Fractalkine Signalling (CX3CL1/CX3CR1 Axis) as an Emerging Target in Coronary Artery Disease.

BACKGROUND: Heart Failure (HF) post MI remains a important cause of mortality and morbidity Whole body periodic acceleration (pGz) is the repetitive motion of the supine body in a sinusoidal head to foot direction achieved with a motorized platform. pGz induces pulsatile shear stress on the vascular endothelium. Pulsatile shear stress activates endothelial nitric oxide synthase (eNOS) to produce increased release of nitric oxide (eNO). pGz pre-and postconditioning can induce cardioprotective affects in an in-vivo rat model of myocardial infarction (MI) reducing mortality, arrhythmias and infarct size. The effects of pGz on myocardial function and remodeling after MI are unknown. Left ventricular (LV) pressure-volume (PV) relationships are an invasive but comprehensive method to assess myocardial function. OBJECTIVE: We investigated the effects of pGz on LV function and remodeling induced by chronic MI in rats. Methods: After MI, rats (SD-300gms) were randomized to receive pGz (MI-pGz) (n=5) Control (MI-C) (n=5) for 4 weeks and a separate sham surgery group (n=5). In vivo LV pressure-volume relationships were analyzed using a conductance catheter (Millar Instruments, Texas). LV fibrosis was analyzed using trichrome staining and digital microscopy. RESULTS: pGz after MI reduced left ventricular fibrosis by 40% [MI-C 36( 4 )% vs MI-pGz 21(2)% (p < 0.01) as a % of the LV]. There were no differences in heart rate between groups. pGz significantly improved ejection fraction (EF), left ventricular end systolic pressure (LVESP), dP/dtmax, and both end systolic (ESPVR) and diastolic (EDPVR) pressure volume relations (Table). Data: X(SD) * p< 0.01 (Sham vs. MI-C) and † p< 0.01 (MI-C vs MI-pGz) Conclusions: In a rat model HF induced by chronic MI, pGz markedly improved LV function. These findings have implications for cardiac rehabilitation post MI.

Microvascular obstruction (MVO) of coronary arteries promotes an increase in mortality and major adverse cardiac events in patients with acute myocardial infarction (AMI) and percutaneous coronary intervention (PCI). Intramyocardial hemorrhage (IMH) is observed in 41-50% of patients with ST-segment elevation myocardial infarction and PCI. The occurrence of IMH is accompanied by inflammation. There is evidence that microthrombi are not involved in the development of MVO. The appearance of MVO is associated with infarct size, the duration of ischemia of the heart, and myocardial edema. However, there is no conclusive evidence that myocardial edema plays an important role in the development of MVO. There is evidence that platelets, inflammation, overload, neuropeptide Y, and endothelin-1 could be involved in the pathogenesis of MVO. The role of endothelial cell damage in MVO formation remains unclear in patients with AMI and PCI. It is unclear whether nitric oxide production is reduced in patients with MVO. Only indirect evidence on the involvement of inflammation in the development of MVO has been obtained. The role of reactive oxygen species (ROS) in the pathogenesis of MVO is not studied. The role of necroptosis and pyroptosis in the pathogenesis of MVO in patients with AMI and PCI is also not studied. The significance of the balance of thromboxane A2, vasopressin, angiotensin II, and prostacyclin in the formation of MVO is currently unknown. Conclusive evidence regarding the role of coronary artery spasm in the development of MVhasn't been established. Correlation analysis of the neuropeptide Y, endothelin-1 levels and the MVO size in patients with AMI and PCI has not previously been performed. It is unclear whether epinephrine aggravates reperfusion necrosis of cardiomyocytes. Dual antiplatelet therapy improves the efficacy of PCI in prevention of MVO. It is unknown whether epinephrine or L-type channel blockers result in the long-term improvement of coronary blood flow in patients with MVO.

