Prognostic value of three iron deficiency definitions in patients with advanced heart failure.

AIMS: There is uncertainty about the definition of iron deficiency (ID) and the association between ID and prognosis in patients with advanced heart failure. We evaluated three definitions of ID in patients referred for heart transplantation. METHODS AND RESULTS: Consecutive patients assessed for heart transplantation at a single UK centre between January 2010 and May 2022 were included. ID was defined as (1) serum ferritin concentration of <100 ng/ml, or 100-299 ng/ml with transferrin saturation <20% (guideline definition), (2) serum iron concentration ≤13 µmol/L, or (3) transferrin saturation <20%. The primary outcome measure was a composite of all-cause mortality, urgent heart transplantation or need for mechanical circulatory support. Overall, 801 patients were included, and the prevalence of ID was 39-55% depending on the definition used. ID, defined by either serum iron or transferrin saturation, was an independent predictor of the primary outcome measure (hazard ratio [HR] 1.532, 95% confidence interval [CI] 1.264-1.944, and HR 1.595, 95% CI 1.323-2.033, respectively), but the same association was not seen with the guideline definition of ID (HR 1.085, 95% CI 0.8827-1.333). These findings were robust in multivariable Cox regression analysis. ID, by all definitions, was associated with lower 6-min walk distance, lower peak oxygen consumption, higher intra-cardiac filling pressures and lower cardiac output. CONCLUSIONS: Iron deficiency, when defined by serum iron concentration or transferrin saturation, was associated with increased frequency of adverse clinical outcomes in patients with advanced heart failure. The same association was not seen with guideline definition of ID.

Assessment of Paclitaxel Drug-Coated Balloon Only Angioplasty in STEMI.

BACKGROUND: Primary percutaneous coronary intervention (pPCI) with drug-eluting stents (DES) has emerged as the standard of care, but stent-related events have persisted. Drug-coated balloon (DCB)-only angioplasty is an emerging technology, although it is not fully evaluated compared with DES in the context of pPCI. OBJECTIVES: The aim of this study was to investigate the safety of DCB-only angioplasty compared with second-generation DES in pPCI. METHODS: All-cause mortality and net adverse cardiac events (cardiovascular mortality, acute coronary syndrome, ischemic stroke or transient ischemic attack, major bleeding, and unplanned target lesion revascularization [TLR]) were compared among all patients treated with DCBs only or with second-generation DES only for first presentation of ST-segment elevation myocardial infarction (STEMI) due to de novo disease between January 1, 2016, and November 15, 2019. Patients treated with both DCBs and DES were excluded. Data were analyzed using Cox regression models, Kaplan-Meier estimator plots and propensity score matching. RESULTS: Among 1,139 patients with STEMI due to de novo disease, 452 were treated with DCBs and 687 with DES. After a median follow-up period of >3 years, all-cause mortality was 49 of 452 and 62 of 687 in the DCB and DES groups, respectively (P = 0.18). On multivariable Cox regression analysis, there was no difference in mortality between DCBs and DES in the full and propensity score-matched cohorts. Age, frailty risk, history of heart failure, and family history of ischemic heart disease remained significant independent predictors of mortality. There was no difference in any of the secondary endpoints, including unplanned TLR. CONCLUSIONS: DCB-only angioplasty appears safe compared with DES for STEMI in terms of all-cause mortality and all net adverse cardiac events, including unplanned TLR. DCB may be an efficacious and safe alternative to DES in selected patient groups. (Drug Coated Balloon Only vs Drug Eluting Stent Angioplasty; NCT04482972).

Effects of Intravenous Iron Replacement Therapy on Cardiovascular Outcomes in Patients with Heart Failure: A Systematic Review and Meta-Analysis.

