Cardiomyocyte Viability Research Articles

METTL3-modified lncRNA-SNHG8 binds to PTBP1 to regulate ALAS2 expression to increase oxidative stress and promote myocardial infarction.

Myocardial infarction (MI) is one of the important factors leading to death in today's society. Therefore, to study the related mechanism of MI and reduce myocardial ischemia-reperfusion injury is an important link to reduce MI injury. MI mice in vivo and cell model in vitro were constructed. The cardiac function and MI area of mice were detected, and myocardial tissue injury was detected by HE staining. ALAS2 expression in mice myocardial tissue was detected by IHC. The expressions of lncRNA-SNHG8, METTL3, PTBP1 and ALAS2 in myocardial tissue or cardiomyocytes were detected by qRT-PCR assay. MTT assay was used to measured viability of cardiomyocytes. The oxidative stress level in myocardial tissue or cardiomyocytes was detected by ELISA assay and ROS assay. RIP-qPCR and RNA pulldown assays determined the interaction between METTL3 and lncRNA-SNHG8, as well as PTBP1 and ALAS2. lncRNA-SNHG8 knockdown in MI mice was reduced myocardial infarction size, alleviated myocardial tissue injury and oxidative stress, and inhibited ALAS2 expression in myocardial tissue. RNA pulldown and RIP assays showed that lncRNA-SNHG8 binged with PTBP1 and PTBP1 interacted with ALAS2 mRNA. Knockdown of lncRNA-SNHG8, METTL3 or PTBP1 in MI cells enhanced viability of myocardial cells, attenuated ROS release and MDA level, increased SOD level, alleviated oxidative stress. ALAS overexpression attenuated the corresponding effect of knockdown of lncRNA-SNHG8 and/or PTBP1 on MI cells. In sum,our paper is demonstrated for the first time that METTL3 can promote lncRNA-SNHG8 through m6A modification, thereby regulating ALAS2 to induce oxidative stress and aggravate myocardial injury.

Human platelet mitochondria improve the mitochondrial and cardiac function of donor heart.

Mitochondria transplantation emerges as an effective therapeutic strategy for ischemic-related diseases but the roles in the donor hearts for transplant remain unidentified. Here, we investigated whether the preservation of the donor heart with human platelet-derived mitochondria (pl-MT) could improve mitochondrial and cardiac function. Incubation with pl-MT resulted in the internalization of pl-MT and the enhancement of ATP production in primary cardiomyocytes. In addition, incubation of rat hearts with pl-MT ex vivo for 9h clearly demonstrated pl-MT transfusion into the myocardium. Mitochondria isolated from the hearts incubated with pl-MT showed increased mitochondrial membrane potential and greater ATP synthase activity and citrate synthase activity. Importantly, the production of reactive oxygen species from cardiac mitochondria was not different with and without pl-MT incubation. Functionally, the heartbeat and the volume of coronary circulation perfusate were significantly increased in the Langendorff perfusion system and the viability of cardiomyocytes was increased from pl-MT hearts.Taken together, these results suggest that incubation with Pl-MT improves mitochondrial activity and maintains the cardiac function of rat hearts with prolonged preservation time. The study provides the proof of principle for pl-MT application as an enhancer of the donor heart.

Adiponectin Protects Hypoxia/Reoxygenation-Induced Cardiomyocyte Injury by Suppressing Autophagy.

Adiponectin is a cytokine produced by adipocytes and acts as a potential cardioprotective agent and plays an important role in myocardial ischemia/reperfusion injury. In a myocardial hypoxia/reoxygenation model using neonatal rat ventricular myocytes, we investigated the contribution of adiponectin-mediated autophagy to its cardioprotective effects. Cardiomyocytes were exposed to hypoxia/reoxygenation pretreated with or without adiponectin in the presence of absence of rapamycin. Cell viability was analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Western blotting assay was used to determine the expression levels of microtubule-associated proteins 1A/1B light chain 3B (LC3B), adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), p62/sequestosome 1, unc-51 like autophagy activating kinase 1 (ULK1), and Beclin-1. Autophagosome formation was detected by monodansylcadaverine staining. We found that hypoxia induced a time dependent decline in cardiomyocyte viability, and increase in autophagy and reoxygenation further augmented hypoxia-induced autophagy induction and consequently reduced cell viability. Adiponectin treatment alleviated hypoxia/reoxygenation-induced cellular damage and autophagy in cardiomyocytes. Adiponectin treatment also attenuated hypoxia/reoxygenation-promoted cardiomyocyte autophagy even in the presence of another autophagy stimulator rapamycin in part by inhibiting vacuolar hydron-adenosine triphosphatase. Additionally, autophagy suppression by adiponectin during hypoxia/reoxygenation was associated with the attenuated phosphorylation of AMPK and ULK1, augmented phosphorylation of mTOR, and the reduced protein expression levels of Beclin-1 in cardiomyocytes. Taken together, these results suggest that adiponectin protects ischemia/reperfusion-induced cardiomyocytes by suppressing autophagy in part through AMPK/mTOR/ULK1/Beclin-1 signaling pathway.

