Suppressing Hippo signaling in the stem cell niche promotes skeletal muscle regeneration.

Lack of blood flow to the lower extremities in peripheral arterial disease causes oxygen and nutrient deprivation in ischemic skeletal muscles, leading to functional impairment. Treatment options for muscle regeneration in this scenario are lacking. Here, we selectively targeted the Hippo pathway in myofibers, which provide architectural support for muscle stem cell niches, to facilitate functional muscle recovery in ischemic extremities by promoting angiogenesis, neovascularization, and myogenesis. We knocked down the core Hippo pathway component, Salvador (SAV1), by using an adeno-associated virus 9 (AAV9) vector expressing a miR30-based triple short-hairpin RNA (shRNA), controlled by a muscle-specific promoter. In a mouse hindlimb-ischemia model, AAV9 SAV1 shRNA administration in ischemic muscles induced nuclear localization of the Hippo effector YAP, accelerated perfusion restoration, and increased exercise endurance. Intravascular lectin labeling of the vasculature revealed enhanced angiogenesis. Using 5-ethynyl-2'-deoxyuridine to label replicating cellular DNA in vivo, we found SAV1 knockdown concurrently increased paired box transcription factor Pax7+ muscle satellite cell and CD31+ endothelial cell proliferation in ischemic muscles. To further study Hippo suppression in skeletal muscle regeneration, we used a cardiotoxin-induced muscle damage model in adult (12-15 weeks old) and aged mice (26-month old). Two weeks after delivery of AAV9 SAV1 shRNA into injured muscles, the distribution of regenerative myofibers shifted toward a larger cross-sectional area and increased capillary density compared with mice receiving AAV9 control. Together, these findings suggest our approach may have clinical promise in regenerative therapy for leg ischemia and muscle injury.

Interactions Between Structural Remodeling and Hypertrophy in the Right Ventricle in Response to Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) exerts substantial pressure overload on the right ventricle (RV), inducing RV remodeling and myocardial tissue adaptation often leading to right heart failure. The associated RV free wall (RVFW) adaptation involves myocardial hypertrophy, augmented intrinsic contractility, collagen fibrosis, and structural remodeling in an attempt to cope with pressure overload. If RVFW adaptation cannot maintain the RV stroke volume (SV), RV dilation will prevail as an exit mechanism, which usually decompensates RV function, leading to RV failure. Our knowledge of the factors determining the transition from the upper limit of RVFW adaptation to RV decompensation and the role of fiber remodeling events such as extracellular fibrosis and fiber reorientation in this transition remains very limited. Computational heart models that connect the growth and remodeling (G&R) events at the fiber and tissue levels with alterations in the organ-level function are essential to predict the temporal order and the compensatory level of the underlying mechanisms. In this work, building upon our recently developed rodent heart models (RHM) of PAH, we integrated mathematical models that describe volumetric growth of the RV and structural remodeling of the RVFW. The time-evolution of RV remodeling from control and post-PAH time points was simulated. The results suggest that the augmentation of the intrinsic contractility of myofibers, accompanied by an increase in passive stiffness of RVFW, is among the first remodeling events through which the RV strives to maintain the cardiac output. Interestingly, we found that the observed reorientation of the myofibers toward the longitudinal (apex-to-base) direction was a maladaptive mechanism that impaired the RVFW contractile pattern and advanced along with RV dilation at later stages of PAH. In fact, although individual fibers were more contractile post-PAH, the disruption in the optimal transmural fiber architecture compromised the effective contractile function of the RVFW, contributing to the depressed ejection fraction (EF) of the RV. Our findings clearly demonstrate the critical need for developing multiscale approaches that can model and delineate relationships between pathological alterations in cardiac function and underlying remodeling events across fiber, cellular, and molecular levels.

Correction to: Disruption of endothelial adherens junctions by high glucose is mediated by protein kinase C-ß-dependent vascular endothelial cadherin tyrosine phosphorylation.

