Maarten Vanhaverbeke

Extracellular Vesicles in Cardiovascular Theranostics

Extracellular vesicles (EVs) are small bilayer lipid membrane vesicles that can be released by most cell types and detected in most body fluids. EVs exert key functions for intercellular communication via transferring their bioactive cargos to recipient cells or activating signaling pathways in target cells. Increasing evidence has shown the important regulatory effects of EVs in cardiovascular diseases (CVDs). EVs secreted by cardiomyocytes, endothelial cells, fibroblasts, and stem cells play essential roles in pathophysiological processes such as cardiac hypertrophy, cardiomyocyte survival and apoptosis, cardiac fibrosis, and angiogenesis in relation to CVDs. In this review, we will first outline the current knowledge about the physical characteristics, biological contents, and isolation methods of EVs. We will then focus on the functional roles of cardiovascular EVs and their pathophysiological effects in CVDs, as well as summarize the potential of EVs as therapeutic agents and biomarkers for CVDs. Finally, we will discuss the specific application of EVs as a novel drug delivery system and the utility of EVs in the field of regenerative medicine.

Leptin-adiponectin ratio in pre-diabetic patients undergoing percutaneous coronary intervention.

Background The obesity-related hormones leptin and adiponectin are independently and oppositely associated with insulin resistance, which is an important risk factor for coronary artery disease (CAD) and restenosis after coronary intervention. In this report, we set out to determine the role of the leptin-adiponectin ratio (LAR) in non-diabetic patients with or without impaired glucose tolerance undergoing a percutaneous coronary intervention. Methods 300 PCI patients were enrolled in this prospective single-centre study. Patients with known diagnosis of diabetes (n = 50) and newly diagnosed diabetes (2h OGTT > 200 mg/dL, n = 25) were excluded. In both stable and acute subjects, assessment was done on the day of discharge and included a fasting glucose level, leptin, adiponectin and an oral glucose tolerance test (OGTT). Results LAR was significantly higher in diabetic (7.2 ± 0.7) than in non-diabetic patients (3.9 ± 0.3, P = 0.001), and even higher in newly diagnosed diabetics (9.8 ± 1.5, P < 0.001). Likewise, among non-diabetic patients, LAR was significantly higher in patients with impaired glucose tolerance. LAR was significantly higher in pre-diabetic (4.57 ± 0.48) versus normoglycaemic patients (3.45 ± 0.33, P = 0.05). LAR was found to be numerically higher in prediabetic versus normoglycaemic patients with two- and three-vessel disease (VD), but not in patients with single VD. In pre-diabetic patients, LAR was found to be significantly increased with more advanced CAD (P = 0.021), independent of stable versus unstable presentation. Conclusions LAR is related to the extent of CAD in pre-diabetic patients but not in normoglycaemic patients. This finding might in part explainthe poorer outcome in revascularized patients with impaired glucose tolerance compared to normoglycaemic patients.

Functional Role of Cardiovascular Exosomes in Myocardial Injury and Atherosclerosis

Extracellular vesicles are now widely recognized as key players in the prevention, repair or progression of cardiovascular disease. Here we first focus on the functional roles of extracellular vesicles in the cross-talk between cardiomyocytes and endothelial cells, important for maintaining normal development and function of the heart. Second, we discuss the role of extracellular vesicles secreted by embryonic and non-embryonic stem cells in repairing cardiomyocyte function and in restoring angiogenic potential after myocardial ischemia-reperfusion injury. Third, we focus on the role of extracellular vesicles in Endothelial to Mesenchymal Transition (EndMT), leading to conversion of endothelial cells to fibroblasts, secretion of extracellular proteins collagen and fibronectin, and fibrosis. Finally, we discuss the role of extracellular vesicles secreted under stress by endothelial cells, macrophages and vascular smooth muscle cells in atherosclerosis. On aggregate, the reviewed preclinical studies present evidence that extracellular vesicles secreted by cardiomyocytes, fibroblasts, endothelial cells, immune-system-related cells, vascular smooth muscle cells and stem cells play an important role in the pathogenesis of cardiovascular disease. However, further studies are needed to gain better insight into the mechanisms used to select specific content to transfer to specific target cells, and to induce or repress signaling pathways in their target cells.

