Effect of COMBinAtion therapy with remote ischemic conditioning and exenatide on the Myocardial Infarct size: a two-by-two factorial randomized trial (COMBAT-MI)

Effects of Glucagon-Like Peptide-1 Receptor Agonist (GLP-1RA) on Cardiac Structure and Function: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials

PURPOSE

Recent trials suggest glucagon-like peptide-1 receptor agonists (GLP-1RAs) may have a cardioprotective role by reducing major adverse cardiac events, stroke mortality and heart failure-related hospitalisations. We examined whether and how GLP-1RAs affect cardiac function in cardiovascular and metabolic diseases including type 2 diabetes, heart failure and post-myocardial infarction.

METHODS

In this PRISMA-adherent systematic review and meta-analysis, three databases were searched from inception to July 2021 and registered on PROSPERO (CRD42021259661).

RESULTS

20 reports of 19 randomized placebo-controlled trials including 2062 participants were meta-analyzed. Among type 2 diabetes patients, GLP-1RA resulted in improved systolic function measured by circumferential strain (mean difference [MD]= -5.48; 95% CI: -10.47 to -0.49; P= 0.03; I2= 89%) and diastolic dysfunction measured by E / A (MD= -0.15; 95% CI: -0.25 to -0.05; P= 0.003; I2= 0%). For post-myocardial infarction patients, GLP-1RA reduced infarct size (g) (MD= -5.36; 95% CI: -10.68 to -0.04; P= 0.05; I2= 78%). Liraglutide, but not exenatide, demonstrated improved systolic function, by increasing left ventricular ejection fraction (MD= 4.89; 95% CI: 3.62 to 6.16; P< 0.00001; I2= 0%) and reducing left ventricular end-systolic volume (MD= -4.15; 95% CI: -7.49 to -0.81; P = 0.01; I2= 0%). Among heart failure patients, no significant changes were noted.

CONCLUSION

GLP-1RA drugs may improve systolic and diastolic function in type 2 diabetes and reduce infarct size post-acute myocardial infarction with no demonstrable effect on cardiac function in heart failure. Tailored recommendations for the use of GLP-1RAs for cardioprotection should be considered for each patient's condition.

Underlying mechanisms and cardioprotective effects of SGLT2i and GLP-1Ra: insights from cardiovascular magnetic resonance

Originally designed as anti-hyperglycemic drugs, Glucagon-Like Peptide-1 receptor agonists (GLP-1Ra) and Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have demonstrated protective cardiovascular effects, with significant impact on cardiovascular morbidity and mortality. Despite several mechanisms have been proposed, the exact pathophysiology behind these effects is not yet fully understood. Cardiovascular imaging is key for the evaluation of diabetic patients, with an established role from the identification of early subclinical changes to long-term follow up and prognostic assessment. Among the different imaging modalities, CMR may have a key-role being the gold standard for volumes and function assessment and having the unique ability to provide tissue characterization. Novel techniques are also implementing the possibility to evaluate cardiac metabolism through CMR and thereby further increasing the potential role of the modality in this context. Aim of this paper is to provide a comprehensive review of changes in CMR parameters and novel CMR techniques applied in both pre-clinical and clinical studies evaluating the effects of SGLT2i and GLP-1Ra, and their potential role in better understanding the underlying CV mechanisms of these drugs.

Targeting blood brain barrier-Remote ischemic conditioning alleviates cognitive impairment in female APP/PS1 rats

AIMS

Alzheimer's disease (AD) is a significant global health concern, and it is crucial that we find effective methods to prevent or slow down AD progression. Recent studies have highlighted the essential role of blood vessels in clearing Aβ, a protein that contributes to AD. Scientists are exploring blood biomarkers as a potential tool for future AD diagnosis. One promising method that may help prevent AD is remote ischemic conditioning (RIC). RIC involves using sub-lethal ischemic-reperfusion cycles on limbs. However, a comprehensive understanding of how RIC can prevent AD and its long-term effectiveness is still lacking. Further research is essential to fully comprehend the potential benefits of RIC in preventing AD.

