Myocardial Electrical Remodeling and the Arrhythmogenic Substrate in Hemorrhagic Shock-Induced Heart: Anti-Arrhythmogenic Effect of Liposome-Encapsulated Hemoglobin (HbV) on the Myocardium

PAD2 disturbs cardiomyocyte calcium homeostasis by citrullinating SERCA2a protein in hemorrhagic shock induced arrhythmia

BACKGROUND

Malignant arrhythmia induced by traumatic hemorrhage is a leading cause of early mortality in hemorrhagic shock. Understanding the mechanisms driving these arrhythmias and identifying therapeutic targets are critical for improving early survival in patients with traumatic hemorrhagic shock.

METHODS

Peripheral blood samples from patients with hemorrhagic shock were collected and analyzed for peptidylarginine deiminase 2 (PAD2) protein levels using ELISA. Pad2 knockout mice (Pad2-/-, Pad2 KO) were generated, and the hemorrhagic shock model was constructed via femoral artery cannulation and bloodletting. Cardiomyocytes were isolated and contractility and calcium content were measured by confocal microscopy. PAD2 subcellular localization was assessed through immunofluorescence and Western blotting. Proteins interacting with PAD2 in cardiomyocytes were identified using co-immunoprecipitation followed by mass spectrometry (CoIP-MS). The effect of PAD2 on sarcoplasmic reticulum calcium-ATPase 2a (SERCA2a) activity and citrullination was evaluated through enzyme activity assays and protein citrullination detection. AAV9-PAD2 was injected into mice via tail vein to induce in vivo overexpression of PAD2 in the myocardium. The effects of PAD2 enzymatic activity mutations and a PAD2-specific inhibitor on survival rate and arrhythmia following hemorrhagic shock were assessed through intraperitoneal injection.

RESULTS

PAD2 protein levels were significantly elevated in the peripheral blood of patients with hemorrhagic shock. Pad2 knockout improved calcium homeostasis in the sarcoplasmic reticulum of cardiomyocytes and alleviated post-shock arrhythmia in mice. Following hypoxia, PAD2 exhibited increased colocalization with the sarcoplasmic reticulum. During hypoxia, PAD2 inhibited SERCA2a activity through citrullination. AAV9-mediated overexpression of PAD2 in cardiomyocytes worsened both survival rates and the incidence of ventricular arrhythmia following hemorrhagic shock in mice. Conversely, PAD2 enzymatic activity mutations and a PAD2-specific inhibitor improved survival rates and reduced arrhythmia after hemorrhagic shock.

CONCLUSION

During myocardial hypoxia occurs in hemorrhagic shock, PAD2 reduces SERCA2a enzyme activity by citrullination, disrupting myocardial calcium homeostasis. Peptidylarginine deiminase 2 gene deficiency or inhibition improves ventricular arrhythmias and increases survival following hemorrhagic shock.

LEVEL OF EVIDENCE

Original Research-basic sciences research; not applicable.

Liposome-encapsulated hemoglobin rescues hemorrhagic shock heart through anti-ischemic and anti-arrhythmogenic effects on myocardium in repetitive 65% bleeding rat model

BACKGROUND

Phase I clinical trial of an artificial oxygen carrier (liposome-encapsulated hemoglobin vesicles [HbVs]) is safely completed, considering the other clinical application. Herein, we aimed to investigate the resuscitation effects of HbVs in cases of lethal hemorrhage, including the mechanisms involved.

METHODS

Optical mapping analysis (OMP) and electrophysiological studies (EPS), immunostaining pathological examination for hypoxia-inducible factor-1α (HIF1-alpha) in the heart tissue, and blood troponin I (TnI) level measurements were performed in rats that underwent five rounds of spontaneous arterial bleeding with up to 65% hemorrhage.

