cytometry, which revealed markedly decreased EPC levels in scleroderma patients relative to healthy subjects.

Circulating progenitor cells can be reliably identified on the basis of aldehyde dehydrogenase activity.

Objectives: Our objective was to develop and assess a novel endogenous progenitor cell (EPC) assay based on aldehyde dehydrogenase (ALDH) activity, and to define the relationship of ALDH-bright (ALDH(br)) cells with previously defined EPCs, patient age, and extent of coronary artery disease.

Background: Accurate assessment of circulating EPCs is of significant interest, yet current assays have limitations. Progenitor cells display high levels of ALDH activity.

Aging in the atherosclerosis milieu may accelerate the consumption of bone marrow endothelial progenitor cells.

Objective: We have demonstrated that bone marrow cells from young and wild-type (WT), but not old apoE-/-, mice are capable of preventing atherosclerosis. This study was performed to elucidate the numerical and functional changes underlying the efficacy difference between young and old bone marrow.

Methods And Results: CD34+/VEGFR2+ conventional endothelial progenitor cells and lin-/cKit+/Sca-1+ hematopoietic stem cells did not differ numerically or functionally between young and old apoE-/- bone marrow.

Paclitaxel modulates TGFbeta signaling in scleroderma skin grafts in immunodeficient mice.

Background: Systemic sclerosis (SSc) is characterized by excessive fibrosis and obliterative vascular lesions. Abnormal TGFbeta activation is implicated in the pathogenesis of SSc. Aberrant TGFbeta/Smad signaling can be controlled by stabilization of microtubules with paclitaxel.

A crucial role for GRK2 in regulation of endothelial cell nitric oxide synthase function in portal hypertension.

Nitric oxide (NO) production by endothelial cell nitric oxide synthase (eNOS) in sinusoidal endothelial cells is reduced in the injured liver and leads to intrahepatic portal hypertension. We sought to understand the mechanism underlying defective eNOS function. Phosphorylation of the serine-threonine kinase Akt, which activates eNOS, was substantially reduced in sinusoidal endothelial cells from injured livers.

Inactivation of monocarboxylate transporter MCT3 by DNA methylation in atherosclerosis.

Background: Monocarboxylate transporters (MCTs) mediate lactate transport across the plasma membrane of cells. The molecular mechanisms regulating monocarboxylate transport in smooth muscle cells (SMCs) remain poorly characterized. The aim of this study was to investigate the effects of DNA methylation on MCT expression and lactate transport in SMCs in relation to atherosclerosis.

Transforming growth factor-beta-induced inhibition of myogenesis is mediated through Smad pathway and is modulated by microtubule dynamic stability.

The expression of muscle-specific genes associated with myogenesis is controlled by several myogenic transcription factors, including myogenin and MEF2D. Transforming growth factor-beta (TGF-beta) has been shown to inhibit myogenesis, yet the molecular mechanisms underlying such inhibition are not known. In the present study, TGF-beta was shown to inhibit myogenin and MEF2D expression and myotube formation in C2C12 myoblasts cultured in differentiation medium in a cell density-dependent manner.

Upregulation of PAI-1 is mediated through TGF-beta/Smad pathway in transplant arteriopathy.

Background: Plasminogen activator inhibitor type 1 (PAI-1) is the primary physiologic inhibitor of plasminogen activator in vivo. Increased PAI-1 expression is associated with arteriosclerosis. Transforming growth factor-beta (TGF-beta) induces PAI-1 production via Smads.

Deficient Smad7 expression: a putative molecular defect in scleroderma.

Scleroderma is a chronic systemic disease that leads to fibrosis of affected organs. Transforming growth factor (TGF) beta has been implicated in the pathogenesis of scleroderma. Smad proteins are signaling transducers downstream from TGF-beta receptors.