The aim of this study was to evaluate the effects of fimasartan/amlodipine fixed-dosed combination (F/A) on left ventricle (LV) systolic function and infarct size in the rat myocardial infarction (MI) model. We induced MI in 20 rats by ligation of the left anterior descending coronary artery and they were divided into two groups [MI group (n=10) vs. MI+F/A 10 mg/kg group (n=10)]. F/A was administered for 28 days between day-7 and day-35 in the MI+F/A group and echocardiography was performed at day-7 and at day-35 after the induction of MI. Picrosirius red staining was performed to confirm the fibrotic tissue and infarct size was measured using image analysis program for Image J. At the 35-day follow-up, the LV ejection fraction (EF) was significantly higher (38.10±3.92% vs. 29.86±4.56%, p<0.001) and delta (day-35 minus day-7) EF was significantly higher (0.14±2.66% vs. −8.53±2.66%. p<0.001) in the MI+F/A group than the MI group. Systolic blood pressure was significantly lower in the MI+F/A group than the MI group (103.23±13.35 mmHg vs. 123.43±14.82 mmHg, p<0.01). The MI+F/A group had a smaller infarct size (26.84±5.31% vs. 36.79±3.10%, p<0.01) than the MI group at the 35-day follow-up. Oral administration of F/A 10 mg/kg could improve LV systolic function and reduce infarct size in a rat MI model.

Prognostic value of β1 adrenergic receptor autoantibodies for microvascular obstruction in patients with STEMI with Post-PCI: A prospective cohort study

The actual role of the coronary microcirculation, which is massively injured by myocardial infarction (MI), in intramyocardial hemorrhage (IMH) pathophysiology is still not fully understood. To determine the change and distribution of microcirculation of myocardial edema (ME), IMH, MI, and the remote area of early reperfusion using 7.0-T cardiovascular magnetic resonance (CMR) in a rat model of acute MI. Eight rats with 60-min myocardial ischemia followed by reperfusion were investigated. On days 2 and 7, after the acquisition of T2*-mapping and T2-mapping images, late gadolinium enhancement imaging was performed to evaluate the extent of myocardial ischemia after an injection of Gd-DTPA. On days 3 and 8, after the injection of ultrasmall superparamagnetic iron oxide (USPIO), T2*- and T2-mapping images were acquired. The R2 values of ME, IMH, MI, and remote areas were measured. From days 2 to 3, R2 values increased in the IMH, MI, ME, and remote area (all P < 0.05) following administration of USPIO, while the delta R2 value of IMH and MI was larger than remote area (P < 0.05). From day 7 to day 8, there was no significant difference in the IMH, MI, ME, and remote area (all P > 0.05). Microvascular injury of IMH and MI is the most severe among all the studied myocardial injuries in the early reperfusion of MI, while microvascular density decreased during follow-up.

Therapeutic Window for Cardioprotection by Recombinant Human Erythropoietin (rhEPO) in the Rat Model of Ischemia-Reperfusion: Implications for Clinical Trial Design

Coronary microvascular obstruction (MVO) occurs frequently in patients with ST-elevation myocardial infarction (STEMI) after percutaneous coronary intervention (PCI). However, mechanisms are multiple and not yet fully understood. Perilipin 2 (PLIN2) is involved in lipid metabolism of macrophages resident in atherosclerotic plaques, along with a role in enhancing plaque inflammation. We studied the association between PLIN2 and MVO in STEMI patients undergoing primary PCI, and we assessed the role of PLIN2 to predict major adverse cardiovascular events (MACEs). STEMI patients undergoing primary PCI were enrolled. PLIN2 was evaluated in peripheral blood monocytes; MVO was assessed using coronary angiogram. MACEs, as a composite of cardiac death, non-fatal myocardial infarction, re-admission for heart failure, and target vessel revascularization were investigated at follow-up. Among 100 STEMI patients, 33 (33.0%) had MVO. Patients with MVO had higher levels of PLIN2 (1.03 ± 0.28 vs. 0.90 ± 0.16, P = 0.019). Age [odds ratio (OR) (95% confidence interval, CI), 1.045 (1.005-1.087), P = 0.026] and PLIN2 [OR (95% CI), 16.606 (2.027-136.030), P = 0.009] were associated with MVO at univariate analysis, although only PLIN2 [OR (95% CI), 12.325 (1.446-105.039), P = 0.022] was associated with MVO at multivariate analysis. After a mean follow-up of 182.2 ± 126.6 days, 13 MACEs occurred. MVO [hazard ratio (HR) (95% CI), 6.791 (2.053-22.462), P = 0.002], hypercholesterolaemia [HR (95% CI), 3.563 (1.094-11.599), P = 0.035], and PLIN2 [HR (95% CI), 82.991 (9.857-698.746), P < 0.001] were predictors of MACEs at univariate analysis, although only PLIN2 [HR (95% CI), 26.904 (2.461-294.100), P = 0.007] predicted MACEs at multivariate analysis. In STEMI patients undergoing primary PCI, PLIN2 was independently associated with MVO and was an independent predictor of MACEs at follow-up, suggesting to further explore PLIN2 as a target for future cardioprotection therapies.

