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Introduction: In contrast to other adult tissues myocardium cannot be sufficiently regenerated following significant myocardial infarction (MI). Efficient cardiac regeneration was demonstrated in neonatal mouse myocardial injury models. Similar observations were reported in other neonatal mammals including newborn human babies suffering from MI. The mechanisms of neonatal mammalian cardiac regeneration remain unclear. Here we show the crucial role of IGF1R which was unraveled in a time-course transcriptome analysis of neonatal mouse hearts. Methods: IGF1R was specifically knocked-down (KD) in cardiomyocytes of wildtype postnatal day one (P1) mice using adeno-associated virus (rAAV9) delivered shRNAmirs. KD of Renilla served as control (REN-CTRL). 5x10 13 viral genomes per kg bodyweight were injected intrathoracally. Three batches of rAAV9 with different shRNAmirs were used for the IGF1R-KD groups. Viral transduction was confirmed by bioluminescence imaging on luciferase containing rAAV9 copies and by immunofluorescence staining of rAAV9 delivered GFP reporter. KD efficiency was confirmed in vitro using a retrovirus system and in vivo. On P2 mice underwent either left anterior descending artery (LAD) ligation for induction of MI or SHAM surgery. Cardiac function was subsequently assessed by echocardiography 1 day post injury (dpi) and 21 dpi. Thereafter, hearts were harvested and left ventricular fibrosis was analyzed histologically. Results: LAD ligation resulted in significant MI in both, IGF1R-KD and REN-CTRL, LAD groups as proven by a markedly reduced ejection fraction (EF) 1 dpi. Importantly, 21 dpi IGF1R-KD and REN-CTRL SHAM groups displayed normal cardiac function proving no effect on neonatal cardiac growth and development of only KD of IGF1R without LAD ligation. In contrast, LAD ligation IGF1R-KD mice presented significantly reduced EF 21dpi compared to the other 3 groups. Histological analysis revealed significant fibrosis in the IGF1R-KD LAD hearts compared to the other 3 groups. Conclusions: Whereas IGF1R-KD or control rAAV9 does not alter physiological cardiac development, KD of IGF1R markedly impairs neonatal cardiac regeneration in neonatal mice after MI suggesting a crucial role in neonatal cardiac regeneration.

Sodium glucose transporter (SGLT)-2 inhibitors have consistently shown cardioprotective effects independent of the glycemic status of treated patients. In this study we aimed to investigate underlying mechanisms of short-term empagliflozin treatment in a mouse model of type II diabetes. Male db/db mice were fed a western type diet with or without enrichment with empagliflozin for 7 days. While glucose tolerance was significantly improved in empagliflozin treated mice, body weight and fasting insulin levels were comparable in both groups. Cardiac insulin signaling activity indicated by reduced proteinkinase B (AKT) phosphorylation was significantly decreased in the empagliflozin treated group. Remarkably, mitochondrial mass estimated by citrate synthase activity was significantly elevated in empagliflozin treated mice. Accordingly, mitochondrial morphology was significantly altered upon treatment with empagliflozin as analysed by transmission electron microscopy. Additionally, short-term empagliflozin therapy was associated with a changed cardiac tissue cytokine expression in favor of an anti-inflammatory pattern. Our data suggest that early cardioprotection in empagliflozin treated mice is independent of a reduction in body weight or hyperinsulinemia. Ameliorated mitochondrial ultrastructure, attenuated cardiac insulin signaling and diminished cardiac inflammation might contribute to the cardioprotective effects of empagliflozin.

