Daily Cardiology Research Analysis
Mechanistic and translational advances dominated today’s cardiology literature. A Nature Communications study uncovers an OTUD1–AMPKα2 deubiquitination axis driving diabetic cardiomyopathy. In a large-animal swine model, apoptotic bodies from umbilical cord MSCs improved post-MI recovery via AMPK/TFEB-regulated autophagy. A Heart Rhythm study shows electrocardiographic imaging during sinus rhythm can noninvasively map arrhythmogenic substrate linked to ventricular tachycardia risk.
Summary
Mechanistic and translational advances dominated today’s cardiology literature. A Nature Communications study uncovers an OTUD1–AMPKα2 deubiquitination axis driving diabetic cardiomyopathy. In a large-animal swine model, apoptotic bodies from umbilical cord MSCs improved post-MI recovery via AMPK/TFEB-regulated autophagy. A Heart Rhythm study shows electrocardiographic imaging during sinus rhythm can noninvasively map arrhythmogenic substrate linked to ventricular tachycardia risk.
Research Themes
- Ubiquitin signaling and metabolic control in cardiac disease
- Acellular extracellular vesicle therapies for myocardial repair
- Noninvasive electrophysiologic substrate mapping for VT risk
Selected Articles
1. Apoptotic bodies derived from human umbilical cord mesenchymal stem cells improve recovery from myocardial infarction in swine.
In a porcine MI model, umbilical cord MSC-derived apoptotic bodies improved contractility, reduced infarct size, and limited adverse remodeling, paralleling MSCs. Mechanistically, ABs activated AMPK and modulated TFEB to regulate autophagy; let-7f-5p targeting PPP2R2A and MAP4K3 contributed to these effects.
Impact: This is the first large-animal demonstration that acellular apoptotic bodies from MSCs can recapitulate and mechanistically explain cardioprotection after MI. It advances a clinically scalable alternative to cell therapy with defined microRNA-mediated pathways.
Clinical Implications: MSC-derived apoptotic bodies could serve as an off-the-shelf, acellular therapy for MI, potentially reducing risks of cell engraftment and immunologic complications. The AMPK/TFEB-autophagy axis and let-7f-5p targets offer biomarkers and druggable nodes for translation.
Key Findings
- In vitro, ABs reduced apoptosis and cytotoxicity in OGD-stressed cardiomyocytes and enhanced endothelial migration and tube formation.
- In vivo in pigs with MI, ABs improved contractile function, reduced infarct size, and mitigated adverse remodeling with increased cardiomyocyte survival and angiogenesis.
- Cardioprotection was mediated by autophagy regulation via AMPK activation and TFEB modulation.
- let-7f-5p was the most abundant microRNA in ABs and promoted AMPK phosphorylation (targeting PPP2R2A) and decreased TFEB phosphorylation (targeting MAP4K3).
Methodological Strengths
- Robust multi-system validation spanning in vitro assays and a large-animal (porcine) MI model
- Mechanistic dissection with miRNA sequencing and target validation (PPP2R2A, MAP4K3) within defined AMPK/TFEB pathways
Limitations
- Preclinical study; durability, dosing, and immunogenicity of ABs in humans remain undefined
- Standardization and scalability of AB isolation/characterization require further development
Future Directions: Define AB manufacturing standards, dose-response, and safety in GLP studies; evaluate biomarkers (let-7f-5p, AMPK/TFEB signaling) and initiate phase 1 trials in post-MI patients.