The aim of this study was to explore the significance of different ST-segment changes before and after percutaneous coronary intervention (PCI), in relation to cardiac magnetic resonance (CMR)-verified microvascular obstruction (MVO) along with intramyocardial hemorrhage (IMH) in ST-elevation myocardial infarction (STEMI) patients.This study enrolled 108 STEMI patients who received primary PCI and had no contraindication of CMR investigation. Sum ST-segment elevation (STE), maximal STE on admission and sum ST-segment resolution (STR), and single-lead STR and residual STE at 60 minutes after primary PCI were assessed. MVO and IMH were determined by contrast-enhanced CMR.Patients were classified into 3 groups: 30 patients with MVO(−)/IMH(−), 25 with MVO(+)/IMH(−), and 53 with MVO(+)/IMH(+). Sum STE (P = 0.001), maximal STE (P < 0.001), and residual STE (P = 0.025) were highest and single-lead STR was lowest (P = 0.044) in the MVO(+)/IMH(+) group. Receiver operator characteristics curve analysis revealed that maximal STE was the most powerful factor for distinguishing between MVO(+) and MVO(−) patients (optimal threshold = 0.5 mV, area under the curve, AUC = 0.718, P < 0.001), or IMH(+) and IMH(−) patients (optimal threshold = 0.5 mV, AUC = 0.697, P < 0.001). In multivariate analysis, maximal STE was identified as the most powerful independent predictor of MVO (odds ratio [OR] = 4.30, P < 0.001) and IMH (OR = 2.44, P = 0.001), whereas sum STE was the strongest correlate of both the number of MVO segments (r = 0.42, P < 0.001) and IMH segments (r = 0.43, P < 0.001).The presence of MVO and IMH in infarcted tissue was relevant to ST-segment changes in STEMI patients. Maximal STE was a powerful independent predictor of the presence of MVO and IMH, whereas sum STE was a strong correlate of the number of MVO and IMH segments.