METHODS

Female wild-type (WT) and APP/PS1 transgenic rats, aged 12 months, underwent ovariectomy and were subsequently assigned to WT, APP/PS1, and APP/PS1 + RIC groups. RIC was conducted five times a week for 4 weeks. The rats' depressive and cognitive behaviors were evaluated using force swimming, open-field tests, novel objective recognition, elevated plus maze, and Barnes maze tests. Evaluation of the neurovascular unit (NVU), synapses, vasculature, astrocytes, and microglia was conducted using immunofluorescence staining (IF), Western blot (WB), and transmission electron microscopy (TEM). Additionally, the cerebro-vasculature was examined using micro-CT, and cerebral blood flow (CBF) was measured using Speckle Doppler. Blood-brain barrier (BBB) permeability was determined by measuring the Evans blue leakage. Finally, Aβ levels in the rat frontal cortex were measured using WB, ELISA, or IF staining.

RESULTS

RIC enhanced memory-related protein expression and rescued depressive-like behavior and cognitive decline in APP/PS1 transgenic rats. Additionally, the intervention protected NVU in the rat frontal cortex, as evidenced by (1) increased expression of TJ (tight junction) proteins, pericyte marker PDGFRβ, and glucose transporter 1 (GLUT1), as well as decreased VCAM1; (2) mitigation of ultrastructure impairment in neuron, cerebral vascular, and astrocyte; (3) upregulation of A2 astrocyte phenotype markers and downregulation of A1 phenotype markers, indicating a shift toward a healthier phenotype. Correspondingly, RIC intervention alleviated neuroinflammation, as evidenced by the decreased Iba1 level, a microglia marker. Meanwhile, RIC intervention elevated CBF in frontal cortex of the rats. Notably, RIC intervention effectively suppressed Aβ toxicity, as demonstrated by the enhancement of α-secretase and attenuation of β-secretase (BACE1) and γ- secretase and Aβ1-42 and Aβ1-40 levels as well.

CONCLUSION

Chronic RIC intervention exerts vascular and neuroprotective roles, suggesting that RIC could be a promising therapeutic strategy targeting the BBB and NVU during AD development.

Common and specific proteins and pathways in heart and cerebral ischemia

OBJECTIVE

To understand the similarities and differences between acute ischemic stroke and acute myocardial infarction (AMI) to help in the development of specific or common treatment strategies.

METHODS

Using an aptamer-based proteomic array, we measured and compared 1310 circulating proteins in the blood of 40 patients with AIS, 9 patients with AMI, and 31 healthy controls. Pathway enrichment analysis was performed using GSEA and g:profiler.

RESULTS

Ninety-four proteins were differentially expressed in AIS, and 284 were differentially expressed in AMI. Of these, 8 were specific to cerebral ischemia, and 197 were specific to myocardial infarction. Forty-two proteins were altered in both ischemia processes. Most altered pathways in AIS could be classified as immune response, cell cycle processing, molecular transport, or signaling. Pathways altered in AMI were mostly related to lipid metabolism and transport, highlighting cholesterol metabolic processes and estrogen signaling. In both types of ischemia, we found pathways related to metabolism, specifically purine metabolism, and signaling processes, such as TNF signaling or MAPK1/3.

CONCLUSIONS

The present study revealed proteins and pathways that were specifically altered in cerebral ischemia, in cardiac ischemia, or in both diseases, providing information on the similarities and differences of ischemic conditions. The role of common and specific proteins and pathways should be explored in detail to find possible therapeutic targets.

Reperfusion Injury: How Can We Reduce It by Pre-, Per-, and Postconditioning

While early coronary reperfusion via primary percutaneous coronary intervention (pPCI) is established as the most efficacious therapy for minimizing infarct size (IS) in acute ST-elevation myocardial infarction (STEMI), the restoration of blood flow also introduces myocardial ischemia-reperfusion injury (IRI), leading to cardiomyocyte death. Among diverse methods, ischemic conditioning (IC), achieved through repetitive cycles of ischemia and reperfusion, has emerged as the most promising method to mitigate IRI. IC can be performed by applying the protective stimulus directly to the affected myocardium or indirectly to non-affected tissue, which is known as remote ischemic conditioning (RIC). In clinical practice, RIC is often applied by serial inflations and deflations of a blood pressure cuff on a limb. Despite encouraging preclinical studies, as well as clinical studies demonstrating reductions in enzymatic IS and myocardial injury on imaging, the observed impact on clinical outcome has been disappointing so far. Nevertheless, previous studies indicate a potential benefit of IC in high-risk STEMI patients. Additional research is needed to evaluate the impact of IC in such high-risk cohorts. The objective of this review is to summarize the pathophysiological background and preclinical and clinical data of IRI reduction by IC.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