Background: Heart failure (HF) survival has improved, and nowadays, many patients with HF die of noncardiac causes, including cancer. Our aim was to investigate whether a causal relationship exists between HF and the development of cancer. Methods: HF was induced by inflicting large anterior myocardial infarction in APC min mice, which are prone to developing precancerous intestinal tumors, and tumor growth was measured. In addition, to rule out hemodynamic impairment, a heterotopic heart transplantation model was used in which an infarcted or sham-operated heart was transplanted into a recipient mouse while the native heart was left in situ. After 6 weeks, tumor number, volume, and proliferation were quantified. Candidate secreted proteins were selected because they were previously associated both with (colon) tumor growth and with myocardial production in post–myocardial infarction proteomic studies. Myocardial gene expression levels of these selected candidates were analyzed, as well as their proliferative effects on HT-29 (colon cancer) cells. We validated these candidates by measuring them in plasma of healthy subjects and patients with HF. Finally, we associated the relation between cardiac specific and inflammatory biomarkers and new-onset cancer in a large, prospective general population cohort. Results: The presence of failing hearts, both native and heterotopically transplanted, resulted in significantly increased intestinal tumor load of 2.4-fold in APC min mice (all P P =0.002 and P =0.016, respectively). We identified several proteins (including serpinA3 and A1, fibronectin, ceruloplasmin, and paraoxonase 1) that were elevated in human patients with chronic HF (n=101) compared with healthy subjects (n=180; P Conclusions: We demonstrate that the presence of HF is associated with enhanced tumor growth and that this is independent of hemodynamic impairment and could be caused by cardiac excreted factors. A diagnosis of HF may therefore be considered a risk factor for incident cancer.

Human life expectancy has significantly increased due to nutritional access, improved hygiene, or medical advances such as vaccinations. Consequently, morbidities shifted from infectious diseases a...

Angiogenesis is a hallmark of cancer, promoting growth and metastasis. Anti‐angiogenic treatment has limited efficacy due to therapy‐induced blood vessel alterations, often followed by local hypoxia, tumor adaptation, progression, and metastasis. It is therefore paramount to overcome therapy‐induced resistance. We show that Apelin inhibition potently remodels the tumor microenvironment, reducing angiogenesis, and effectively blunting tumor growth. Functionally, targeting Apelin improves vessel function and reduces polymorphonuclear myeloid‐derived suppressor cell infiltration. Importantly, in mammary and lung cancer, Apelin prevents resistance to anti‐angiogenic receptor tyrosine kinase (RTK) inhibitor therapy, reducing growth and angiogenesis in lung and breast cancer models without increased hypoxia in the tumor microenvironment. Apelin blockage also prevents RTK inhibitor‐induced metastases, and high Apelin levels correlate with poor prognosis of anti‐angiogenic therapy patients. These data identify a druggable anti‐angiogenic drug target that reduces tumor blood vessel densities and normalizes the tumor vasculature to decrease metastases.

Rationale : Cardiac remodeling and subsequent heart failure remain critical issues after myocardial infarction despite improved treatment and reperfusion strategies. Recently, cardiac regeneration has been demonstrated in fish and newborn mice after apex resection or cardiac infarctions. Two key issues remain to translate findings in model organisms to future therapies in humans: what is the mechanism and can cardiac regeneration indeed occur in newborn humans? Objective : To assess whether human neonatal hearts can functionally recover after myocardial infarction. Methods and Results : Here, we report the case of a newborn child having a severe myocardial infarction due to coronary artery occlusion. The child developed massive cardiac damage as defined by serum markers for cardiomyocyte cell death, electrocardiograms, echocardiography, and cardiac angiography. Remarkably, within weeks after the initial ischemic insult, we observed functional cardiac recovery, which translated into long-term normal heart function. Conclusions : These data indicate that, similar to neonatal rodents, newborn humans might have the intrinsic capacity to repair myocardial damage and completely recover cardiac function.