Biodegradable Redox-Responsive AIEgen-Based-Covalent Organic Framework Nanocarriers for Long-Term Treatment of Myocardial Ischemia/Reperfusion Injury.

Timely restoration of blood supply after myocardial ischemia is imperative for the treatment of acute myocardial infarction but causes additional myocardial ischemia/reperfusion (MI/R) injury, which has not been hitherto effectively targeted by interventions for MI/R injury. Hence, the development of advanced nanomedicine that can reduce apoptosis of cardiomyocytes while protecting against MI/R in vivo is of utmost importance. Herein, a redox-responsive and emissive TPE-ss covalent organic framework (COF) nanocarrier by integrating aggregation-induced emission luminogens and redox-responsive disulfide motifs into the COF skeleton is developed. TPE-ss COF allows for efficient loading and delivery of matrine, a renowned anti-cryptosporidial drug, which significantly reduces MI/R-induced functional deterioration and cardiomyocyte injury when injected through the tail vein into MI/R models at 5min after 30min of ischemia. Moreover, TPE-ss COF@Matrine shows a drastic reduction in cardiomyocyte apoptosis and improvements in cardiac function and survival rate. The effect of the TPE-ss COF carrier is further elucidated by enhanced cardiomyocyte viability and triphenyltetrazolium chloride staining in vitro. This work demonstrates the cardioprotective effect of TPE-ss COFs for MI/R injury, which unleashes the immense potential of using COFs as smart drug carriers for the peri-reperfusion treatment of ischemic heart disease with low cost, high stability, and single postoperative intervention.

Omentin1 ameliorates myocardial ischemia-induced heart failure via SIRT3/FOXO3a-dependent mitochondrial dynamical homeostasis and mitophagy

BackgroundAdipose tissue-derived adipokines are involved in various crosstalk between adipose tissue and other organs. Omentin1, a novel adipokine, exerts vital roles in the maintenance of body metabolism, insulin resistance and the like. However, the protective effect of omentin1 in myocardial ischemia (MI)-induced heart failure (HF) and its specific mechanism remains unclear and to be elucidated.MethodsThe model of MI-induced HF mice and oxygen glucose deprivation (OGD)-injured cardiomyocytes were performed. Mice with overexpression of omentin1 were constructed by a fat-specific adeno-associated virus (AAV) vector system.ResultsWe demonstrated that circulating omentin1 level diminished in HF patients compared with healthy subjects. Furthermore, the fat-specific overexpression of omentin1 ameliorated cardiac function, cardiac hypertrophy, infarct size and cardiac pathological features, and also enhanced SIRT3/FOXO3a signaling in HF mice. Additionally, administration with AAV-omentin1 increased mitochondrial fusion and decreased mitochondrial fission in HF mice, as evidenced by up-regulated expression of Mfn2 and OPA1, and downregulation of p-Drp1(Ser616). Then, it also promoted PINK1/Parkin-dependent mitophagy. Simultaneously, treatment with recombinant omentin1 strengthened OGD-injured cardiomyocyte viability, restrained LDH release, and enhanced the mitochondrial accumulation of SIRT3 and nucleus transduction of FOXO3a. Besides, omentin1 also ameliorated unbalanced mitochondrial fusion-fission dynamics and activated mitophagy, thereby, improving the damaged mitochondria morphology and controlling mitochondrial quality in OGD-injured cardiomyocytes. Interestingly, SIRT3 played an important role in the improvement effects of omentin1 on mitochondrial function, unbalanced mitochondrial fusion-fission dynamics and mitophagy.ConclusionOmentin1 improves MI-induced HF and myocardial injury by maintaining mitochondrial dynamical homeostasis and activating mitophagy via upregulation of SIRT3/FOXO3a signaling. This study provides evidence for further application of omentin1 in cardiovascular diseases from the perspective of crosstalk between heart and adipose tissue.

Circulating microRNA-122-5p is associated with a lack of improvement in left-ventricular function after TAVR and regulates viability of cardiomyocytes via extracellular vesicles