This article was unintentionally published twice in this journal, by the same authors. The following should be considered the version of record and used for citation purposes: "Mehran Haidari, Wei Zhang, James T Willerson and Richard AF Dixon, Disruption of endothelial adherens junctions by high glucose is mediated by protein kinase C-ß-dependent vascular endothelial cadherin tyrosine phosphorylation, Cardiovascular Diabetology, Volume 13, Issue 1, doi: 10.1186/1475-2840-13-112 ". The duplicate "Mehran Haidari, Wei Zhang, James T Willerson and Richard AF Dixon, Disruption of endothelial adherens junctions by high glucose is mediated by protein kinase C-ß-dependent vascular endothelial cadherin tyrosine phosphorylation, Cardiovascular Diabetology, Volume 13, Issue 1, doi: 10.1186/1475-2840-13-105 " is to be ignored. The Publisher apologizes to the readers of the journal for not detecting the duplication during the publication process.

Small molecule agonist of very late antigen-4 (VLA-4) integrin induces progenitor cell adhesion.

Activation of the integrin family of cell adhesion receptors on progenitor cells may be a viable approach to enhance the effects of stem cell-based therapies by improving cell retention and engraftment. Here, we describe the synthesis and characterization of the first small molecule agonist identified for the integrin α4ß1 (also known as very late antigen-4 or VLA-4). The agonist, THI0019, was generated via two structural modifications to a previously identified α4ß1 antagonist. THI0019 greatly enhanced the adhesion of cultured cell lines and primary progenitor cells to α4ß1 ligands VCAM-1 and CS1 under both static and flow conditions. Furthermore, THI0019 facilitated the rolling and spreading of cells on VCAM-1 and the migration of cells toward SDF-1α. Molecular modeling predicted that the compound binds at the α/ß subunit interface overlapping the ligand-binding site thus indicating that the compound must be displaced upon ligand binding. In support of this model, an analog of THI0019 modified to contain a photoreactive group was used to demonstrate that when cross-linked to the integrin, the compound behaves as an antagonist instead of an agonist. In addition, THI0019 showed cross-reactivity with the related integrin α4ß7 as well as α5ß1 and αLß2. When cross-linked to αLß2, the photoreactive analog of THI0019 remained an agonist, consistent with it binding at the α/ß subunit interface and not at the ligand-binding site in the inserted ("I") domain of the αL subunit. Co-administering progenitor cells with a compound such as THI0019 may provide a mechanism for enhancing stem cell therapy.

Endothelial-like progenitor cells engineered to produce prostacyclin rescue monocrotaline-induced pulmonary arterial hypertension and provide right ventricle benefits.

BACKGROUND: Intravenous prostacyclin is approved for treating pulmonary arterial hypertension (PAH), but it has a short half-life and must be delivered systemically via an indwelling intravenous catheter. We hypothesize that localized jugular vein delivery of prostacyclin-producing cells may provide sustained therapeutic effects without the limitations of systemic delivery. METHODS AND RESULTS: We generated a vector expressing a human cyclooxygenase isoform 1 and prostacyclin synthase fusion protein that produces prostacyclin from arachidonic acid. Endothelial-like progenitor cells (ELPCs) were transfected with the cyclooxygenase isoform 1-prostacyclin synthase plasmid and labeled with lentivirus expressing nuclear-localized red fluorescent protein (nuRFP). The engineered ELPCs (expressing cyclooxygenase isoform 1-prostacyclin synthase and nuRFP) were tested in rats with monocrotaline (MCT)-induced PAH. In PAH prevention studies, treatment with engineered ELPCs or control ELPCs (expressing nuRFP alone) attenuated MCT-induced right ventricular systolic pressure increase, right ventricular hypertrophy, and pulmonary vessel wall thickening. Engineered ELPCs were more effective than control ELPCs in all variables evaluated. In PAH reversal studies, engineered ELPCs or control ELPCs increased the survival rate of rats with established PAH and decreased right ventricular hypertrophy. Engineered ELPCs provided a survival benefit 2 weeks earlier than did control ELPCs. Microarray-based gene ontology analysis of the right ventricle revealed that a number of MCT-altered genes and neurotransmitter pathways (dopamine, serotonin, and γ-aminobutyric acid) were restored after ELPC-based prostacyclin gene therapy. CONCLUSIONS: Cyclooxygenase isoform 1-prostacyclin synthase-expressing ELPCs reversed MCT-induced PAH. A single jugular vein injection offered survival benefits for at least 4 weeks and may provide a promising option for PAH patients.