Klotho is an antiaging protein which exerts known cardioprotection. In kidney, trans-membrane Klotho acts as essential co-receptor of fibroblast growth factor 23 (FGF23). In the heart, soluble Klotho (sKlotho) protects from systolic dysfunction independently of FGF23. Here, we analyzed the association of FGF23 and sKlotho upon progression of chronic heart failure (CHF) and analyzed Klotho expression in human hearts. Serum levels of sKlotho and FGF23 were measured in 287 patients with cardiomyopathy (CMP). Tissue samples from CMP (n = 10) and healthy control hearts (n = 10) were analyzed for Klotho mRNA and protein expression. Individuals in the first FGF23 tertile were 4.1 times more likely of freedom from death, heart transplantation or assist device implantation compared to third tertile. No relationship was found between sKlotho and the combined endpoint. Instead, Klotho mRNA encoding the full-length form was upregulated in human CMP hearts. Immunoblotting confirmed upregulation of sKlotho associated with increased expression of proteases involved in cleavage of Klotho suggesting rather local effects of Klotho in the heart. Therefore, we conclude that in contrast to FGF23, serum sKlotho is not associated with disease severity or progression in CHF. Instead, Klotho is expressed and upregulated in diseased hearts, suggesting local paracrine effects.

Background: The adult mammalian heart has little regenerative capacity after myocardial infarction (MI), whereas neonatal mouse heart regenerates without scarring or dysfunction. However, the underlying pathways are poorly defined. We sought to derive insights into the pathways regulating neonatal development of the mouse heart and cardiac regeneration post-MI. Methods and Results: Total RNA-seq of mouse heart through the first 10 days of postnatal life (referred to as P3, P5, P10) revealed a previously unobserved transition in microRNA (miRNA) expression between P3 and P5 associated specifically with altered expression of protein-coding genes on the focal adhesion pathway and cessation of cardiomyocyte cell division. We found profound changes in the coding and noncoding transcriptome after neonatal MI, with evidence of essentially complete healing by P10. Over two-thirds of each of the messenger RNAs, long noncoding RNAs, and miRNAs that were differentially expressed in the post-MI heart were differentially expressed during normal postnatal development, suggesting a common regulatory pathway for normal cardiac development and post-MI cardiac regeneration. We selected exemplars of miRNAs implicated in our data set as regulators of cardiomyocyte proliferation. Several of these showed evidence of a functional influence on mouse cardiomyocyte cell division. In addition, a subset of these miRNAs, miR-144-3p, miR-195a-5p, miR-451a, and miR-6240 showed evidence of functional conservation in human cardiomyocytes. Conclusions: The sets of messenger RNAs, miRNAs, and long noncoding RNAs that we report here merit further investigation as gatekeepers of cell division in the postnatal heart and as targets for extension of the period of cardiac regeneration beyond the neonatal period.

Cardiac remodeling and subsequent heart failure remain critical issues after myocardial infarction despite improved treatment and reperfusion strategies. Recently, complete cardiac regeneration has been demonstrated in fish and newborn mice following resection of the cardiac apex. However, it remained entirely unclear whether the mammalian heart can also completely regenerate following a complex cardiac ischemic injury. We established a protocol to induce a severe heart attack in one-day-old mice using left anterior descending artery (LAD) ligation. LAD ligation triggered substantial cardiac injury in the left ventricle defined by Caspase 3 activation and massive cell death. Ischemia-induced cardiomyocyte death was also visible on day 4 after LAD ligation. Remarkably, 7 days after the initial ischemic insult, we observed complete cardiac regeneration without any signs of tissue damage or scarring. This tissue regeneration translated into long-term normal heart functions as assessed by echocardiography. In contrast, LAD ligations in 7-day-old mice resulted in extensive scarring comparable to adult mice, indicating that the regenerative capacity for complete cardiac healing after heart attacks can be traced to the first week after birth. RNAseq analyses of hearts on day 1, day 3, and day 10 and comparing LAD-ligated and sham-operated mice surprisingly revealed a transcriptional programme of major changes in genes mediating mitosis and cell division between days 1, 3 and 10 postnatally and a very limited set of genes, including genes regulating cell cycle and extracellular matrix synthesis, being differentially regulated in the regenerating hearts. We present for the first time a mammalian model of complete cardiac regeneration following a severe ischemic cardiac injury. This novel model system provides the unique opportunity to uncover molecular and cellular pathways that can induce cardiac regeneration after ischemic injury, findings that one day could be translated to human heart attack patients.

