ACE2 deficiency inhibits thoracic aortic dissection by enhancing SIRT3 mediated inhibition of inflammation and VSCMs phenotypic switch.

BACKGROUND: Thoracic aortic dissection (TAD) is an irreversible cardiovascular disorder with high mortality and morbidity. However, the molecular mechanisms remain elusive. Thus, identifying an effective therapeutic target to prevent TAD is especially critical. The purpose of this study is to elucidate the potential mechanism of inflammation and vascular smooth muscle cell (VSMCs) phenotypic switch in ß-aminopropionitrile fumarate (BAPN)-induced TAD. METHODS: A mouse model of TAD induced by BAPN and IL-1ß -stimulated HVSMCs in vivo and in vitro models, respectively. ACE2 Knockdown mice treated with BAPN or without, and the TAD mouse model was treated with or without AAV-ACE2. Transthoracic ultrasound was conducted for assessment the maximum internal diameter of the thoracic aorta arch. RNA sequencing analysis was performed to recapitulate transcriptome profile changes. Western blot were used to detect the expression of MMP2, MMP9, ACE2, SIRT3, OPN, SM22α and other inflammatory markers. The circulating levels of ACE2 was measured by ELISA assay. Histological changes of thoracic aorta tissues were assessed by H&E, EVG and IHC analysis. RESULTS: We found that circulating levels of and the protein levels of ACE2 were increased in the TAD mouse model and in patients with TAD. For further evidence, ACE2 deficiency decelerated the formation of TAD. However, overexpression of ACE2 aggravated BAPN-induced aortic injury and VSMCs phenotypic switch via lowered SIRT3 expression and elevated inflammatory cytokine expression. CONCLUSION: ACE2 deficiency prevented the development of TAD by inhibiting inflammation and VSMCs phenotypic switch in a SIRT3-dependent manner, suggesting that the ACE2/SIRT3 signaling pathway played a pivotal role in the pathological process of TAD and might be a potential therapeutical target.

RIP3 orchestrates oxidative stress and pyroptosis in doxorubicin-induced cardiotoxicity through regulation of AKT/Nrf2 signaling cascade.

This study was designed to explore the role of RIP3 in DOX-induced cardiotoxicity and its underlying molecular mechanisms. Our results demonstrate that RIP3 exacerbates DOX-induced cardiotoxicity through promoting oxidative stress and pyroptosis by regulating the AKT/Nuclear factor erythroid 2-related factor 2 (Nrf2) signal pathway. Inhibition of RIP3 using GSK-872 attenuated DOX-induced cardiac remodeling and contractile dysfunction. Moreover, using GSK-872 in vivo, the results revealed that inhibition of RIP3 alleviated DOX-induced cardiotoxicity by the resulting inhibition of oxidative stress and pyroptosis. In addition, inhibition of RIP3 increased the protein levels of AKT and Nrf2 in DOX-treated mouse hearts. Furthermore, the AKT inhibitor LY294002 lessened RIP3 reduction-offered protection against DOX-induced H9c2 cell injury by moderating oxidative stress and pyroptosis. Taken together, these data demonstrate that RIP3 activation orchestrates DOX-induced cardiotoxicity through elevated oxidative stress and pyroptosis in an AKT/Nrf2-dependent manner. Those findings highlight the clinical relevance and therapeutic potential of targeting RIP3 for the treatment of DOX-induced cardiotoxicity.

Follistatin-like protein 1 attenuates doxorubicin-induced cardiomyopathy by inhibiting MsrB2-mediated mitophagy.

Doxorubicin (DOX) is a potent chemotherapeutic drug; however, its clinical use is limited due to its cardiotoxicity. Mitochondrial dysfunction plays a vital role in the pathogenesis of DOX-induced cardiomyopathy. Follistatin-like protein 1 (FSTL1) is a potent cardiokine that protects the heart from diverse cardiac diseases, such as myocardial infarction, cardiac ischemia/reperfusion injury, and heart failure. However, its role in DOX-induced cardiomyopathy is unclear. Therefore, the present study investigated whether administering recombinant FSTL1 could mitigate DOX-induced cardiomyopathy and clarified the underlying molecular mechanisms. FSTL1 treatment attenuated DOX-induced cardiac dysfunction, cardiac fibrosis, and cellular apoptosis by inhibiting excess mitochondrial matrix protein methionine sulfoxide reductase B2 (MsrB2)-mediated mitophagy. Furthermore, FSTL1 administration reduced the expression of apoptotic proteins, including MsrB2, Bax, caspase 3, mitochondrial Parkin, and LC3-II, increased myocardial ATP content, and decreased cardiac malondialdehyde levels, thus protecting mitochondrial function against DOX-induced cardiac injury. Furthermore, FSTL1 treatment protected the contractile properties of adult cardiomyocytes against DOX-induced injury in vitro. Furthermore, carbonyl cyanide m-chlorophenylhydrazone, a mitophagy inducer, impaired the protective effects of FSTL1 in DOX-treated H9c2 cardiomyocytes. In conclusion, these results show that FSTL1 is a novel therapeutic agent against DOX-induced cardiotoxicity that improves mitochondrial function and decreases mitophagy.