HomeCirculation: Cardiovascular ImagingVol. 10, No. 7Mapping Myocardial Salvage Index by Extracellular Volume Fraction Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBMapping Myocardial Salvage Index by Extracellular Volume FractionAre We There Yet? Heerajnarain Bulluck, PhD and Derek J. Hausenloy, MBChB, PhD Heerajnarain BulluckHeerajnarain Bulluck From the The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom (H.B., D.J.H.); The National Institute of Health Research, Biomedical Research Centre, University College London Hospitals, United Kingdom (H.B., D.J.H.); Papworth Hospital NHS Trust, Cambridge, United Kingdom (H.B.); Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom (D.J.H.); National Heart Research Institute Singapore, National Heart Centre, Singapore (D.J.H.); Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore (D.J.H.); and Yong Loo Lin School of Medicine, National University of Singapore (D.J.H.). and Derek J. HausenloyDerek J. Hausenloy From the The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, United Kingdom (H.B., D.J.H.); The National Institute of Health Research, Biomedical Research Centre, University College London Hospitals, United Kingdom (H.B., D.J.H.); Papworth Hospital NHS Trust, Cambridge, United Kingdom (H.B.); Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom (D.J.H.); National Heart Research Institute Singapore, National Heart Centre, Singapore (D.J.H.); Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore (D.J.H.); and Yong Loo Lin School of Medicine, National University of Singapore (D.J.H.). Originally published3 Jul 2017https://doi.org/10.1161/CIRCIMAGING.117.006680Circulation: Cardiovascular Imaging. 2017;10:e006680In ST-segment–elevation myocardial infarction (STEMI) patients treated by primary percutaneous coronary intervention (PPCI), the myocardial salvage index (MSI) provides a more sensitive measure for assessing the efficacy of novel cardioprotective therapies, than an absolute reduction in myocardial infarct (MI) size. Knowledge of the MI size and the size of the area at risk (AAR) are prerequisites for measuring the MSI, and both may be obtained by cardiovascular magnetic resonance (CMR) in reperfused STEMI patients, with the MSI shown to predict clinical outcomes after PPCI.1 CMR is considered the gold standard imaging modality for quantifying MI size, and it can also delineate the edema-based AAR, with T2- and T1-mapping CMR emerging as the most robust techniques,2 although no consensus has yet been reached.See Article by Garg et alIn this issue of Circulation: Cardiovascular Imaging, Garg et al3 report on a potentially novel approach for quantifying the AAR, chronic MI size, and MSI in a study of 50 STEMI patients reperfused by PPCI, based on extracellular volume fraction (ECV) maps from an acute CMR scan. The study derived specific ECV cutoff values on an acute CMR scan (performed at a median of 48 hours post-PPCI) in a subset of 10 patients, to delineate the AAR (when compared with T2-STIR imaging), and chronic MI size (when compared with late gadolinium enhancement [LGE]) on a follow-up scan performed at 3 months post-PPCI). Using acute ECV cutoff values of >33% to delineate the AAR and >46% to delineate chronic MI size, they concluded that acute ECV maps could be used to reliably quantify AAR, chronic MI size, and MSI. Being able to accurately quantify MI size using a pixel-wise acute ECV map would be appealing and could be potentially easily implemented in clinical practice with the wider availability of in-line, automated ECV map generation from the scanner, to improve workflow.4 However, there are several potential limitations to consider concerning the use of acute ECV maps to detect the AAR, chronic MI size, and MSI in reperfused STEMI patients.First, the study did not specifically compare the performance of ECV-derived MSI with conventional MSI (from LGE and T2-STIR), and whether acute ECV maps can be used to estimate the MSI remains to be demonstrated. The authors could have considered using the reference standard of manual delineation of AAR and MI size by experienced operators, rather than semiautomated thresholding methods, which are known to have their limitations.5,6 The presence of microvascular obstruction (MVO) on the acute CMR scan is known to pseudonormalize the ECV,5,7 because of failure of the gadolinium chelate to penetrate areas of MVO, which could have affected MI size regression, thereby making it challenging to estimate chronic MI size from the acute ECV in patients with MVO. Finally, the study used ≤75% transmural MI on the follow-up CMR scan to define viable myocardium, instead of the conventionally accepted definitions of ≤50% for viability on CMR.8 In addition, the study defined an increase of ≥15% in left ventricular (LV) end-systolic volume to define adverse LV remodeling, instead of the conventional definition of ≥20% increase in LV end-diastolic volume for adverse LV remodeling on echocardiography.9 In this regard, we have recently proposed CMR-based definitions for assessing adverse LV remodeling after STEMI, which may be helpful for future CMR studies.10 The study findings are also thought-provoking and raise some interesting questions for the field.Can Acute ECV Maps Be Used to Accurately Delineate the Chronic MI Size Given the Pathological Differences That Exist Between Acute and Chronic MI?It is well recognized that acute MI size is dynamic, and acutely reduces in size within the first week,11,12 and more chronically reduces over the first few months.5,11 The regression in MI size represents the gradual resolution of myocardial edema, intramyocardial hemorrhage and MVO, and the gradual replacement of necrotic tissue with fibrosis in the chronic infarct.11 Furthermore, LV remodeling leads to thinning of the infarcted territory and compensatory LV hypertrophy of the adjacent and remote myocardium, resulting in the overall reduction in LGE mass observed in the chronic phase. The overestimation of acute MI size by LGE on the acute CMR scan can be minimized by acquiring LGE images at least 15 minutes after contrast injection and undertaking the acute CMR scan at day 7.13 In addition, acute MI size has recently been shown to be prognostic14 and may help to reduce sample size in clinical cardioprotection studies in reperfused STEMI patients, thereby obviating the need to measure chronic MI size, which can be challenging to perform in clinical cardioprotection studies.6 Therefore, the differences between the pathologies underlying acute and chronic MI, may in part, have impacted on the study findings and may have contributed to the substantial variability observed between acute MI size by ECV and chronic MI size by LGE, with the Bland–Altman analysis showing a bias of 1.9% and wide limits of agreement of ±10.5%. This suggests that acute ECV maps may not yet be ready to reliably predict chronic MI size after STEMI.Can Acute ECV Maps Be Used to Accurately Delineate the AAR Given That Edema in Salvaged Myocardium Can Be Both Intracellular and Interstitial After STEMI?During acute myocardial ischemia, interruption of the blood supply to the myocardium disrupts cardiomyocyte Na+/K+ channel function, leading to increased transmembrane Na+ gradients and intracellular edema. Prolonged periods of ischemia can result in cardiomyocyte cell membrane rupture, thereby adding to the intracellular edema. Alterations in capillary permeability can promote interstitial edema, resulting in both intracellular and interstitial edema during acute myocardial ischemia. Furthermore, reperfusion can exacerbate both interstitial and intracellular edema and may also lead to extravasation of red blood cells.15 Native T1-mapping, T2-mapping, or T2-STIR CMR imaging detect both intracellular and interstitial edema, whereas acute ECV can only detect edema in the latter compartment,16 and, therefore, areas of intracellular edema in the salvaged myocardium may be overlooked by acute ECV.It may also be challenging for acute ECV maps to reliably differentiate salvaged myocardium within the AAR from remote myocardium outside the AAR, given that there can be overlap in acute ECV values between the salvaged and remote myocardium after STEMI. In this regard, Hammer-Hansen et al17 have recently reported an overlap in acute ECV values between salvaged versus remote myocardium (95% of the acute ECV values were 18%–30% in the remote, and 28%–51% in the salvaged myocardium) after STEMI. An overlap in acute ECV values between the salvaged and remote myocardium may also have affected the study by Garg et al,3 with areas of acute ECV >33% observed in the remote myocardium (Figure 3, case 1). Furthermore, a previous study by the same research group had reported an acute ECV of 29±6% in the remote myocardium,18 confirming the potential for overlap in acute ECV values between salvaged and remote myocardium. Again, this may explain, in part, the wide limits of agreement (±10.4%) observed in this study, indicating a large variability in the observed values between acute ECV AAR and T2-STIR AAR.3 In a previous study, we had observed limits of agreement of ±5.1% when comparing T1 and T2 mapping to detect the AAR in reperfused STEMI patients,2 and limits of agreement of ±10.4% observed with acute ECV maps for delineating T2-weighted AAR may be too wide for clinical application. This suggests that acute ECV maps may not yet be ready to measure AAR after STEMI.In summary, performing a comprehensive CMR study in acutely reperfused STEMI patients can be very challenging, and Garg et al3 should be congratulated on their study investigating the potential role of acute ECV mapping for assessing AAR, chronic MI size, and MSI. Multiparametric CMR mapping has provided valuable insights into the changes occurring in areas of MI, MVO, intramyocardial hemorrhage, and salvaged/remote myocardium following STEMI.7,19,20 However, more validation work is needed before acute ECV mapping, can be used to reliably assess AAR, MI size, and MSI in reperfused STEMI patients.Sources of FundingDr Hausenloy is supported by the British Heart Foundation (FS/10/039/28270), Duke-National University Singapore Medical School, and the National Institute for Health Research, Biomedical Research Centre, University College London Hospitals. This research is supported by the Singapore Ministry of Health's National Medical Research Council under its Clinician Scientist-Senior Investigator scheme (NMRC/CSA-SI/0011/2017) and Collaborative Centre Grant scheme (NMRC/CGAug16C006). This research is supported by the Singapore Ministry of Education Academic Research Fund Tier 2 (MOE2016-T2-2–021).DisclosuresNone.FootnotesThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.Correspondence to Derek J. Hausenloy, MBChB, PhD, Cardiovascular and Metabolic Diseases Program, Duke-NUS Graduate Medical School Singapore, 8 College Rd, Singapore 169857. E-mail [email protected]