The introduction of injury models for neonatal mouse hearts has accelerated research on the mechanisms of cardiac regeneration in mammals. However, some existing models such as apical resection and ligation of the left anterior descending artery produce variable results, which may be due to technical difficulties associated with these methods. Here, we present an alternative model for studying cardiac regeneration in neonatal mice in which cryoinjury is used to induce heart injury. This model yields a reproducible injury size, does not induce known mechanisms of cardiac regeneration, and leads to a sustained reduction of cardiac function. This protocol uses reusable cryoprobes that can be assembled in 5 minutes, with the entire procedure taking 15 minutes per pup. The subsequent heart collection and fixation takes 2 days to complete. Cryoinjury results in a myocardial scar, and the size of injury can be scaled by use of different cryoprobes (0.5 and 1.5 mm). Cryoinjury models are medically relevant to diseases in human infants with heart disease. In summary, the myocardial cryoinjury model in neonatal mice described here is a useful tool for cardiac translational and regeneration research.

Every year millions of tourists spend their vacation in Tyrol, Austria during the winter season. They often perform sports at high altitudes and at low temperatures, factors that might cause acute myocardial infarction (AMI). This study aimed to evaluate the relationship of first physical activity and the onset of AMI in winter tourists.We carried out a retrospective analysis of consecutive patients admitted to the Department of Internal Medicine III at the Medical University of Innsbruck with the diagnosis of an AMI between 2006 and 2010. We identified 172 patients as potential candidates for the questionnaire. We successfully contacted 110 patients (mean age: 60 ± 10 years). The location of visit, duration of stay, time of arrival, first sportive activity and onset of symptoms were assessed.During the first 2 days of physical activity , 56% of AMIs occurred. In tourists who suffered AMI during, or within 1 h after cessation of activity (52%), the mean time from the start of the activity to the onset of symptoms was 2.0 ± 1.7 h. 56% of patients performed less than 2.5 h of sport per week before their vacation and 70% had ≥2 cardiovascular risk factors. Although the mean planned vacation time was 8.3 ± 3.7 days, 39% of the patients suffered from AMI on the day of arrival or the day after.The majority of AMIs in winter tourists happens within the first 2 days after arrival and within the first 2 days of physical activity.

Rationale : Lamina-associated polypeptide (LAP)2α is a mammalian chromatin-binding protein that interacts with a fraction of A-type lamins in the nuclear interior. Because mutations in lamins and LAP2α lead to cardiac disorders in humans, we hypothesized that these factors may play important roles in heart development and adult tissue homeostasis. Objective : We asked whether the presence of LAP2α was required for normal cardiac function. Methods and Results : To study the molecular mechanisms of the disease, we analyzed heart structure and function in complete and conditional Lap2 α −/− mice as well as Lap2 α −/− /Mdx mutants. Unlike conditional deletion of LAP2α in late embryonic striated muscle, its complete knockout caused systolic dysfunction in young mice, accompanied by sporadic fibrosis in old animals, as well as deregulation of major cardiac transcription factors GATA4 and myocyte enhancer factor 2c. Activation of compensatory pathways, including downregulation of β-adrenergic receptor signaling, resulted in reduced responsiveness of the myocardium to chronic β-adrenergic stimulation and stalled the progression of LAP2α-deficient hearts from hypertrophy toward cardiac failure. Dystrophin deficiency in an Mdx background resulted in a transient rescue of the Lap2 α −/− phenotype. Conclusions : Our data suggest a novel role of LAP2α in the maintenance of cardiac function under normal and stress conditions.