Rectifying METTL4-Mediated N6-Methyladenine Excess in Mitochondrial DNA Alleviates Heart Failure.

BACKGROUND: Myocardial mitochondrial dysfunction underpins the pathogenesis of heart failure (HF), yet therapeutic options to restore myocardial mitochondrial function are scarce. Epigenetic modifications of mitochondrial DNA (mtDNA), such as methylation, play a pivotal role in modulating mitochondrial homeostasis. However, their involvement in HF remains unclear. METHODS: Experimental HF models were established through continuous angiotensin II and phenylephrine (AngII/PE) infusion or prolonged myocardial ischemia/reperfusion injury. The landscape of N6-methyladenine (6mA) methylation within failing cardiomyocyte mtDNA was characterized using high-resolution mass spectrometry and methylated DNA immunoprecipitation sequencing. A tamoxifen-inducible cardiomyocyte-specific Mettl4 knockout mouse model and adeno-associated virus vectors designed for cardiomyocyte-targeted manipulation of METTL4 (methyltransferase-like protein 4) expression were used to ascertain the role of mtDNA 6mA and its methyltransferase METTL4 in HF. RESULTS: METTL4 was predominantly localized within adult cardiomyocyte mitochondria. 6mA modifications were significantly more abundant in mtDNA than in nuclear DNA. Postnatal cardiomyocyte maturation presented with a reduction in 6mA levels within mtDNA, coinciding with a decrease in METTL4 expression. However, an increase in both mtDNA 6mA level and METTL4 expression was observed in failing adult cardiomyocytes, suggesting a shift toward a neonatal-like state. METTL4 preferentially targeted mtDNA promoter regions, which resulted in interference with transcription initiation complex assembly, mtDNA transcriptional stalling, and ultimately mitochondrial dysfunction. Amplifying cardiomyocyte mtDNA 6mA through METTL4 overexpression led to spontaneous mitochondrial dysfunction and HF phenotypes. The transcription factor p53 was identified as a direct regulator of METTL4 transcription in response to HF-provoking stress, thereby revealing a stress-responsive mechanism that controls METTL4 expression and mtDNA 6mA. Cardiomyocyte-specific deletion of the Mettl4 gene eliminated mtDNA 6mA excess, preserved mitochondrial function, and mitigated the development of HF upon continuous infusion of AngII/PE. In addition, specific silencing of METTL4 in cardiomyocytes restored mitochondrial function and offered therapeutic relief in mice with preexisting HF, irrespective of whether the condition was induced by AngII/PE infusion or myocardial ischemia/reperfusion injury. CONCLUSIONS: Our findings identify a pivotal role of cardiomyocyte mtDNA 6mA and the corresponding methyltransferase, METTL4, in the pathogenesis of mitochondrial dysfunction and HF. Targeted suppression of METTL4 to rectify mtDNA 6mA excess emerges as a promising strategy for developing mitochondria-focused HF interventions.

Irisin improves diabetic cardiomyopathy-induced cardiac remodeling by regulating GSDMD-mediated pyroptosis through MITOL/STING signaling.

Diabetic cardiomyopathy (DCM) is a common complication of diabetes mellitus (DM). However, the mechanisms underlying DCM-induced cardiac injury remain unclear. Recently, the role of cyclic GMP-AMP synthase/stimulator of interferon gene (cGAS/STING) signaling and pyroptosis in DCM has been investigated. Based on our previous results, this study was designed to examine the impact of irisin, mitochondrial ubiquitin ligase (MITOL/MARCH5), and cGAS/STING signaling in DCM-induced cardiac dysfunction and the effect of gasdermin D (GSDMD)-dependent pyroptosis. High-fat diet-induced mice and H9c2 cells were used for cardiac geometry and function or pyroptosis-related biomarker assessment at the end of the experiments. Here, we show that DCM impairs cardiac function by increasing cardiac fibrosis and GSDMD-dependent pyroptosis, including the activation of MITOL and cGAS/STING signaling. Our results confirmed that the protective role of irisin and MITOL was partially offset by the activation of cGAS/STING signaling. We also demonstrated that GSDMD-dependent pyroptosis plays a pivotal role in the pathological process of DCM pathogenesis. Our results indicate that irisin treatment protects against DCM injury, mitochondrial homeostasis, and pyroptosis through MITOL upregulation.

