Aims Succinate accumulates significantly during myocardial ischaemia, and its rapid oxidation upon reperfusion is a critical driver of ischaemia/reperfusion (I/R) injury. The transport of succinate across the mitochondrial inner membrane, particularly by the dicarboxylate carrier (DIC; SLC25A10), is hypothesized to play a crucial role in mediating these pathological succinate dynamics. However, tools to test this hypothesis by modulating mitochondrial succinate transport in biological systems are lacking.Methods and results C57BL/6J mice, isolated Wistar Rat heart mitochondria, bovine heart mitochondrial membranes, C2C12 mouse myoblasts, and primary adult mouse cardiomyocytes were used as in vitro and in vivo models. Butylmalonate prodrugs were synthesized and tested. Isolated mitochondria were used to assess succinate-dependent respiration and reactive oxygen species (ROS) production. Cells were treated with succinate dehydrogenase (SDH) inhibitors or exposed to anoxia and butylmalonate esters. Mouse hearts were subjected to in vivo left anterior descending coronary artery ligation. Succinate and butylmalonate levels were measured by targeted liquid chromatography-tandem mass spectrometry, and infarct size by TTC (23,5-triphenyl-2H-tetrazolium chloride) staining. Knockdown of DIC, but not of the oxoglutarate carrier OGC, in C2C12 cells prevented succinate accumulation by SDH inhibition and anoxia. The only extant DIC inhibitor butylmalonate, is limited by poor cell permeability. We synthesized diacetoxymethyl butylmalonate (DAB), which efficiently delivers butylmalonate intramitochondrially in isolated heart mitochondria and cells. DAB inhibited succinate-dependent respiration and ROS production. DAB prevented succinate accumulation in cells treated with SDH inhibitors. DAB delivered butylmalonate to cardiac mitochondria when administered to mice in vivo and reduced infarct size by perturbing mitochondrial succinate transport.Conclusion The DIC is a key node in the cellular distribution of succinate, controlling its transport between mitochondria and the cytosol. These findings highlight the potential of DIC as a promising therapeutic target for conditions where succinate elevation contributes to pathogenesis, such as cardiac I/R injury.

Lead dislodgement is a rare complication of epicardial leads, which are generally chosen for pacemaker implantation in pediatric patients. Here, we report the case of a 12-year-old girl with trisomy 21 and a complete atrioventricular septal defect. The patient required epicardial pacemaker implantation; however, the epicardial left ventricular lead unexpectedly dislodged twice. This report discusses the potential causes and outlines our management strategy. Learning objective Age, body size, growth-related changes, lifestyle, and durability complicate pacemaker implantation in children. Therefore, epicardial leads are commonly used for pacemaker implantation. Epicardial leads are not limited by body size or disease, and venous obstruction is not an issue; however, they are more invasive. Pacemaker implantation in pediatric patients with congenital heart disease requires meticulous consideration of patient-specific anatomical and physiological factors. Careful preoperative discussions among pediatric and adult cardiology teams, as well as cardiovascular surgery teams, are essential to optimize patient outcomes.

Intracellular transfer of intact mitochondria has primarily been reported as a therapeutic approach to restore cellular function; however, controlled intracellular delivery of mitochondria-derived components remains largely unexplored, particularly from a materials and manufacturing perspective. Here, we present Trans MIT, microfluidically fabricated lipid nano capsules designed for robust intracellular delivery of mitochondria-derived components. Trans MIT is constructed based on the MITO-Porter concept, a lipid-based delivery platform originally developed for mitochondrial targeting via membrane fusion, and is manufactured using a controlled microfluidic (iLiNP) process to ensure reproducible particle properties. In cultured cells, treatment with Trans MIT resulted in consistent enhancement of cellular bioenergetic function, as evidenced by increased basal and maximal oxygen consumption rates and elevated ATP levels. Metabolomic analyses further revealed activation of the tricarboxylic acid cycle and oxidative phosphorylation pathways following Trans MIT delivery. In this system, cellular uptake is mediated by an octaarginine (R8) moiety, while the fusogenic lipid envelope facilitates mitochondrial targeting of mitochondria-derived components without inducing overt cytotoxicity. The microfluidic fabrication process further supports batch-to-batch consistency and scalability. In contrast to direct addition of isolated mitochondria under specific experimental conditions, Trans MIT provides a materials-driven platform for controlled intracellular delivery of mitochondria-derived components. These results establish Trans MIT as a robust lipid nano capsule system for organelle-inspired nanomedicine and materials-based modulation of cellular metabolism.