Evidence indicates that the intercellular adhesion molecule-1 and its counter-receptor beta2 integrin are cardioprotective proteins during myocardial ischaemia-reperfusion, but no data are available concerning the role of blood cell beta1 integrins in this process. We studied the effects of temporary myocardial ischaemia and reperfusion in blood cell-restricted beta1 integrin knockout mice (beta1(-/-)). The left descending coronary artery in conditional beta1(-/-) integrin (beta1(-/-)), beta1 integrin +/+ (beta1(+/+)) and beta1 integrin -/- bone marrow chimeric (beta1(-/-) BM) mice was ligated for 30 min, followed by reperfusion of either 3 h or 3 weeks. Plasma levels of troponin T were evaluated as an index of cardiac cellular damage. The histological evaluation of tissue damage was performed with Haematoxylin and Eosin stained sections. Cell infiltrations in the ischaemic area were investigated by immunofluorescence studies. It was found that plasma troponin T was at a similar level in beta1(-/-), beta1(+/+) and beta1(-/-) BM mice treated with 30 min ischaemia and 3 h reperfusion. Histological analysis showed that ischaemia-reperfusion resulted in marked myocardial injury in all groups of animals, but the damage score of the hearts was not significantly different between beta1(-/-), beta1(+/+) and beta1(-/-) BM mice after 3 h of reperfusion following 30 min of ischaemia (2.8 +/- 0.5, 2.6 +/- 0.5 and 2.8 +/- 0.6, respectively, n.s.). Furthermore, no difference in scar sizes in ischaemia-injured hearts was found 3 weeks after ischaemia. Semi-quantification of cells demonstrated that, compared with beta1(+/+) mice, the number of infiltrating neutrophils was significantly reduced in beta1(-/-) and beta1(-/-) BM mice, whereas MAC-1(CD11b/CD18)-positive cells in the ischaemic regions were similar in myocardial tissues of all groups. We conclude that absence of beta1 integrin expression in haematopoietic cells results in reduced neutrophil infiltration in the ischaemic regions, but does not influence myocardial damage of ischaemic hearts.

Objective Endothelial dysfunction by the loss of nitric oxide (NO) is a critical event during reperfusion of ischemic myocardium. Reduced NO availability signals important pathophysiological changes leading to myocardial reperfusion injury. We have recently shown that NO biosynthesis can be disturbed by the endogenous NO synthase (NOS) inhibitor ADMA and that these changes are mediated by an impairment of its metabolism by dimethylarginine dimethylaminohydrolase (DDAH). We therefore analyzed the role of ADMA and its metabolism in the setting of myocardial ischemia and reperfusion. Methods C57-bl6 mice underwent myocardial ischemia for exactly 30 min followed by 2, 4, 8, 12, 24, and 72 h of reperfusion achieved by occlusion and re-opening of the left coronary artery. The reperfused left ventricle was subsequently homogenized for measurements of determinants of the NO synthase pathway. Furthermore, the effects and its mechanisms of ADMA on reperfusion injury were analyzed in a genetic mouse model. Results A significant accumulation of ADMA was found in myocardial tissue when mice were subjected to 30 min of ischemia followed by reperfusion in our in vivo model. The maximum increase of tissue ADMA at 4 h of reperfusion coincided with reductions of NO tissue concentrations and DDAH activity; protein expression of NOS isoforms, however, was not changed. Furthermore, DDAH overexpression in a genetic mouse model as well as treatment with oral l-arginine markedly reduced reperfusion injury by 40–50% at 4 h of reperfusion. The effects of ADMA on reperfusion injury were shown to be mediated by reduced eNOS activity and phosphorylation, expression of adhesion molecules, and leukocyte activity. Conclusion Accumulation of tissue ADMA by impairment of DDAH was found to be a significant determinant of reperfusion injury. Our results indicate that ADMA could be a potential new target for the treatment of myocardial ischemia/reperfusion injury.