Integrative analysis reveals chemokines CCL2 and CXCL5 mediated shear stress-induced aortic dissection formation.

Background: Aortic dissection (AD) is a critical emergency in cardiovascular disease. AD occurs only in specific sites of the aorta, and the variation of shear stress in different aortic segments is a possible cause not reported. This study investigated the key molecules involved in shear stress-induced AD through quantitative bioinformatic analysis of a public RNA sequencing database and clinical tissue sample validation. Methods: Gene expression data from the GSE153434, GSE147026, and GSE52093 datasets were downloaded from the Gene Expression Omnibus. Next, differently expressed genes (DEGs) in each dataset were identified and integrated to identify common AD DEGs. STRING, Cytoscape, and MCODE were used to identify hub genes and crucial clustering modules, and Connectivity Map (CMap) was used to identify positive and negative agents. The same procedure was performed for the GSE160611 dataset to obtain shear stress-induced human aortic endothelial cell (HAEC) DEGs. After the integration of these two DEGs sets to identify shear stress-associated hub DEGs in AD, Gene Ontology Enrichment Analysis was performed. The common chemokine receptors and ligands in AD were identified by analyzing AD's three RNA sequencing datasets. Their origin was verified by analyzing AD single-cell sequencing data and validated by immunoblotting and immunofluorescence. Results: We identified 100 down-regulated and 50 up-regulated AD common DEGs. Enrichment results showed that common DEGs were closely related to blood vessel morphogenesis, muscle structure development, muscle tissue development, and chemotaxis. Among those DEGs, MYC, CCL2, and SPP1 are the three molecules with the highest degree. A crucial cluster of 15 genes was identified using MCODE, which contained inflammation-related genes with elevated expression and muscle cell-related genes with decreased expression, and CCL2 is central to immune-related genes. CMap confirmed MEK inhibitors and ALK inhibitors as possible therapeutic agents for AD. Moreover, 366 shear stress-associated DEGs in HAEC were identified in the GSE160611 dataset. After taking the intersection, we identified five shear stress-associated hub DEGs in AD (ANGPTL4, SNAI2, CCL2, GADD45B, and PROM1), and the enrichment analysis indicated they were related to the endothelial cell apoptotic process. Chemokine CCL2 was the molecule with a high degree in both DEG sets. Besides CCL2, CXCL5 was the only chemokine ligand differentially expressed in the three datasets. Additionally, immunoblotting confirmed the increased expression of CCL2 and CXCL5 in clinical tissue samples. Further research at the single-cell level revealed that CCL2 has multiple origins, and CXCL5 is macrophage-derived. Conclusion: Through integrative analysis, we identified core common AD DEGs and possible therapeutic agents based on these DEGs. We elucidated that the chemokine CCL2 and CXCL5-mediated "Endothelial-Monocyte-Neutrophil" axis may contribute to the development of shear stress-induced AD. These findings provide possible therapeutic targets for the prevention and treatment of AD.

Melatonin Restores Autophagic Flux by Activating the Sirt3/TFEB Signaling Pathway to Attenuate Doxorubicin-Induced Cardiomyopathy.