RESULTS

Ten rats in each group were resuscitated by a transvenous infusion of 5% albumin (ALB), washed erythrocytes (wRBC), HbVs (HbV), 50% HbV diluted by 5% albumin (50% HbV), and 66% HbV diluted by 5% albumin (66% HbV). The rats in the ALB and 50% HbV groups died, whereas those in the other groups survived. OMP showed impaired action potential duration dispersion (APDd) in the left ventricle in the ALB and 50% HbV groups, which was attenuated in the other groups. Lethal arrhythmias were provoked by EPS in the ALB and 50% HbV groups but not in the other groups. HIF1-alpha was positively stained only in the ALB and 50% HbV groups. TnI levels were elevated in the ALB and 50% HbV groups.

CONCLUSIONS

Acute lethal hemorrhage causes myocardial ischemia with hypoxia and arrhythmias, which may be induced by impaired APDd and myocardial damage, reflected in the increased levels of HIF1-alpha and TnI. HbVs could be useful for resuscitation and may help save patients with injuries such as gunshot wounds.

LncRNA-TUG1: Implications in the Myocardial and Endothelial Cell Oxidative Stress Injury Caused by Hemorrhagic Shock and Fluid Resuscitation

BACKGROUND

LncRNA taurine-upregulated gene 1 (TUG1) can regulate vascular endothelial cell injury, a critical mechanism in treating hemorrhagic shock and fluid resuscitation (HS/R). Therefore, this study explored the influence of TUG1 in HS/R.

METHODS

An in vivo rat model of ischemia-reperfusion (I/R) injury post-HS/R and an in vitro model of oxidative stress injury in rat cardiomyocyte cell line (H9C2) were constructed. In vivo, we silenced TUG1 and quantified its expression along with inflammatory factors through quantitative reverse transcription polymerase chain reaction (qRT-PCR), mean arterial pressure (MAP) detection and blood gas analysis. Myocardial functional impairment was assessed via Triphenyl-2H-Tetrazolium Chloride (TTC), Hematoxylin and eosin, and Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) stainings. Oxidative stress level in rat serum was measured. In vitro, we examined the changes of cell viability, apoptosis, oxidative stress levels, inflammatory factor secretion and nuclear factor-κB (NF-κB)/p65 expression by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, Enzyme-linked immunosorbent assay (ELISA) and Western blot.

RESULTS

TUG1 level was elevated in rats of I/R model caused by HS/R. TUG1 silencing ameliorated the decline in MAP, acid-base imbalance and myocardial tissue damage, and suppressed oxidative stress and inflammatory factor levels in model rat. TUG1 silencing enhanced viability, impeded apoptosis, and reduced oxidative stress, inflammatory factor contents and NF-κB/p65 expression in H2O2 treated H9C2 cells.

CONCLUSION

TUG1 participates in regulating oxidative stress damage and inflammation induced by HS/R.

The Prognostic Impact of In-Hospital Major Bleeding and Recurrence of Myocardial Infarction during Acute Phase after Percutaneous Coronary Intervention for Acute Myocardial Infarction

AIM

Both recurrent myocardial infarction (ReMI) and bleeding events after acute myocardial infarction (AMI) were reportedly associated with increased mortality. To date, the prognostic impact of these events on subsequent outcomes in East Asians is still unclear. In this study, we aimed to investigate the impact of bleeding or thrombotic events during acute phase on subsequent mortality and time-dependent change of the impact in patients with AMI undergoing percutaneous coronary intervention (PCI).

METHOD

We conducted a prospective, multicenter, observational study of patients with AMI (n=12,093). The patients who did not undergo emergent PCI were excluded. In addition, the patients registered before 2003 were excluded because the data of bleeding severity was not obtained. Eligible patients were divided into two groups based on the occurrence of major bleeding within 7 days of PCI, and the same approach was performed for ReMI within 7 days of PCI. The endpoint of this study was all-cause death. We assessed the impact of major bleeding and ReMI, which occurred within 7 days of index PCI, on the subsequent clinical outcomes up to 5 years.