Incidence and Impact of Takotsubo Syndrome in Hospitalized Patients With COVID-19.

BACKGROUND: Takotsubo syndrome has been reported in patients with COVID-19, although minimal data are available. This investigation assessed the incidence and impact of takotsubo syndrome on patients hospitalized with COVID-19. METHODS: A retrospective cohort study was conducted using International Statistical Classification of Diseases, Tenth Revision, codes to identify patients with a primary diagnosis of COVID-19 with or without takotsubo syndrome in the National Inpatient Sample 2020 database. Outcomes between groups were compared after propensity score matching for patient and hospital demographics and comorbidities. RESULTS: A total of 211,448 patients with a primary diagnosis of COVID-19 were identified. Of these, 171 (0.08%) had a secondary diagnosis of takotsubo syndrome. Before matching, patients with COVID-19 and takotsubo syndrome, compared with patients without takotsubo syndrome, were older (68.95 vs 64.26 years; P < .001); more likely to be female (64.3% vs 47.2%; P < .001); and more likely to have anxiety (24.6% vs 12.8%; P < .001), depression (17.5% vs 11.4%; P = .02), and chronic obstructive pulmonary disease (24.6% vs 14.7%; P < .001). The takotsubo syndrome group had worse outcomes than the non-takotsubo syndrome group for death (30.4% vs 11.1%), cardiac arrest (7.6% vs 2.1%), cardiogenic shock (12.9% vs 0.4%), length of hospital stay (10.7 vs 7.5 days), and total charges ($152,685 vs $78,468) (all P < .001). After matching and compared with the non-takotsubo syndrome group (n = 508), the takotsubo syndrome group (n = 170) had a higher incidence of inpatient mortality (30% vs 14%; P < .001), cardiac arrest (7.6% vs 2.8%; P = .009), and cardiogenic shock (12.4% vs 0.4%; P < .001); a longer hospital stay (10.7 vs 7.6 days; P < .001); and higher total charges ($152,943 vs $79,523; P < .001). CONCLUSION: Takotsubo syndrome is a rare but severe in-hospital complication in patients with COVID-19.

Integrin α2ß1 mediates tyrosine phosphorylation of vascular endothelial cadherin induced by invasive breast cancer cells.

The molecular mechanisms that regulate the endothelial response during transendothelial migration (TEM) of invasive cancer cells remain elusive. Tyrosine phosphorylation of vascular endothelial cadherin (VE-cad) has been implicated in the disruption of endothelial cell adherens junctions and in the diapedesis of metastatic cancer cells. We sought to determine the signaling mechanisms underlying the disruption of endothelial adherens junctions after the attachment of invasive breast cancer cells. Attachment of invasive breast cancer cells (MDA-MB-231) to human umbilical vein endothelial cells induced tyrosine phosphorylation of VE-cad, dissociation of ß-catenin from VE-cad, and retraction of endothelial cells. Breast cancer cell-induced tyrosine phosphorylation of VE-cad was mediated by activation of the H-Ras/Raf/MEK/ERK signaling cascade and depended on the phosphorylation of endothelial myosin light chain (MLC). The inhibition of H-Ras or MLC in endothelial cells inhibited TEM of MDA-MB-231 cells. VE-cad tyrosine phosphorylation in endothelial cells induced by the attachment of MDA-MB-231 cells was mediated by MDA-MB-231 α(2)ß(1) integrin. Compared with highly invasive MDA-MB-231 breast cancer cells, weakly invasive MCF-7 breast cancer cells expressed lower levels of α(2)ß(1) integrin. TEM of MCF-7 as well as induction of VE-cad tyrosine phosphorylation and dissociation of ß-catenin from the VE-cad complex by MCF-7 cells were lower than in MDA-MB-231 cells. These processes were restored when MCF-7 cells were treated with ß(1)-activating antibody. Moreover, the response of endothelial cells to the attachment of prostatic (PC-3) and ovarian (SKOV3) invasive cancer cells resembled the response to MDA-MB-231 cells. Our study showed that the MDA-MB-231 cell-induced disruption of endothelial adherens junction integrity is triggered by MDA-MB-231 cell α(2)ß(1) integrin and is mediated by H-Ras/MLC-induced tyrosine phosphorylation of VE-cad.