Abstract Transcatheter aortic valve replacement (TAVR) is a well-established treatment option for high- and intermediate-risk patients with severe symptomatic aortic valve stenosis (AVS). However, a specific role for circulating microRNAs (miRNAs) in the improvement of cardiac function for patients after TAVR has not yet been investigated. Herein, we profiled the differential expression of miRNAs in circulating extracellular vesicles (EV-miRNAs) in patients after TAVR and, in particular, the novel role of circulating miR-122-5p in cardiomyocytes. Circulating EV-associated miRNAs were investigated by using an unbiased Taqman-based human miR array. Several EV-miRNAs (miR-122-5p, miR-26a, miR-192, miR-483-5p, miR-720, miR-885-5p, and miR-1274) were significantly deregulated in aortic stenosis patients at day seven after TAVR in comparison to the pre-procedural levels in patients without LVEF-improvement. The higher levels of miR-122-5p were negatively correlated with LVEF improvement at both day seven (r=−0.264 and p=0.015) and at six months (r=−0.328 and p=0.0018) after TAVR. At the three-year follow-up, patients with a higher level of miR-122-5p displayed significantly increased cardiovascular mortality (p=0.03). By utilization of patient-derived samples and a murine aortic-stenosis model, we observed that the expression of miR-122-5p correlates negatively with cardiac function, which is associated with LVEF. Graded wire-injury-induced aortic-valve-stenotic mice demonstrated a higher level of miR-122-5p, which was related to cardiomyocytes dysfunction. Murine ex vivo experiments revealed that miR-122-5p is highly enriched in endothelial cells in comparison to cardiomyocytes. Gain- and loss-of-function experiments suggested that EV-mediated shuttling of miR-122-5p increases the level of miR-122-5p in recipient cardiomyocytes and regulates the viability of cardiomyocytes. Mechanistically, miR pulldown, electrophoretic mobility shift assay, and RNA immunoprecipitation confirmed that miR-122-5p interacts with the RNA-binding protein, hnRNPU, in a sequence-specific manner to encapsulate miR-122-5p into large EVs. Upon shuttling into recipient cells, miR-122-5p reduces the expression of the anti-apoptotic gene BCL2, by binding to its 3' untranslated region to inhibit its translation, and thereby decreasing the viability of target cardiomyocytes. Increased levels of circulating pro-apoptotic EV-incorporated miR-122-5p are associated with reduced LVEF after TAVR. Extracellular vesicular shuttling of miR-122-5p regulates the viability and apoptosis of cardiomyocytes in a BCL2-dependent manner. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): German Research Foundation (DFG)German Society of Cardiology (DGK)

Senolytics rejuvenate the reparative activity of human cardiomyocytes and endothelial cells

Abstract Background Senescent cells have emerged as bona fide drivers of ageing and age-related cardiovascular disease, with senescent cells accumulating in the aged heart and following damage/injury. We have shown that removal of senescent cells using senolytics can rejuvenate the regenerative capacity of the aged heart. Purpose We investigate the effects of cell senescence and action of the senolytics, Dasatinib (D) and Quercetin (Q), on human cardiomyocyte and endothelial cell viability, survival, proliferation, angiogenesis and senescence in vitro. Methods We developed a transwell insert co-culture stress-induced premature senescence model system in vitro. Doxorubicin was used to induce premature senescence to cardiac stromal progenitor cells or HUVECs, which were seeded on the bottom chamber. In separate well plates, untreated cells (non-senescent) were seeded on the bottom chamber and acted as control. Human iPSC-cardiomyocytes (iPSC-CMs) or HUVECs were seeded on the top chamber insert. Co-cultures were left for 7 days and then iPSC-CMs or HUVECs in the top chamber were analysed for viability, proliferation and markers of senescence, and the conditioned medium analysed for SASP factors. The cultures were then treated with D+Q (0.5μM D with 20μM Q) for 3 days to clear the senescent cells in the bottom chamber. Then 7 days later the iPSC-CMs or HUVECs in the top chamber were analysed for viability, proliferation and the markers of senescence, and conditioned medium analysed for SASP factors (total of 17 days). Results Co-culture of iPSC-CMs with senescent cells led to decreased iPSC-CM viability (64±11% vs. 100±3% control; p<0.05) and proliferation (5±2% vs. 11±1% control; p<0.05). There was no increased senescence in co-cultured iPSC-CMs. Treatment with senolytics D+Q resulted in rescue of viability (79±23% 17d co-culture+D+Q; 64±9% 17d co-culture; 100±4% 17d control) and proliferation (7±2% 17d co-culture+D+Q; 3±0.3% 17d co-culture; 8±0.3% 17d control). Similar effects were observed with HUVECs, which showed decreased viability (83±5% vs. 100±6% control; p<0.05) and proliferation (21±7% vs. 44±7% control; p<0.05) when co-cultured with senescent HUVECs. Treatment with senolytics ameliorated HUVEC viability (61±22% 17d co-culture+D+Q; 21±12% 17d co-culture; 100±5% 17d control), proliferation (30±5% 17d co-culture+D+Q; 22±4% 17d co-culture; 48±4% 17d control) and angiogenesis (Score relative to control: 1.1±0.5 D+Q conditioned media; 0.2±0.1 senescent cell conditioned media; 1.0±0.3 control media). Luminex analysis of the senescent cell conditioned media revealed upregulation of SASP factors, but the level of SASP factors were reduced with application of D+Q. Conclusion We show that D+Q senolytics have therapeutic potential in rejuvenating the reparative activity of cardiomyocytes and endothelial cells. These results open the path to further studies on using senolytic therapy in age-related cardiac deterioration and rejuvenation. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Heart Research UK