Doxorubicin (DOX) chemotherapy in cancer patients increases the risk of the occurrence of cardiac dysfunction and even results in congestive heart failure. Despite the great progress of pathology in DOX-induced cardiomyopathy, the underlying molecular mechanisms remain elusive. Here, we investigate the protective effects and the underlying mechanisms of melatonin in DOX-induced cardiomyopathy. Our results clearly show that oral administration of melatonin prevented the deterioration of cardiac function caused by DOX treatment, which was evaluated by left ventricular ejection fraction and fractional shortening as well as cardiac fibrosis. The ejection fraction and fractional shortening in the DOX group were 49.48% and 25.5%, respectively, while melatonin treatment increased the ejection fraction and fractional shortening to 60.33 and 31.39 in wild-type mice. Cardiac fibrosis in the DOX group was 3.97%, while melatonin reduced cardiac fibrosis to 1.95% in wild-type mice. Sirt3 is a mitochondrial deacetylase and shows protective effects in diverse cardiovascular diseases. Therefore, to test whether Sirt3 is a key factor in protection, Sirt3 knockout mice were used, and it was found that the protective effects of melatonin in DOX-induced cardiomyopathy were partly abolished. Further analysis revealed that Sirt3 and its downstream molecule TFEB were downregulated in response to DOX treatment, while melatonin administration was able to significantly enhance the expressions of Sirt3 and TFEB. Our in vitro study demonstrated that melatonin enhanced lysosomal function by increasing the Sirt3-mediated increase at the TFEB level, and the accumulation of autolysosomes induced by DOX treatment was attenuated. Thus, autophagic flux disrupted by DOX treatment was restored by melatonin supplementation. In summary, our results demonstrate that melatonin protects the heart against DOX injury by the restoration of autophagic flux via the activation of the Sirt3/TFEB signaling pathway.

1-Deoxynojirimycin attenuates septic cardiomyopathy by regulating oxidative stress, apoptosis, and inflammation via the JAK2/STAT6 signaling pathway.

Cardiac dysfunction caused by sepsis is the predominant reason for death in patients with sepsis. However, the effective drugs for its prevention and the molecular mechanisms remain elusive. 1-Deoxynojirimycin (DNJ), a natural iminopyranose, exhibits various biological properties, such as hypoglycemic, antitumor, antiviral, and anti-inflammatory activities. However, whether DNJ can mediate biological activity resistance in sepsis-induced myocardial injury and the underlying mechanisms are unclear. Janus kinase and signal transducer and activator of transcription (JAK/STAT) signaling is an important pathway for the signal transduction of several key cytokines in the pathogenesis of sepsis, which can transcribe and modulate the host immune response. This study was conducted to confirm whether DNJ mediates oxidative stress, apoptosis, and inflammation in cardiomyocytes, thereby alleviating myocardial injury in sepsis via the JAK2/STAT6 signaling pathway. Septic cardiomyopathy was induced in mice using lipopolysaccharide (LPS), and they were then treated with DNJ. The results showed that DNJ markedly improved sepsis-induced cardiac dysfunction, attenuated reactive oxygen species generation, reduced cardiomyocyte apoptosis, and mitigated inflammation. Mechanistically, increased JAK2/STAT6 phosphorylation was observed in the mouse sepsis models, which decreased significantly after DNJ oral treatment. To further confirm whether DNJ mediates the JAK2/STAT6 pathway, the selective inhibitor fedratinib was used to block the JAK2 signaling pathway in vitro, which enhanced the protective effects of DNJ against the sepsis-induced cardiac damage. Collectively, these findings suggest that DNJ attenuates sepsis-induced myocardial injury by decreasing myocardial oxidative damage, apoptosis, and inflammation via the regulation of the JAK2/STAT6 signaling pathway.

Exosome from BMMSC Attenuates Cardiopulmonary Bypass-Induced Acute Lung Injury Via YAP/ß-Catenin Pathway: Downregulation of Pyroptosis.

Acute lung injury (ALI) accompanied with systemic inflammatory response is an important complication after cardiopulmonary bypass (CPB). Pyroptosis, which is induced by the secretion of inflammatory factors, has been implicated in ALI. However, recent studies have suggested that bone marrow mesenchymal stem cell-derived exosomes (BMMSC-Exo) can ameliorate ALI, but the mechanism is poorly understood. Therefore, we aim to examine the effects of BMMSC-Exo in CPB-induced ALI, and its underlying mechanism. CPB rat models (male Sprague-Dawley rats) were administered BMMSC-Exo intravenously before induction of ALI. Lung tissue, bronchoalveolar lavage fluid (BALF), and alveolar macrophage (AM) were collected after the treatments for further analysis, and rat AM NR8383 cells were used for in vitro study. HE staining was performed to detect macrophage infiltration. Western blot was used to detect related proteins expression. And ELISA assay was performed to investigate secretion of inflammatory factors. These results showed that BMMSC-Exo treatment ameliorated macrophage infiltration and oxidative stress, and downregulated expression of pyroptosis-related proteins, including NLRP3, cleaved caspase-1, and GSDMD-N, in the lung tissue and AM, as well as decreased the secretion of IL-18 and IL-1ß in BALF. Moreover, BMMSC-Exo activated YAP/ß-catenin signaling pathway. Overall, these findings of this study indicated that BMMSC-Exo suppressed CPB-induced pyroptosis in ALI by activating YAP/ß-catenin axis, which could be a novel strategy for lung protection during CPB.