Duchenne muscular dystrophy (DMD) is a genetic disease, with no curative therapy, and is associated with mitochondrial dysfunction in skeletal muscle. Thus, mitochondrial treatment is a potential therapy for DMD. However, few studies have reported on such treatments because of the difficulty of drug delivery to mitochondria. Here, we used MITO-Porter to deliver coenzyme Q10 to the mitochondria of primary skeletal muscle cells isolated from DMD model rats. Our results show the therapeutic potential of mitochondrial activation for DMD.

Central to the development of heart failure with preserved ejection fraction (HFpEF) is the redox disruption of metabolic processes; however, the underlying mechanisms are not fully understood. This study utilized a murine model (ND6) carrying a homoplasmic mitochondrial DNA point mutation (ND6 G13997A), which maintains functional NADH oxidation but lacks the site-specific reactive oxygen species (ROS) generation via reverse electron transport (RET). We demonstrate that mice with RET-ROS deficiency have reduced exercise capacity despite higher lean body mass, impaired resilience to high-fat/high-sucrose dietary stress, and cardiac hypertrophy with diastolic dysfunction. Importantly, dobutamine-induced stress elevated succinate levels in the heart, accompanied by RET-ROS production in wild-type but not in ND6 mice. Furthermore, ND6 mice showed perturbation in metabolite profiles following dobutamine stress. Mechanistically, the ND6 heart had an upregulated expression of fatty acid transport, oxidation, and synthesis genes (CD36, Cpt1b, Acly, Fas, Elovl6, and Scd1) and increased protein levels of lipid metabolism regulators (acetyl-CoA carboxylase and perilipin 2). Interestingly, 8 wk of forced treadmill running increased acetyl-CoA abundance, alleviated metabolic stress, and improved diastolic function in RET-ROS mutant hearts. In summary, these findings reveal a critical role for RET-ROS in regulating exercise capacity and cardiometabolic health, identifying it as a potentially selective target for modulating cardiac metabolism.NEW & NOTEWORTHY Loss of reverse electron transport (RET)-reactive oxygen species (ROS) impairs diastolic function and exercise capacity, which can be improved by long-term aerobic exercise. RET-ROS may act as a modulator of cardiac metabolism.

Enhancing cardiomyocyte mitochondrial function has been reported as a potential therapeutic approach for various diseases. However, this is technically difficult, and its practical use has not been described. Although treatments such as exon skipping for skeletal muscle have been established for Duchenne muscular dystrophy (DMD), no curative treatment has been developed for DMD cardiomyopathy, and only cardioprotective medications and symptomatic treatments are available. In this study, we attempted to activate cardiac myocyte mitochondria via direct drug delivery using lipid nanoparticles and investigated the application of this strategy to diseased cells. First, we delivered CoQ10, a mitochondrial activator with cellular antioxidant capacity, into mitochondria in H9C2 cells using MITO-Porter, a mitochondria-directed nanoparticle. Cellular MITO-Porter uptake was measured using flow cytometry. Co-localization of mitochondria and MITO-Porter was confirmed using confocal laser microscopy. Mitochondrial respiratory capacity was measured using an extracellular flux analyzer. Furthermore, the concentration-response relationships of the amount of nanoparticles or CoQ10 with mitochondrial energy production capacity were confirmed. Next, we examined the possibility of improving mitochondrial energy production capacity in diseased cells. Cells were isolated from the myocardium of DMD model rats generated using the CRISPR-Cas9 system. Mitochondrial energy production capacity was lower in DMD primary cardiomyocytes than in wild-type primary cardiomyocytes. CoQ10 delivery to mitochondria in DMD primary cardiomyocytes using MITO-Porter improved mitochondrial energy production capacity. Thus, enhanced cardiomyocyte mitochondrial energy production might represent a potential treatment for cardiomyopathy.