Berberine associated to SGLT2i Dapagliflozin synergistically reduces cardiac cell apoptosis during exposure to Trastuzumab through reduction of AGEs and IL-6 and induction of pAMPK

Abstract Background Trastuzumab has improved the prognosis in patients with HER2-positive breast cancer, but it can induce left ventricular dysfunction with reduced ejection fraction or HF during treatment. Dapagliflozin is a SGLT2i with cardio-renal benefits. In the DAPA-HF (Dapagliflozin And Prevention of Adverse-outcomes in Heart Failure) trial, the sodium-glucose cotransporter 2 inhibitor dapagliflozin decreased the risk of worsening HF events and cardiovascular death in patients with HF and reduced ejection fraction. Berberine is a nutraceutical compound characterized by multiple metabolic effects in patients with/without cardiovascular diseases. Recent preclinical systematic review indicated that Berberine significantly reduces myocardial infarct size and the incidence of ventricular arrhythmia, improves cardiac function, ameliorates myocardial apoptosis. Purpose To investigate on the potential cardioprotective properties of Berberine associated to SGLT2i Dapagliflozin against HER-2 blocking agent-induced cardiotoxicity Methods Human fetal cardiomyocytes (HFC cell line) were exposed to subclinical concentration of trastuzumab (200 nM) alone or co-incubated with Berberine (200 mM) or Dapagliflozin (50 nM) or both in combination for 48 h. After the incubation period, we performed the following tests: cell viability, apoptosis, expression of NLRP3 inflammasome, methylglyoxal and leukotrienes-B4. Expression of pAMPK was analyzed through western blot. Moreover, quantification of IL-6 was performed through ELISA method. Results Berberine and Dapagliflozin increased significantly the cell viability of cardiomyocytes exposed to Trastuzumab. When combined, Berberine and Dapagliflozin increased synergistically cell viability of cardiac cells (p<0.001 vs Trastuzumab). Cell apoptosis was reduced of 32.5, 41.8 and 72.7% for berberine, dapagliflozin and both combined (vs trastuzumab group). Methylglyoxal,a marker of AGEs, was strongly reduced compared to untreated cells. Western blot analysis clearly demonstrate that pAMPK was induced by berberine and Dapagliflozin, improving mitochondrial metabolism. No significant changes in Leukotriene B4 expression were seen. Intracellular levels of IL-6 were reduced of 46.3, 62.7 and 86.3% for berberine, dapagliflozin and both combined (vs trastuzumab group). Conclusion Berberine and Dapagliflozin exerts significant cardioprotective effects in cardiac cells exposed to the HER2-bloking agent Trastuzumab. Berberine and Dapagliflozin in combination induces an anti-inflammatory phenotype to myocardial cells through the reduction of biomarkers involved in heart failure and apoptosis Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Ricerca Corrente, Ministero della Salute

Systemic GDF11 replenishment ignites myocardial injury through diminishing anti-apoptotic activity of cardiac progenitor cells

Abstract Background Tissue damage due to acute myocardial infarction is caused by both the ischemic insult and subsequent reperfusion injury (I/R). Restoration of coronary blood flow accelerates cardiomyocyte death, a phenomenon referred to as reperfusion injury, the extent of which is partly modulated by cardiac progenitor cells (CPC). Development of novel therapies to reduce infarct size, the main determinant of outcome, represent a huge unmet medical need (1). Systemic levels of growth differentiation factor 11 (GDF11), a TGF-β superfamily member that shares 90% homology with myostatin, decline with age, and GDF11 replenishment by heterochronic parabiosis or systemic recombinant GDF11 (rGDF11) delivery was postulated to have rejuvenating effects (2). Purpose We aimed to probe the effects of systemic GDF11 replenishment on I/R injury and deepen insights into the molecular mechanisms involved. Methods We designed a vehicle-controlled study in which young (3–4 months) and old (22–24 months) C57Bl/6 mice were randomly assigned to either daily systemic rGDF11 or control treatment over 30 days before myocardial I/R injury was induced. Dissected hearts were subjected to in-depth profiling followed by IPA-guided -omics to identify key regulatory mechanisms. Finally, in vitro experiments on human CPCs and HL-1 cardiomyocytes were performed. Results Myocardial Gdf11 expression declined with age, whereas myostatin (Mstn) showed an opposing expression pattern (Fig. 1A), a trend similarly observed upon I/R (Fig. 1B). Surprisingly, after the 30-day study period (Fig. 1C), young and aged rGDF11-treated mice showed higher I/R-induced infarct size and serum cardiac troponin I levels than controls, despite comparable areas at risk (Fig. 1D). Importantly, while proxies of necroptosis/pyroptosis remained unchanged, rGDF11-treated animals showed reduced cardiomyocyte viability irrespective of their age (Fig. 2A). Targeted transcriptomics applied on cardiac tissues of both groups identified the CPC-marker Nkx2–5 to be differentially regulated (Fig. 2B-C), an expression pattern validated in an independent cohort at both mRNA and protein levels (Fig. 2D). In the adult myocardium, the expression of both Nkx2–5 and its cofactor Gata4 is mainly confined to CPCs; indeed, similar reductions in Nkx2–5 and Gata4 expression were observed in CPCs exposed to rGDF11 (Fig. 2E) which coincided with accelerated cardiomyocyte death if cultured in conditioned media obtained from CPCs treated with rGDF11 (Fig. 2F), pointing toward a paracrine signalling pathway. Conclusions Myocardial expression of GDF11 declines with age, and is blunted upon I/R injury, thereby opposing the expression pattern of myostatin. Surprisingly, however, systemic GDF11 replenishment by rGDF11 supplementation enhances rather than reduces myocardial infarct size through augmented apoptosis, a phenomenon mediated by diminished cardioprotective function of CPCs. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Foundation for Cardiovascular Research – Zurich Heart House

