Adiponectin secretion by perivascular adipose tissue supports impaired vasodilation in a mouse model of accelerated vascular smooth muscle cell and adipose tissue aging.

OBJECTIVE: Perivascular adipose tissue (PVAT) function during aging has not been investigated in detail so far and its effect on vasodilation remains to be fully elucidated. The aim of this study was to investigate endothelium-dependent vasodilation of thoracic aorta in a mouse model of accelerated, selective vascular smooth muscle and PVAT aging, induced by SM22α-Cre-driven genetic deletion of the endonuclease ERCC1 (SMC-KO mice) versus healthy littermates (LM). We hypothesized that PVAT enhances vasodilation in LM, possibly through adiponectin secretion, which might be compromised in SMC-KO animals. METHODS: Thoracic aorta was isolated from SMC-KO animals and LM and segments with and without PVAT were mounted in wire myography setups. The endothelium-dependent vasodilation was assessed via acetylcholine dose-response curves and pathway contribution was studied. Moreover, adiponectin secretion was measured after stimulating the aortic segments with PVAT with acetylcholine. RESULTS: Adiponectin, secreted by PVAT, led to increased NO-contribution to endothelium-dependent vasodilation in healthy LM, although this did not increase maximum relaxation due to loss of EDH. Endothelium-dependent vasodilation was decreased in SMC-KO animals due to reduced NO-contribution and complete EDH loss. Despite strong lipodystrophy the PVAT partially compensated for lost vasodilation in SMC-KO. LM PVAT contained acetylcholinesterase that attenuated acetylcholine responses. This was lost in SMC-KO. CONCLUSIONS: PVAT-derived adiponectin is able to partially compensate for age-related decline in NO-mediated vasodilation, even during strong lipodystrophy, in conditions of absence of compensating EDH. In aorta with healthy PVAT acetylcholinesterase modulates vascular tone, but this is lost during aging, further compensating for decreased acetylcholine responsiveness. Thus, preservation of adiponectin levels, through relatively increased production in lipodystrophic PVAT, and reduction of cholinesterase might be regulatory mechanisms of the PVAT to preserve cholinergic vasodilation during aging.

Restricted diet delays accelerated ageing and genomic stress in DNA-repair-deficient mice.

Mice deficient in the DNA excision-repair gene Ercc1 (Ercc1∆/-) show numerous accelerated ageing features that limit their lifespan to 4-6 months. They also exhibit a 'survival response', which suppresses growth and enhances cellular maintenance. Such a response resembles the anti-ageing response induced by dietary restriction (also known as caloric restriction). Here we report that a dietary restriction of 30% tripled the median and maximal remaining lifespans of these progeroid mice, strongly retarding numerous aspects of accelerated ageing. Mice undergoing dietary restriction retained 50% more neurons and maintained full motor function far beyond the lifespan of mice fed ad libitum. Other DNA-repair-deficient, progeroid Xpg-/- (also known as Ercc5-/-) mice, a model of Cockayne syndrome, responded similarly. The dietary restriction response in Ercc1∆/- mice closely resembled the effects of dietary restriction in wild-type animals. Notably, liver tissue from Ercc1∆/- mice fed ad libitum showed preferential extinction of the expression of long genes, a phenomenon we also observed in several tissues ageing normally. This is consistent with the accumulation of stochastic, transcription-blocking lesions that affect long genes more than short ones. Dietary restriction largely prevented this declining transcriptional output and reduced the number of γH2AX DNA damage foci, indicating that dietary restriction preserves genome function by alleviating DNA damage. Our findings establish the Ercc1∆/- mouse as a powerful model organism for health-sustaining interventions, reveal potential for reducing endogenous DNA damage, facilitate a better understanding of the molecular mechanism of dietary restriction and suggest a role for counterintuitive dietary-restriction-like therapy for human progeroid genome instability syndromes and possibly neurodegeneration in general.

Diet-induced weight loss and markers of endothelial dysfunction and inflammation in treated patients with type 2 diabetes.

BACKGROUND & AIMS: Overweight and obesity increase cardiovascular mortality in patients with type 2 diabetes (T2D). In a recent trial, however, diet-induced weight loss did not reduce the cardiovascular risk of patients with T2D, possibly due to the parallel intensive medical treatment. We investigated the effect of diet-induced weight loss on cardiovascular risk factors in overweight and obese patients with T2D, and whether this effect was influenced by the use of statins, ACE inhibitors, metformin and duration of T2D. METHODS: Patients with T2D and BMI >27 were subjected to an energy-restricted diet during 4 months. Before and after intervention, plasma levels of sICAM-1, sVCAM-1, hsCRP, vWF and classical biomarkers were measured. The association of the change in biomarker levels with medication use and T2D history, corrected for age, sex and change in insulin dose, was tested by matched linear regression analyses. RESULTS: In 131 patients, the diet resulted in weight loss of 10.2 kg (95%CI 9.2, 11.3; p < 0.001), improved median levels of HbA1c (-7.0 mmol/mol (95%CI -8.5, -5.0); p < 0.001), LDL cholesterol (-0.2 mmol/L (95%CI -0.4, -0.1); p < 0.001), sICAM-1 (-22.4 ng/mL (95%CI -37.1, -8.7); p = 0.001), vWF (-3.9 IU/mL (95%CI -6.4, -1.4); p = 0.003) and hs-CRP (-0.6 mg/L (95%CI -1.2, -0.2); p = 0.007), but did not affect sVCAM-1 levels (1.6 ng/mL (95%CI -41.5, 48.6); p = 0.949). Duration of T2D and medical treatment were not associated with these effects, except for an association between statin use and change in sVCAM-1, where statin users improved more. CONCLUSION: Diet-induced weight loss reduced the levels of biomarkers of endothelial dysfunction and inflammation in overweight and obese patients with T2D independently of medication use and T2D duration. Even on intensive medical drug treatment as well as after a long history of T2D, patients may still profit from diet-induced weight reduction.