AIMS:Ischemic stroke is increasingly treated by mechanical thrombectomy (MT) with the more rapid and complete reperfusion of the ischemic tissue, enhancing patient outcome, compared to recombinant tissue plasminogen activator (rtPA) alone. Even so, there is still extensive brain infarction and disability following MT, which is exacerbated by ischemia-reperfusion injury (IRI) and other pathological processes during reperfusion. Hence, an adjunct therapy to MT that decreases IRI should enhance patient outcomes. METHODS AND RESULTS:To test this possibility, we adapted the transient middle cerebral artery occlusion (tMCAO) mouse model to allow local intra-arterial administration of acidified disodium malonate (aDSM) to decrease IRI as the ischemic tissue was reperfused. Administration of aDSM (160 mg/kg; pH 6) during reperfusion decreased brain infarct volume by ∼60% when assessed by magnetic resonance imaging (MRI) 24 h after reperfusion and improved neurological function. CONCLUSION:These findings suggest aDSM as a potential adjunct therapy to further improve outcomes for stroke patients treated by MT.

The efficacy of mesenchymal stem cell (MSC) transplantation has been reported for various diseases. We previously developed a drug delivery system targeting mitochondria (MITO-Porter) by using a microfluidic device to encapsulate Coenzyme Q10 (CoQ10) on a large scale. The current study aimed to confirm if treatment with CoQ10 encapsulated by MITO-Porter enhanced mitochondrial functions in MSCs, with the potential to improve MSC transplantation therapy. We used highly purified human bone marrow-derived MSCs, described as rapidly expanding clones (RECs), and attempted to control and increase the amount of CoQ10 encapsulated in the MITO-Porter using microfluidic device system. We treated these RECs with CoQ10 encapsulated MITO-Porter, and evaluated its cellular uptake, co-localization with mitochondria, changes in mitochondrial respiratory capacity, and cellular toxicity. There was no significant change in mitochondrial respiratory capacity following treatment with the previous CoQ10 encapsulated MITO-Porter; however, mitochondrial respiratory capacity in RECs was significantly increased by treatment with CoQ10-rich MITO-Porter. Utilization of a microfluidic device enabled the amount of CoQ10 encapsulated in MITO-Porter to be controlled, and treatment with CoQ10-rich MITO-Porter successfully activated mitochondrial functions in MSCs. The MITO-Porter system thus provides a promising tool to improve MSC cell transplantation therapy.

The mitochondrial metabolite succinate is a key driver of ischemia/reperfusion injury (IRI). Targeting succinate metabolism by inhibiting succinate dehydrogenase (SDH) upon reperfusion using malonate is an effective therapeutic strategy to achieve cardioprotection in the short term (< 24 h reperfusion) in mouse and pig in vivo myocardial infarction (MI) models. We aimed to assess whether inhibiting IRI with malonate given upon reperfusion could prevent post-MI heart failure (HF) assessed after 28 days. Male C57BL/6 J mice were subjected to 30 min left anterior coronary artery (LAD) occlusion, before reperfusion for 28 days. Malonate or without-malonate control was infused as a single dose upon reperfusion. Cardiac function was assessed by echocardiography and fibrosis by Masson's trichrome staining. Reperfusion without malonate significantly reduced ejection fraction (~ 47%), fractional shortening (~ 23%) and elevated collagen deposition 28 days post-MI. Malonate, administered as a single infusion (16 mg/kg/min for 10 min) upon reperfusion, gave a significant cardioprotective effect, with ejection fraction (~ 60%) and fractional shortening (~ 30%) preserved and less collagen deposition. Using an acidified malonate formulation, to enhance its uptake into cardiomyocytes via the monocarboxylate transporter 1, both 1.6 and 16 mg/kg/min 10 min infusion led to robust long-term cardioprotection with preserved ejection fraction (> 60%) and fractional shortening (~ 30%), as well as significantly less collagen deposition than control hearts. Malonate administration upon reperfusion prevents post-MI HF. Acidification of malonate enables lower doses of malonate to also achieve long-term cardioprotection post-MI. Therefore, the administration of acidified malonate upon reperfusion is a promising therapeutic strategy to prevent IRI and post-MI HF.

