Significant Reduction In Infarct Size Research Articles

Aptamer BT200 is protective against myocardial ischemia-reperfusion injury in mice

BackgroundMyocardial ischemia-reperfusion (MI/R) injury tends to affect cardiac function and leads to poor patient prognosis, and there is still no effectively targeted drug to develop anti–von Willebrand factor (VWF) aptamer in acute coronary heart disease. However, the newly anti-VWF aptamer BT200 is applied for not only stroke and hemophilia but also antithrombolism function in clinical development. The role of BT200 in acute myocardial injury during MI/R is still unknown. ObjectivesTo investigate the cardioprotective effect of aptamer BT200 in an experiment mouse model of MI/R. MethodsC57BL/6 mice were subjected to 30-minute ischemia and 24-hour reperfusion to establish MI/R model. Mice were treated with intravenous injection of cy3-labeled BT200 and were observed by an in vivo imaging system at different time points. Then, mice were sampled and evaluated by echocardiography, Evans triphenyltetrazolium chloride staining, histopathologic, western blotting, and real-time quantitative polymerase chain reaction assays to detect cardiac injury and inflammation response after 24-hour reperfusion. ResultsBT200 aptamer can enter and infiltrate into the ischemic myocardium after 24-hour reperfusion. BT200 was shown to inhibit VWF A1 activity and prolong bleeding time in MI/R mice. Moreover, BT200-treated mice had a significant reduction in infarct size and an improvement in cardiac function post-MI/R. BT200 treatment can also alleviate MI/R-induced microvascular obstruction, inflammation response, and cardiomyocyte apoptosis. ConclusionPharmacologic targeting of VWF with BT200 alleviates acute MI/R injury in a murine model and may be a novel therapy strategy for acute myocardial infarction.

Progesterone Receptor Agonist, Nestorone, Exerts Long-Term Neuroprotective Effects Against Permanent Focal Cerebral Ischemia in Adult and Aged Male Rats.

Stroke is a leading cause of death and disability worldwide. Tissue plasminogen activator (tPA) is currently the most effective medicine for stroke; however, it has a narrow therapeutic time window (4.5h after symptom onset). We demonstrated that nestorone, a progesterone (P4) receptor agonist, exerted neuroprotective effects against transient focal cerebral ischemia 6h post-ischemic administration in adult male rats. This study examines its effects on permanent focal cerebral ischemia in adult and aged male rats, which are better models for evaluating treatment outcomes in typical stroke patients. Adult (6-month-old) or aged (18-month-old) male rats subjected to permanent middle cerebral artery occlusion (pMCAO) were continuously administered nestorone (10µg/day) or its vehicle (30% hydroxypropyl-β-cyclodextrin) for 7days via an osmotic pump subcutaneously implanted, starting at 18h post-pMCAO. Nestorone-treated adult male rats showed marked improvements in behavioral outcomes in the adhesive removal and rotarod tests and a significant reduction in infarct size compared to vehicle-treated rats 9 and 30days post-pMCAO. The same administration of nestorone resulted in apparently comparable neuroprotective effects in aged male rats. The inflammatory mediator NF-κB/p65 was increased in Iba-1 positive cells 24h post-pMCAO, but was significantly suppressed by subcutaneous injection of nestorone. These results suggested that nestorone exerts long-term neuroprotective effects against permanent focal cerebral ischemia in adult and aged male rats. Nestorone is thus a promising agent for post-stroke treatment owing to its wide age-independent therapeutic time window (18h after symptom onset), which is longer than that of tPA therapy.

Abstract Tu131: Counteracting Cardiac Ischemia and Reperfusion Injury: the role of Sialidase Neu3

Coronary reperfusion procedures are crucial for restoring blood flow to the heart tissue after an acute myocardial infarction. However, they also lead to ischemia and reperfusion injury (IRI), which exacerbate the damage and promote heart failure. Despite the urgent need for cardioprotective strategies against IRI, none have been clinically implemented, emphasizing the need for a comprehensive understanding of the pathophysiology of IRI. Our research team found that sialidase Neu3, an enzyme responsible for the removal of sialic acid from glycosphingolipids, is modulated during IRI in vivo. Constitutive overexpression of Neu3 in rat cardiomyoblasts was shown to attenuate IRI through activation of the reperfusion injury salvage kinase (RISK) and HIF-1α signaling pathways. To further investigate the role of Neu3 in promoting cardioprotection, in this study we developed an inducible Neu3 overexpression model in human cardiac cells and mice. Inducible upregulation of Neu3 significantly improved cell resistance and reduced oxidative stress in AC16 cells exposed to IRI in vitro. These effects were attributed to Neu3-mediated maintenance of mitochondrial membrane potential, which was impaired in control cells. When looking at the upregulated genes exclusively in cells overexpressing the sialidase Neu3, RNAseq analysis revealed the predominant activation of MAP kinases typical of the RISK pathway. We also generated, for the first time, αMHC-Cre/LSL-Neu3 mice overexpressing Neu3 in an inducible and cardiomyocyte-specific manner. These mice showed no significant differences in cardiac morphology and functionality compared to wild-type animals. However, the Neu3-overexpressing mice exhibited a significant reduction in infarct size and improved cardiac functionality after surgical induction of IRI. These results suggest that Neu3 is a promising target for improving cardioprotection and attenuating the incidence and severity of myocardial infarction.