Therapies developed for adult patients with heart failure have been shown to be ineffective in pediatric clinical trials, leading to the recognition that new pediatric-specific therapies for heart failure must be developed. Administration of the recombinant growth factor neuregulin-1 (rNRG1) stimulates regeneration of heart muscle cells (cardiomyocytes) in adult mice. Because proliferation-competent cardiomyocytes are more abundant in growing mammals, we hypothesized that administration of rNRG1 during the neonatal period might be more effective than in adulthood. If so, neonatal rNRG1 delivery could be a new therapeutic strategy for treating heart failure in pediatric patients. To evaluate the effectiveness of rNRG1 administration in cardiac regeneration, newborn mice were subjected to cryoinjury, which induced myocardial dysfunction and scar formation and decreased cardiomyocyte cell cycle activity. Early administration of rNRG1 to mice from birth to 34 days of age improved myocardial function and reduced the prevalence of transmural scars. In contrast, administration of rNRG1 from 4 to 34 days of age only transiently improved myocardial function. The mechanisms of early administration involved cardiomyocyte protection (38%) and proliferation (62%). We also assessed the ability of rNRG1 to stimulate cardiomyocyte proliferation in intact cultured myocardium from pediatric patients. rNRG1 induced cardiomyocyte proliferation in myocardium from infants with heart disease who were less than 6 months of age. Our results identify an effective time period within which to execute rNRG1 clinical trials in pediatric patients for the stimulation of cardiomyocyte regeneration.

Aims Increased myocardial wall strain triggers the cardiac hypertrophic response by increasing cardiomyocyte size, reprogramming gene expression, and enhancing contractile protein synthesis. The LIM protein, migfilin, is a cytoskeleton-associated protein that was found to translocate in vitro into the nucleus in a Ca2+-dependent manner, where it co-activates the pivotal cardiac transcription factor Csx/Nkx2.5. However, the in vivo role of migfilin in cardiac function and stress response is unclear. Methods and results To define the role of migfilin in cardiac hypertrophy, we induced hypertension by transverse aortic constriction (TAC) and compared cardiac morphology and function of migfilin knockout (KO) with wild-type (WT) hearts. Heart size and myocardial contractility were comparable in untreated migfilin KO and WT hearts, but migfilin-null hearts presented a reduced extent of hypertrophic remodelling in response to chronic hypertensile stress. Migfilin KO mice maintained their cardiac function for a longer time period compared with WT mice, which presented extensive fibrosis and death due to heart failure. Migfilin translocated into the nucleus of TAC-treated cardiomyocytes, and migfilin KO hearts showed reduced Akt activation during the early response to pressure overload. Conclusions Our findings indicate an important role of migfilin in the regulation of cardiac hypertrophy upon experimental TAC.

The ability to perceive noxious stimuli is critical for an animal's survival in the face of environmental danger, and thus pain perception is likely to be under stringent evolutionary pressure. Using a neuronal-specific RNAi knock-down strategy in adult Drosophila, we recently completed a genome-wide functional annotation of heat nociception that allowed us to identify α2δ3 as a novel pain gene. Here we report construction of an evolutionary-conserved, system-level, global molecular pain network map. Our systems map is markedly enriched for multiple genes associated with human pain and predicts a plethora of novel candidate pain pathways. One central node of this pain network is phospholipid signaling, which has been implicated before in pain processing. To further investigate the role of phospholipid signaling in mammalian heat pain perception, we analysed the phenotype of PIP5Kα and PI3Kγ mutant mice. Intriguingly, both of these mice exhibit pronounced hypersensitivity to noxious heat and capsaicin-induced pain, which directly mapped through PI3Kγ kinase-dead knock-in mice to PI3Kγ lipid kinase activity. Using single primary sensory neuron recording, PI3Kγ function was mechanistically linked to a negative regulation of TRPV1 channel transduction. Our data provide a systems map for heat nociception and reinforces the extraordinary conservation of molecular mechanisms of nociception across different species., Author Summary Nociception is the perception of noxious, potentially damaging stimuli; and this pain or its equivalent behavioral readout is evolutionarily conserved from fruit flies to humans. Using genetic techniques in the fruit fly, we have been able to evaluate the potential functional contribution of every gene in the fruit fly genome for a role in avoidance of high noxious temperatures (heat pain-like responses). Using this functional genomics data set, we have developed a conserved network map of heat pain/nociception that predicts numerous conserved genes and pathways as novel pain pathways, including phospholipid signaling. Studies in multiple mutant mice confirmed a role for lipid signaling in pain perception, and more specifically we identify the critical lipid kinase (PI3Kγ) as a negative regulator of TRPV1 (receptor for noxious heat and capsaicin, the active component in chili peppers) signaling. This finding shows that our fly-based genetic pain network map is a valuable tool for the discovery of novel “nociception genes” in mammals.