(1) Background: Iron deficiency (ID) is an important adverse prognostic marker in patients with heart failure (HF); however, it is unclear whether intravenous iron replacement reduces cardiovascular mortality in this patient group. Here, we estimate the effect of intravenous iron replacement therapy on hard clinical outcomes following the publication of IRONMAN, the largest trial in this field. (2) Methods: In this systematic review and meta-analysis, prospectively registered with PROSPERO and reported according to PRISMA guidelines, we searched PubMed and Embase for randomized controlled trials investigating intravenous iron replacement in patients with HF and co-existing ID. The primary outcome was cardiovascular mortality and secondary outcomes were all-cause mortality, hospitalizations for HF and a combination of the primary outcome and hospitalizations for HF. (3) Results: A total of 1671 items were identified and after removal of duplicates we screened titles and abstracts of 1202 records. Some 31 studies were identified for full-text review and 12 studies were included in the final review. The odds ratio (OR) for cardiovascular death using a random effects model was 0.85 (95% CI 0.69 to 1.04) and for all-cause mortality it was 0.83 (95% CI 0.59 to 1.15). There was a significant reduction in hospitalizations for HF (OR 0.49, 95% CI 0.35 to 0.69) and the combination of hospitalizations for HF and cardiovascular death (OR 0.65, 95% CI 0.5 to 0.85). (4) Conclusions: This review supports the use of IV iron replacement reducing hospitalization rates for HF, however more research is required to determine the effect on cardiovascular mortality and to identify the patient population most likely to benefit.

Drug-Coated Balloon vs. Drug-Eluting Stents for De Novo Unprotected Left Main Stem Disease: The SPARTAN-LMS Study.

The objective of this study is to compare the outcomes of patients treated with drug-coated balloons (DCBs) or second-generation drug-eluting stents (DESs) for de novo unprotected left main stem (LMS) disease. Previous studies comparing the treatment of LMS disease suggest that the mortality for DES PCI is not worse than CABG. There are limited data from studies investigating the treatment of de novo LMS disease with DCB angioplasty. We compared the all-cause and cardiac mortality of patients treated with paclitaxel DCB to those with second-generation DES for de novo LMS disease from July 2014 to November 2019. Data were analysed using Kaplan-Meier analyses and propensity-matched analyses. A total of 148 patients were treated with either a DCB or DES strategy. There was no significant difference in all-cause mortality in the DCB group (19.5%) compared to the DES group (15.9%) (HR 1.42 [0.61-3.32], p = 0.42). Regarding cardiac mortality, 2 (4.9%) were recorded for the DCB group and 7 (6.5%) for the DES group (HR 1.21 [0.31-4.67], p = 0.786); for target vessel myocardial infarction, there were 0 (0%) for the DCB group and 7 (6.5%) for the DES group; and for target lesion revascularisation, there were 3 (7.3%) in the DCB group and 9 (8.3%) in the DES group (HR: 0.89 [0.24-3.30]). p = 0.86. These remained not significant after propensity score matching. We found no difference in the mortality outcomes with DCB angioplasty compared to second-generation DES, with a median follow-up of 33 months. DCB can therefore be regarded as a safe option in the treatment of LMS disease in suitable patients.

Shared decision making in cardiology: a systematic review and meta-analysis.

OBJECTIVES: To evaluate the effectiveness of interventions to improve shared decision making (SDM) in cardiology with particular focus on patient-centred outcomes such as decisional conflict. METHODS: We searched Embase (OVID), the Cochrane library, PubMed and Web of Science electronic databases from inception to January 2021 for randomised controlled trials that investigated the effects of interventions to increase SDM in cardiology. The primary outcomes were decisional conflict, decisional anxiety, decisional satisfaction or decisional regret; a secondary outcome was knowledge gained by the patients. RESULTS: Eighteen studies which reported on at least one outcome measure were identified, including a total of 4419 patients. Interventions to increase SDM had a significant effect on reducing decisional conflict (standardised mean difference (SMD) -0.211, 95% CI -0.316 to -0.107) and increasing patient knowledge (SMD 0.476, 95% CI 0.351 to 0.600) compared with standard care. CONCLUSIONS: Interventions to increase SDM are effective in reducing decisional conflict and increasing patient knowledge in the field of cardiology. Such interventions are helpful in supporting patient-centred healthcare and should be implemented in wider cardiology practice.

Ischemia-Selective Cardioprotection by Malonate for Ischemia/Reperfusion Injury.