The Sirtuin 5 Inhibitor MC3482 Ameliorates Microglia‑induced Neuroinflammation Following Ischaemic Stroke by Upregulating the Succinylation Level of Annexin-A1.

In our previous study, we concluded that sirtuin 5 (SIRT5) was highly expressed in microglia following ischaemic stroke, which induced excessive neuroinflammation and neuronal injury. Therefore, SIRT5-targeting interventions should reduce neuroinflammation and protect against ischaemic brain injury. Here, we showed that treatment with a specific SIRT5 inhibitor, MC3482, alleviated microglia-induced neuroinflammation and improved long-term neurological function in a mouse model of stroke. The mice were administrated with either vehicle or 2mg/kg MC3482 daily for 7days via lateral ventricular injection following the onset of middle cerebral artery occlusion. The outcome was assessed by a panel of tests, including a neurological outcome score, declarative memory, sensorimotor tests, anxiety-like behavior and a series of inflammatory factors. We observed a significant reduction of infarct size and inflammatory factors, and the improvement of long-term neurological function in the early stages during ischaemic stroke when the mice were treated with MC3482. Mechanistically, the administration of MC3482 suppressed the desuccinylation of annexin-A1, thereby promoting its membrane recruitment and extracellular secretion, which in turn alleviated neuroinflammation during ischaemic stroke. Based on our findings, MC3482 offers promise as an anti-ischaemic stroke treatment that targets directly the disease's underlying factors.

Long-Term Protective Effects of Succinate Dehydrogenase Inhibition during Reperfusion with Malonate on Post-Infarction Left Ventricular Scar and Remodeling in Mice.

Succinate dehydrogenase inhibition with malonate during initial reperfusion reduces myocardial infarct size in both isolated mouse hearts subjected to global ischemia and in in situ pig hearts subjected to transient coronary ligature. However, the long-term effects of acute malonate treatment are unknown. Here, we investigated whether the protective effects of succinate dehydrogenase inhibition extend to a reduction in scar size and adverse left ventricular remodeling 28 days after myocardial infarction. Initially, ten wild-type mice were subjected to 45 min of left anterior descending coronary artery (LAD) occlusion, followed by 24 h of reperfusion, and were infused during the first 15 min of reperfusion with saline with or without disodium malonate (10 mg/kg/min, 120 μL/kg/min). Malonate-treated mice depicted a significant reduction in infarct size (15.47 ± 3.40% of area at risk vs. 29.34 ± 4.44% in control animals, p < 0.05), assessed using triphenyltetrazolium chloride. Additional animals were then subjected to a 45 min LAD ligature, followed by 28 days of reperfusion. Treatment with a single dose of malonate during the first 15 min of reperfusion induced a significant reduction in scar area, measured using Picrosirius Red staining (11.94 ± 1.70% of left ventricular area (n = 5) vs. 23.25 ± 2.67% (n = 9), p < 0.05), an effect associated with improved ejection fraction 28 days after infarction, as determined using echocardiography, and an attenuated enhancement in expression of the pro-inflammatory and fibrotic markers NF-κB and Smad2/3 in remote myocardium. In conclusion, a reversible inhibition of succinate dehydrogenase with a single dose of malonate at the onset of reperfusion has long-term protective effects in mice subjected to transient coronary occlusion.