Apoptotic bodies (ABs) are a type of extracellular vesicles (EVs) that could contribute to the paracrine effect of stem cells. However, their potential in treating cardiovascular diseases is largely unexplored. This study investigated the therapeutic effects of ABs derived from human umbilical cord mesenchymal stem cells (MSCs) on cardiac recovery in a porcine model of myocardial infarction (MI). In vitro, ABs reduced apoptosis and cytotoxicity in cardiomyocytes under oxygen and glucose deprivation (OGD) conditions and enhanced the capacity of migration and tube formation in endothelial cells. In vivo, akin to MSCs, administration of ABs improved contractile function, reduced infarct size, and mitigated adverse remodeling in pig hearts with MI, concomitantly with increased cardiomyocyte survival and angiogenesis. These cardioprotective effects were mediated through the regulation of autophagy by activating the adenosine monophosphate - activated protein kinase (AMPK) and transcription factor EB (TFEB) signaling pathways. microRNAs contained in ABs were sequenced, revealing that let-7f-5p was the most abundant. let-7f-5p promoted AMPK phosphorylation by targeting protein phosphatase 2 regulatory subunit B alpha (PPP2R2A) and decreased TFEB phosphorylation by targeting MAP4K3 to regulate autophagy, thereby contributing to the effects of ABs. Overall, these findings indicate that MSC-derived ABs have the potential to be a promising and effective acellular therapeutic option for treating MI.
2. Cardiomyocyte OTUD1 drives diabetic cardiomyopathy via directly deubiquitinating AMPKα2 and inducing mitochondrial dysfunction.
OTUD1 is upregulated in diabetic mouse hearts and primarily expressed in cardiomyocytes. Cardiomyocyte-specific OTUD1 deletion prevents hypertrophy and dysfunction in type 1 and type 2 diabetes by restoring AMPK activity and mitochondrial function; OTUD1 directly deubiquitinates AMPKα2 at K60/K379, suppressing AMPK signaling.
Impact: This study reveals a previously unknown DUB–kinase interaction whereby OTUD1 deubiquitinates AMPKα2 to drive diabetic cardiomyopathy, opening a new therapeutic avenue targeting proteostasis-metabolism crosstalk.
Clinical Implications: Targeting the OTUD1–AMPK axis (e.g., DUB inhibition or AMPK activation) may prevent or reverse diabetic cardiomyopathy; OTUD1 expression could serve as a biomarker for disease activity.
Key Findings
- OTUD1 expression is significantly increased in diabetic mouse hearts and predominantly localized to cardiomyocytes by scRNA-seq.
- Cardiomyocyte-specific OTUD1 knockout prevents cardiac hypertrophy and dysfunction in both type 1 and type 2 diabetic male mice.
- OTUD1 deficiency restores AMPK activity and mitochondrial function in diabetic hearts and cardiomyocytes.
- OTUD1 binds AMPKα2 and deubiquitinates it at K60/K379, thereby inhibiting AMPK signaling.
Methodological Strengths
- Integrated single-cell transcriptomics, genetic cardiomyocyte-specific knockout, and functional mitochondrial assays
- Precise mapping of deubiquitination sites on AMPKα2 (K60/K379) supporting causal mechanism
Limitations
- Findings are preclinical and primarily in male mice; sex differences and human relevance need validation
- Therapeutic modulation of OTUD1 or AMPK was not tested clinically
Future Directions: Validate OTUD1–AMPK signaling in human cardiac tissue; develop selective OTUD1 inhibitors and test AMPK activators in diabetic cardiomyopathy models with both sexes.
Deubiquitinating modification of proteins is involved in the pathogenesis of diseases. Here, we investigated the role and regulating mechanism of a deubiquitinating enzyme (DUB), ovarian tumor domain-containing protein 1 (OTUD1), in diabetic cardiomyopathy (DCM). We find a significantly increased OTUD1 expression in diabetic mouse hearts, and single-cell RNA sequencing shows OTUD1 mainly distributing in cardiomyocytes. Cardiomyocyte-specific OTUD1 knockout prevents cardiac hypertrophy and dysfunction in both type 2 and type 1 diabetic male mice. OTUD1 deficiency restores cardiac AMPK activity and mitochondrial function in diabetic hearts and cardiomyocytes. Mechanistically, OTUD1 binds to AMPKα2 subunit, deubiquitinates AMPKα2 at K60/K379 sites, and then inhibits AMPK
3. Noninvasive assessment of the ventricular arrhythmogenic substrate using electrocardiographic imaging during sinus rhythm: The NIAVAS study.
