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Neuronal injuries in cerebral infarction and ischemic stroke: From mechanisms to treatment (Review).International Journal of Molecular... Feb 2022Stroke is the leading cause of disabilities and cognitive deficits, accounting for 5.2% of all mortalities worldwide. Transient or permanent occlusion of cerebral... (Review)
Review
Stroke is the leading cause of disabilities and cognitive deficits, accounting for 5.2% of all mortalities worldwide. Transient or permanent occlusion of cerebral vessels leads to ischemic strokes, which constitutes the majority of strokes. Ischemic strokes induce brain infarcts, along with cerebral tissue death and focal neuronal damage. The infarct size and neurological severity after ischemic stroke episodes depends on the time period since occurrence, the severity of ischemia, systemic blood pressure, vein systems and location of infarcts, amongst others. Ischemic stroke is a complex disease, and neuronal injuries after ischemic strokes have been the focus of current studies. The present review will provide a basic pathological background of ischemic stroke and cerebral infarcts. Moreover, the major mechanisms underlying ischemic stroke and neuronal injuries are summarized. This review will also briefly summarize some representative clinical trials and up‑to‑date treatments that have been applied to stroke and brain infarcts.
Topics: Animals; Brain Ischemia; Cerebral Infarction; Humans; Ischemic Stroke; Neurons; Neuroprotection; Oxidative Stress
PubMed: 34878154
DOI: 10.3892/ijmm.2021.5070 -
Circulation Jul 2021Over the past few decades, advances in pharmacological, catheter-based, and surgical reperfusion have improved outcomes for patients with acute myocardial infarctions.... (Review)
Review
Over the past few decades, advances in pharmacological, catheter-based, and surgical reperfusion have improved outcomes for patients with acute myocardial infarctions. However, patients with large infarcts or those who do not receive timely revascularization remain at risk for mechanical complications of acute myocardial infarction. The most commonly encountered mechanical complications are acute mitral regurgitation secondary to papillary muscle rupture, ventricular septal defect, pseudoaneurysm, and free wall rupture; each complication is associated with a significant risk of morbidity, mortality, and hospital resource utilization. The care for patients with mechanical complications is complex and requires a multidisciplinary collaboration for prompt recognition, diagnosis, hemodynamic stabilization, and decision support to assist patients and families in the selection of definitive therapies or palliation. However, because of the relatively small number of high-quality studies that exist to guide clinical practice, there is significant variability in care that mainly depends on local expertise and available resources.
Topics: Acute Disease; American Heart Association; Humans; Myocardial Infarction; United States
PubMed: 34126755
DOI: 10.1161/CIR.0000000000000985 -
American Journal of Physiology. Cell... Oct 2022The heart contains a population of resident macrophages that markedly expands following injury through recruitment of monocytes and through proliferation of macrophages.... (Review)
Review
The heart contains a population of resident macrophages that markedly expands following injury through recruitment of monocytes and through proliferation of macrophages. In myocardial infarction, macrophages have been implicated in both injurious and reparative responses. In coronary atherosclerotic lesions, macrophages have been implicated in disease progression and in the pathogenesis of plaque rupture. Following myocardial infarction, resident macrophages contribute to initiation and regulation of the inflammatory response. Phagocytosis and efferocytosis are major functions of macrophages during the inflammatory phase of infarct healing, and mediate phenotypic changes, leading to acquisition of an anti-inflammatory macrophage phenotype. Infarct macrophages respond to changes in the cytokine content and extracellular matrix composition of their environment and secrete fibrogenic and angiogenic mediators, playing a central role in repair of the infarcted heart. Macrophages may also play a role in scar maturation and may contribute to chronic adverse remodeling of noninfarcted segments. Single cell studies have revealed a remarkable heterogeneity of macrophage populations in infarcted hearts; however, the relations between transcriptomic profiles and functional properties remain poorly defined. This review manuscript discusses the fate, mechanisms of expansion and activation, and role of macrophages in the infarcted heart. Considering their critical role in injury, repair, and remodeling, macrophages are important, but challenging, targets for therapeutic interventions in myocardial infarction.