Apoptosis Signal-Regulating Kinase 1 (Ask1) Inhibition Prevents In Vivo Thrombosis without Compromising Hemostasis

Cardiovascular diseases are currently among the leading causes of death in mankind. Although significant progress has been made in prevention and treatment, the currently available pharmacological interventions have a significant rate of severe bleeding side effects due to their effect on hemostasis. Recently, we have shown that apoptosis signal-regulating kinase 1 (ASK1) plays an important role in platelet activation and thrombus formation. Here, we show that two chemically distinct ASK1 inhibitors, dose-dependently inhibited thrombin-induced phosphorylation of ASK1 and its downstream effectors MKK3/4/6, p38 MAPK, and cPLA2 in human platelets, as detected by western blotting using phospho-specific antibodies. ASK1 inhibitors also dose-dependently inhibited platelet a granule release and α IIbβ 3 activation which are the readouts for inside-out signaling events as analyzed by flow cytometry. Moreover, pretreatment of human platelets with ASK1 inhibitors completely impaired clot retraction and platelet spreading on immobilized fibrinogen two events regulated by outside-in signaling. To investigate the in-vivo effect of Ask1 inhibitor on thrombus formation, we intraperitoneally injected C57BL/6 mice with Ask1 inhibitor (1mg/kg), and the blood was withdrawn at 1-, 4-, and 24-hour time points and analyzed for in vitro thrombus formation on collagen matrix under arterial flow. Ask1 inhibitor significantly decreased thrombus growth ( P&amp;lt;0.01) which was sustained for at least 24 hours. Platelet adhesion to collagen was not affected as determined by surface coverage.In a 10% FeCl 3 -induced carotid artery injury model of thrombosis, we found that Ask1 inhibitor (100μg/kg)showed a significantly extended time of vessel occlusion ( P&amp;lt;0.01) . Moreover, Ask1 inhibitor (100μg/kg) treated C57BL/6 mice were protected from collagen/epinephrine-induced pulmonary thromboembolism ( P&amp;lt;0.001). Furthermore, in a well-established ischemic stroke model of transient middle cerebral artery occlusion, C57BL/6 mice treated with Ask1 inhibitor (1mg/kg) showed increased survival and improved neurological deficits than vehicle treated mice. The extent of the brain damage was assessed by staining the brain sections with 2% 2,3,5-triphenyltetrazoliun chloride, which showed significant reduction in infarct size and edema ( P&amp;lt;0.0001). Interestingly, mice treated with Ask1 inhibitor (1mg/kg), a 10-fold more than the amount needed to inhibit thrombosis, had no effect on hemostasis as observed by both the tail bleeding assay and laser-induced cremaster injury model. Whereas clopidogrel (5-30mg/kg) showed significantly increased ( P&amp;lt;0.0001) tail bleeding time. Next, we performed cerebral bleeding assay in which brain injury was induced by inserting a 26-gauge needle through the skull in the cerebrum 2mm laterally to the bregma and 4mm deep into the cerebrum and rotated 360 degrees. After 20 minutes the extent of bleeding in the brain was assessed by imaging. Treatment of C57BL/6 mice with clopidogrel (30mg/kg) showed significantly enhanced bleeding ( P&amp;lt;0.05) compared to vehicle treated mice. However, Ask1 inhibitor treated mice had same extent of bleeding as that of vehicle treated mice. Additionally, a liver bleeding assay was performed by excising a calibrated piece (~4-5mg) of inferior edge of the right lobe of the liver of the mouse under anesthesia. After 20 minutes the bleeding was assessed by counting red blood cells in the peritoneal lavage. As observed in brain bleeding assay, treatment of mice with clopidogrel (30mg/kg), showed significantly increased liver bleeding ( P&amp;lt;0.05) compared to vehicle treated mice whereas Ask1 inhibitor treated mice had same extent of liver bleeding as that of vehicle treated mice. Taken together, our results provide evidence that ASK1 inhibitors are novel therapeutic agents to combat thrombotic disorders without any side effects of bleeding, which is inherent to current anti-thrombotic drugs.

The effect of electrical stimulation of skeletal muscle on cardioprotection and on muscle-derived myokine levels in rats: A pilot study.