Regional activation dispersion (rAD) measured by ECGI during sinus rhythm was higher in scarred regions and identified deceleration zones with 70.4% detection. Patient-level rAD thresholds discriminated ICM patients with and without prior VT and distinguished ICM from controls, supporting ECGI as a functional complement to LGE-CMR.
Impact: Provides a practical, noninvasive functional marker (rAD) for arrhythmogenic substrate that correlates with invasive mapping and improves VT risk stratification beyond structure alone.
Clinical Implications: ECGI-derived rAD could complement LGE-CMR for selecting patients for VT ablation, ICD decisions, and longitudinal risk monitoring without inducing arrhythmias.
Key Findings
- Scarred regions had higher rAD (46.3 ± 2.2 vs 30.1 ± 1.7 ms, P < .001) and lower pseudo-rCV (149.9 ± 3.0 vs 165.7 ± 2.4 cm/s, P < .001) than healthy regions.
- In a subgroup with electroanatomic mapping, ECGI identified 70.4% of deceleration zones and these zones had increased rAD (64.9 ± 5.4 vs 43.1 ± 3.1 ms, P < .001).
- Patient-level rAD thresholds (≥60.0 ms) differentiated ICM patients with vs without prior VT (AUC 0.75) and rAD ≥39.5 ms identified ICM vs controls (AUC 0.93).
Methodological Strengths
- Multimodal comparison with LGE-CMR and correlation to invasive electroanatomic mapping
- Defined quantitative thresholds for rAD with diagnostic performance metrics (AUC, sensitivity)
Limitations
- Single-center sample size is modest; cross-sectional design limits prognostic inference
- Generalizability to non-ischemic cardiomyopathy and longitudinal outcomes not assessed
Future Directions: Prospective multicenter studies to validate rAD thresholds for VT prediction and to assess impact on ablation strategy and clinical outcomes.
BACKGROUND: Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) identifies structural properties associated with ventricular tachycardia (VT) but lacks functional information. Noninvasive identification of slow conduction regions using electrocardiographic imaging (ECGI) could complement LGE-CMR to aid VT risk stratification. OBJECTIVE: This study aimed to evaluate the relationship between ventricular arrhythmogenic substrate and regional ECGI markers during sinus rhythm in patients with ischemic cardiomyopathy (ICM). METHODS: Seventy-two patients were included: 29 with ICM evidenced by LGE-CMR referred for VT ablation, 17 with ICM with implantable cardioverter-defibrillator for primary prevention without documented VT, and 26 controls. ECGI-derived regional activation dispersion (rAD) and pseudo-regional conduction velocity (pseudo-rCV) were analyzed and compared between scarred and healthy regions based on LGE, and between patients with ICM with and without previous VT. In a subgroup with electroanatomic mapping (n = 16), deceleration zones were correlated with ECGI. RESULTS: Scarred regions showed higher rAD (46.3 ± 2.2 vs 30.1 ± 1.7 ms, P < .001) and reduced pseudo-rCV (149.9 ± 3.0 vs 165.7 ± 2.4 cm/s, P < .001) than healthy regions. In the subgroup with sinus rhythm electroanatomic mapping, regions containing deceleration zones showed increased rAD (64.9 ± 5.4 vs 43.1 ± 3.1 ms, P < .001), and ECGI identified 70.4% of those zones. At the patient level, the mean of the 3 regions with the highest activation dispersion differentiated patients with ICM with and without previous VT (rAD ≥60.0 ms, sensitivity 75.9%, area under the curve [AUC] 0.75, P = .005) and identified patients with ICM from controls (rAD ≥39.5 ms, AUC 0.93). CONCLUSION: This study introduces a novel regional ECGI methodology demonstrating that rAD identifies abnormalities linked to arrhythmogenic substrate and could help identify patients at risk of VT. These findings highlight ECGI's potential as a complementary tool to LGE-CMR.