BackgroundAngiogenesis is the main therapeutic mechanism of cell therapy for cardiovascular diseases, but diabetes is reported to reduce the function and number of progenitor cells. Therefore, we studied the effect of streptozotocin-induced diabetes on the bone marrow-mesenchymal stem cell (MSC) function, and examined whether diabetes-impaired MSC could be rescued by pretreatment with oxytocin.ResultsMSCs were isolated and cultured from diabetic (DM) or non-diabetic (non-DM) rat, and proliferation rate was compared. DM-MSC was pretreated with oxytocin and compared with non-DM-MSC. Angiogenic capacity was estimated by tube formation and Matrigel plug assay, and therapeutic efficacy was studied in rat myocardial infarction (MI) model.The proliferation and angiogenic activity of DM-MSC were severely impaired but significantly improved by pretreatment with oxytocin. Krüppel-like factor 2 (KLF2), a critical angiogenic factor, was dramatically reduced in DM-MSC and significantly restored by oxytocin. In the Matrigel plug assay, vessel formation of DM-BMSCs was attenuated but was recovered by oxytocin. In rat MI model, DM-MSC injection did not ameliorate cardiac injury, whereas oxytocin-pretreated DM-MSC improved cardiac function and reduced fibrosis.ConclusionsOur results show that diabetes influenced MSC by reducing angiogenic capacity and therapeutic potential. We demonstrate the striking effect of oxytocin on stem cell dysfunction and suggest the use of oxytocin as a priming reagent in autologous stem cell therapy.