Electrical muscle stimulation (EMS) is a widely used method in sports and rehabilitation therapies to simulate physical exercise. EMS treatment via skeletal muscle activity improves the cardiovascular functions and the overall physical condition of the patients. However, the cardioprotective effect of EMS has not been proven so far, therefore, the aim of this study was to investigate the potential cardiac conditioning effect of EMS in an animal model. Low-frequency 35-min EMS was applied to the gastrocnemius muscle of male Wistar rats for three consecutive days. Their isolated hearts were then subjected to 30 min global ischemia and 120 min reperfusion. At the end of reperfusion cardiac specific creatine kinase (CK-MB) and lactate dehydrogenase (LDH) enzyme release and myocardial infarct size were determined. Additionally, skeletal muscle-driven myokine expression and release were also assessed. Phosphorylation of cardioprotective signaling pathway members AKT, ERK1/2, and STAT3 proteins were also measured. EMS significantly attenuated cardiac LDH and CK-MB enzyme activities in the coronary effluents at the end of the ex vivo reperfusion. EMS treatment considerably altered the myokine content of the stimulated gastrocnemius muscle without altering circulating myokine levels in the serum. Additionally, phosphorylation of cardiac AKT, ERK1/2, and STAT3 was not significantly different in the two groups. Despite the lack of significant infarct size reduction, the EMS treatment seems to influence the course of cellular damage due to ischemia/reperfusion and favorably modifies skeletal muscle myokine expressions. Our results suggest that EMS may have a protective effect on the myocardium, however, further optimization is required.

No robust reduction of infarct size and no-reflow by metoprolol pretreatment in adult Göttingen minipigs

Whereas prior experiments in juvenile pigs had reported infarct size reduction by intravenous metoprolol early during myocardial ischaemia, two major clinical trials in patients with reperfused acute myocardial infarction were equivocal. We, therefore, went back and tested the translational robustness of infarct size reduction by metoprolol in minipigs. Using a power analysis-based prospective design, we pretreated 20 anaesthetised adult Göttingen minipigs with 1 mg kg−1 metoprolol or placebo and subjected them to 60-min coronary occlusion and 180-min reperfusion. Primary endpoint was infarct size (triphenyl tetrazolium chloride staining) as a fraction of area at risk; no-reflow area (thioflavin-S staining) was a secondary endpoint. There was no significant reduction in infarct size (46 ± 8% of area at risk with metoprolol vs. 42 ± 8% with placebo) or area of no-reflow (19 ± 21% of infarct size with metoprolol vs. 15 ± 23% with placebo). However, the inverse relationship between infarct size and ischaemic regional myocardial blood flow was modestly, but significantly shifted downwards with metoprolol, whereas ischaemic blood flow tended to be reduced by metoprolol. With an additional dose of 1 mg kg−1 metoprolol after 30-min ischaemia in 4 additional pigs, infarct size was also not reduced (54 ± 9% vs. 46 ± 8% in 3 contemporary placebo, n.s.), and area of no-reflow tended to be increased (59 ± 20% vs. 29 ± 12%, n.s.).Infarct size reduction by metoprolol in pigs is not robust, and this result reflects the equivocal clinical trials. The lack of infarct size reduction may be the result of opposite effects of reduced infarct size at any given blood flow and reduced blood flow, possibly through unopposed alpha-adrenergic coronary vasoconstriction.

TRIM67 alleviates cerebral ischemia‒reperfusion injury by protecting neurons and inhibiting neuroinflammation via targeting IκBα for K63-linked polyubiquitination

BackgroundExcessive and unresolved neuroinflammation plays an important role in the pathophysiology of many neurological disorders, such as ischemic stroke, yet there are no effective treatments. Tripartite motif-containing 67 (TRIM67) plays a crucial role in the control of inflammatory disease and pathogen infection-induced inflammation; however, the role of TRIM67 in cerebral ischemia‒reperfusion injury remains poorly understood.ResultsIn the present study, we demonstrated that the expression level of TRIM67 was significantly reduced in middle cerebral artery occlusion and reperfusion (MCAO/R) mice and primary cultured microglia subjected to oxygen–glucose deprivation and reperfusion. Furthermore, a significant reduction in infarct size and neurological deficits was observed in mice after TRIM67 upregulation. Interestingly, TRIM67 upregulation alleviated neuroinflammation and cell death after cerebral ischemia‒reperfusion injury in MCAO/R mice. A mechanistic study showed that TRIM67 bound to IκBα, reduced K48-linked ubiquitination and increased K63-linked ubiquitination, thereby inhibiting its degradation and promoting the stability of IκBα, ultimately inhibiting NF-κB activity after cerebral ischemia.ConclusionTaken together, this study demonstrated a previously unidentified mechanism whereby TRIM67 regulates neuroinflammation and neuronal apoptosis and strongly indicates that upregulation of TRIM67 may provide therapeutic benefits for ischemic stroke.Graphical

Diazoxide is a powerful cardioprotectant but is not feasible in a realistic infarct scenario.

