Truncated YY1 interacts with BASP1 through a 339KLK341 motif in YY1 and suppresses vascular smooth muscle cell growth and intimal hyperplasia after vascular injury.

AIMS: In-stent restenosis and late stent thrombosis are complications associated with the use of metallic and drug-coated stents. Strategies that inhibit vascular smooth muscle cell (SMC) proliferation without affecting endothelial cell (EC) growth would be helpful in reducing complications arising from percutaneous interventions. SMC hyperplasia is also a pathologic feature of graft stenosis and fistula failure. Our group previously showed that forced expression of the injury-inducible zinc finger (ZNF) transcription factor, yin yang-1 (YY1), comprising 414 residues inhibits neointima formation in carotid arteries of rabbits and rats. YY1 inhibits SMC proliferation without affecting EC growth in vitro. Identifying a shorter version of YY1 retaining cell-selective inhibition would make it more amenable for potential use as a gene therapeutic agent. METHODS AND RESULTS: We dissected YY1 into a range of shorter fragments (YY1A-D, YY1Δ) and found that the first two ZNFs in YY1 (construct YY1B, spanning 52 residues) repressed SMC proliferation. Receptor binding domain analysis predicts a three-residue (339KLK341) interaction domain. Mutation of 339KLK341 to 339AAA341 in YY1B (called YY1Bm) abrogated YY1B's ability to inhibit SMC but not EC proliferation and migration. Incubation of recombinant GST-YY1B and GST-YY1Bm with SMC lysates followed by precipitation with glutathione-agarose beads and mass spectrometric analysis identified a novel interaction between YY1B and BASP1. Overexpression of BASP1, like YY1, inhibited SMC but not EC proliferation and migration. BASP1 siRNA partially rescued SMC from growth inhibition by YY1B. In the rat carotid balloon injury model, adenoviral overexpression of YY1B, like full-length YY1, reduced neointima formation, whereas YY1Bm had no such effect. CD31+ immunostaining suggested YY1B could increase re-endothelialization in a 339KLK341-dependent manner. CONCLUSION: These studies identify a truncated form of YY1 (YY1B) that can interact with BASP1 and inhibit SMC proliferation, migration, and intimal hyperplasia after balloon injury of rat carotid arteries as effectively as full length YY1. We demonstrate the therapeutic potential of YY1B in vascular proliferative disease.

Endothelial progenitor cell-derived exosomes facilitate vascular endothelial cell repair through shuttling miR-21-5p to modulate Thrombospondin-1 expression.

Background: Our previous studies observed that administration of exosomes from endothelial progenitor cells (EPC) facilitated vascular repair in the rat model of balloon injury. However, the molecular events underlying this process remain elusive. Here, we aim to interrogate the key miRNAs within EPC-derived exosomes (EPC-exosomes) responsible for the activation of endothelial cell (EC) repair. Methods: The efficacy of EPC-exosomes in re-endothelialization was examined by Evans Blue dye and histological examination in the rat model of balloon-induced carotid artery injury. The effects of EPC-exosomes on human vascular EC (HUVEC) were also studied by evaluating the effects on growth, migratory and tube formation. To dissect the underlying mechanism, RNA-sequencing assays were performed to determine miRNA abundance in exosomes and mRNA profiles in exosome-treated HUVECs. Meanwhile, in vitro loss of function assays identified an exosomal miRNA and its target gene in EC, which engaged in EPC-exosomes-induced EC repair. Results: Administration of EPC-exosomes potentiated re-endothelialization in the early phase after endothelial damage in the rat carotid artery. The uptake of exogenous EPC-exosomes intensified HUVEC in proliferation rate, migration and tube-forming ability. Integrative analyses of miRNA-mRNA interactions revealed that miR-21-5p was highly enriched in EPC-exosomes and specifically suppressed the expression of an angiogenesis inhibitor Thrombospondin-1 (THBS1) in the recipient EC. The following functional studies demonstrated a fundamental role of miR-21-5p in the pro-angiogenic activities of EPC-exosomes. Conclusions: The present work highlights a critical event for the regulation of EC behavior by EPC-exosomes, which EPC-exosomes may deliver miR-21-5p and inhibit THBS1 expression to promote EC repair.

Hyperbaric oxygen decreases intimal thickness and area after carotid artery balloon injury in a rat model.

BACKGROUND: Clinical studies have suggested a benefit for hyperbaric oxygen (HBO) treatment in decreasing symptomatic restenosis after coronary angioplasty. We hypothesize that HBO treatment will decrease hyperplastic intimal area after arterial balloon injury in a rat. METHODS: Fifty-four male Sprague-Dawley rats (Charles River Laboratories, Wilmington, MA) were randomly assigned either to room air (n = 27) or a treatment group (n = 27) receiving HBO treatment (2 hyperbaric treatments of 100% oxygen at 2 bars for 90 min). A 2F balloon-tipped catheter was used to injure the right common carotid arteries, which were harvested at 7, 14, and 28 days. Postinjury intimal thickness and area were measured from hematoxylin-eosin-stained specimens at each time point. Computer-assisted histomorphometry was used to calculate maximal intimal thickness, relative intimal thickness (ratio of intimal to intimal plus medial thickness), intimal area, and the intimal to medial area ratio. RESULTS: There was a 42.3% reduction in maximal intimal thickness (P = 0.0012) and a 36.5% reduction in intimal area (P = 0.0337) at day 28 in the HBO-treated group (mean ± standard error [SE], 0.0425 ± 0.0054 mm for maximal thickness and 0.065 ± 0.0056 mm(2) for area) when compared to the normoxic group (0.0737 ± 0.004 mm for maximal thickness and 0.0413 ± 0.0074 mm(2) for area). The relative intimal thickness also showed a 28.3% reduction at day 28 in the HBO-treated group (ratio of 0.38 ± 0.0329) compared to the normoxic group (ratio of 0.53 ± 0.0141; P = 0.0065). CONCLUSIONS: Our results indicate that HBO treatment decreases maximal intimal thickness and intimal area of the carotid artery after balloon injury. This could have significant clinical implications on the increasing number of endovascular interventions in vascular surgery and cardiology.

Vascular complications of transsphenoidal surgery.

Vascular complication of transsphenoidal surgery can lead to mortality and serious morbidity. In a series of 3,061 transsphenoidal operations for pituitary disease, 24 such complications were encountered, seven of which were fatal. The anatomic substrate for such complications is discussed, along with technical aspects of surgery and other methods for the avoidance of vascular complications.