Topics: Cytokines; Humans; Macrophages; Monocytes; Myocardial Infarction; Phagocytosis
PubMed: 36094436
DOI: 10.1152/ajpcell.00230.2022 -
Circulation Research Jun 2016In adult mammals, massive sudden loss of cardiomyocytes after infarction overwhelms the limited regenerative capacity of the myocardium, resulting in the formation of a... (Review)
Review
In adult mammals, massive sudden loss of cardiomyocytes after infarction overwhelms the limited regenerative capacity of the myocardium, resulting in the formation of a collagen-based scar. Necrotic cells release danger signals, activating innate immune pathways and triggering an intense inflammatory response. Stimulation of toll-like receptor signaling and complement activation induces expression of proinflammatory cytokines (such as interleukin-1 and tumor necrosis factor-α) and chemokines (such as monocyte chemoattractant protein-1/ chemokine (C-C motif) ligand 2 [CCL2]). Inflammatory signals promote adhesive interactions between leukocytes and endothelial cells, leading to extravasation of neutrophils and monocytes. As infiltrating leukocytes clear the infarct from dead cells, mediators repressing inflammation are released, and anti-inflammatory mononuclear cell subsets predominate. Suppression of the inflammatory response is associated with activation of reparative cells. Fibroblasts proliferate, undergo myofibroblast transdifferentiation, and deposit large amounts of extracellular matrix proteins maintaining the structural integrity of the infarcted ventricle. The renin-angiotensin-aldosterone system and members of the transforming growth factor-β family play an important role in activation of infarct myofibroblasts. Maturation of the scar follows, as a network of cross-linked collagenous matrix is formed and granulation tissue cells become apoptotic. This review discusses the cellular effectors and molecular signals regulating the inflammatory and reparative response after myocardial infarction. Dysregulation of immune pathways, impaired suppression of postinfarction inflammation, perturbed spatial containment of the inflammatory response, and overactive fibrosis may cause adverse remodeling in patients with infarction contributing to the pathogenesis of heart failure. Therapeutic modulation of the inflammatory and reparative response may hold promise for the prevention of postinfarction heart failure.
Topics: Animals; Cell Proliferation; Fibrosis; Humans; Inflammation; Myocardial Infarction; Myocytes, Cardiac; Regeneration
PubMed: 27340270
DOI: 10.1161/CIRCRESAHA.116.303577 -
EBioMedicine Apr 2022Myocardial infarction is lethal to patients because of insufficient blood perfusion to vital organs. Several attempts have been made to improve its prognosis, among... (Review)
Review
Myocardial infarction is lethal to patients because of insufficient blood perfusion to vital organs. Several attempts have been made to improve its prognosis, among which nanomaterial research offers an opportunity to address this problem at the molecular level and has the potential to improve disease prevention, diagnosis, and treatment significantly. Up to now, nanomaterial-based technology has played a crucial role in broad novel diagnostic and therapeutic strategies for cardiac repair. This review summarizes various nanomaterial applications in myocardial infarction from multiple aspects, including high precision detection, pro-angiogenesis, regulating immune homeostasis, and miRNA and stem cell delivery vehicles. We also propose promising research hotspots that have not been reported much yet, such as conjugating pro-angiogenetic elements with nanoparticles to construct drug carriers, developing nanodrugs targeting other immune cells except for macrophages in the infarcted myocardium or the remote region. Though most of those strategies are preclinical and lack clinical trials, there is tremendous potential for their further applications in the future.
Topics: Drug Carriers; Humans; Myocardial Infarction; Myocardium; Nanoparticles; Stem Cells
PubMed: 35367772
DOI: 10.1016/j.ebiom.2022.103968 -
Cell Reports Oct 2023The immune system plays a critical role during myocardial injury, contributing to repair and remodeling post myocardial infarction (MI). The myocardial infarct and...
The immune system plays a critical role during myocardial injury, contributing to repair and remodeling post myocardial infarction (MI). The myocardial infarct and border zone exhibit high heterogeneity, in turn leading to reconstructing macrophage subsets and specific functions. Here we use a combination of single-cell RNA sequencing, spatial transcriptomes, and reporter mice to characterize temporal-spatial dynamics of cardiac macrophage subtype in response to MI. We identify that transient appearance of monocyte-derived Bhlhe41 Mφs in the "developing" infarct zone peaked at day 7, while other monocyte-derived macrophages are identified in "old" infarct zone. Functional characterization by co-culture of Bhlhe41 Mφs with cardiomyocytes and fibroblasts or depletion of Bhlhe41 Mφs unveils a crucial contribution of Bhlhe41 Mφs in suppression of myofibroblast activation. This work highlights the importance of Bhlhe41 Mφ phenotype and plasticity in preventing excessive fibrosis and limiting the expansion of developing infarct area.