To perform cardiac imaging in mice without having to invest in expensive dedicated equipment, we adapted a clinical 1.5 Tesla (T) magnetic resonance imaging (MRI) scanner for use in a murine ischemia/reperfusion model. Phase-sensitive inversion recovery (PSIR) sequence facilitated the determination of infarct sizes in vivo by late gadolinium enhancement. Results were compared to histological infarct areas in mice after ischemia/reperfusion procedure with a good correlation ( 𝑟 = 0 . 8 0 7 , 𝑃 < . 0 0 1 ). In addition, fractional area change (FAC) was assessed with single slice cine MRI and was matched to infarct size ( 𝑟 = − 0 . 8 3 7 ) and fractional shortening (FS) measured with echocardiography ( 𝑟 = 0 . 8 6 0 ); both 𝑃 < . 0 0 1 . Here, we demonstrate the use of clinical 1.5 MRI scanners as a feasible method for basic phenotyping in mice. These widely available scanners are capable of investigating in vivo infarct dimensions as well as assessment of cardiac functional parameters in mice with reasonable throughput.

BACKGROUND: PI3Kgamma functions in the immune compartment to promote inflammation in response to G-protein-coupled receptor (GPCR) agonists and PI3Kgamma also acts within the heart itself both as a negative regulator of cardiac contractility and as a pro-survival factor. Thus, PI3Kgamma has the potential to both promote and limit M I/R injury. METHODOLOGY/PRINCIPAL FINDINGS: Complete PI3Kgamma-/- mutant mice, catalytically inactive PI3KgammaKD/KD (KD) knock-in mice, and control wild type (WT) mice were subjected to in vivo myocardial ischemia and reperfusion (M I/R) injury. Additionally, bone-marrow chimeric mice were constructed to elucidate the contribution of the inflammatory response to cardiac damage. PI3Kgamma-/- mice exhibited a significantly increased infarction size following reperfusion. Mechanistically, PI3Kgamma is required for activation of the Reperfusion Injury Salvage Kinase (RISK) pathway (AKT/ERK1/2) and regulates phospholamban phosphorylation in the acute injury response. Using bone marrow chimeras, the cardioprotective role of PI3Kgamma was mapped to non-haematopoietic cells. Importantly, this massive increase in M I/R injury in PI3Kgamma-/- mice was rescued in PI3Kgamma kinase-dead (PI3KgammaKD/KD) knock-in mice. However, PI3KgammaKD/KD mice exhibited a cardiac injury similar to wild type animals, suggesting that specific blockade of PI3Kgamma catalytic activity has no beneficial effects. CONCLUSIONS/SIGNIFICANCE: Our data show that PI3Kgamma is cardioprotective during M I/R injury independent of its catalytic kinase activity and that loss of PI3Kgamma function in the hematopoietic compartment does not affect disease outcome. Thus, clinical development of specific PI3Kgamma blockers should proceed with caution.