BACKGROUND: Inhibiting SDH (succinate dehydrogenase), with the competitive inhibitor malonate, has shown promise in ameliorating ischemia/reperfusion injury. However, key for translation to the clinic is understanding the mechanism of malonate entry into cells to enable inhibition of SDH, its mitochondrial target, as malonate itself poorly permeates cellular membranes. The possibility of malonate selectively entering the at-risk heart tissue on reperfusion, however, remains unexplored. METHODS: C57BL/6J mice, C2C12 and H9c2 myoblasts, and HeLa cells were used to elucidate the mechanism of selective malonate uptake into the ischemic heart upon reperfusion. Cells were treated with malonate while varying pH or together with transport inhibitors. Mouse hearts were either perfused ex vivo (Langendorff) or subjected to in vivo left anterior descending coronary artery ligation as models of ischemia/reperfusion injury. Succinate and malonate levels were assessed by liquid chromatography-tandem mass spectrometry LC-MS/MS, in vivo by mass spectrometry imaging, and infarct size by TTC (2,3,5-triphenyl-2H-tetrazolium chloride) staining. RESULTS: Malonate was robustly protective against cardiac ischemia/reperfusion injury, but only if administered at reperfusion and not when infused before ischemia. The extent of malonate uptake into the heart was proportional to the duration of ischemia. Malonate entry into cardiomyocytes in vivo and in vitro was dramatically increased at the low pH (≈6.5) associated with ischemia. This increased uptake of malonate was blocked by selective inhibition of MCT1 (monocarboxylate transporter 1). Reperfusion of the ischemic heart region with malonate led to selective SDH inhibition in the at-risk region. Acid-formulation greatly enhances the cardioprotective potency of malonate. CONCLUSIONS: Cardioprotection by malonate is dependent on its entry into cardiomyocytes. This is facilitated by the local decrease in pH that occurs during ischemia, leading to its selective uptake upon reperfusion into the at-risk tissue, via MCT1. Thus, malonate's preferential uptake in reperfused tissue means it is an at-risk tissue-selective drug that protects against cardiac ischemia/reperfusion injury.

The Role of SGLT2 Inhibitors in Heart Failure: A Systematic Review and Meta-Analysis.

AIMS: Recent randomised controlled trials (RCTs) have shown a significant prognostic benefit of sodium-glucose cotransporter 2 (SGLT2) inhibitors in the cardiovascular (CV) profile of patients with diabetes. This systematic review and meta-analysis aim to provide a concise evaluation of all the available evidence for the use of these agents in patients with heart failure (HF) regardless of their baseline diabetes status. METHODS AND RESULTS: PubMed, Web of Science, and Cochrane library databases were systematically searched from inception until November 20th 2020. Eight studies consisting of 13,275 patients were included in the meta-analysis. For the total population, SGLT2 inhibitors reduced the risk of all-cause mortality (HR: 0.83; 95% CI: 0.75-0.91; I 2 0%), hospitalisation for HF (HR: 0.68; 95% CI: 0.61-0.75; I 2: 0%), CV death (HR: 0.82; 95% CI: 0.74-0.92; I 2: 0%), and hospitalisation for HF or CV death (HR: 0.72; 95% CI: 0.66-0.78; I 2: 0%). Subgroup analyses of the total population according to the diabetes status showed that SGLT2 inhibitors significantly reduced the risk of hospitalisation for HF (HR: 0.68; 95% CI: 0.61, 0.75; I 2: 0%), as well as the risk of hospitalisation for HF or CV death (HR: 0.72; 95% CI: 0.66, 078; I 2: 0%) and CV death (HR: 0.82; 95% CI: 0.74, 0.91; I 2: 0%). CONCLUSIONS: The results of this meta-analysis confirm the growing evidence in the literature of the favourable profile of SGLT2 inhibitors in cardiovascular outcomes and mortality in patients with heart failure regardless of the baseline diabetes status. This systematic review has been registered with PROSPERO (CRD42021224777).

Modelling Metabolic Shifts during Cardiomyocyte Differentiation, Iron Deficiency and Transferrin Rescue Using Human Pluripotent Stem Cells.

Cardiomyocytes rely on specialised metabolism to meet the high energy demand of the heart. During heart development, metabolism matures and shifts from the predominant utilisation of glycolysis and glutamine oxidation towards lactate and fatty acid oxidation. Iron deficiency (ID) leads to cellular metabolism perturbations. However, the exact alterations in substrate metabolism during ID are poorly defined. Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM), the present study investigated changes in major metabolic substrate utilisation in the context of ID or upon transferrin rescue. Typically, during hiPSC-CM differentiation, the greatest increase in total metabolic output and rate was seen in fatty acid metabolism. When ID was induced, hiPSC-CMs displayed increased reliance on glycolytic metabolism, and six TCA cycle, five amino acid, and four fatty acid substrates were significantly impaired. Transferrin rescue was able to improve TCA cycle substrate metabolism, but the amino acid and fatty acid metabolism remained perturbed. Replenishing iron stores partially reverses the adverse metabolic changes that occur during ID. Understanding the changes in metabolic substrate utilisation and their modification may provide potential for discovery of new biomarkers and therapeutic targets in cardiovascular diseases.