Clinical outcomes associated with type II myocardial infarction caused by bleeding

BACKGROUND

Type ll myocardial infarction (T2MI) is caused by a mismatch between myocardial oxygen supply and demand. One subset of individuals is T2MI caused by acute hemorrhage. Traditional MI treatments including antiplatelets, anticoagulants, and revascularization can worsen bleeding. We aim to report outcomes of T2MI patients due to bleeding, stratified by treatment approach.

METHODS

The MGB Research Patient Data Registry followed by manual physician adjudication was used to identify individuals with T2MI caused by bleeding between 2009 and 2022. We defined 3 treatment groups: (1) invasively managed, (2) pharmacologic, and (3) conservatively managed Clinical parameters and outcomes for 30-day, mortality, rebleeding, and readmission were abstracted compared between the treatment groups.

RESULTS

We identified 5,712 individuals coded with acute bleeding, of which 1,017 were coded with T2MI during their admission. After manual physician adjudication, 73 individuals met the criteria for T2MI caused by bleeding. 18 patients were managed invasively, 39 received pharmacologic therapy alone, and 16 were managed conservatively. The invasively managed group experienced lower mortality (P = .021) yet higher readmission (P = .045) than the conservatively managed group. The pharmacologic group also experienced lower mortality (P= .017) yet higher readmission (P = .005) than the conservatively managed group.

CONCLUSION

Individuals with T2MI associated with acute hemorrhage are a high-risk population. Patients treated with standard procedures experienced higher readmission but lower mortality than conservatively managed patients. These results raise the possibility of testing ischemia-reduction approaches for such high-risk populations. Future clinical trials are required to validate treatment strategies for T2MI caused by bleeding.

Spontaneous reperfusion enhances succinate concentration in peripheral blood from stemi patients but its levels does not correlate with myocardial infarct size or area at risk

Succinate is enhanced during initial reperfusion in blood from the coronary sinus in ST-segment elevation myocardial infarction (STEMI) patients and in pigs submitted to transient coronary occlusion. Succinate levels might have a prognostic value, as they may correlate with edema volume or myocardial infarct size. However, blood from the coronary sinus is not routinely obtained in the CathLab. As succinate might be also increased in peripheral blood, we aimed to investigate whether peripheral plasma concentrations of succinate and other metabolites obtained during coronary revascularization correlate with edema volume or infarct size in STEMI patients. Plasma samples were obtained from peripheral blood within the first 10 min of revascularization in 102 STEMI patients included in the COMBAT-MI trial (initial TIMI 1) and from 9 additional patients with restituted coronary blood flow (TIMI 2). Metabolite concentrations were analyzed by ¹H-NMR. Succinate concentration averaged 0.069 ± 0.0073 mmol/L in patients with TIMI flow ≤ 1 and was significantly increased in those with TIMI 2 at admission (0.141 ± 0.058 mmol/L, p < 0.05). However, regression analysis did not detect any significant correlation between most metabolite concentrations and infarct size, extent of edema or other cardiac magnetic resonance (CMR) variables. In conclusion, spontaneous reperfusion in TIMI 2 patients associates with enhanced succinate levels in peripheral blood, suggesting that succinate release increases overtime following reperfusion. However, early plasma levels of succinate and other metabolites obtained from peripheral blood does not correlate with the degree of irreversible injury or area at risk in STEMI patients, and cannot be considered as predictors of CMR variables.Trial registration: Registered at www.clinicaltrials.gov (NCT02404376) on 31/03/2015. EudraCT number: 2015-001000-58.