Low MT‐CO1 in Monocytes and Microvesicles Is Associated With Outcome in Patients With Coronary Artery Disease

Background Cytochrome oxidase (COX) IV complex regulates energy production in mitochondria. Impaired COX gene expression is related to obesity and type 2 diabetes mellitus, but whether it is directly related to the incidence of cardiovascular events is unknown. We investigated whether COX gene expression in monocytes is predictive for cardiovascular events in coronary artery disease patients. To avoid monocyte isolation from fresh blood, we then aimed to validate our findings in monocyte‐derived microvesicles isolated from plasma. Methods and Results We enrolled 142 consecutive patients undergoing diagnostic coronary angiography between June 2010 and January 2011 and followed 67 patients with stable coronary artery disease prospectively for at least 3 years. Twenty‐two patients experienced a new cardiovascular event (32.8%). Circulating CD14+ monocytes and microvesicles were isolated with magnetic beads, and COX mRNA levels were measured with quantitative polymerase chain reaction, after normalization with 5 validated house‐keeping genes. Patients in the lowest tertile of mitochondrial cytochrome oxidase, subunit I (MT‐COI) in monocytes at baseline had a higher risk for developing a new event after adjusting for age, sex, (ex)smoking, body mass index, blood pressure, diabetes mellitus, low‐density lipoprotein– and high‐density lipoprotein–cholesterol, triglycerides, high‐sensitivity C‐reactive protein, interleukin‐6, and number of diseased vessels (harzard ratio [HR], 3.95; 95% CI, 1.63–9.57). Patients in the lowest tertile of MT‐COI in monocyte‐specific microvesicles had also a higher risk of developing a new event (adjusted HR, 5.00; 95% CI, 1.77–14). Conclusions In the current blinded study, low MT‐COI in monocytes of coronary artery disease patients identifies a population at risk for new cardiovascular events. For the first time, we show that signatures in monocyte‐specific microvesicles in plasma have similar predictive properties.

Absorb Bioresorbable Vascular Scaffold in Complex Coronary Bifurcation Interventions: Insights From an In Vivo Multimodality Imaging Study

Background—Although bioresorbable scaffolds offer potential advantages compared with metallic drug-eluting stents in the treatment of complex coronary bifurcation lesions, there are concerns that the polymeric scaffold integrity may be compromised. This in vivo study sought to provide insights about the feasibility of performing complex bifurcation stenting with Absorb bioresorbable vascular scaffolds (Abbott Vascular, Santa Clara, CA). Methods and Results—Twenty New Zealand white rabbits underwent stenting of the nondiseased aortoiliac bifurcation with bioresorbable vascular scaffolds using provisional (PS, n=5), culotte (n=5), modified-T (n=5), or T-and protrusion (n=5) stenting techniques. Angiography, optical coherence tomography, and microcomputed tomography were performed. Angiographic results were excellent without evidence of dissection or side branch (SB) compromise. PS optimally opened the SB ostium without deforming the main vessel (MV) bioresorbable vascular scaffolds, avoiding malapposition, and revealing a single connector fracture in 1 of 5 cases on microcomputed tomography. Culotte stenting resulted in complete bifurcation coverage with extensive segments of double-layered struts and inappropriately apposed struts at the bifurcation level in 3 of 5 cases. On microcomputed tomography, there was MV and SB scaffold distortion at the bifurcation with single strut fractures in 4 of 5 and double fractures in 1 of 5. Modified-T and T-and protrusion resulted in complete bifurcation coverage and in minimal double-strut layers at the neocarina. On microcomputed tomography, no strut fractures were present after modified-T, whereas in 3 of 5 T-and protrusion procedures single strut fractures were noted. Conclusions—Bifurcation stenting using bioresorbable vascular scaffolds is feasible with excellent angiographic results. PS with additional T-and protrusion whenever needed seems a reasonable approach. Whenever a 2-stent technique is planned, modified T-stenting appears the most promising.

Molecular signature of progenitor cells isolated from young and adult human hearts

The loss of endogenous cardiac regenerative capacity within the first week of postnatal life has intensified clinical trials to induce cardiac regeneration in the adult mammalian heart using different progenitor cell types. We hypothesized that donor age-related phenotypic and functional characteristics of cardiac progenitor cells (CPC) account for mixed results of cell-based cardiac repair. We compared expression profiles and cell turnover rates of human heart-derived c-kitpos progenitors (c-kitpos CPC) and cardiosphere-derived cells (CDC) from young and adult donor origin and studied their in vitro angiogenic and cardiac differentiation potential, which can be relevant for cardiac repair. We report that 3-dimensional CDC expansion recapitulates a conducive environment for growth factor and cytokine release from adult donor cells (aCDC) that optimally supports vascular tube formation and vessel sprouting. Transdifferentiation capacity of c-kitpos CPCs and CDCs towards cardiomyocyte-like cells was modest, however, most notable in young c-kitpos cells and adult CDCs. Progenitors isolated with different methods thus show cell- and donor-specific characteristics that may account for variable contributions in functional myocardial recovery.