Regenerative cell therapy and pharmacotherapeutic intervention in heart failure: Part 2: Pharmacological targets, agents and intervention perspectives.

Regenerative medicine represents a promising perspective on therapeutic angiogenesis in patients with cardiovascular disease, including heart failure. However, previous or ongoing clinical trials show ambiguous outcomes with respect to the benefit of regenerative therapy by means of bone marrow stem cell infusion in myocardial infarction patients. Therefore, it is necessary to set up a rational therapeutic strategy in the treatment of congestive heart failure. Chemokines, cytokines and growth factors, as well as pharmaceutical agents, may have an impact on endothelial progenitor cell (EPC) physiology and thus can provide targets for pharmacological intervention. Indeed, EPCs and stem cell niches both in bone marrow and myocardial tissue can be treated as an integral target for recruitment of EPCs from the bone marrow to the cardiac ischaemic niche. In this article, we individually place the signalling factors in their specified context, and explain their roles in the various phases of neovascularisation (see Part 1). (Neth Heart J 2008;16:337-43.).

Regenerative cell therapy and pharmacotherapeutic intervention in heart failure: Part 1: Cardiovascular progenitor cells, their functions and sources.

It has been postulated that bone marrow derived endothelial progenitor cells (BM-EPCs) are essential for neovascularisation and endothelial repair and are involved in pharmacological treatment, and even its potential targets. There is no doubt that the ultimate success of angiogenic cell therapy will be determined by an appropriate stimulation of certain angiogenic progenitor cell subpopulations. Unfortunately, the biology of EPCs is still poorly understood. In particular, the understanding of endogenous microenvironments within the progenitor cell niches is critical, and will provide us with information about the signalling systems that supply a basis to develop rational pharmacotherapy to enhance the functional activity of endogenous or transplanted progenitor cells. The final success of clinical improvement of progenitor cell-mediated vascular repair and angiogenic therapy depends on a better understanding of EPC biology and a smart therapeutic design. In the first part of this review we first briefly discuss the possible involvement of progenitor cells in chronic heart failure. In part 2 we focus on factors that beneficially affect BMEPCs, with an emphasis on pharmacological molecular pathways involved in BM-EPC-induced neovascularisation. (Neth Heart J 2008;16:305-9.).

Cardiac overexpression of human VEGF(165) by recombinant Semliki Forest virus leads to adverse effects in pressure-induced heart failure.

Semliki Forest virus (SFV) is an efficient vector for cardiac gene delivery. The relatively short transgene expression induced by SFV seems appropriate for angiogenic gene therapy. We tested the effects of SFV expressing vascular endothelial growth factor (VEGF) on cardiac angiogenesis and heart failure in the mRen2 transgenic rat.Six-week-old mRen2 rats received SFV-VEGF or control virus (n=7 each) administered intracoronarily. Twelve days after transfection, cardiac capillary density and function were assessed. Capillary density in cardiac regions where SFV expression was highest had decreased by 20% in the SFV-VEGF-treated group. The decrease in capillary density was accompanied by impaired systolic function as illustrated by increased endsystolic volumes and a 34% decrease in cardiac output.We conclude that the time frame of SFV expression is sufficient to induce structural alterations, but that VEGF in mRen2 transgenic rats did not elicit the expected angiogenic effect. Rather, capillary density was decreased and subsequently cardiac function was impaired. This paradoxical finding is possibly related to the pathophysiology associated with this model and warrants caution if one is to pursue VEGF-mediated, angiogenic therapy before proceeding to a clinical setting. (Neth Heart J 2007;15:335-41.).

Recombinant Semliki Forest virus as a vector system for fast and selective in vivo gene delivery into balloon-injured rat aorta.

Previously, we demonstrated that recombinant Semliki Forest virus (SFV) vector rapidly and selectively transfers genes into cultured vascular smooth muscle cells (VSMC), leaving endothelial cells (EC) unaffected. From this, we hypothesized that recombinant SFV in vivo only transfers genes into the media of balloon-injured but not intact vessel, that gene expression in VSMC is fast, and that the specificity of SFV for VSMC is caused by specific binding sites. To address these hypotheses, we studied the time course of in vivo SFV-LacZ and Ad-LacZ expression in balloon-injured rat aorta. In addition, the fusion characteristics of fluorescent pyrene-labeled SFV were explored in cultured VSMC and EC. In intact aorta, no LacZ expression was found in the intima or media at 24 h. In contrast, in denuded aorta, LacZ expression was detected in as early as 12 h after incubation. LacZ expression was predominantly present in the media. Ad-LacZ expression started after 12 h, but was predominantly present in the adventitia. Ad-LacZ expression in the media started after 72 h. In vitro transfection with SFV showed that fusion was higher and, moreover, saturable in VSMC as compared with EC, indicating the presence of specific SFV binding sites on VSMC, but not EC. From this we conclude that in vivo selectivity of SFV in balloon-injured vessels is based on the removal of the endothelium, which results in accessibility of VSMC in the media that carry specific binding sites for the SFV vector.