Diazoxide is a powerful cardioprotective agent that activates mitochondrial ATP-dependent K-channels and stimulates mitochondrial respiration. Diazoxide reduced infarct size in isolated rodent heart preparations and upon pretreatment in juvenile pigs with coronary occlusion/reperfusion. We aimed to study the use of diazoxide in a more realistic adult pig model of reperfused acute myocardial infarction when diazoxide was administered just before reperfusion. In a first approach, we pretreated anaesthetised adult Göttingen minipigs with 7 mg kg-1 diazoxide (n = 5) or placebo (n = 5) intravenously over 10 min and subjected them to 60 min coronary occlusion and 180 min reperfusion; blood pressure was maintained by use of an aortic snare. The primary endpoint was infarct size (triphenyl tetrazolium chloride staining) as a fraction of area at risk; no-reflow area (thioflavin-S staining) was the secondary endpoint. In a second approach, diazoxide (n = 5) was given from 50 to 60 min coronary occlusion, and blood pressure was not maintained. There was a significant reduction in infarct size (22% ± 11% of area at risk with diazoxide pretreatment vs. 47% ± 11% with placebo) and area of no-reflow (14% ± 14% of infarct size with diazoxide pretreatment vs. 46% ± 20% with placebo). With diazoxide from 50 to 60 min coronary occlusion, however, there was marked hypotension, and infarct size (44% ± 7%) and area of no-reflow were not reduced (35% ± 25%). Cardioprotection by diazoxide pretreatment was confirmed in adult pigs with reperfused acute myocardial infarction but is not feasible when diazoxide is administered in a more realistic scenario before reperfusion and causes hypotension.

Influence of Short and Long Hyperglycemia on Cardioprotection by Remote Ischemic Preconditioning-A Translational Approach.

The adverse impact of common diseases like diabetes mellitus and acute hyperglycemia on morbidity and mortality from myocardial infarction (MI) has been well documented over the past years of research. In the clinical setting, the relationship between blood glucose and mortality appears linear, with amplifying risk associated with increasing blood glucose levels. Further, this seems to be independent of a diagnosis of diabetes. In the experimental setting, various comorbidities seem to impact ischemic and pharmacological conditioning strategies, protecting the heart against ischemia and reperfusion injury. In this translational experimental approach from bedside to bench, we set out to determine whether acute and/or prolonged hyperglycemia have an influence on the protective effect of transferred human RIPC-plasma and, therefore, might obstruct translation into the clinical setting. Control and RIPC plasma of young healthy men were transferred to isolated hearts of young male Wistar rats in vitro. Plasma was administered before global ischemia under either short hyperglycemic (HGs Con, HGs RIPC) conditions, prolonged hyperglycemia (HGl Con, HGl RIPC), or under normoglycemia (Con, RIPC). Infarct sizes were determined by TTC staining. Control hearts showed an infarct size of 55 ± 7%. Preconditioning with transferred RIPC plasma under normoglycemia significantly reduced infarct size to 25 ± 4% (p < 0.05 vs. Con). Under acute hyperglycemia, control hearts showed an infarct size of 63 ± 5%. Applying RIPC plasma under short hyperglycemic conditions led to a significant infarct size reduction of 41 ± 4% (p < 0.05 vs. HGs Con). However, the cardioprotective effect of RIPC plasma under normoglycemia was significantly stronger compared with acute hyperglycemic conditions (RIPC vs. HGs RIPC; p < 0.05). Prolonged hyperglycemia (HGl RIPC) completely abolished the cardioprotective effect of RIPC plasma (infarct size 60 ± 7%; p < 0.05 vs. HGl Con; HGl Con 59 ± 5%).

Abstract 13857: Reduction of Infarct Size in Anterior ST Segment Elevation Myocardial Infarction (STEMI) With LAD Occlusion and LV Unloading Using a Micro-Axial Pump for 30 Minutes Before PCI: A Per Protocol Analysis of the STEMI DTU Pilot Study