Irisin attenuates sepsis-induced cardiac dysfunction by attenuating inflammation-induced pyroptosis through a mitochondrial ubiquitin ligase-dependent mechanism.

Sepsis-induced cardiac dysfunction is a leading cause of mortality in intensive care units. However, the molecular mechanisms underlying septic cardiomyopathy remain elusive. Irisin is a cleaved product of fibronectin type III domain-containing protein 5 (FNDC5) that protects the heart from ischemia/reperfusion injury through upregulation of mitochondrial ubiquitin ligase (MITOL). Gasdermin D (GSDMD)-dependent pyroptosis plays a pivotal role in septic cardiomyopathy by regulating mitochondrial homeostasis. However, whether irisin can regulate MITOL to inhibit GSDMD-dependent pyroptosis in septic cardiomyopathy is yet to be investigated. Thus, this study was designed to explore the role of irisin in septic cardiomyopathy and its underlying molecular mechanisms. Our results demonstrate that irisin improves cardiac function against sepsis-induced cardiac dysfunction by reducing cardiac inflammation and myocardial pyroptosis. Using MITOL siRNA in vitro, the results revealed that the protective role of irisin against lipopolysaccharide (LPS)-induced cell injury was mediated by MITOL activation and the resulting inhibition of GSDMD-dependent pyroptosis. Moreover, irisin alleviated LPS-induced H9c2 cell injury by suppressing IL-1ß expression and reducing serum LDH and CK-MB concentrations in a MITOL/GSDMD-dependent manner. Collectively, our data suggest that irisin treatment ameliorates cardiac dysfunction in septic cardiomyopathy by activating MITOL and inhibiting GSDMD-dependent pyroptosis. These findings highlight the clinical relevance and therapeutic potential of irisin and MITOL for the management of sepsis-induced cardiac dysfunction.

FSTL1-USP10-Notch1 Signaling Axis Protects Against Cardiac Dysfunction Through Inhibition of Myocardial Fibrosis in Diabetic Mice.

The incidence of type 2 diabetes mellitus (T2DM) has been increasing globally, and T2DM patients are at an increased risk of major cardiac events such as myocardial infarction (MI). Nevertheless, the molecular mechanisms underlying MI injury in T2DM remain elusive. Ubiquitin-specific protease 10 (USP10) functions as a NICD1 (Notch1 receptor) deubiquitinase that fine-tunes the essential myocardial fibrosis regulator Notch signaling. Follistatin-like protein 1 (FSTL1) is a cardiokine with proven benefits in multiple pathological processes including cardiac fibrosis and insulin resistance. This study was designed to examine the roles of FSTL1/USP10/Notch1 signaling in MI-induced cardiac dysfunction in T2DM. High-fat-diet-treated, 8-week-old C57BL/6J mice and db/db T2DM mice were used. Intracardiac delivery of AAV9-FSTL1 was performed in T2DM mice following MI surgery with or without intraperitoneal injection of crenigacestat (LY3039478) and spautin-1. Our results demonstrated that FSTL1 improved cardiac function following MI under T2DM by reducing serum lactate dehydrogenase (LDH) and myocardial apoptosis as well as cardiac fibrosis. Further in vivo studies revealed that the protective role of FSTL1 against MI injury in T2DM was mediated by the activation of USP10/Notch1. FSTL1 protected cardiac fibroblasts (CFs) against DM-MI-induced cardiofibroblasts injury by suppressing the levels of fibrosis markers, and reducing LDH and MDA concentrations in a USP10/Notch1-dependent manner. In conclusion, FSTL1 treatment ameliorated cardiac dysfunction in MI with co-existent T2DM, possibly through inhibition of myocardial fibrosis and apoptosis by upregulating USP10/Notch1 signaling. This finding suggests the clinical relevance and therapeutic potential of FSTL1 in T2DM-associated MI and other cardiovascular diseases.

Effect of Eccentric Calcification of an Aortic Valve on the Implant Depth of a Venus-A Prosthesis During Transcatheter Aortic Valve Replacement: A Retrospective Study.