The efficacy of mesenchymal stem cell (MSC) transplantation has been reported for various diseases. We previously developed a drug delivery system targeting mitochondria (MITO-Porter) by using a microfluidic device to encapsulate Coenzyme Q10 (CoQ10) on a large scale. The current study aimed to confirm if treatment with CoQ10 encapsulated by MITO-Porter enhanced mitochondrial functions in MSCs, with the potential to improve MSC transplantation therapy. We used highly purified human bone marrow-derived MSCs, described as rapidly expanding clones (RECs), and attempted to control and increase the amount of CoQ10 encapsulated in the MITO-Porter using microfluidic device system. We treated these RECs with CoQ10 encapsulated MITO-Porter, and evaluated its cellular uptake, co-localization with mitochondria, changes in mitochondrial respiratory capacity, and cellular toxicity. There was no significant change in mitochondrial respiratory capacity following treatment with the previous CoQ10 encapsulated MITO-Porter; however, mitochondrial respiratory capacity in RECs was significantly increased by treatment with CoQ10-rich MITO-Porter. Utilization of a microfluidic device enabled the amount of CoQ10 encapsulated in MITO-Porter to be controlled, and treatment with CoQ10-rich MITO-Porter successfully activated mitochondrial functions in MSCs. The MITO-Porter system thus provides a promising tool to improve MSC cell transplantation therapy.

Background We present a severe neonatal consequence due to the unexpected and crucial inversion of the fetal position after sudden termination of tocolysis during early labor of a woman with congenital uterine anomaly. It has been reported that congenital uterine anomalies latently affect the fetal position. The clinical pitfalls in childbirth with uterine anomalies are discussed here on the basis of clinical evidence.Case presentation At a perinatal medical center in Japan, a 29-year-old Japanese mother who had a history of bicornuate uterus, received tocolysis to prolong her pregnancy for 5 days during the late preterm period after preterm-premature rupture of the membrane. She gave birth to a 2304 g male neonate of the gestational age of 35 weeks and 5 days with severe asphyxia by means of crash cesarean section for fetal sustained bradycardia after sudden termination of tocolysis. We found the fetal position to reverse from cephalic to breech position during early labor. He ended up having severe cerebral palsy after brain cooling against hypoxic-ischemic encephalopathy for 3 days. The mechanism of inversion from cephalic to breech position without amnionic fluid remains unclear, although women with a known diagnosis of a uterine anomaly have higher risk of adverse outcomes such as malpresentation.Conclusions When considering the clinical course of this case on the basis of the medical reports, we suspected that uterine anomalies and changes in intrauterine pressure could cause fetal malpresentation and adverse neonatal outcomes.

The authors declare no conflicts of interest. The data that support the findings of this study are openly available. The data that support the findings of this study are openly available in Clinical Genomic Database at https://research.nhgri.nih.gov/CGD/. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Abstract Barth syndrome (BTHS) is an X‐linked disorder characterized by cardiomyopathy, skeletal myopathy, and 3‐methylglutaconic aciduria. The causative pathogenic variants for BTHS are in TAZ, which encodes a putative acyltransferase named tafazzin and is involved in the remodeling of cardiolipin in the inner mitochondrial membranes. Pathogenic variants in TAZ result in mitochondrial structural and functional abnormalities. We report a case of infantile BTHS with severe heart failure, left ventricular noncompaction, and lactic acidosis, having a missense c.640C>T (p.His214Tyr) variant in TAZ, which is considered a pathogenic variant based on the previously reported amino acid substitution at the same site (c.641A>G, p.His214Arg). However, in this previously reported case, heart function was compensated and not entirely similar to the present case. Silico prediction analysis suggested that c.640C>T could alter the TAZ messenger RNA (mRNA) splicing process. TAZ mRNAs in isolated peripheral mononuclear cells from the patient and in vitro splicing analysis using minigenes of TAZ found an 8 bp deletion at the 3′ end of exon 8, which resulted in the formation of a termination codon in the coding region of exon 9 (H214Nfs*3). These findings suggest that splicing abnormalities should always be considered in BTHS.