Iron deficiency for prognosis in acute coronary syndrome - A systematic review and meta-analysis.

BACKGROUND: Iron deficiency (ID) is an important predictor of adverse outcomes in patients with heart failure, however it is unclear whether ID also affects prognosis in patients with acute coronary syndrome (ACS). The aim of this systematic review and meta-analysis was to assess the prognostic value of iron deficiency in patients with ACS. METHODS: We searched PubMed, Web of Science, and the Cochrane library and included cohort studies of patients with ACS that were stratified by ID status. There were no restrictions on definition of ACS or ID. Studies were systematically appraised and data extracted by two independent reviewers. Meta-analysis was performed where two or more studies reported on the same pre-determined outcome measure. RESULTS: Seven studies with 2821 participants were identified, reporting a high prevalence of ID in the ACS population. Three studies reported worse long-term outcomes in the ID population, whereas short-term outcomes were heterogeneous across studies. CONCLUSIONS: Patients with ID presenting with ACS may have a worse long-term prognosis but more studies are required for confirmation. A role for ID in prognosis of patients with ACS and as a potentially treatable condition may have implication for the current management of this patient population.

Restoring mitochondrial DNA copy number preserves mitochondrial function and delays vascular aging in mice.

Aging is the largest risk factor for cardiovascular disease, yet the molecular mechanisms underlying vascular aging remain unclear. Mitochondrial DNA (mtDNA) damage is linked to aging, but whether mtDNA damage or mitochondrial dysfunction is present and directly promotes vascular aging is unknown. Furthermore, mechanistic studies in mice are severely hampered by long study times and lack of sensitive, repeatable and reproducible parameters of arterial aging at standardized early time points. We examined the time course of multiple invasive and noninvasive arterial physiological parameters and structural changes of arterial aging in mice, how aging affects vessel mitochondrial function, and the effects of gain or loss of mitochondrial function on vascular aging. Vascular aging was first detected by 44 weeks (wk) of age, with reduced carotid compliance and distensibility, increased ß-stiffness index and increased aortic pulse wave velocity (PWV). Aortic collagen content and elastin breaks also increased at 44 wk. Arterial mtDNA copy number (mtCN) and the mtCN-regulatory proteins TFAM, PGC1α and Twinkle were reduced by 44 wk, associated with reduced mitochondrial respiration. Overexpression of the mitochondrial helicase Twinkle (Tw+ ) increased mtCN and improved mitochondrial respiration in arteries, and delayed physiological and structural aging in all parameters studied. Conversely, mice with defective mitochondrial polymerase-gamma (PolG) and reduced mtDNA integrity demonstrated accelerated vascular aging. Our study identifies multiple early and reproducible parameters for assessing vascular aging in mice. Arterial mitochondrial respiration reduces markedly with age, and reduced mtDNA integrity and mitochondrial function directly promote vascular aging.

Mitochondrial Respiration Is Reduced in Atherosclerosis, Promoting Necrotic Core Formation and Reducing Relative Fibrous Cap Thickness.