3-Phosphoinositide-dependent protein kinase-1 (PDK1) is involved in numerous cellular responses. In this study, we investigated the protective effects of PDK1 gene expression against hypoxic conditions in cultured rat CMCs (rCMCs) and in a rat myocardial infarction (MI) model using the lentiviral vector (LeV) system. LeV-PDK1 transfer effectively reduced the apoptotic cell death caused by hypoxic injury as compared to LeV-GFP transfer in rCMCs the expression of survival proteins increased in the LeV-PDK1 group, whereas apoptosis signaling decreased in the rCMCs and in infarcted hearts treated with LeV-PDK1. LeV-PDK1 transfer also reduced apoptosis and infarct size and attenuated myocardial wall thinning and ventricular remodeling in a rat MI model. These findings suggest that PDK1 has a protective role in the injured ischemic myocardium via overexpression of the cell survival pathway in CMCs. Hence PDK1 can be used as a treatment strategy for myocardial salvage inin hypoxic injury.

Background Clinical-grade human induced pluripotent stem cells (iPSCs) established from a healthy volunteer are currently being considered as a quality controlled cell source for regenerative therapy. Transplantation of three-dimensional bioengineered cardiac tissues composed of human iPSC-derived cardiovascular cell lineages is reported to hold potential for cardiac functional recovery. Purpose The aims of this study were to evaluate tissue conformation and cellular viability of human iPSC-derived cardiac tissues (HiCTs) generated from clinical-grade cells and to validate functional efficacy of HiCT transplantation. Methods Clinical-grade human iPSC lines were simultaneously differentiated into cardiovascular cell lineages by a high-density monolayer culture. The differentiation efficacy was analyzed by flow cytometry. We seeded the cells on temperature responsive culture dishes to form cell sheets. HiCTs are generated by stacking 5 cell sheets with insertion of gelatin hydrogel microspheres (GHMs) between each sheet to promote oxygen and nutrition supply. Characteristics of the HiCTs are histologically and immunohistochemically evaluated. The HiCTs were transplanted onto an athymic nude rat myocardial infarction (MI) model. Cardiac function was evaluated by echocardiography and cardiac magnetic resonance imaging (MRI) until 4 weeks after surgery, and compared to those in animals with sham operation and with cell sheet stacks without GHMs [GHM(−)]. Results Flow cytometry at differentiation day15 revealed cellular components as follows: 52.5±1.4% of cardiomyocytes (cardiac isoform of troponin-T+), 9.8±0.7% of vascular endothelial cells (VE-cadherin+), 14.8±1.8% of vascular mural cells (PDGFRβ+) and 0.2±0.1% of undifferentiated cells (TRA-1-60+). HiCTs were significantly thicker [GHM(−) vs HiCT: 357.3±81.5 vs 723.0±84.0μm, p&amp;lt;0.05], composed of higher area of cardiomyocytes (27.7±7.9 vs 71.9±15.5mm2, p&amp;lt;0.05) and endothelial cells (CD31+) (1.6±0.7 vs 9.2±1.5mm2, p&amp;lt;0.05), free from hypoxia (HIF-1α+) (3.1±0.1 vs 0.8±0.2%, p&amp;lt;0.05) and cell death (TUNEL+) (3.2±0.1 vs 1.4±0.3%, p&amp;lt;0.05) after 7 days of in vitro culture. Echocardiography revealed significantly lower left ventricular end diastolic volume (LVEDV) and higher left ventricular ejection fraction (LVEF) in HiCT group [sham (n=27) vs GHM(−) (n=12) vs HiCT (n=12): LVEDV; 1.4±0.1 vs 1.3±0.1 vs 0.9±0.1mL, p&amp;lt;0.0001/LVEF; 55.3±1.1 vs 58.2±2.3 vs 78.2±1.5%, p&amp;lt;0.0001]. Cardiac MRI showed lower LVEDV and higher LVEF as well [sham (n=8) vs GHM(−) (n=6) vs HiCT (n=6): LVEDV; 0.7±0.03 vs 0.7±0.03 vs 0.6±0.02mL, p&amp;lt;0.01 / LVEF; 39.2±2.1 vs 43.8±1.4 vs 54.0±2.8%, p&amp;lt;0.001]. Conclusions We conclude that HiCTs generated from clinical-grade cells hold sufficient viability and tissue conformation suitable for functional recovery validated by a rat MI model. Clinical-grade human iPSCs potentially serve as a reasonable cell source for stem cell-derived product transplantation therapy with foreseeable clinical applications. Funding Acknowledgement Type of funding source: Other. Main funding source(s): Japan Agency for Medical Research and Development (AMED), Invited Research Project of Institute for Advancement of Clinical Transnational Science, Kyoto University Hospital