Local haemostatic measures after tooth removal in patients on antithrombotic therapy: a systematic review

ObjectiveThe interruption of antithrombotics prior to tooth removal because of the fear of bleeding or following postoperative bleeding increases the risk of thromboembolic events. The aim of this systematic review was to investigate which local haemostatic measures can effectively prevent postoperative bleeding in patients continuing oral antithrombotics.MethodsA systematic review was conducted by running a search in PubMed, Embase, Web of Science and Cochrane Library. Clinical randomised trials investigating bleeding and haemostatics after tooth removal in patients on antithrombotics were identified.ResultsIn total, 15 articles were included. The investigated haemostatics included gauze pressure, tranexamic acid-soaked gauze, sponges, glue, calcium sulfate, plant extract Ankaferd Blood Stopper, epsilon-aminocaproic acid and tranexamic acid. In patients treated with vitamin K antagonists, tranexamic acid mouthwash significantly reduced bleeding compared to placebo. Further, histoacryl glue was proven better than gelatin sponges. Other studies failed to show significant differences between haemostatics, but bleeding events were low.ConclusionsTranexamic acid seems to effectively reduce bleeding, although its superiority to other haemostatics was not proven. In view of the rapidly changing landscape of antithrombotics and the lack of standardization of bleeding outcome, adequately powered clinical studies are required to optimise postoperative management in patients on antithrombotics.Clinical relevanceIn order to optimise postoperative management, the best haemostatics over different patient groups have to be identified and implemented in guidelines.

C-reactive protein during and after myocardial infarction in relation to cardiac injury and left ventricular function at follow-up

Acute myocardial infarction (MI) invokes a large inflammatory response, which contributes to myocardial repair.

Low Cytochrome Oxidase 1 Links Mitochondrial Dysfunction to Atherosclerosis in Mice and Pigs.

Background Cytochrome oxidase IV complex regulates energy production in mitochondria. Therefore, we determined the relation of COX genes with atherosclerosis in mice and pigs. Methods and results First, we compared atherosclerosis in the aortic arch of age-matched (24 weeks) C57BL/6J control (n = 10), LDL-receptor deficient (n = 8), leptin-deficient ob/ob (n = 10), and double knock-out (lacking LDL-receptor and leptin) mice (n = 12). Low aortic mitochondria-encoded cytochrome oxidase 1 in obese diabetic double knock-out mice was associated with a larger plaque area and higher propensity of M1 macrophages and oxidized LDL. Caloric restriction increased mitochondria-encoded cytochrome oxidase 1 and reduced plaque area and oxidized LDL. This was associated with a reduction of titer of anti-oxidized LDL antibodies, a proxy of systemic oxidative stress. Low of mitochondria-encoded cytochrome oxidase 1 was related to low expression of peroxisome proliferative activated receptors α, δ, and γ and of peroxisome proliferative activated receptor, gamma, co-activator 1 alpha reflecting mitochondrial dysfunction. Caloric restriction increased them. To investigate if there was a diabetic/obesity requirement for mitochondria-encoded cytochrome oxidase 1 to be down-regulated, we then studied atherosclerosis in LAD of hypercholesterolemic pigs (n = 37). Pigs at the end of the study were divided in three groups based on increasing LAD plaque complexity according to Stary (Stary I: n = 12; Stary II: n = 13; Stary III: n = 12). Low mitochondria-encoded cytochrome oxidase 1 in isolated plaque macrophages was associated with more complex coronary plaques and oxidized LDL. Nucleus-encoded cytochrome oxidase 4I1 and cytochrome oxidase 10 did not correlate with plaque complexity and oxidative stress. In mice and pigs, MT-COI was inversely related to insulin resistance. Conclusions Low MT-COI is related to mitochondrial dysfunction, oxidative stress and atherosclerosis and plaque complexity.

Long-term intravascular follow-up of coronary bifurcation treatment with Absorb bioresorbable vascular scaffold

The feasibility of using the Absorb bioresorbable vascular scaffold (BVS) in complex bifurcation techniques has been investigated in ex and in vivo investigations. However, long-term clinical evaluations of different approaches are still ongoing. We present the longterm intravascular follow-up of a patient treated with modified-T stenting of a true bifurcation lesion. A 53year-old male smoker underwent PCI of a LAD/diagonal lesion (Medina 1,1,1) following presentation with stable angina. Using a modified-T technique, the bifurcation lesion was successfully treated with implantation of 2.5 18mm BVS in D1 and 3.0 18mm BVS in LAD, with good bifurcation coverage and stent apposition on optical coherence tomography (OCT). The patient remained angina free at 30 months. Baseline (preand post-PCI) and (planned) 30-month angiography and OCT (Figure 1) revealed complete restoration of the bifurcation anatomy and excellent vessel-wall healing characteristics at 30 months. When considering which two-stent technique to use when treating complex bifurcation lesions with Absorb BVS, modified T-stenting seems to be more favourable than Culotte or TAP-stenting based on in vivo investigations. Nevertheless, in view of worrying reports of intraluminal scaffold dismantling and very late scaffold thrombosis, the long-term performance of bifurcation procedures with Absorb BVS has to be further investigated. The presented images highlight that modified T-stenting is a promising technique with excellent healing characteristics at 30 months, provided an optimal result post-PCI has been obtained. Although recent data from the Absorb II and III studies have shown an increased risk of target lesion failure with the Absorb BVS, the modified-T approach may warrant re-evaluation in future generation bioresorbable scaffolds.