OBJECTIVE: Mitochondrial DNA (mtDNA) damage is present in murine and human atherosclerotic plaques. However, whether endogenous levels of mtDNA damage are sufficient to cause mitochondrial dysfunction and whether decreasing mtDNA damage and improving mitochondrial respiration affects plaque burden or composition are unclear. We examined mitochondrial respiration in human atherosclerotic plaques and whether augmenting mitochondrial respiration affects atherogenesis. APPROACH AND RESULTS: Human atherosclerotic plaques showed marked mitochondrial dysfunction, manifested as reduced mtDNA copy number and oxygen consumption rate in fibrous cap and core regions. Vascular smooth muscle cells derived from plaques showed impaired mitochondrial respiration, reduced complex I expression, and increased mitophagy, which was induced by oxidized low-density lipoprotein. Apolipoprotein E-deficient (ApoE-/-) mice showed decreased mtDNA integrity and mitochondrial respiration, associated with increased mitochondrial reactive oxygen species. To determine whether alleviating mtDNA damage and increasing mitochondrial respiration affects atherogenesis, we studied ApoE-/- mice overexpressing the mitochondrial helicase Twinkle (Tw+/ApoE-/-). Tw+/ApoE-/- mice showed increased mtDNA integrity, copy number, respiratory complex abundance, and respiration. Tw+/ApoE-/- mice had decreased necrotic core and increased fibrous cap areas, and Tw+/ApoE-/- bone marrow transplantation also reduced core areas. Twinkle increased vascular smooth muscle cell mtDNA integrity and respiration. Twinkle also promoted vascular smooth muscle cell proliferation and protected both vascular smooth muscle cells and macrophages from oxidative stress-induced apoptosis. CONCLUSIONS: Endogenous mtDNA damage in mouse and human atherosclerosis is associated with significantly reduced mitochondrial respiration. Reducing mtDNA damage and increasing mitochondrial respiration decrease necrotic core and increase fibrous cap areas independently of changes in reactive oxygen species and may be a promising therapeutic strategy in atherosclerosis.

Glucagon-like peptide-1 derived cardioprotection does not utilize a KATP-channel dependent pathway: mechanistic insights from human supply and demand ischemia studies.

BACKGROUND: Glucagon-like peptide-1 (7-36) amide (GLP-1) protects against stunning and cumulative left ventricular dysfunction in humans. The mechanism remains uncertain but GLP-1 may act by opening mitochondrial K-ATP channels in a similar fashion to ischemic conditioning. We investigated whether blockade of K-ATP channels with glibenclamide abrogated the protective effect of GLP-1 in humans. METHODS: Thirty-two non-diabetic patients awaiting stenting of the left anterior descending artery (LAD) were allocated into 4 groups (control, glibenclamide, GLP-1, and GLP-1 + glibenclamide). Glibenclamide was given orally prior to the procedure. A left ventricular conductance catheter recorded pressure-volume loops during a 1-min low-pressure balloon occlusion (BO1) of the LAD. GLP-1 or saline was then infused for 30-min followed by a further 1-min balloon occlusion (BO2). In a non-invasive study, 10 non-diabetic patients were randomized to receive two dobutamine stress echocardiograms (DSE) during GLP-1 infusion with or without oral glibenclamide pretreatment. RESULTS: GLP-1 prevented stunning even with glibenclamide pretreatment; the Δ % dP/dtmax 30-min post-BO1 normalized to baseline after GLP-1: 0.3 ± 6.8 % (p = 0.02) and GLP-1 + glibenclamide: -0.8 ± 9.0 % (p = 0.04) compared to control: -11.5 ± 10.0 %. GLP-1 also reduced cumulative stunning after BO2: -12.8 ± 10.5 % (p = 0.02) as did GLP-1 + glibenclamide: -14.9 ± 9.2 % (p = 0.02) compared to control: -25.7 ± 9.6 %. Glibenclamide alone was no different to control. Glibenclamide pretreatment did not affect global or regional systolic function after GLP-1 at peak DSE stress (EF 74.6 ± 6.4 vs. 74.0 ± 8.0, p = 0.76) or recovery (EF 61.9 ± 5.7 vs. 61.4 ± 5.6, p = 0.74). CONCLUSIONS: Glibenclamide pretreatment does not abrogate the protective effect of GLP-1 in human models of non-lethal myocardial ischemia. Trial registration Clinicaltrials.gov Unique Identifier: NCT02128022.

Vascular Smooth Muscle Cell Senescence Promotes Atherosclerosis and Features of Plaque Vulnerability.