BACKGROUND: The STEMI-DTU pilot trial was the first exploratory study to identify that LV unloading and delaying reperfusion is safe and feasible in anterior STEMI without cardiogenic shock. We now report new findings in patients who met all protocol inclusion and exclusion criteria (per protocol cohort). Methods: In a multicenter, prospective, randomized safety and feasibility trial, we assigned 50 patients with anterior STEMI to LV unloading by using the Impella CP followed by immediate reperfusion (U-IR) versus delayed reperfusion after 30 minutes of unloading (U-DR). Cardiac magnetic resonance (CMR) imaging assessed infarct size normalized to the area at risk (IS/AAR) 3-5 days after PCI. Patients without CMR at 3-5 days (n=10; 5/arm), without PCI of a culprit LAD lesion (n=2; 1/arm) and without STEMI (n=5; 4 in U-IR, 1 in U-DR) were not per protocol and thus excluded from this analysis. Results: A total of 33 patients met all inclusion and exclusion criteria (U-IR n=15; U-DR n=18) with respective door-to-balloon times of 75±26 and 89±23 minutes (p=.10) and mean unload-to-balloon times of 10±5 and 34±3 (p&lt;0.01). In the total cohort, IS/AAR was significantly associated with microvascular obstruction (MVO), 30-day IS normalized to total LV mass, 90 day LVEF, and 90dday LV end systolic volume with or without a delay to reperfusion (Table, R&gt;0.5, p&lt;0.005 for all). Despite longer symptom to balloon times in the U-DR arm (174±59 vs 228±78, p&lt;0.01), IS/AAR was lower in the U-DR arm (62±16 vs 48±16, p=0.04) and remained significantly lower irrespective of the magnitude of precordial STE. MVO was significantly lower in the U-DR arm among patients with the highest precordial STE (Figure). Conclusion: A per protocol analysis of the STEMI-DTU Pilot trial identified a significant reduction in infarct size among patients with unloading and delayed reperfusion irrespective of precordial STE magnitude. These findings are currently under investigation in the STEMI-DTU Pivotal trial.

Combined Transplantation of Human MSCs and ECFCs Improves Cardiac Function and Decrease Cardiomyocyte Apoptosis After Acute Myocardial Infarction.

Ischemic heart disease, often caused by an acute myocardial infarction (AMI) is one of the leading causes of morbidity and mortality worldwide. Despite significant advances in medical and procedural therapies, millions of AMI patients progress to develop heart failure every year. Here, we examine the combination therapy of human mesenchymal stromal cells (MSCs) and endothelial colony-forming cells (ECFCs) to reduce the early ischemic damage (MSCs) and enhance angiogenesis (ECFCs) in a pre-clinical model of acute myocardial infarction. NOD/SCID mice were subjected to AMI followed by transplantation of MSCs and ECFCs either alone or in combination. Cardiomyocyte apoptosis and cardiac functional recovery were assessed in short- and long-term follow-up studies. At 1day after AMI, MSC- and ECFC-treated animals demonstrated significantly lower cardiomyocyte apoptosis compared to vehicle-treated animals. This phenomenon was associated with a significant reduction in infarct size, cardiac fibrosis, and improvement in functional cardiac recovery 4weeks after AMI. The use of ECFCs, MSCs, and the combination of both cell types reduce cardiomyocyte apoptosis, scar size, and adverse cardiac remodeling, compared to vehicle, in a pre-clinical model of AMI. These results support the use of this combined cell therapy approach in future human studies during the acute phase of ischemic cardiac injury.

Acute myocardial infarction therapy using calycosin and tanshinone co-loaded mitochondria targeted lipid-polymer hybrid nano-system: Preparation, characterization, and anti myocardial infarction activity assessment

BackgroundAcute myocardial infarction (AMI) is one of the most common ischemic heart diseases. However, lack of sufficient drug concentrations in the ischemic heart may led to treatment failure. It is urgent for researchers to engineer novel drug delivery systems to enhance the targeted delivery of cardioprotective agents. ObjectiveThe aim of the present study was to investigate the anti-AMI ability of calycosin (CAL) and tanshinone (TAN) co-loaded mitochondria targeted lipid-polymer hybrid nano-system. MethodsCAL and TAN combined lipid-polymer hybrid nano-systems were prepared and MTP-131 was conjugated with PEG and modified onto the nanoparticles to achieve MTP-CAL/TAN NS. The physicochemical properties of nano-systems were characterized, the AMI therapy ability of the systems was investigated in AMI rats’ model. ResultsThe size of MTP-CAL/TAN NS was 168.7 ± 5.1 nm, with a surface charge of − 21.3 ± 2.3 mV. The area under the curve (AUC) and blood circulation half-life (T1/2) of MTP-CAL/TAN NS was 178.86 ± 6.62 μg·min/mL and 0.47 h, respectively. MTP-CAL/TAN NS exhibited the most significant infarct size reduction effect of 23.9 %. ConclusionMTP-CAL/TAN NS exhibited the highest heart accumulation and best infarct size reduction effect, which could be used as a promising system for efficient treatment of cardiovascular diseases.