RESULTS

A total of 6,769 patients were found to be eligible. All-cause death occurred in 898 (13.3%) patients during a median follow-up period of 1,726 [511-1,840] days. After adjustment for multiple confounders, major bleeding in 7 days from index PCI was independently associated with higher 30-day and 30-day to 1-year mortality (odds ratio [OR]: 2.06 [1.45-2.92] p＜0.001, OR: 2.03 [1.28-3.15] p=0.002), whereas ReMI was not (OR: 1.93 [0.92-3.80] p=0.07, OR: 0.81 [0.24-2.03] p=0.68). Major bleeding and ReMI did not affect mortality between 1 and 5 years (hazard ratio [HR]: 1.32 [0.77-2.26] p=0.31, HR: 0.48 [0.12-1.94] p=0.30).

CONCLUSION

Major bleeding in 7 days from admission was independently associated with higher 30-day and 1-year mortality but not during 1-5 years. ReMI did not affect mortality in all phases. We should be more concerned about bleeding event during acute phase after PCI.

Liposome-Encapsulated Hemoglobin Vesicle Improves Persistent Anti-arrhythmogenesis through Improving Myocardial Electrical Remodeling and Modulating Cardiac Autonomic Activity in a Hemorrhagic Shock-Induced Rat Heart Model

OBJECTIVE

Shock heart syndrome (SHS) is associated with lethal arrhythmias (ventricular tachycardia/ventricular fibrillation, VT/VF). We investigated whether liposome-encapsulated human hemoglobin vesicles (HbVs) has comparable persistent efficacy to washed red blood cells (wRBCs) for improving arrhythmogenesis in the subacute to chronic phase of SHS.

METHODS

Optical mapping analysis (OMP), electrophysiological study (EPS), and pathological examinations were performed on blood samples from Sprague-Dawley rats following induction of hemorrhagic shock. After hemorrhagic shock, the rats were immediately resuscitated by transfusing 5% albumin (ALB), HbV, or wRBCs. All rats survived for 1 week. OMP and EPS were performed on Langendorff-perfused hearts. Spontaneous arrhythmias and heart rate variability (HRV) were evaluated using awake 24-h telemetry, cardiac function by echocardiography, and pathological examination of Connexin43.

RESULTS

OMP showed significantly impaired action potential duration dispersion (APDd) in the left ventricle (LV) in the ALB group whereas APDd was substantially preserved in the HbV and wRBCs groups. Sustained VT/VF was easily provoked by EPS in the ALB group. No VT/VF was induced in the HbV and wRBCs groups. HRV, spontaneous arrhythmias, and cardiac function were preserved in the HbV and wRBCs groups. Pathology showed myocardial cell damage and Connexin43 degradation in the ALB group, all of which were attenuated in the HbV and wRBCs groups.

CONCLUSION

LV remodeling after hemorrhagic shock caused VT/VF in the presence of impaired APDd. Similar to wRBCs, HbV persistently prevented VT/VF by inhibiting persistent electrical remodeling, preserving myocardial structures, and ameliorating arrhythmogenic modifying factors in the subacute to chronic phase of hemorrhagic shock-induced SHS.

Erythrocyte-Inspired Functional Materials for Biomedical Applications

Erythrocytes are the most abundant cells in the blood. As the results of long-term natural selection, their specific biconcave discoid morphology and cellular composition are responsible for gaining excellent biological performance. Inspired by the intrinsic features of erythrocytes, various artificial biomaterials emerge and find broad prospects in biomedical applications such as therapeutic delivery, bioimaging, and tissue engineering. Here, a comprehensive review from the fabrication to the applications of erythrocyte-inspired functional materials is given. After summarizing the biomaterials mimicking the biological functions of erythrocytes, the synthesis strategies of particles with erythrocyte-inspired morphologies are presented. The emphasis is on practical biomedical applications of these bioinspired functional materials. The perspectives for the future possibilities of the advanced erythrocyte-inspired biomaterials are also discussed. It is hoped that the summary of existing studies can inspire researchers to develop novel biomaterials; thus, accelerating the progress of these biomaterials toward clinical biomedical applications.