Interaction of Cardiovascular Nonmodifiable Risk Factors, Comorbidities and Comedications With Ischemia/Reperfusion Injury and Cardioprotection by Pharmacological Treatments and Ischemic Conditioning

Preconditioning, postconditioning, and remote conditioning of the myocardium enhance the ability of the heart to withstand a prolonged ischemia/reperfusion insult and the potential to provide novel therapeutic paradigms for cardioprotection. While many signaling pathways leading to endogenous cardioprotection have been elucidated in experimental studies over the past 30 years, no cardioprotective drug is on the market yet for that indication. One likely major reason for this failure to translate cardioprotection into patient benefit is the lack of rigorous and systematic preclinical evaluation of promising cardioprotective therapies prior to their clinical evaluation, since ischemic heart disease in humans is a complex disorder caused by or associated with cardiovascular risk factors and comorbidities. These risk factors and comorbidities induce fundamental alterations in cellular signaling cascades that affect the development of ischemia/reperfusion injury and responses to cardioprotective interventions. Moreover, some of the medications used to treat these comorbidities may impact on cardioprotection by again modifying cellular signaling pathways. The aim of this article is to review the recent evidence that cardiovascular risk factors as well as comorbidities and their medications may modify the response to cardioprotective interventions. We emphasize the critical need for taking into account the presence of cardiovascular risk factors as well as comorbidities and their concomitant medications when designing preclinical studies for the identification and validation of cardioprotective drug targets and clinical studies. This will hopefully maximize the success rate of developing rational approaches to effective cardioprotective therapies for the majority of patients with multiple comorbidities. SIGNIFICANCE STATEMENT: Ischemic heart disease is a major cause of mortality; however, there are still no cardioprotective drugs on the market. Most studies on cardioprotection have been undertaken in animal models of ischemia/reperfusion in the absence of comorbidities; however, ischemic heart disease develops with other systemic disorders (e.g., hypertension, hyperlipidemia, diabetes, atherosclerosis). Here we focus on the preclinical and clinical evidence showing how these comorbidities and their routine medications affect ischemia/reperfusion injury and interfere with cardioprotective strategies.

Protective effect of ischaemic postconditioning combined with nicorandil on myocardial ischaemia‒reperfusion injury in diabetic rats

BACKGROUND

The diabetic heart exhibits a high sensitivity to ischaemia/reperfusion (I/R) injury. Diabetes mellitus (DM) can affect the efficacy of cardioprotective interventions and reduce the therapeutic potential of existing treatment options. This study aimed to investigate the feasibility of shifting from monotherapy to combination therapy in diabetic myocardial I/R injury.

METHODS

6-8 week rats were randomized into 10 groups: sham, I/R, ischaemia postconditioning (I-Post), nicorandil (Nic), combination therapy (I-Post + Nic), DM sham, DM I/R, DM I-Post, DM Nic and DM I-Post + Nic. The extent of myocardial injury was clarified by measuring CK-MB and NO levels in plasma, ROS content in myocardial tissues, and TTC/Evans Blue staining to assess the area of myocardial infarction. Pathological staining of cardiac tissue sections were performed to clarify the structural changes in myocardial histopathology. Finally, Western blotting was performed to detect the phosphorylation levels of some key proteins in the PI3K/Akt signalling pathway in myocardial tissues.

RESULTS

We confirms that myocardial injury in diabetic I/R rats remained at a high level after treatment with I-Post or nicorandil alone. I-Post combined with nicorandil showed better therapeutic effects in diabetic I/R rats, and the combined treatment further reduced the area of myocardial injury in diabetic I/R rats compared with I-Post or nicorandil treatment alone (P < 0.001), as well as the levels of the myocardial injury markers CK-MB and ROS (P < 0.001); it also significantly increased plasma NO levels. Pathological staining also showed that diabetic rats benefited significantly from the combination therapy. Further mechanistic studies confirmed this finding. The protein phosphorylation levels of PI3K/Akt signalling pathway in the heart tissue of diabetic I/R rats were significantly higher after the combination treatment than after one treatment alone (all P < 0.05).

CONCLUSION

I-Post combined with nicorandil treatment maintains effective cardioprotection against diabetic myocardial I/R injury by activating the PI3K/Akt signalling pathway.