BACKGROUND: Although vascular smooth muscle cell (VSMC) proliferation is implicated in atherogenesis, VSMCs in advanced plaques and cultured from plaques show evidence of VSMC senescence and DNA damage. In particular, plaque VSMCs show shortening of telomeres, which can directly induce senescence. Senescence can have multiple effects on plaque development and morphology; however, the consequences of VSMC senescence or the mechanisms underlying VSMC senescence in atherosclerosis are mostly unknown. METHODS AND RESULTS: We examined the expression of proteins that protect telomeres in VSMCs derived from human plaques and normal vessels. Plaque VSMCs showed reduced expression and telomere binding of telomeric repeat-binding factor-2 (TRF2), associated with increased DNA damage. TRF2 expression was regulated by p53-dependent degradation of the TRF2 protein. To examine the functional consequences of loss of TRF2, we expressed TRF2 or a TRF2 functional mutant (T188A) as either gain- or loss-of-function studies in vitro and in apolipoprotein E(-/-) mice. TRF2 overexpression bypassed senescence, reduced DNA damage, and accelerated DNA repair, whereas TRF2(188A) showed opposite effects. Transgenic mice expressing VSMC-specific TRF2(T188A) showed increased atherosclerosis and necrotic core formation in vivo, whereas VSMC-specific TRF2 increased the relative fibrous cap and decreased necrotic core areas. TRF2 protected against atherosclerosis independent of secretion of senescence-associated cytokines. CONCLUSIONS: We conclude that plaque VSMC senescence in atherosclerosis is associated with loss of TRF2. VSMC senes cence promotes both atherosclerosis and features of plaque vulnerability, identifying prevention of senescence as a potential target for intervention.

Cardioprotection by S-nitrosation of a cysteine switch on mitochondrial complex I.

Oxidative damage from elevated production of reactive oxygen species (ROS) contributes to ischemia-reperfusion injury in myocardial infarction and stroke. The mechanism by which the increase in ROS occurs is not known, and it is unclear how this increase can be prevented. A wide variety of nitric oxide donors and S-nitrosating agents protect the ischemic myocardium from infarction, but the responsible mechanisms are unclear. Here we used a mitochondria-selective S-nitrosating agent, MitoSNO, to determine how mitochondrial S-nitrosation at the reperfusion phase of myocardial infarction is cardioprotective in vivo in mice. We found that protection is due to the S-nitrosation of mitochondrial complex I, which is the entry point for electrons from NADH into the respiratory chain. Reversible S-nitrosation of complex I slows the reactivation of mitochondria during the crucial first minutes of the reperfusion of ischemic tissue, thereby decreasing ROS production, oxidative damage and tissue necrosis. Inhibition of complex I is afforded by the selective S-nitrosation of Cys39 on the ND3 subunit, which becomes susceptible to modification only after ischemia. Our results identify rapid complex I reactivation as a central pathological feature of ischemia-reperfusion injury and show that preventing this reactivation by modification of a cysteine switch is a robust cardioprotective mechanism and hence a rational therapeutic strategy.

Troponins: redefining their limits.

The diagnosis of myocardial infarction (MI) depends on a rise and/or fall of cardiac biomarkers such as troponins in the appropriate clinical context. Conventional troponin assays lack sensitivity and precision at the low serum concentrations observed in the early hours after the onset of chest pain. New, highly sensitive troponin assays may offer improved certainty in these early hours. Many of these assays can detect troponins reliably at serum concentrations that occur in patients with chronic stable heart disease and even in asymptomatic healthy individuals. Indiscriminate use of these previously undetectable concentrations for the early diagnosis of acute MI will be accompanied by reduced specificity. However, they are likely to improve risk stratification of patients with chronic heart disease. This review focuses on the available highly sensitive troponin assays and their likely use in the diagnosis of acute MI and risk stratification of patients with heart disease.

Sphingosine-1-phosphate stimulates the functional capacity of progenitor cells by activation of the CXCR4-dependent signaling pathway via the S1P3 receptor.

OBJECTIVE: Sphingosine-1-phosphate (S1P) is a bioactive lipid, which influences migration and proliferation of endothelial cells through activation of S1P receptors and has been shown to support SDF-1 induced migration and bone marrow homing of CD34+ progenitors. METHODS AND RESULTS: Here, we show that incubation of patient-derived endothelial progenitor cells (EPCs) with S1P or its synthetic analog FTY720 improved blood flow recovery in ischemic hind limbs. Likewise, recovery of blood flow was dramatically reduced after induction of hindlimb ischemia in mice deficient for the S1P receptor 3 (S1P3). S1P3-/- bone marrow-derived mononuclear cells (BMCs) failed to augment neovascularization after hind limb ischemia. Of note, treatment of BMCs derived from S1P3-/- mice with S1P did not rescue blood flow recovery. Mechanistically, S1P and FTY720 induced phosphorylation of CXCR4, activated the Src kinase, and stimulated phosphorylation of JAK2. The contribution of CXCR4 for S1P-mediated effects was further supported by the findings that S1P preincubation failed to stimulate invasion capacity and in vivo blood flow recovery of BMCs from CXCR4+/- mice. The activation of CXCR4 was dependent on the Src kinase family as demonstrated by preincubation with the Src inhibitor PP2. The activation of the CXCR4 signaling by S1P is mediated via the S1P3 receptor, since S1P-induced Src phosphorylation was abrogated in EPC from S1P3-/- mice. CONCLUSIONS: S1P agonists might serve as sensitizers of CXCR4-mediated signaling and may be applied in clinical progenitor cell therapy to improve EPC or BMC function in patients with coronary artery disease.