Activating transcription factor 3 inhibits angiotensinII‑induced cardiomyocyte viability and fibrosis by activating the transcription of cysteine‑rich angiogenic protein 61.

Depletion of activating transcription factor 3 (ATF3) expression has previously been reported to promote hypertrophy, dysfunction and fibrosis in stress overload-induced hearts; however, the mechanism involved remains poorly understood. In the present study, the mechanism underlying the activation of cysteine-rich angiogenic protein 61 (Cyr61) by ATF3 in hyperproliferative and fibrotic human cardiac fibroblasts (HCFs), induced by angiotensin II (Ang II), was evaluated. The mRNA and protein expression levels of ATF3 and Cyr61 were assessed using reverse transcription-quantitative PCR and western blotting, respectively. The Cell Counting Kit-8 assay was used to assess cell viability. Cell migration was assessed using the wound healing assay and western blotting, whereas the extent of cell fibrosis was evaluated using immunofluorescence staining and western blotting. The binding site of ATF3 to the Cyr61 promoter was predicted using the JASPAR database, and verified using luciferase reporter and chromatin immunoprecipitation assays. The results demonstrated that the mRNA and protein expression levels of ATF3 were significantly upregulated in Ang II-induced HCFs. Overexpression of ATF3 significantly inhibited the Ang II-induced viability, migration and fibrosis of HCFs, whereas ATF3 knockdown mediated significant opposing effects. Mechanistically, ATF3 was demonstrated to transcriptionally activate Cyr61. Cyr61 silencing was subsequently revealed to reverse the effects of ATF3 overexpression on HCFs potentially via regulation of the TGF-β/Smad signaling pathway. The results of the present study suggested that ATF3 could suppress HCF viability and fibrosis via the TGF-β/Smad signaling pathway by activating the transcription of Cyr61.

Universal and Sensitive Drug Assessment Biosensing Platform Using Optimal Mechanical Beating Detection of Single Cardiomyocyte.

The preclinical assessment of efficacy and safety is essential for cardiovascular drug development in order to guarantee effective prevention and treatment of cardiovascular disease and avoid human health endangerment and a huge waste of resources. Rhythmic mechanical beating as one of the crucial cardiomyocyte properties has been exploited to establish a drug assessment biosensing platform. However, the conventional label-free biosensing platforms are difficult to perform high-throughput and high-resolution mechanical beating detection for a single cardiomyocyte, while label-based strategies are limited by pharmacologically adverse effects and phototoxicity. Herein, we propose a biosensing platform involving the multichannel electrode array device and the universal mechanical beating detection system. The platform can determine the optimal characteristic working frequency of different devices and dynamically interrogate the viability of multisite single cardiomyocytes to establish the optimized cell-based model for sensitive drug assessment. The subtle changes of mechanical beating signals induced by cardiovascular drugs can be detected by the platform, thereby demonstrating its high performance in pharmacological assessment. The universal and sensitive drug assessment biosensing platform is believed to be widely applied in cardiology investigating and preclinical drug screening.

Upregulation of miR-144-3p alleviates Doxorubicin-induced heart failure and cardiomyocytes apoptosis via SOCS2/PI3K/AKT axis.