Preclinical multi-target strategies for myocardial ischemia-reperfusion injury

Despite promising breakthroughs in diagnosing and treating acute coronary syndromes, cardiovascular disease’s high global mortality rate remains indisputable. Nearly half of these patients died of ischemic heart disease. Primary percutaneous coronary intervention (PCI) and coronary artery bypass grafting can rapidly restore interrupted blood flow and become the most effective method for salvaging viable myocardium. However, restoring blood flow could increase the risk of other complications and myocardial cell death attributed to myocardial ischemia-reperfusion injury (IRI). How to reduce the damage of blood reperfusion to ischemic myocardium has become an urgent problem to be solved. In preclinical experiments, many treatments have substantial cardioprotective effects against myocardial IRI. However, the transition from these cardioprotective therapies to clinically beneficial therapies for patients with acute myocardial infarction remains elusive. The reasons for the failure of the clinical translation may be multi-faceted, and three points are summarized here: (1) Our understanding of the complex pathophysiological mechanisms of myocardial IRI is far from enough, and the classification of specific therapeutic targets is not rigorous, and not clear enough; (2) Most of the clinical patients have comorbidities, and single cardioprotective strategies including ischemia regulation strategies cannot exert their due cardioprotective effects under conditions of hyperglycemia, hypertension, hyperlipidemia, and aging; (3) Most preclinical experimental results are based on adult, healthy animal models. However, most clinical patients had comorbidities and received multiple drug treatments before reperfusion therapy. In 2019, COST Action proposed a multi-target drug combination initiative for prospective myocardial IRI; the optimal cardioprotective strategy may be a combination of additive or synergistic multi-target therapy, which we support. By establishing more reasonable preclinical models, screening multi-target drug combinations more in line with clinical practice will benefit the translation of clinical treatment strategies.

Aging, sex and NLRP3 inflammasome in cardiac ischaemic disease

Experimentally, many strong cardioprotective treatments have been identified in different animal models of acute ischaemia/reperfusion injury (IRI) and coronary artery disease (CAD). However, the translation of these cardioprotective therapies for the benefit of the patients into the clinical scenario has been very disappointing. The reasons for this lack are certainly multiple. Indeed, many confounding factors we must deal in clinical reality, such as aging, sex and inflammatory processes are neglected in many experiments. Due to the pivotal role of aging, sex and inflammation in determining cardiac ischaemic disease, in this review, we take into account age as a modifier of tolerance to IRI in the two sexes, dissecting aging and myocardial reperfusion injury mechanisms and the sex differences in tolerance to IRI. Then we focus on the role of the gut microbiota and the NLRP3 inflammasome in myocardial IRI and on the possibility to consider NLRP3 inflammasome as a potential target in the treatment of CAD in relationship with age and sex. Finally, we consider the cardioprotective mechanisms and cardioprotective treatments during aging in the two sexes.

Complementary Pharmacotherapy for STEMI Undergoing Primary PCI: An Evidence-Based Clinical Approach

Antithrombotic therapy is the cornerstone of pharmacological treatment in patients undergoing primary percutaneous coronary intervention (PCI). However, the acute management of ST elevation myocardial infarction (STEMI) patients includes therapy for pain relief and potential additional strategies for cardioprotection. The safety and efficacy of some commonly used treatments have been questioned by recent evidence. Indeed a concern about morphine use is the interaction between opioids and oral P2Y₁₂ inhibitors; early beta-blocker treatment has shown conflicting results for the improvement of clinical outcomes; and supplemental oxygen therapy lacks benefit in patients without hypoxia and may be of potential harm. Other additional strategies remain disappointing; however, some treatments may be selectively used. Therefore, we intend to present a critical updated review of complementary pharmacotherapy for a modern treatment approach for STEMI patients undergoing primary PCI.

Therapeutic Peptides to Treat Myocardial Ischemia-Reperfusion Injury

Cardiovascular diseases (CVD) including acute myocardial infarction (AMI) rank first in worldwide mortality and according to the World Health Organization (WHO), they will stay at this rank until 2030. Prompt revascularization of the occluded artery to reperfuse the myocardium is the only recommended treatment (by angioplasty or thrombolysis) to decrease infarct size (IS). However, despite beneficial effects on ischemic lesions, reperfusion leads to ischemia-reperfusion (IR) injury related mainly to apoptosis. Improvement of revascularization techniques and patient care has decreased myocardial infarction (MI) mortality however heart failure (HF) morbidity is increasing, contributing to the cost-intense worldwide HF epidemic. Currently, there is no treatment for reperfusion injury despite promising results in animal models. There is now an obvious need to develop new cardioprotective strategies to decrease morbidity/mortality of CVD, which is increasing due to the aging of the population and the rising prevalence rates of diabetes and obesity. In this review, we will summarize the different therapeutic peptides developed or used focused on the treatment of myocardial IR injury (MIRI). Therapeutic peptides will be presented depending on their interacting mechanisms (apoptosis, necroptosis, and inflammation) reported as playing an important role in reperfusion injury following myocardial ischemia. The search and development of therapeutic peptides have become very active, with increasing numbers of candidates entering clinical trials. Their optimization and their potential application in the treatment of patients with AMI will be discussed.