Chymotrypsin activity is rapidly inactivated by the N-mustard anti-tumor drug, chlorambucil. Since mustards react with thiols, amines, carboxyls, imidazoles, and sulfide sites on proteins, N-acetylcysteine, 2 proprietary protein hydrolyzates, beta-mercaptoethanol, ethanolamine, and sodium lactate were tested for their capacity to protect chymotrypsin from inactivation by the mustard. In each instance, protection was afforded to chymotrypsin. In as much as N-acetylcysteine protected chymotrypsin from inactivation by chlorambucil, it is suggested that this thiol compound may serve as a detoxication agent and may not require prior transformation into glutathione by cells in order to reduce mustard levels within the cells, as suggested by Smith and Gross (Proceedings of the NATO Panel VIII meeting, Grenoble, France, 1991.) It is further suggested that amino acids present as biosynthetic and degradative components of cells may detoxify mustards.

Given the potential for myocardial stem cell transplantation as a promising treatment for heart failure, numerous clinical trials have been conducted and its usefulness has been clearly confirmed. However, the low rate of engraftment of transplanted cells has become a clinical problem, and this needs to be improved in the case of transplanting cells to the heart. To address this issue, we report on attempts to prepare mitochondria-activated stem cells (MITO cells) for use in transplantation. MITO cells, which is cardiac progenitor cells (CPCs) activated by the mitochondrial delivery of resveratrol with an anti-oxidant and mitochondrial activation effects were successfully prepared using a mitochondrial targeting nanocarrier (MITO-Porter). The purpose of this study was to validate the therapeutic effect of cell transplantation by the MITO cells using a mouse model of myocardial ischemia-reperfusion. Mouse CPCs were used as transplanted cells. The transplantation of CPCs and MITO cells were conducted after myocardial ischemia-reperfusion, and the therapeutic effect was determined. The MITO cells transplanted group showed increase in postoperative weight gain, improve cardiac function and inhibition of fibrosis compared to the non-transplanted group and the CPC group. The transplantation of MITO cells to the ischemic myocardium showed a stronger transplantation effect compared to conventional CPC transplantation.

AIMS:Mitochondrial cardiomyopathy (MCM) is difficult to make a definite diagnosis because of various cardiovascular phenotypes and no diagnostic criteria in the pathology examination. We aim to add myocardial pathology to the diagnostic criteria for mitochondrial respiratory chain disorders.METHODS:Quantitative analysis of mitochondria using electron microscopy and immunohistopathological analysis with respiratory chain enzyme antibodies were performed in 11 patients with hypertrophic or restrictive cardiomyopathy who underwent endomyocardial biopsy for possible MCM . Respiratory chain enzymatic assay in biopsied myocardium and genetic studies were also performed in all the subjects to define MCM.RESULTS:Four patients were diagnosed with MCM according to the recent criteria of mitochondrial respiratory chain disorders. Using electron microscopy with quantitative analysis, the volume density of mitochondria within cardiac muscle cells was significantly increased in the MCM group compared with the non-MCM group (p=0.007). Immunohistopathological results were compatible with the result of the respiratory chain enzymatic assay.CONCLUSIONS:Pathological diagnosis of MCM could be confirmed by a quantitative study of electron microscopy and immunohistopathological analysis using the mitochondrial respiratory chain enzyme subunit antibody.