OBJECT: Our goal was to assess the implant depth of a Venus-A prosthesis during transcatheter aortic valve replacement (TAVR) when the areas of eccentric calcification were distributed in different sections of the aortic valve. METHODS: A total of 53 patients with eccentric calcification of the aortic valve who underwent TAVR with a Venus-A prosthesis from January 2018 to November 2019 were retrospectively analyzed. The patients were divided into three groups (A, B, and C) according to the location of the eccentric calcification, which was determined by preprocedural computerized tomography angiography (CTA) images. The prosthesis release process and position were evaluated by contrast aortography during TAVR, and the differences in valve implant depths were compared among the three groups. The effects of different aortic root structures and procedural strategies on prosthesis implant depth were analyzed. RESULTS: Eleven patients had eccentric calcification in region A; 19 patients, in region B; and 23 patients, in region C. The patients with eccentric calcification in region B had a higher risk of prosthesis migration (10.5% upward and 21.1% downward), and the position of the prosthesis after TAVR in group B was the deepest among the three groups. When eccentric calcification was located in region A or C, the prosthesis was released at the standard position with more stability, and the location of the prosthesis was less deep after TAVR (region A: 4.12 ± 3.4 mm; region B: 10.2 ± 5.3 mm; region C: 8.4 ± 4.0 mm; region A vs. region B, P = 0.0004; region C vs. region B; and P = 0.0360). In addition, the left ventricular outflow tract (LVOT) (P = 0.0213) and aortic root angulation (P = 0.0263) also had a significant effect on implant depth in the aortic root structure of the patients. The prosthesis size was 28.3 ± 2.4 in the deep implant group and 26.4 ± 2.0 in the appropriate implant group (P = 0.0068). CONCLUSION: The implant depth of the Venus-A prosthesis is closely related to the distribution of eccentric calcification in the aortic valve during TAVR. Surgeons should adjust the surgical strategy according to aortic root morphology to prevent prosthesis migration.

Electroacupuncture Pretreatment Mitigates Myocardial Ischemia/Reperfusion Injury via XBP1/GRP78/Akt Pathway.

Myocardial ischemia/reperfusion injury is a common clinical problem and can result in severe cardiac dysfunction. Previous studies have demonstrated the protection of electroacupuncture against myocardial ischemia/reperfusion injury. However, the role of X-box binding protein I (XBP1) signaling pathway in the protection of electroacupuncture was still elusive. Thus, we designed this study and demonstrated that electroacupuncture significantly improved cardiac function during myocardial ischemia/reperfusion injury and reduced cardiac infarct size. Electroacupuncture treatment further inhibited cardiac injury manifested by the decrease of the activities of serum lactate dehydrogenase and creatine kinase-MB. The results also revealed that electroacupuncture elevated the expressions of XBP1, glucose-regulated protein 78 (GRP78), Akt, and Bcl-2 and decreased the Bax and cleaved Caspase 3 expressions. By using the inhibitor of XBP1 in vitro, the results revealed that suppression of XBP1 expression could markedly increase the activities of lactate dehydrogenase and creatine kinase-MB and cell apoptosis, thus exacerbating stimulated ischemia/reperfusion-induced H9c2 cell injury. Compared with stimulated ischemia/reperfusion group, inhibition of XBP1 inhibited the downstream GRP78 and Akt expressions during stimulated ischemia/reperfusion injury. Collectively, our data demonstrated that electroacupuncture treatment activated XBP1/GRP78/Akt signaling to protect hearts from myocardial ischemia/reperfusion injury. These findings revealed the underlying mechanisms of electroacupuncture protection against myocardial ischemia/reperfusion injury and may provide novel therapeutic targets for the clinical treatment of myocardial ischemia/reperfusion injury.

Hydrogel-mesh composite for wound closure.

During operations, surgical mesh is commonly fixed on tissues through fasteners such as sutures and staples. Attributes of surgical mesh include biocompatibility, flexibility, strength, and permeability, but sutures and staples may cause stress concentration and tissue damage. Here, we show that the functions of surgical mesh can be significantly broadened by developing a family of materials called hydrogel-mesh composites (HMCs). The HMCs retain all the attributes of surgical mesh and add one more: adhesion to tissues. We fabricate an HMC by soaking a surgical mesh with a precursor, and upon cure, the precursor forms a polymer network of a hydrogel, in macrotopological entanglement with the fibers of the surgical mesh. In a surgery, the HMC is pressed onto a tissue, and the polymers in the hydrogel form covalent bonds with the tissue. To demonstrate the concept, we use a poly(N-isopropylacrylamide) (PNIPAAm)/chitosan hydrogel and a polyethylene terephthalate (PET) surgical mesh. In the presence a bioconjugation agent, the chitosan and the tissue form covalent bonds, and the adhesion energy reaches above 100 J⋅m-2 At body temperature, PNIPAAm becomes hydrophobic, so that the hydrogel does not swell and the adhesion is stable. Compared with sutured surgical mesh, the HMC distributes force over a large area. In vitro experiments are conducted to study the application of HMCs to wound closure, especially on tissues under high mechanical stress. The performance of HMCs on dynamic living tissues is further investigated in the surgery of a sheep.