Helium Conditioning Increases Cardiac Fibroblast Migration Which Effect Is Not Propagated via Soluble Factors or Extracellular Vesicles

Helium inhalation induces cardioprotection against ischemia/reperfusion injury, the cellular mechanism of which remains not fully elucidated. Extracellular vesicles (EVs) are cell-derived, nano-sized membrane vesicles which play a role in cardioprotective mechanisms, but their function in helium conditioning (HeC) has not been studied so far. We hypothesized that HeC induces fibroblast-mediated cardioprotection via EVs. We isolated neonatal rat cardiac fibroblasts (NRCFs) and exposed them to glucose deprivation and HeC rendered by four cycles of 95% helium + 5% CO2 for 1 h, followed by 1 h under normoxic condition. After 40 h of HeC, NRCF activation was analyzed with a Western blot (WB) and migration assay. From the cell supernatant, medium extracellular vesicles (mEVs) were isolated with differential centrifugation and analyzed with WB and nanoparticle tracking analysis. The supernatant from HeC-treated NRCFs was transferred to naïve NRCFs or immortalized human umbilical vein endothelial cells (HUVEC-TERT2), and a migration and angiogenesis assay was performed. We found that HeC accelerated the migration of NRCFs and did not increase the expression of fibroblast activation markers. HeC tended to decrease mEV secretion of NRCFs, but the supernatant of HeC or the control NRCFs did not accelerate the migration of naïve NRCFs or affect the angiogenic potential of HUVEC-TERT2. In conclusion, HeC may contribute to cardioprotection by increasing fibroblast migration but not by releasing protective mEVs or soluble factors from cardiac fibroblasts.

Therapies to prevent post-infarction remodelling: From repair to regeneration

Myocardial infarction is the first cause of worldwide mortality, with an increasing incidence also reported in developing countries. Over the past decades, preclinical research and clinical trials continually tested the efficacy of cellular and acellular-based treatments. However, none of them resulted in a drug or device currently used in combination with either percutaneous coronary intervention or coronary artery bypass graft. Inflammatory, proliferation and remodelling phases follow the ischaemic event in the myocardial tissue. Only recently, single-cell sequencing analyses provided insights into the specific cell populations which determine the final fibrotic deposition in the affected region. In this review, ischaemia, inflammation, fibrosis, angiogenesis, cellular stress and fundamental cellular and molecular components are evaluated as therapeutic targets. Given the emerging evidence of biomaterial-based systems, the increasing use of injectable hydrogels/scaffolds and epicardial patches is reported both as acellular and cellularised/functionalised treatments. Since several variables influence the outcome of any experimented treatment, we return to the pathological basis with an unbiased view towards any specific process or cellular component. Thus, by evaluating the benefits and limitations of the approaches based on these targets, the reader can weigh the rationale of each of the strategies that reached the clinical trials stage. As recent studies focused on the relevance of the extracellular matrix in modulating ischaemic remodelling and enhancing myocardial regeneration, we aim to portray current trends in the field with this review. Finally, approaches towards feasible translational studies that are as yet unexplored are also suggested.

Sex and Response to Cardioprotective Conditioning Maneuvers

Ischemic heart disease (IHD) is a multifactorial pathological condition strictly related to genetic, dietary, and lifestyle factors. Its morbidity and mortality rate represent one of the most important pathological issues that today involve younger people in a stronger way than in the past. IHD clinical outcomes are difficult to treat and have a high economic impact on health care. So prevention of this pathological condition through cardioprotective maneuvers represents the first line of intervention, as already underlined by several animal and human studies. Even if the time of intervention is important to prevent severe outcomes, many studies highlight that sex-dependent responses are crucial for the result of cardioprotective procedures. In this scenario sexual hormones have revealed an important role in cardioprotective approach, as women seem to be more protected toward cardiac insults when compared to male counterparts. The aim of this mini review is to show the molecular pathways involved in cardioprotective protocols and to elucidate how sexual hormones can contribute in ameliorating or worsening the physiological responses to IHD.