Intraosseous infusion of liposome-encapsulated hemoglobin (HbV) acutely prevents hemorrhagic anemia-induced lethal arrhythmias and its efficacy persists with preventing proarrhythmic side effects in subacute phase of severe hemodilution model

BACKGROUND

Artificial oxygen carriers (HbV) can treat hemorrhagic shock with lethal arrhythmias (VT/VF). No reports exist on subacute HbV's effects.

METHODS

Acute and subacute resuscitation effects with anti-arrhythmogenesis of HbV were studied in 85% blood exchange rat model (85%-Model). Lethal 85%-Model was created by bone marrow transfusion and femoral artery bleeding in 80 SD rats in HbV-administered group (HbV-group), washed erythrocyte-administered group (wRBC-group), and 5% albumin-administered group (ALB-group). Survival rates, anti-arrhythmic efficacy by optical mapping analysis (OMP) with electrophysiological stimulation (EPS) in Langendorff heart, cardiac autonomic activity by heart rate variability (HRV) and ventricular arrhythmias by 24-hour electrocardiogram telemetry monitoring (24h-ECG) in awake, and left ventricular function by echocardiography (LVEF) were measured.

RESULTS

All rats in HbV- and wRBC-groups survived for 4 weeks whereas no rats in ALB-group. HbV and wRBC acutely suppressed VT/VF in Langendorff heart through ameliorating action potential duration dispersion (APDd) analyzed by OMP with EPS. For subacute analysis, 50% blood exchange by 5% albumin was utilized (ALB-group 50). Subacute salutary effect on APDd and VT/VF inducibility was confirmed in HbV- and wRBC-groups. 24h-ECG showed that HbV and wRBC suppressed none-sustained VT (NSVT) and sympathetic component of HRV (LF/HF) with preserved LVEF (HbV-group, wRBC-group vs. ALB-group 50;NSVT numbers/days, 0.5±0.3, 0.4±0.3 vs. 3.9±1.2*; LF/HF, 1.1±0.2, 0.8±0.2 vs. 3.5±1.0*;LVEF, 84±5, 83±4, vs. 77±4%*; *p<0.05).

CONCLUSIONS

Collectively, HbV has sustained antiarrhythmic effect in subacute 85%-Model by ameliorating electrical remodeling and improving arrhythmogenic modifying factors (HRV and LVEF). These findings are useful in now continuing clinical trials of HbV.

Translational research of hemoglobin vesicles as a transfusion alternative

Clinical situations arise in which blood for transfusion becomes scarce or unavailable. Considerable demand for a transfusion alternative persists because of various difficulties posed by blood donation and transfusion systems. Hemoglobin-vesicles (HbV) are artificial oxygen carriers being developed for use as a transfusion alternative. Just as biomembranes of red blood cells (RBCs) do, phospholipid vesicles (liposomes) for Hb encapsulation can protect the human body from toxic effects of molecular Hb. The main HbV component, Hb, is obtained from discarded human donated blood. Therefore, HbV can be categorized as a biologic agent targeting oxygen for peripheral tissues. The purification procedure strictly eliminates the possibility of viral contamination. It also removes all concomitant unstable enzymes present in RBC for utmost safety from infection. The deoxygenated HbVs, which are storable for over years at ambient temperature, can function as an alternative to blood transfusion for resuscitation from hemorrhagic shock and O₂ therapeutics. Moreover, a recent study clarified beneficial effects for anti-oxidation and anti-inflammation by carbon monoxide (CO)-bound HbVs. Autoxidation of HbV (HbO₂ → metHb + O₂-.) is unavoidable after intravenous administration. Co-injection of methylene blue can extract the intraerythrocytic glycolytic electron energy effectively and reduce metHb. Other phenothiazine dyes can also function as electron mediators to improve the functional life span of HbV. This review paper summarizes recent progress of the research and development of HbV, aimed at clinical applications.