TCT-49 Significant Infarct Size Reduction Through Isolated Coronary Sinus Retroperfusion Cooling: A Pilot Preclinical Study in a Reperfusion Delay Model

TCT-49 Significant Infarct Size Reduction Through Isolated Coronary Sinus Retroperfusion Cooling: A Pilot Preclinical Study in a Reperfusion Delay Model

Acute myocardial infarction therapy using calycosin and tanshinone co-loaded; mitochondrion-targeted tetrapeptide and cyclic arginyl-glycyl-aspartic acid peptide co-modified lipid-polymer hybrid nano-system: preparation, characterization, and anti myocardial infarction activity assessment

Acute myocardial infarction (AMI) is one of the most common ischemic heart diseases. However, lack of sufficient drug concentration (in the ischemic heart) is the major factor of treatment failure. It is urgent for researchers to engineer novel drug delivery systems to enhance the targeted delivery of cardioprotective agents. The aim of the present study was to investigate the anti-AMI ability of calycosin (CAL) and tanshinone (TAN) co-loaded; mitochondrion-targeted tetrapeptide (MTP) and cyclic arginyl-glycyl-aspartic acid (RGD) peptide co-modified nano-system.: We prepared CAL and TAN combined lipid-polymer hybrid nano-system, and RGD was modified to the system to achieve RGD-CAL/TAN NS. MTP-131 was conjugated with PEG and modified onto the nanoparticles to achieve dual ligands co-modified MTP/RGD-CAL/TAN NS. The physicochemical properties of nano-systems were characterized. The AMI therapy ability of the systems was investigated in AMI rats’ model. The size of MTP/RGD-CAL/TAN NS was 170.2 ± 5.6 nm, with a surface charge of −18.9 ± 1.9 mV. The area under the curve (AUC) and blood circulation half-life (T1/2) of MTP/RGD-CAL/TAN NS was 178.86 ± 6.62 μg·min/mL and 0.47 h, respectively. MTP/RGD-CAL/TAN NS exhibited the most significant infarct size reduction effect of 22.9%. MTP/RGD-CAL/TAN NS exhibited the highest heart accumulation and best infarct size reduction effect, which could be used as a promising system for efficient treatment of cardiovascular diseases.

Effect of Classic or Delayed Ischemic Conditioning on Left Ventricular Pressure-Volume Relations in Dogs

Objective: Non-pharmacologic interventions such as ischemic conditioning (IC) markedly reduce infarct size but it remains unclear whether this protection translates to a significant attenuation of ischemia-mediated LV contractile dysfunction. In this study we evaluated pressure-volume (P-V) data obtained by the load-insensitive conductance catheter method, to examine LV pressure-volume (LVP-V), diastolic function and ventricular-arterial coupling in anesthetized dogs exposed to ischemic conditioning (IC) or delayed IC (dIC; 48h prior to ischemia). The objective was to determine if IC, or dIC pre-treatment could influence post-ischemic recovery of LV contractile function. Methods: Three groups were studied – nIC, IC and dIC; all dogs underwent 90-min acute coronary occlusion (CO) followed by 180-min reperfusion (REP). IC consisted of 4 cycles of 5-min CO and 5-min REP of the left main coronary artery. LV P-V relations were constructed under steady-state conditions (by transient occlusion of the inferior vena cava) prior to IC treatment and at the end of the experiment; P-V loop data was also acquired at different points during the experiment to evaluate changes in end-systolic and end-diastolic parameters. Results: During CO dP/dtmax and dP/dtmin (indicator of rate of LV relaxation) decreased significantly compared to baseline in the IC group; these variables were unchanged in the dIC group. LVEF decreased during CO and REP in the nIC and IC groups but was stable in the dIC group. Tau was increased only in the IC group during CO and REP. ESV and EDV increased significantly in all groups during CO and REP; none of these negative effects was resorbed by the end of the experimental period. Conclusions: Diminished LV contractile function caused by CO did not improve with IC, or dIC pre-treatment, despite significant reduction in infarct size.