Glucagon-like peptide-1 (GLP-1) receptor activation dilates cerebral arterioles, increases cerebral blood flow, and mediates remote (pre)conditioning neuroprotection against ischaemic stroke

Stroke remains one of the most common causes of death and disability worldwide. Several preclinical studies demonstrated that the brain can be effectively protected against ischaemic stroke by two seemingly distinct treatments: remote ischaemic conditioning (RIC), involving cycles of ischaemia/reperfusion applied to a peripheral organ or tissue, or by systemic administration of glucagon-like-peptide-1 (GLP-1) receptor (GLP-1R) agonists. The mechanisms underlying RIC- and GLP-1-induced neuroprotection are not completely understood. In this study, we tested the hypothesis that GLP-1 mediates neuroprotection induced by RIC and investigated the effect of GLP-1R activation on cerebral blood vessels, as a potential mechanism of GLP-1-induced protection against ischaemic stroke. A rat model of ischaemic stroke (90 min of middle cerebral artery occlusion followed by 24-h reperfusion) was used. RIC was induced by 4 cycles of 5 min left hind limb ischaemia interleaved with 5-min reperfusion periods. RIC markedly (by ~ 80%) reduced the cerebral infarct size and improved the neurological score. The neuroprotection established by RIC was abolished by systemic blockade of GLP-1R with a specific antagonist Exendin(9-39). In the cerebral cortex of GLP-1R reporter mice, ~ 70% of cortical arterioles displayed GLP-1R expression. In acute brain slices of the rat cerebral cortex, activation of GLP-1R with an agonist Exendin-4 had a strong dilatory effect on cortical arterioles and effectively reversed arteriolar constrictions induced by metabolite lactate or oxygen and glucose deprivation, as an ex vivo model of ischaemic stroke. In anaesthetised rats, Exendin-4 induced lasting increases in brain tissue PO2, indicative of increased cerebral blood flow. These results demonstrate that neuroprotection against ischaemic stroke established by remote ischaemic conditioning is mediated by a mechanism involving GLP-1R signalling. Potent dilatory effect of GLP-1R activation on cortical arterioles suggests that the neuroprotection in this model is mediated via modulation of cerebral blood flow and improved brain perfusion.

Citric Acid Cycle Metabolites Predict Infarct Size in Pigs Submitted to Transient Coronary Artery Occlusion and Treated with Succinate Dehydrogenase Inhibitors or Remote Ischemic Perconditioning

Succinate dehydrogenase (SDH) inhibition with malonate during reperfusion reduced myocardial infarction in animals, whereas its endogenous substrate, succinate, is detected in plasma from STEMI patients. We investigated whether protection by SDH inhibition is additive to that of remote ischemic perconditioning (RIC) in pigs submitted to transient coronary artery occlusion, and whether protective maneuvers influence plasma levels of citric acid cycle metabolites. Forty pigs were submitted to 40 min coronary occlusion and reperfusion, and allocated to four groups (controls, sodium malonate 10 mmol/L, RIC, and malonate + RIC). Plasma was obtained from femoral and great cardiac veins and analyzed by LC-MS/MS. Malonate, RIC, and malonate + RIC reduced infarct size (24.67 ± 5.98, 25.29 ± 3.92 and 29.83 ± 4.62% vs. 46.47 ± 4.49% in controls, p < 0.05), but no additive effects were detected. Enhanced concentrations of succinate, fumarate, malate and citrate were observed in controls during initial reperfusion in the great cardiac vein, and most were reduced by cardioprotective maneuvers. Concentrations of succinate, fumarate, and malate significantly correlated with infarct size. In conclusion, despite the combination of SDH inhibition during reperfusion and RIC did not result in additive protection, plasma concentrations of selected citric acid cycle metabolites are attenuated by protective maneuvers, correlate with irreversible injury, and might become a prognosis tool in STEMI patients.