Atorvastatin preserves the integrity of endothelial adherens junctions by inhibiting vascular endothelial cadherin tyrosine phosphorylation.

Vascular endothelial cadherin (VE-cad) tyrosine (Tyr) phosphorylation has been implicated in the disruption of adherens junctions (AJs) induced by inflammatory reactions. The impacts of statins on integrity of AJs and VE-cad Tyr phosphorylation have not been explored. The effects of atorvastatin on IL-1ß and monocyte-induced VE-cad Tyr phosphorylation in human umbilical vein endothelial cells (ECs) were studied. In ECs treated with interleukin (IL)-1ß for 30 min, VE-cad Tyr phosphorylation, dissociation of the VE-cad/ß-catenin complex and transendothelial migration (TEM) of monocytes were increased. These processes were mediated by activation of HRas and RhoA that leads to phosphorylation of myosin light chain (MLC). Atorvastatin inhibited IL-1ß-induced Tyr phosphorylation of VE-cad by inhibiting RhoA and by dephosphorylating MLC. The attenuating effect of atorvastatin on VE-cad Tyr phosphorylation was reversed when RhoA was activated or MLC phosphatase was inhibited. Furthermore, inhibiting farnesyl transferase or geranylgeranyl transferase reproduced the inhibitory effects of atorvastatin on VE-cad Tyr phosphorylation. In addition, atorvastatin inhibited monocyte-induced VE-cad Tyr phosphorylation in ECs and attenuated IL-1ß-induced TEM of monocytes. Our study introduces a novel pleiotropic effect of atorvastatin and suggests that statins protect the integrity of AJs in ECs by inhibiting RhoA-mediated Tyr phosphorylation of VE-cad.

Hippo pathway inhibition promotes metabolic adaptability and antioxidant response in myoblasts.

Metabolic plasticity in a hostile environment ensures cell survival. We investigated whether Hippo pathway inhibition contributed to cell adaptations under challenging conditions. We examined metabolic profiles and fuel substrate choices and preferences in C2C12 myoblasts after Hippo pathway inhibition via Salvador knockdown (SAV1 KD). SAV1 KD induced higher ATP production and a more energetic phenotype. Bioenergetic profiling showed enhanced key mitochondrial parameters including spare respiratory capacity. SAV1 KD cells showed markedly elevated glycolysis and glycolytic reserves; blocking other fuel-oxidation pathways enhanced mitochondrial flexibility of glucose oxidation. Under limited glucose, endogenous fatty acid oxidation increased to cope with bioenergetic stress. Gene expression patterns after SAV1 KD suggested transcriptional upregulation of key metabolic network regulators to promote energy production and free radical scavenging that may prevent impaired lipid and glucose metabolism. In SAV1 KD cells, sirtuin signaling was the top enriched canonical pathway linked with enhanced mitochondrial ATP production. Collectively, we demonstrated that Hippo pathway inhibition in SAV1 KD cells induces multiple metabolic properties, including enhancing mitochondrial spare respiratory capacity or glycolytic reserve to cope with stress and upregulating metabolic pathways supporting elevated ATP demand, bioenergetics, and glycolysis and counteracting oxidative stress. In response to metabolic challenges, SAV1 KD cells can increase fatty acid oxidation or glucose-coupled oxidative phosphorylation capacity to compensate for substrate limitations or alternative fuel oxidation pathway inhibition.

Association of atrial fibrillation burden with in-hospital outcomes in patients with Takotsubo cardiomyopathy.

