MicroRNAs are 20-to 23-nucleotide RNA molecules that can regulate gene expression. Currently >400 microRNAs have been experimentally identified in mammalian genomes, whereas estimates go up to 1000 and beyond. Here we show that many more mammalian microRNAs exist. We discovered novel microRNA candidates using two approaches: testing of computationally predicted microRNAs by a modified microarray-based detection system, and cloning and sequencing of large numbers of small RNAs from different human and mouse tissues. Together these efforts experimentally identified 348 novel mouse and 81 novel human microRNA candidate genes. Most novel microRNAs candidates are not conserved beyond mammals, and ∼10% are taxon-specific. Our analyses indicate that the entire microRNA repertoire is not remotely exhausted.

Objective-Collateral artery development (arteriogenesis), a vital compensatory mechanism in patients with arterial obstructive disease, may be deregulated by vascular risk factors, eg, diabetes or hypercholesterolemia. Here, we compared the effects of either disturbed glucose metabolism or disturbed lipid metabolism on arteriogenesis. Methods and Results-Femoral artery occlusion was performed in streptozotocin(STZ)-treated mice, nonobese diabetic (NOD) mice, and insulin-resistant Ob/Ob mice on regular diet, and APOE3*Leiden mice on different hypercholesterolemic diets. Angiography and laser Doppler perfusion analysis of hindlimbs were performed postoperatively. Surprisingly, angiographic arteriogenesis was not impaired in diabetic and insulin-resistant mice. Perfusion recovery in STZ-treated and Ob/Ob mice was only decreased by 19% and 16%, respectively (PϽ0.05). Furthermore, perfusion recovery was unchanged between high-glycemic and mild-glycemic NOD mice. Angiographic arteriogenesis in APOE3*Leiden mice, however, was markedly impaired at 7 days and 14 days (PՅ0.01). Correspondingly, perfusion recovery was 41% decreased in APOE3*Leiden mice (PϽ0.05). There was an inverse correlation of perfusion recovery with plasma cholesterol (Pϭ0.02), but not with triglyceride, free fatty acid, glucose, or insulin levels. Conclusions-Hypercholesterolemia reduces arteriogenesis more dominantly than hyperglycemia or hyperinsulinemia in mice. This suggests that a disturbed lipid metabolism as observed in diabetic patients might be crucial for the impairment of collateral formation. Key Words: arteriogenesis Ⅲ cholesterol Ⅲ collateral circulation Ⅲ diabetes Ⅲ NOD mice Ⅲ peripheral vascular disease H yperlipidemia and diabetes mellitus are 2 major risk factors for coronary and peripheral arterial disease, in addition to nicotine abuse, hypertension, and other factors, by increasing the progression of atherosclerosis. 1 Moreover, collateral artery development (arteriogenesis), a vital compensatory mechanism in patients with arterial occlusive disease, 2,3 is deregulated by both hyperlipidemia 4 -8 and diabetes. 9,10 Poor arteriogenesis may influence the rate of disease progression and susceptibility for therapeutic intervention, such as direct revascularization techniques, exercise training, or experimental therapies to promote arteriogenesis. 11,12 Because both hyperlipidemia and diabetes often coexist in patients with arterial obstructive disease, it is difficult to determine which risk factor plays a predominant role in the impairment of collateral formation.Moreover, evidence is accumulating that a disturbed lipid metabolism is a crucial determinant of the development of diabetes and its complications, such as accelerated atherosclerosis. For example, disordered fat storage and mobilization, mainly involving triglyceride and free fatty acid metabolism, were implicated in the pathogenesis of insulin resistance and type 2 diabetes. [13][14][15][16][17][18] Furthermore, considerable attention has been drawn to the glycation and/...

Summary.  Background: Blood outgrowth endothelial cells (BOEC) are good candidates for vascular (re‐) generating cell therapy. Although cord blood (CB) BOEC have been reported as more proliferative than peripheral blood (PB) BOEC, not much is known about their functional properties. Objectives: We have studied the following determinants in BOEC expanded from CB and PB: endothelial phenotype, in vitro adhesion, migration, proliferation, and angiogenic tube forming capacity. Methods/Results: Endothelial phenotype of BOEC was evaluated by fluorescence activated cell sorting (FACS) analysis and confirmed the presence of endothelial markers including CD31, CD105, CD144, CD146, KDR/VEGFR‐2, Tie‐2, and TNF‐α‐induced VCAM‐1 and ICAM‐1. Evaluation of cell proliferation revealed a higher basal proliferation of CB‐BOEC, which increased after exposure to bFGF but not VEGF. The lower basal proliferation of PB‐BOEC increased with VEGF or bFGF addition. Array analysis of angiogenic genes showed many comparable expressions in both BOEC, and a slightly more pronounced pro‐angiogenic profile in CB‐BOEC than PB‐BOEC. Both BOEC were able to form tubular structures in a three‐dimensional fibrin matrix. Tube formation in CB‐BOEC was markedly induced by TNF‐α only and inhibited by anti‐urokinase antibodies. It was comparable to that induced by combined addition of TNF‐α and VEGF or bFGF, while maximal tube formation in PB‐BOEC required simultaneous exposure to TNF‐α/VEGF or TNF‐α/bFGF. Conclusions: The endothelial phenotype and characteristics for homing, adhesion, migration, inflammation, and angiogenic tube formation are almost equal for BOEC from CB and PB. A slightly more angiogenic phenotype favors CB‐BOEC. However, addition of VEGF to PB‐BOEC induces equal proliferation and tube formation.

This study demonstrates that furin-like PCs are involved in the arterial response to injury possibly through activation of the TGF-beta-Smad signaling pathway and identifies furin-like PCs as a possible target to inhibit intimal hyperplasia.