MicroRNAs (miRs) are implicated in heart failure (HF). Thereby, we aim to uncover the role of miR-144-3p in HF. Doxorubicin (Dox)-induced HF model was constructed in rats and cardiomyocytes H9C2, and the cardiac function was determined using ultrasound cardiogram. Morphology of cardiac tissue was observed using hematoxylin-eosin (H&E) staining. The viability and apoptosis of Dox-treated and transfected cardiomyocytes were determined using Cell Counting Kit-8 (CCK-8) assay and flow cytometry. Relative expressions of the HF-associated miRs (including miR-144-3p), suppressor of cytokine signaling 2 (SOCS2), apoptosis- and phosphoinositide 3-kinase (PI3K)/AKT pathway-related factors (B-cell lymphoma 2, Bcl-2; Bcl-2 associated X protein, Bax; cleaved [C] capsase-3; phosphoinositide 3-kinase, PI3K; phosphorylated-PI3K, p-PI3K; p-AKT; AKT) were measured with quantitative real-time polymerase chain reaction or Western blot. Target gene of miR-144-3p was predicted by Starbase and TargetScan and confirmed with dual-luciferase reporter assay. Dox caused rat cardiac dysfunction, aggravated cardiac injury, decreased cardiomyocytes viability, and the expression of miR-144-3p, Bcl-2, and phosphorylation of both PI3K and AKT yet the upregulated those of Bax and C caspase-3, which was reversed by upregulating miR-144-3p, whereas downregulating miR-144-3p did oppositely. SOCS2 was the target gene of miR-144-3p, Dox promoted SOCS2 expression, which was reversed by upregulating miR-144-3p, while downregulating miR-144-3p did conversely. In addition, silencing SOCS2 reversed the effects of miR-144-3p downregulation in Dox-treated cardiomyocytes. Upregulating miR-144-3p alleviated Dox-induced cardiac dysfunction and cell apoptosis via targeting SOCS2, providing a novel evidence of miR-144-3p in HF.

Cardioprotective factors against myocardial infarction selected in vivo from an AAV secretome library.

Therapies for patients with myocardial infarction and heart failure are urgently needed, in light of the breadth of these conditions and lack of curative treatments. To systematically identify previously unidentified cardioactive biologicals in an unbiased manner in vivo, we developed cardiac FunSel, a method for the systematic, functional selection of effective factors using a library of 1198 barcoded adeno-associated virus (AAV) vectors encoding for the mouse secretome. By pooled vector injection into the heart, this library was screened to functionally select for factors that confer cardioprotection against myocardial infarction. After two rounds of iterative selection in mice, cardiac FunSel identified three proteins [chordin-like 1 (Chrdl1), family with sequence similarity 3 member C (Fam3c), and Fam3b] that preserve cardiomyocyte viability, sustain cardiac function, and prevent pathological remodeling. In particular, Chrdl1 exerted its protective activity by binding and inhibiting extracellular bone morphogenetic protein 4 (BMP4), which resulted in protection against cardiomyocyte death and induction of autophagy in cardiomyocytes after myocardial infarction. Chrdl1 also inhibited fibrosis and maladaptive cardiac remodeling by binding transforming growth factor-β (TGF-β) and preventing cardiac fibroblast differentiation into myofibroblasts. Production of secreted and circulating Chrdl1, Fam3c, and Fam3b from the liver also protected the heart from myocardial infarction, thus supporting the use of the three proteins as recombinant factors. Together, these findings disclose a powerful method for the in vivo, unbiased selection of tissue-protective factors and describe potential cardiac therapeutics.

Curcumin activates Nrf2/HO-1 signaling to relieve diabetic cardiomyopathy injury by reducing ROS in vitro and in vivo.

The hallmark feature of Diabetes mellitus (DM) is hyperglycemia which can lead to excess production of reactive oxygen species (ROS) in the myocardium, contributing to diabetic cardiomyopathy (DCM). Nuclear factor erythroid2-related factor2 (Nrf2), a transcriptional activator, enhances its ability to resist oxidative stress by activating multiple downstream anti-oxidants, anti-inflammatory proteins, and detoxifying enzymes. However, the mechanism of Nrf2 signaling in HG-induced DCM is unclear. In this study, we used HG pretreated H9c2 cells as the experimental basis in vitro, and established a high fat-diet, streptozotocin (STZ) induced Type 2 diabetic rat model in vivo. Meanwhile, we used shRNA-Nrf2 and curcumin (CUR) (as an activator) to affect H9c2 cells, to verify the role of the Nrf2 signaling pathway in DCM. The results showed that the excessive production of ROS caused by HG, which could inhibit the activation of Nrf2-related signaling, resulting in a decrease in cell energy metabolism and an increase in cell apoptosis. Surprisingly, we found that the activation of the Nrf2 signaling pathway significantly increased cardiomyocyte viability, reduced ROS formation, increased antioxidant enzyme activity, and inhibited cardiomyocyte apoptosis. In conclusion, these findings conclusively infer that CUR activation of the Nrf2/HO-1 signaling pathway exerts myocardial protection by reducing ROS formation.

Pinoresinol diglucoside ameliorates H/R-induced injury of cardiomyocytes by regulating miR-142-3p and HIF1AN.