Impaired CXCR4 signaling contributes to the reduced neovascularization capacity of endothelial progenitor cells from patients with coronary artery disease.

Transplantation of bone marrow cells as well as circulating endothelial progenitor cells (EPC) enhances neovascularization after ischemia. The chemokine receptor CXCR4 is essential for migration and homing of hematopoietic stem cells. Therefore, we investigated the role of CXCR4 and its downstream signaling cascade for the angiogenic capacity of cultured human EPC. Ex vivo, differentiated EPC derived from peripheral blood abundantly expressed CXCR4. Incubation of EPC from healthy volunteers with neutralizing antibodies against CXCR4 profoundly inhibited vascular endothelial growth factor- and stromal-derived factor-1-induced migration as well as EPC-induced angiogenesis in an ex vivo assay. Preincubation of transplanted EPC with CXCR4 antibody reduced EPC incorporation and impaired blood-flow recovery in ischemic hindlimbs of nude mice (57+/-4% of normal perfusion versus untreated EPC: 80+/-11%, P<0.001). Bone marrow mononuclear cells (BM-MNC) or EPC of heterozygous CXCR4(+/-) mice displayed reduced CXCR4 expression and disclosed impaired in vivo capacity to enhance recovery of ischemic blood flow in nude mice (blood flow 27+/-11% versus 66+/-25% using wild-type cells, P<0.01). Importantly, impaired blood flow in ischemic CXCR4(+/-) mice was rescued by injection of wild-type BM-MNC. Next, we investigated the role of CXCR4 for functional capacities of EPC from patients with coronary artery disease (CAD). Surface expression of CXCR4 was similar in EPC from patients with CAD compared with healthy controls. However, basal Janus kinase (JAK)-2 phosphorylation was significantly reduced and less responsive to stromal-derived factor-1 in EPC from patients with CAD compared with healthy volunteers, indicating that CXCR4-mediated JAK-2 signaling is dysregulated in EPC from patients with CAD. The CXCR4 receptor signaling profoundly modulates the angiogenic activity and homing capacity of cultured human EPC. Disturbance of CXCR4 signaling, as demonstrated by reduced JAK-2 phosphorylation, may contribute to functional impairment of EPC from patients with CAD. Stimulating CXCR4 signaling might improve functional properties of EPC and may rescue impaired neovascularization capacity of EPC derived from patients with CAD.

Change in knowledge and skills of Year 3 undergraduates in evidence-based medicine seminars.

PURPOSE: To evaluate the effect of a compulsory evidence-based medicine (EBM) seminar in critical appraisal skills and the overall acceptance of compulsory EBM seminars for Year 3 medical undergraduate students. METHODS: Small group seminars by peer teaching were conducted for up to 23 undergraduates. Knowledge and skills in EBM before and after the compulsory seminars were evaluated by 2 different sets of 20 questions. To apply knowledge, each undergraduate had to analyse an individual paper case using the principles of EBM. Undergraduates gave anonymous feedback using separate evaluation sheets at the end of the seminar. Main outcome variables were changes in knowledge and skills. RESULTS: A total of 132 Year 3 undergraduates at the University of Frankfurt participated in a compulsory EBM seminar during the academic half-year 2003/04 as part of their regular curriculum. Complete datasets were available for evaluation from 124 undergraduates (94%). The seminars led to an overall increase in knowledge (question paper score increase from 2.37 to 7.48, 99% CI 6.61-8.36, or 216%). Transfer of knowledge into a paper case scenario was generally good, with a mean score of 49.5 (SD 5.24) out of 55 points. Feedback indicated good overall acceptance of the seminars, with a median of 2 (score range from 1 = excellent to 6 = failed). CONCLUSION: Trained medical students are effective and well accepted EBM trainers in compulsory undergraduate seminars.