Topics: Mice; Animals; Myocardium; Macrophages; Myocardial Infarction; Heart; Monocytes; Mice, Inbred C57BL
PubMed: 37751357
DOI: 10.1016/j.celrep.2023.113174 -
The Journal of Clinical Investigation Jan 2022Acute myocardial infarction (AMI) induces blood leukocytosis, which correlates inversely with patient survival. The molecular mechanisms leading to leukocytosis in the...
Acute myocardial infarction (AMI) induces blood leukocytosis, which correlates inversely with patient survival. The molecular mechanisms leading to leukocytosis in the infarcted heart remain poorly understood. Using an AMI mouse model, we identified gasdermin D (GSDMD) in activated leukocytes early in AMI. We demonstrated that GSDMD is required for enhanced early mobilization of neutrophils to the infarcted heart. Loss of GSDMD resulted in attenuated IL-1β release from neutrophils and subsequent decreased neutrophils and monocytes in the infarcted heart. Knockout of GSDMD in mice significantly reduced infarct size, improved cardiac function, and increased post-AMI survival. Through a series of bone marrow transplantation studies and leukocyte depletion experiments, we further clarified that excessive bone marrow-derived and GSDMD-dependent early neutrophil production and mobilization (24 hours after AMI) contributed to the detrimental immunopathology after AMI. Pharmacological inhibition of GSDMD also conferred cardioprotection after AMI through a reduction in scar size and enhancement of heart function. Our study provides mechanistic insights into molecular regulation of neutrophil generation and mobilization after AMI, and supports GSDMD as a new target for improved ventricular remodeling and reduced heart failure after AMI.
Topics: Animals; Female; Male; Mice; Gene Knockout Techniques; Heart Failure; Mice, Knockout; Myocardial Infarction; Myocardium; Neutrophils; Phosphate-Binding Proteins; Pore Forming Cytotoxic Proteins; Ventricular Remodeling
PubMed: 34752417
DOI: 10.1172/JCI151268 -
Journal of Nuclear Medicine : Official... Dec 2019Heart failure remains a major source of late morbidity and mortality after myocardial infarction (MI). The temporospatial presence of activated fibroblasts in the...
Heart failure remains a major source of late morbidity and mortality after myocardial infarction (MI). The temporospatial presence of activated fibroblasts in the injured myocardium predicts the quality of cardiac remodeling after MI. Therefore, monitoring of activated fibroblasts is of great interest for studying cardiac remodeling after MI. Fibroblast activation protein (FAP) expression is upregulated in activated fibroblasts. This study investigated the feasibility of imaging activated fibroblasts with a new Ga-labeled FAP inhibitor (Ga-FAPI-04) for PET imaging of fibroblast activation in a preclinical model of MI. MI and sham-operated rats were scanned with Ga-FAPI-04 PET/CT (1, 3, 6, 14, 23, and 30 d after MI) and with F-FDG (3 d after MI). Dynamic Ga-FAPI-04 PET and blocking studies were performed on MI rats 7 d after coronary ligation. After in vivo scans, the animals were euthanized and their hearts harvested for ex vivo analyses. Cryosections were prepared for autoradiography, hematoxylin and eosin (H&E), and immunofluorescence staining. Ga-FAPI-04 uptake in the injured myocardium peaked on day 6 after coronary ligation. The tracer accumulated intensely in the MI territory, as identified by decreased F-FDG uptake and confirmed by PET/MR and H&E staining. Autoradiography and H&E staining of cross-sections revealed that Ga-FAPI-04 accumulated mainly at the border zone of the infarcted myocardium. In contrast, there was only minimal uptake in the infarct of the blocked rats, comparable to the uptake in the remote noninfarcted myocardium (PET image-derived ratio of infarct uptake to remote uptake: 6 ± 2). Immunofluorescence staining confirmed the presence of FAP-positive myofibroblasts in the injured myocardium. Morphometric analysis of the whole-heart sections demonstrated 3- and 8-fold higher FAP-positive fibroblast density in the border zone than in the infarct center and remote area, respectively. Ga-FAPI-04 represents a promising radiotracer for in vivo imaging of post-MI fibroblast activation. Noninvasive imaging of activated fibroblasts may have significant diagnostic and prognostic value, which could aid clinical management of patients after MI.