This study is aimed to investigate the effect of pinoresinol diglucoside (PDG) in ameliorating myocardial ischemia-reperfusion injury (MIRI).Hypoxia/reperfusion (H/R)-induced H9c2 cardiomyocytes were used to establish an in-vitro ischemia-reperfusion injury model of cardiomyocytes. Cells were treated with 1 μmol/L of PDG. Reactive oxygen species (ROS) level was detected by a 2',7'-dichlorofluorescein-diacetateassay. The release of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) was examined by enzyme-linked immunosorbent assay. The viability and apoptosis of H9c2 cells were probed by MTT assay and flow cytometry. Besides this, Western blot and quantitative real-time PCR were used to detect microRNA-142-3p (miR-142-3p) and hypoxia-inducible factor 1 subunit alpha inhibitor (HIF1AN) expression levels. The binding sequence between miR-142-3p and HIF1AN 3'-untranslated region was validated by a dual-luciferase reporter gene assay.PDG treatment significantly reduced the level of ROS, LDH, and CK-MB, promoted viability, and inhibited the apoptosis of H9c2 cells. PDG treatment promoted miR-142-3p expression and inhibited HIF1AN expression in H9c2 cells. MiR-142-3p overexpression enhanced the effects of PDG on ROS, LDH, CK-MB levels, cell viability, and apoptosis in H9c2 cardiomyocytes, while overexpression of HIF1AN reversed the above effects.PDG ameliorates H/R-induced injury of cardiomyocytes by regulating miR-142-3p and HIF1AN.

Abstract P3121: Serological Mechanisms Driving Cardiotoxicity In Covid-19

Cardiac involvement is common in patients severely ill with COVID-19 and is associated with increased morbidity and mortality. The mechanism for myocardial injury in COVID-19 has been proposed to be at least in part due to a direct viral cytotoxic effect on cardiomyocytes. Preclinical data corroborate the notion that SARSCoV-2 can enter and replicate within hiPSC-derived cardiomyocytes. However, clinical evidence demonstrating direct viral effects on the heart remains limited. Alternatively, cardiac injury may result from excessive inflammatory cytokine production which is the main driver for the pathogenesis in COVID-19. Despite this, cardiotoxicity secondary to hyperinflammation constitutes a potentially amenable mechanism that remains largely unexplored. To investigate serological drivers of cardiotoxicity in COVID-19 we have established a bioassay that assessed the effects of serum from COVID-19 confirmed patients on human embryonic stem cell-derived cardiomyocytes (hESC-CMs). We demonstrate that serum from COVID-19 positive patients significantly reduced cardiomyocyte viability and contractility independent of viral transduction. Serum from patients with greater disease severity led to worse cardiomyocyte viability and this significantly correlated with levels of key inflammatory cytokines, including IL-6, TNF-α, IL1-β, IL-10, CRP and neutrophil to lymphocyte ratio with a specific reduction of CD4+ and CD8+ cells. Combinatorial blockade of IL-6 and TNF-α partially reversed the phenotype and preserved cardiomyocyte viability and function. Interestingly, treatment with serum from Systemic Inflammatory Response Syndrome (SIRS) patients recapitulates the effect observed with COVID-19 patients’ serum indicating that the phenotype observed is most likely not unique to COVID-19 disease. In conclusion, our results provide direct evidence that inflammatory cytokines are at least in part responsible for the cardiovascular damage seen in COVID-19 and indicate possible targets for therapeutic intervention.

Abstract P3117: Validating Genetic Risk Markers Causing Doxorubicin-induced Cardiotoxicity In African American And European American Pediatric Patients Using A Hipsc Model

The W.H.O. estimates that globally 400,000 children under 19 are diagnosed with cancer annually. 60% of pediatric cancers are treated with chemotherapy using anthracyclines, mainly doxorubicin. Survivors of childhood cancer are approximately 15 times more likely to be diagnosed with congestive heart failure. African American (AA) survivors had a 2.5-fold increased risk of severe or life-threatening cardiomyopathy vs European Americans (EA). In recent WGS studies, 2 novel loci in chromosome 1 & 6 were identified to be correlated with an increased risk of doxorubicin-induced cardiotoxicity (DIC) in AA and EA population groups respectively and were reduced or absent in the other group. Our study aims to validate these loci using patient specific hiPSC-derived cardiomyocytes (hiPSC-CM), and for that we recruited and generated 20 hiPSC lines from the blood of AA and EA pediatric patients. Using a novel bioreactor system, a large-scale production of hiPSC-CM for this patient specific samples is underway, and the cells will be utilized for phenotypic and genotypic characterization. Our aim is to assess the effect of doxorubicin on cardiomyocyte viability, apoptosis, mitochondrial function, and calcium dynamics. Differential cardiac gene regulation after exposure to doxorubicin will be studied using RNA sequencing. In conclusion, our findings will validate the genetic variants predisposing AA and EA populations to DIC. This study will clinically impact therapeutic approaches on both AA and EA populations and at individual levels while using doxorubicin. The validated hiPSC-CMs could help in identifying personalized cardioprotectants to reduce DIC without modifying chemotherapy. This study could also potentially provide data for genomically-informed drug discovery for novel cardioprotectants.