Abstract P1041: Redox Regulator MnTnBuOE-PyP5+ Protects Cardiomyocyte Against Oxidative Stress Mediated Myocardial Ischemia/reperfusion Injury

Background: Much evidence suggests that oxidative stress plays a major role in the pathogenesis of myocardial ischemia/reperfusion (I/R) injury and is a potential target for therapeutic interventions. We tested the hypothesis that the novel redox regulator, MnTnBUOE-2-PyP 5+ (BMX-001), mediates cardioprotection through reduction of oxidative stress in myocardial tissue following I/R injury. Methods and Results: BMX-001 (2mg/Kg, IP) or vehicle was administered in mice 4 hours before myocardial ischemia. Mice were then subjected to I/R injury by ligating the left anterior descending artery for 1 hour followed by 24 hours of reperfusion. Following 24 hours of reperfusion, infarct size, cardiomyocyte apoptosis, and SOD2 level were determined, and echocardiography was performed. Our study revealed that the redox regulator provided protection against I/R-induced injury in mice as evident by a significant reduction in infarct size, plasma LDH level, and oxidative stress. In addition, BMX-001 administration in mice markedly increased FoxO3a and SOD2 levels. BMX-001 treatment attenuated I/R induced cardiomyocyte apoptosis in-vivo and in-vitro as evident by a reduction in the number of TUNEL positive cells and improved cell viability. Echocardiography at 24 hours of reperfusion revealed improved ejection fraction and fractional shortening in mice treated with BMX-001. Furthermore, in-vitro treatment of BMX-001 (10μM) 24 hours before hypoxia/reoxygenation in H9c2 cells improved oxidative stress as evident by a reduction in cardiolipin peroxidation, mitochondrial superoxide level, and 4-HNE adducted proteins. Conclusion: Pre-treatment with redox regulator BMX-001 showed a beneficial effect in attenuating cardiomyocyte death, mitochondrial superoxide, and cardiolipin peroxidation following I/R injury in H9c2 cells. Pre-treatment with SOD2 mimetic improved heart function, decreased infarct size, and cardiomyocyte apoptosis in mice following I/R injury. Therefore, BMX-001 can be a novel cardioprotective agent against oxidative stress-induced myocardial I/R injury.

Beneficial properties of the biosynthesized silver/chitosan nanoparticles mediated by Mentha piperita in rats with heart failure following myocardial infarction

• The recent bio-nanocomposite has antioxidant activities against DPPH. • The recent bio-nanocomposite has therapeutic activities. • The recent bio-composite has been synthesized as the best. In this study, we report the green synthesis of nontoxic, stable, and small size silver nanoparticle by using chitosan/ Mentha piperita extract with reducing/capping ability without any toxic reducing agents. Mentha piperita was used as a reducing agent for the synthesis of Ag NPs that next stabilized by chitosan polymers. The in situ prepared Ag NPs/CS- Mentha piperita bio-composite were characterized by advanced physicochemical techniques like FE- SEM, TEM, EDX and XRD study. It has been established that Ag NPs/CS- Mentha piperita bio-composite have a spherical shape with a mean diameter from 5 to 15 nm. In heart failure model, the rats were subjected to coronary artery ligation, and orally administered with Ag NPs/CS- Mentha piperita 12.5, 25 and 50 µg kg(-1) daily, from the 7th day after surgery. Administration with Ag NPs/CS- Mentha piperita led to a significant reduction in infarct size and improvement in cardiac function as demonstrated by lower left ventricular end diastolic pressure (LVEDP) and elevated +/-dp/dt(max). We found that Ag NPs/CS- Mentha piperita significantly reduced left ventricular (LV)/body weight ratio, lung/body weight ratio and significantly inhibited neurohormonal activation. The antioxidant activity of Ag NPs/CS- Mentha piperita bio-composite was determined by DPPH method. The Ag NPs/CS- Mentha piperita bio-composite showed the high antioxidant activity according to the IC 50 value.

Antioxidant Cardioprotection against Reperfusion Injury: Potential Therapeutic Roles of Resveratrol and Quercetin.

Ischemia-reperfusion myocardial damage is a paradoxical tissue injury occurring during percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI) patients. Although this damage could account for up to 50% of the final infarct size, there has been no available pharmacological treatment until now. Oxidative stress contributes to the underlying production mechanism, exerting the most marked injury during the early onset of reperfusion. So far, antioxidants have been shown to protect the AMI patients undergoing PCI to mitigate these detrimental effects; however, no clinical trials to date have shown any significant infarct size reduction. Therefore, it is worthwhile to consider multitarget antioxidant therapies targeting multifactorial AMI. Indeed, this clinical setting involves injurious effects derived from oxygen deprivation, intracellular pH changes and increased concentration of cytosolic Ca2+ and reactive oxygen species, among others. Thus, we will review a brief overview of the pathological cascades involved in ischemia-reperfusion injury and the potential therapeutic effects based on preclinical studies involving a combination of antioxidants, with particular reference to resveratrol and quercetin, which could contribute to cardioprotection against ischemia-reperfusion injury in myocardial tissue. We will also highlight the upcoming perspectives of these antioxidants for designing future studies.