Noninvasively monitoring activated fibroblasts is of great value for understanding the dynamic process of myocardial fibrosis after myocardial infarction (MI). This study aimed to evaluate the feasibility of 68Ga-labeled fibroblast activation protein inhibitor 04 (68Ga-FAPI-04) for monitoring reparative fibrosis and reactive fibrosis after MI. MI models were prepared by ligation of the left anterior descending (LAD) coronary artery and validated by electrocardiogram and 18F-FDG PET/CT 1 day after MI and hematoxylin and eosin (HE) staining. 68Ga-FAPI-04 PET/CT scans (1, 3, 6, 9, 12, 15, 18, 21, 28, and 35 days after MI) were carried out in MI rats and sham-operated rats without ligation of LAD. Blocking experiments were carried out on MI rats on day 7 after MI with 68Ga-FAPI-04 and excessive FAPI-04. Autoradiography, HE staining, Masson's trichrome staining, and immunofluorescence staining were carried out for ex vivo validation. The infarcted area with decreased or defective myocardial metabolic activity in 18F-FDG PET/CT correspondingly showed high 68Ga-FAPI-04 uptake in the MI rats. The myocardial tracer uptake was significantly different between MI and sham-operated rats from day 1 to 28 after MI and reached peak value 6 days after MI (0.806 ± 0.257%ID/cc vs 0.199 ± 0.012%ID/cc, P < 0.05). Tracer uptake at the infarcted myocardium and normal tissues in MI rats decreased significantly after blocking. Obvious tracer uptake was confirmed by autoradiography, and immunofluorescence staining showed FAP+ cells in the infarcted myocardium and border zone. Masson's trichrome staining of the heart sections of MI rats at different times suggested the presence of myocardial fibrosis. 68Ga-FAPI-04 uptake was not observed in the distal uninjured myocardium throughout the observation period. In conclusion, 68Ga-FAPI-04 PET could noninvasively monitor the activated fibroblasts in the early stage post acute MI and may be helpful for evaluating the degree of reparative fibrosis, while reactive fibrosis monitoring still needs further study.