Transcatheter mitral valve implantation using a novel system: preclinical results.

BACKGROUND: This preclinical study in sheep sought to demonstrate the initial safety and feasibility of a novel transcatheter mitral valve system (Mi-thos valve) composed of a self-expanding frame and a bovine pericardial tissue bioprosthesis. METHODS: The valve was implanted in 26 sheep using a transapical approach for short- and long-term evaluation. The technical feasibility, safety, durability, and valve function were evaluated during and 6 months after the procedure using intracardiac and transthoracic echocardiography, multisliced computed tomography, histological analysis, and electron microscopy. RESULTS: The success rate of valve implantation was 100%, and the immediate survival rate after surgery was 84%. Five animals died within 90 min after the development of the prosthetic valve due to an acute left ventricular outflow tract obstruction (n = 2) and sudden intraoperative ventricular fibrillation (n = 3). Twelve animals died within 1 month due to acute left heart dysfunction. Mild (n = 5) and moderate (n = 2) paravalvular leakage occurred in seven animals, and two moderate PVL animals died of chronic heart failure within three months. Multimodality imaging studies of the remaining seven animals showed excellent function and alignment of the valves, with no coronary artery obstruction, no left ventricular outflow tract obstruction, no severe transvalvular gradients and no paravalvular leakage. Macroscopic evaluation demonstrated stable, secure positioning of the valve, with full endothelialization of the valve leaflets without injury to the ventricular or atrial walls. Histological and electron microscopic examinations at six months showed no obvious macro- or microcalcification in the leaflets. CONCLUSIONS: Preclinical studies indicate that transcatheter implantation of the Mi-thos valve is technically safe and feasible. The durability, functionality, and lack of leaflet calcification were all verified in animal experiments. The information from these preclinical studies will be applied to patient selection criteria and the first-in-human studies.

Exosomes Derived from Mesenchymal Stem Cells Protect the Myocardium Against Ischemia/Reperfusion Injury Through Inhibiting Pyroptosis.

OBJECTIVE: Mesenchymal stem cells (MSCs) show unique advantages in cardiomyocyte repairment. Exosomes derived from MSCs can enhance the viability of myocardial cells after ischemia/reperfusion (I/R) injury and regulate inflammation response. The study was designed to ascertain whether MSCs-exo protect the myocardium against I/R injury through inhibiting pyroptosis, and the underlying mechanisms. METHODS AND RESULTS: Experiments were carried out in H/R and I/R model. Cell viability was inhibited and NLRP3 and caspase1 protein levels were upregulated in H/R model. However, MSCs could inhibit cell apoptosis and pyroptosis in H/R model. Moreover, we used MSCs-exo to treated H/R model, and flow cytometric analysis results showed the inhibition function of MSCs-exo on cell apoptosis, and Western blot data suggested that NLRP3 and Caspase-1 expressions were downregulated in H/R model. Furthermore, exosomal miR-320b targeted NLRP3 protein, and MSCs-exo OE could inhibit NLRP3 expression and pyroptosis in H/R. In addition, the inhibition function of MSCs-exo on pyroptosis also was found in I/R model, and HE and Tunel staining also got similar results. CONCLUSION: Exosomes derived from mesenchymal stem cells could protect the myocardium against ischemia/reperfusion injury through inhibiting pyroptosis.

Irisin attenuates myocardial ischemia/reperfusion-induced cardiac dysfunction by regulating ER-mitochondria interaction through a mitochondrial ubiquitin ligase-dependent mechanism.