Abstract GS106: Asporin, An Extracellular Matrix Protein, Is A Beneficial Regulator Of Cardiac Remodeling

Heart failure is accompanied by adverse cardiac remodeling involving extracellular matrix (ECM). Cardiac ECM acts as a major reservoir for many proteins including growth factors, cytokines, collagens, and proteoglycans. Activated fibroblasts during cardiac injury can alter the composition and activity of these ECM proteins. Through unbiased analysis of a microarray dataset of human heart tissue comparing normal hearts (n=135) to hearts with ischemic cardiomyopathy (n=94), we identified Asporin (ASPN) as the top differentially regulated gene (DEG) in ischemic cardiomyopathy; its gene-ontology terms relate closely to fibrosis and cell death. ASPN is a Class I small leucine repeat protein member implicated in cancer, osteoarthritis, and periodontal ligament mineralization. However, its role in cardiac remodeling is still unknown. Here, we initially confirmed our big dataset analysis through cells, mice, and clinical atrial biopsy samples to demonstrate increased ASPN expression after pressure overload or cardiac ischemia/reperfusion injury. We tested the hypothesis that ASPN, being a TGFβ1 inhibitor, can attenuate fibrosis in mouse models of cardiac injury. We found that ASPN is released by cardiac fibroblasts and attenuates TGFβ signaling. Moreover, ASPN -/- mice displayed increased fibrosis and decreased cardiac function after pressure overload by transverse aortic constriction (TAC) in mice. In addition, ASPN protected cardiomyocytes from hypoxia/reoxygenation-induced cell death and regulated autophagy and mitochondrial bioenergetics in cardiomyocytes. Increased infarct size after ischemia/reperfusion injury in ASPN -/- mice confirmed ASPN’s contribution to cardiomyocyte viability. Echocardiography revealed a greater reduction in left ventricular systolic function post-I/R in the ASPN -/- animals compared to wild type. Furthermore, we developed an ASPN-mimic peptide using molecular modeling and docking which when administered to mice prevented TAC-induced fibrosis and preserved heart function. The peptide also reduced infarct size after I/R in mice, demonstrating the translational potential of ASPN-based therapy. Thus, we establish the role of ASPN as a critical ECM molecule that regulates cardiac remodeling to preserve heart function.

Association of irisin levels with cardiac magnetic resonance, inflammatory, and biochemical parameters in patients with chronic heart failure versus controls

Background and aimsChronic heart failure (CHF) represents a significant cause of morbidity and mortality globally. Metabolic maladaptation has proven to be critical in the progression of this condition. Preclinical studies have shown that irisin, an adipomyokine involved in metabolic regulations, can induce positive cardioprotective effects by improving cardiac remodeling, cardiomyocyte viability, calcium delivery, and reducing inflammatory mediators. However, data on clinical studies identifying the associations between irisin levels and functional imaging parameters are scarce in CHF patients. The objective of this study was to determine the association of irisin levels with cardiac imaging measurements through cardiac magnetic resonance, inflammatory markers, and biochemical parameters in patients with CHF compared with control subjects. Methods and resultsThirty-two subjects diagnosed with CHF and thirty-two healthy controls were evaluated in a cross-sectional study. Serum irisin levels were significantly lower in patients with CHF than in controls. This is the first study to report a significant positive correlation between irisin levels and cardiac magnetic resonance parameters such as left ventricular ejection fraction, fraction shortening, and global radial strain. A negative correlation was demonstrated between irisin levels and brain natriuretic peptide, insulin levels, and Homeostatic model assessment for insulin resistance index. We did not observe significant correlations between irisin levels and inflammatory cytokines. ConclusionsGiven the importance of fraction shortening and global radial strain as accurate markers of ventricular wall motion, these results support the hypothesis that irisin may play an essential role in maintaining an adequate myocardial wall architecture, deformation, and thickness.

NF-κB p65 Attenuates Cardiomyocyte PGC-1α Expression in Hypoxia.

Hypoxia exerts broad effects on cardiomyocyte function and viability, ranging from altered metabolism and mitochondrial physiology to apoptotic or necrotic cell death. The transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a key regulator of cardiomyocyte metabolism and mitochondrial function and is down-regulated in hypoxia; however, the underlying mechanism is incompletely resolved. Using primary rat cardiomyocytes coupled with electrophoretic mobility shift and luciferase assays, we report that hypoxia impaired mitochondrial energetics and resulted in an increase in nuclear localization of the Nuclear Factor-κB (NF-κB) p65 subunit, and the association of p65 with the PGC-1α proximal promoter. Tumor necrosis factor α (TNFα), an activator of NF-κB signaling, similarly reduced PGC-1α expression and p65 binding to the PGC-1α promoter in a dose-dependent manner, and TNFα-mediated down-regulation of PGC-1α expression could be reversed by the NF-κB inhibitor parthenolide. RNA-seq analysis revealed that cardiomyocytes isolated from p65 knockout mice exhibited alterations in genes associated with chromatin remodeling. Decreased PGC-1α promoter transactivation by p65 could be partially reversed by the histone deacetylase inhibitor trichostatin A. These results implicate NF-κB signaling, and specifically p65, as a potent inhibitor of PGC-1α expression in cardiac myocyte hypoxia.