Topics: Animals; Feasibility Studies; Fibroblasts; Gallium Radioisotopes; Isotope Labeling; Male; Membrane Proteins; Myocardial Infarction; Positron Emission Tomography Computed Tomography; Quinolines; Rats; Rats, Wistar
PubMed: 31405922
DOI: 10.2967/jnumed.119.226993 -
Macrophage Smad3 Protects the Infarcted Heart, Stimulating Phagocytosis and Regulating Inflammation.Circulation Research Jun 2019TGF (transforming growth factor)-β is critically involved in myocardial injury, repair, and fibrosis, activating both Smad (small mothers against...
RATIONALE
TGF (transforming growth factor)-β is critically involved in myocardial injury, repair, and fibrosis, activating both Smad (small mothers against decapentaplegic)-dependent and non-Smad pathways. The in vivo role of TGF-β signaling in regulation of macrophage function is poorly understood. We hypothesized that in the infarcted myocardium, activation of TGF-β/Smad signaling in macrophages may regulate repair and remodeling.
OBJECTIVE
To investigate the role of macrophage-specific TGF-β Smad3 signaling in a mouse model of myocardial infarction and to dissect the mechanisms mediating Smad-dependent modulation of macrophage function.
METHODS AND RESULTS
TGF-βs markedly activated Smad3 in macrophages, without affecting Smad-independent pathways. Phagocytosis rapidly and directly activated macrophage Smad3, in the absence of active TGF-β release. MyS3KO (myeloid cell-specific Smad3 knockout) mice had no baseline defects but exhibited increased late mortality and accentuated dilative postmyocardial infarction remodeling. Adverse outcome in infarcted MyS3KO mice was associated with perturbations in phagocytic activity, defective transition of macrophages to an anti-inflammatory phenotype, scar expansion, and accentuated apoptosis of border zone cardiomyocytes. In vitro, Smad3 null macrophages exhibited reduced expression of genes associated with eat-me signals, such as Mfge8 (milk fat globule-epidermal growth factor factor 8), and reduced capacity to produce the anti-inflammatory mediators IL (interleukin)-10 and TGF-β1, and the angiogenic growth factor VEGF (vascular endothelial growth factor). Mfge8 partly rescued the phagocytic defect of Smad3 null macrophages, without affecting inflammatory activity. Impaired anti-inflammatory actions of Smad3 null macrophages were associated with marked attenuation of phagocytosis-induced PPAR (peroxisome proliferator-activated receptor) expression. MyS3KO mice had no significant alterations in microvascular density and interstitial fibrosis in remodeling myocardial segments.
CONCLUSIONS
We demonstrate that Smad3 critically regulates function of infarct macrophages, by mediating acquisition of a phagocytic phenotype and by contributing to anti-inflammatory transition. Smad3-dependent actions in macrophages protect the infarcted heart from adverse remodeling.
Topics: Animals; Cells, Cultured; Female; Inflammation; Macrophages; Male; Mice; Mice, Knockout; Mice, Transgenic; Myocardial Infarction; Myocytes, Cardiac; Phagocytosis; Smad3 Protein
PubMed: 31092129
DOI: 10.1161/CIRCRESAHA.119.315069 -
Nature Biotechnology Aug 2018Pluripotent stem cell-derived cardiomyocyte grafts can remuscularize substantial amounts of infarcted myocardium and beat in synchrony with the heart, but in some...
Pluripotent stem cell-derived cardiomyocyte grafts can remuscularize substantial amounts of infarcted myocardium and beat in synchrony with the heart, but in some settings cause ventricular arrhythmias. It is unknown whether human cardiomyocytes can restore cardiac function in a physiologically relevant large animal model. Here we show that transplantation of ∼750 million cryopreserved human embryonic stem cell-derived cardiomyocytes (hESC-CMs) enhances cardiac function in macaque monkeys with large myocardial infarctions. One month after hESC-CM transplantation, global left ventricular ejection fraction improved 10.6 ± 0.9% vs. 2.5 ± 0.8% in controls, and by 3 months there was an additional 12.4% improvement in treated vs. a 3.5% decline in controls. Grafts averaged 11.6% of infarct size, formed electromechanical junctions with the host heart, and by 3 months contained ∼99% ventricular myocytes. A subset of animals experienced graft-associated ventricular arrhythmias, shown by electrical mapping to originate from a point-source acting as an ectopic pacemaker. Our data demonstrate that remuscularization of the infarcted macaque heart with human myocardium provides durable improvement in left ventricular function.
Topics: Animals; Cell Differentiation; Cryopreservation; Disease Models, Animal; Human Embryonic Stem Cells; Humans; Macaca; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Pluripotent Stem Cells; Primates
PubMed: 29969440
DOI: 10.1038/nbt.4162