BACKGROUND: Myocardial ischemia/reperfusion (MI/R) injury imposes devastating cardiovascular sequelae in particular cardiac dysfunction as a result of restored blood flow. However, the mechanism behind MI/R injury remains elusive. Mitochondrial ubiquitin ligase (MITOL/MARCH5) is localized at the mitochondria-ER contact site and may be activated in response to a variety of pathophysiological processes, such as apoptosis, mitochondrial injury, ER stress, hypoxia, and reactive oxygen species (ROS) generation. Irisin as a cleaved product of fibronectin type III domain-containing protein 5 (FNDC5) displays cardioprotection in diverse cardiac diseases. METHODS: This study was designed to examine the role of irisin and MITOL in MI/R injury. Male C57BL/6J mice (8-10-week-old) were administered adenovirus MITOL shRNA through intracardiac injection followed by MI/R surgery through ligation and release the slipknot of cardiac left anterior descending coronary artery. RESULTS: Our results showed that irisin improved myocardial function in the face of MI/R injury as evidenced by reduced myocardial infarct size, apoptotic rate, serum lactate dehydrogenase (LDH), ROS generation, and malondialdehyde (MDA) levels as well as lessened ER stress injury. Moreover, our results indicated that protective role of irisin was mediated by upregulation of MITOL. Irisin also protected H9c2 cells against simulated I/R through negating ER stress, apoptosis, ROS and MDA levels, as well as facilitating superoxide dismutase (SOD) by way of elevated MITOL expression. CONCLUSIONS: To this end, our data favored that irisin pretreatment protects against MI/R injury, ER stress, ROS production, and mitochondrial homeostasis through upregulation of MITOL. These findings depicted the therapeutic potential of irisin and MITOL in the management of MI/R injury in patients with ST-segment elevation.

Effectiveness of a novel, completely biomaterial valved pulmonary arterial conduit: An in vivo study.

As a pre-clinical assessment, the present study aimed to investigate the safety and effectiveness of a novel valved pulmonary arterial conduit constructed entirely from biomaterials by transplanting it in the outflow tract of the right ventricle in sheep. Under extracorporeal circulation, the valved pulmonary arterial conduit was used to replace the pulmonary artery of sheep with a beating heart. The performance was assessed at 30, 90 and 180 days post-surgery. Hemodynamic and structural changes were evaluated, and safety was assessed after 180 postoperative days. The hemodynamic effect and biosafety of the implant were further evaluated by observing the changes in various pressure indicators of the heart, echocardiographic results, anatomical and pathological examination results, liver and kidney functions, routine blood tests, a blood coagulation test, and other test results following implantation of the purely biotic valved conduit. The conduit was successfully implanted in 12 sheep and no mortality occurred postoperatively. During the 180-day follow-up, there was no obvious stenosis or regurgitation of the right ventricular outflow tract and pulmonary valve after valved conduit implantation. The findings of autopsy, pathology and laboratory examinations were unremarkable. The implantation of this biosynthetic vascular graft into animals meets the safety and effectiveness requirements for clinical application. This pulmonary arterial conduit has potential clinical application for children with complex congenital heart disease who require pulmonary artery reconstruction to achieve a radical cure.

Melatonin Ameliorates MI-Induced Cardiac Remodeling and Apoptosis through a JNK/p53-Dependent Mechanism in Diabetes Mellitus.

Diabetes mellitus, a worldwide health threat, is considered an independent risk factor for cardiovascular diseases. The overall cardiovascular risk of diabetes is similar to the one having one myocardial infarction (MI) attack although the precise impact of diabetes on MI-induced myocardial anomalies remains elusive. Given that mortality following MI is much greater in diabetic patients compared to nondiabetic patients, this study was designed to examine the effect of melatonin on MI injury-induced myocardial dysfunction in diabetes. Adult mice were made diabetic using high-fat feeding and streptozotocin (100 mg/kg body weight) prior to MI and were treated with melatonin (50 mg/kg/d, p.o.) for 4 weeks prior to assessment of cardiac geometry and function. The MI procedure in diabetes displayed overt changes in cardiac geometry (chamber dilation and interstitial fibrosis) and functional anomalies (reduced fractional shortening and cardiomyocyte contractile capacity) in association with elevated c-Jun N-terminal kinase (JNK) phosphorylation and p53 level. Melatonin treatment markedly attenuated cardiac dysfunction and myocardial fibrosis in post-MI diabetic mice. Furthermore, melatonin decreased JNK phosphorylation, reduced p53 levels, and suppressed apoptosis in hearts from the post-MI diabetic group. In vitro findings revealed that melatonin effectively counteracted high-glucose/high fat-hypoxia-induced cardiomyocyte apoptosis and contractile dysfunction through a JNK-mediated mechanism, the effects of which were impaired by the JNK activator anisomycin. In summary, our study suggests that melatonin protects against myocardial injury in post-MI mice with diabetes, which offers a new therapeutic strategy for the management of MI-induced cardiac injury in diabetes.