Background: Brain-derived neurotrophic factor (BDNF) is associated with coronary artery diseases. However, its role and mechanism in myocardial infarction (MI) is not fully understood.Methods: Wistar rat and Kunming mouse model of MI were induced by the ligation of left coronary artery. Blood samples were collected from MI rats and patients. Plasma BDNF level, protein expression of BDNF, tropomyosin-related kinase B (TrkB) and its downstream transient receptor potential canonical (TRPC)3/6 channels were examined by enzyme-linked immunosorbent assay and Western blot. Infarct size, cardiac function and cardiomyocyte apoptosis were measured after intra-myocardium injection with recombinant human BDNF. Protective role of BDNF against cardiomyocyte apoptosis was confirmed by BDNF scavenger TrkB-Fc. The regulation of TRPC3/6 channels by BDNF was validated by pretreating with TRPC blocker (2-Aminoethyl diphenylborinate, 2-APB) and TRPC3/6 siRNAs.Results: Circulating BDNF was significantly enhanced in MI rats and patients. Protein expression of BDNF, TrkB and TRPC3/6 channels were upregulated in MI. 3 days post-MI, BDNF treatment markedly reduced the infarct size and serum lactate dehydrogenase activity. Meanwhile, echocardiography indicated that BDNF significantly improved cardiac function of MI mice. Furthermore, BDNF markedly inhibited cardiomyocyte apoptosis by upregulating Bcl-2 expression and downregulating caspase-3 expression and activity in ischemic myocardium. In neonatal rat ventricular myocytes, cell viability was dramatically increased by BDNF in hypoxia, which was restored by TrkB-Fc. Furthermore, protective role of BDNF against hypoxia-induced apoptosis was reversed by 2-APB and TRPC3/6 siRNAs.Conclusion: BDNF/TrkB alleviated cardiac ischemic injury and inhibited cardiomyocytes apoptosis by regulating TRPC3/6 channels, which provides a novel potential therapeutic candidate for MI.

Background The recently proposed Canadian Cardiovascular Society (CCS) classification of acute myocardial infarction (MI) describes 4 stages of tissue injury identified by cardiac magnetic resonance imaging (CMR); 1) oedema without late gadolinium enhancement (LGE); 2) LGE without microvascular obstruction (MVO); 3) MVO; and 4) intramyocardial haemorrhage (IMH). Prior studies examining the relationship between these characteristics and outcomes are limited by variations in imaging and measurement techniques, in particular the distinction between MVO and IMH. The relationship between the proposed CCS classification of MI and outcomes has not been described. Purpose To explore the prognostic significance of the CCS classification of MI tissue injury in patients with ST-elevation MI (STEMI). Methods The British Heart Foundation MR-MI study was a prospective single-centre CMR cohort study in patients with STEMI (July 2011-November 2012). CMR was performed on a single Siemens MAGNETOM Avanto 1.5-Tesla scanner at 2 days post-STEMI. The imaging protocol included LGE and T2* mapping, allowing for the identification of infarct, MVO, and IMH. Follow-up for the occurance of major adverse cardiovascular events (MACE) (recurrent MI, ischaemic stroke and cardiovascular death) and a composite outcome of heart failure hospitalization/ICD implantation (HFH) or all-cause death was performed via electronic case note review. Results 246 patients had complete data for this analysis. Of these, 6 (2%) were CCS Stage 1, 105 (43%) were Stage 2, 33 (13%) were Stage 3, and 102 (41%) were Stage 4. Due to the low number in CCS stage 1, these patients were pooled with Stage 2 for the purposes of this analysis (CCS Stage 1/2). Average age was 58 (SD 11) years and 188 (76%) were male. With higher CCS stage, more patients were Killip class III/IV at presentation, had the LAD as culprit artery and had TIMI flow 0/1 pre-PCI. Patients with higher CCS stage had higher peak troponin-I and NT-proBNP, lower left ventricular function, higher left ventricular volumes and larger infarct size (Table). Median follow-up was 11.8 years. HFH or all-cause death occurred in 80 (33%) patients (22 HFH and 58 all-cause deaths), and MACE occurred in 63 (26%) patients (41 recurrent MI, 11 ischaemic stroke events, and 11 cardiovascular deaths). There were no significant differences in outcomes between CCS Stage 3 and CCS Stage 1/2 (Figure). Patients with CCS Stage 4 had a higher risk of HFH or all-cause death (HR 1.73, 95%CI 1.08-2.77; p=0.022) and MACE (HR 1.88, 95%CI 1.10-3.20; p=0.021) as compared with those in CCS Stage 1/2 (Figure). Conclusion The novel CCS classification of MI tissue injury identifies patients at the highest risk of adverse outcomes following STEMI. The relationship between the presence of IMH (CCS Stage 4) and adverse outcomes highlights the importance of T2* imaging in post-MI CMR protocols in order to identify this prognostically important biomarker.