We sought to assess the relation of N-terminal brain natriuretic peptide (NT-pro BNP) determined on day 3 after onset of acute myocardial infarction (AMI) symptoms with acute and chronic infarct size and functional parameters assessed by cardiac magnetic resonance (CMR) imaging. Furthermore, we wanted to investigate its predictive value for recovery of myocardial function.CMR was performed in 49 consecutive patients within 6 days and in a subgroup 4 (n = 27) and 12 (n = 22) months after first acute ST-elevation AMI and successful primary angioplasty. NT-pro BNP was measured in the subacute phase at 66 ± 8 h after onset of symptoms.Log-transformed NT-pro BNP (lgNT-pro BNP) significantly correlated with infarct size in % of left ventricular myocardial mass (r = 0.59 to 0.64; p0.004), with ejection fraction (EF) (r = -0.49 to -0.55; p0.004) as well as with segmental wall thickening (SWT, mm) (r = 0.41 to -0.52; p0.04) at any time of assessment. Multiple linear regression analysis revealed baseline EF and lgNT-pro BNP to predict global functional recovery. Patients with NT-pro BNP concentrationsthe mean level of 1115 pg/ml significantly improved in EF and SWT (all p0.02) during the study period, whereas patients with NT-pro BNP1115 pg/ml did not show significant functional recovery (all p = NS).NT-pro BNP on day 3 after admission correlates with acute and chronic infarct size and myocardial function after AMI. Global and regional myocardial function did not recover in patients with higher NT-pro BNP (1115 pg/ml) during subacute phase of AMI.

Introduction - Phosphoinositide 3-Kinase gamma (PI3Kγ) is a well-known key enzyme in inflammation pathways. Emerging data demonstrate that PI3Kγ plays a distinct role in cardiomyocytes, but its influence in the setting of myocardial ischemia and reperfusion is still an enigma. To clarify these effects we examined the morphology and contractility of PI3Kγ−/−hearts after ischemia and reperfusion. Methods - PI3Kγ knock out (KO) mice and C57 Bl6 wild type (WT) mice were subjected to 30 minutes of ischemia followed by 3 hours, 1 week and 3 weeks of reperfusion. We therefore reversibly ligated the left anterior descending artery (LAD) in an in vivo model and harvested the myocardium after the defined time of reperfusion. Histological sections were stained with H&E and Masson Trichrome in order to measure the area of infartion and the amount of interstitial fibrosis. Furthermore, Troponin T serum levels were determined and transthoracic echocardiography was performed for measuring the differences in myocardial contractiliy. Results - Comparing PI3Kγ KO mice with WT mice, we found a significant decrement of Troponin T serum levels in the transgenic group 3 hours after reperfusion (0.77±0.28 vs. 1.28±0.48 ng/ml, p2 , p=0.001; 1 week: 0.88±0.32 vs. 1.29±0.34 mm 2 , p=0.001; 3 weeks: 0.62±0.18 vs. 1.87±0.59 mm 2 , p Conclusions - Our data provide the first evidence for the crucial role of PI3Kγ signalling in myocardial ischemia/reperfusion injury: PI3Kγ deficient mice show a significantly better outcome concerning infarction area, Troponin T elevation, scar size, fibrosis, and contractility at all stages of reperfusion (3 hours to 3 weeks).

Cardiac regeneration is one of the prime visions in cardiovascular research. The mouse neonatal apical resection and left anterior descending artery (LAD) ligation model introduced novel in vivo mammalian assays to study cardiac regeneration. However, recent reports and editorials discussed and critically questioned the value and technical reproducibility of the mouse neonatal myocardial infarction approach, making it paramount to develop and use a reproducible model system. We established a mouse neonatal myocardial infarction model by visually confirmed ligation of the LAD using microsurgery. TdT-mediated dUTP nick-end labeling (TUNEL) proved reproducible massive myocardial infarctions in a defined region of the apex and anterior wall of neonatal and 7-day-old mice. Whereas hearts ligated on postnatal day 7 displayed chronic injury, cardiac samples ligated immediately after birth always showed complete structural regeneration after long-term follow-up. Cardiac regeneration was observed in all mouse stains (C57BL/6J, ICR, and mixed background C57BL/6JxSv129) tested so far. We present a detailed in vivo protocol to study complex mechanisms of complete cardiac repair following ischemic cardiac damage. Neonatal LAD ligation surgery is feasible, and results in reproducible myocardial infarctions 24 h after ligation, and no structural myocardial defects are detectable following long-term follow-up. We encourage the cardiovascular community to use our protocol and teaching video to answer key scientific questions in the field of cardiac regeneration. Electronic supplementary material The online version of this article (doi:10.1007/s00395-016-0580-3) contains supplementary material, which is available to authorized users.