BACKGROUND: The effects of atrial fibrillation (AF) and its burden on in-hospital mortality in patients with Takotsubo cardiomyopathy (TCM) are unclear. Here, we examined the effect of AF and paroxysmal AF on in-hospital outcomes in patients with TCM. METHODS: We used ICD-10 codes to retrospectively identify patients with a primary diagnosis of TCM in the National Inpatient Sample database 2016-2018. We compared in-hospital outcomes in TCM patients with and without AF before and after propensity score matching. The effect of AF burden on outcomes was assessed in patients with paroxysmal AF and no AF. RESULTS: Of the 4,733 patients with a primary diagnosis of TCM, 650 (13.7%) had AF, and 4,083 (86.3%) did not. Of TCM patients with AF, 368 (56.6%) had paroxysmal AF. In-hospital mortality was higher in patients with AF before (3.4% vs 1.2%, P <  0.001) and after propensity matching (3.4% vs 1.7%, P = 0.021) but did not differ between the paroxysmal AF and the no AF groups (P = 0.205). In the matched cohorts, both AF and paroxysmal AF groups were associated with a higher rate of cardiogenic shock (AF, P < 0.001; paroxysmal AF, P < 0.001), ventricular arrhythmia (AF, P = 0.002; paroxysmal AF, P = 0.02), acute kidney injury (AF, P = 0.007; paroxysmal AF, P = 0.008), and acute respiratory failure (AF, P < 0.001; paroxysmal AF, P < 0.001) compared with the no AF group. CONCLUSIONS: Although AF was associated with increased in-hospital mortality, paroxysmal AF did not affect in-hospital mortality, suggesting a higher AF burden is associated with worse clinical outcome in patients with TCM.

Therapeutic angiogenesis and tissue revascularization in ischemic vascular disease.

Ischemic vascular disease is a major healthcare problem. The keys to treatment lie in vascular regeneration and restoration of perfusion. However, current treatments cannot satisfy the need for vascular regeneration to restore blood circulation. As biomedical research has evolved rapidly, a variety of potential alternative therapeutics has been explored widely, such as growth factor-based therapy, cell-based therapy, and material-based therapy including nanomedicine and biomaterials. This review will comprehensively describe the main pathogenesis of vascular injury in ischemic vascular disease, the therapeutic function of the above three treatment strategies, the corresponding potential challenges, and future research directions.

Contractile Adaptation of the Left Ventricle Post-myocardial Infarction: Predictions by Rodent-Specific Computational Modeling.

Myocardial infarction (MI) results in cardiac myocyte death and the formation of a fibrotic scar in the left ventricular free wall (LVFW). Following an acute MI, LVFW remodeling takes place consisting of several alterations in the structure and properties of cellular and extracellular components with a heterogeneous pattern across the LVFW. The normal function of the heart is strongly influenced by the passive and active biomechanical behavior of the LVFW, and progressive myocardial structural remodeling can have a detrimental effect on both diastolic and systolic functions of the LV leading to heart failure. Despite important advances in understanding LVFW passive remodeling in the setting of MI, heterogeneous remodeling in the LVFW active properties and its relationship to organ-level LV function remain understudied. To address these gaps, we developed high-fidelity finite-element (FE) rodent computational cardiac models (RCCMs) of MI using extensive datasets from MI rat hearts representing the heart remodeling from one-week (1-wk) to four-week (4-wk) post-MI timepoints. The rat-specific models (n = 2 for each timepoint) integrate detailed imaging data of the heart geometry, myocardial fiber architecture, and infarct zone determined using late gadolinium enhancement prior to terminal measurements. The computational models predicted a significantly higher level of active tension in remote myocardium in early post-MI hearts (1-wk post-MI) followed by a return to near the control level in late-stage MI (3- and 4-wk post-MI). The late-stage MI rats showed smaller myofiber ranges in the remote region and in-silico experiments using RCCMs suggested that the smaller fiber helicity is consistent with lower contractile forces needed to meet the measured ejection fractions in late-stage MI. In contrast, in-silico experiments predicted that collagen fiber transmural orientation in the infarct region has little influence on organ-level function. In addition, our MI RCCMs indicated that reduced and potentially positive circumferential strains in the infarct region at end-systole can be used to infer information about the time-varying properties of the infarct region. The detailed description of regional passive and active remodeling patterns can complement and enhance the traditional measures of LV anatomy and function that often lead to a gross and limited assessment of cardiac performance. The translation and implementation of our model in patient-specific organ-level simulations offer to advance the investigation of individualized prognosis and intervention for MI.

Engineered endothelial progenitor cells that overexpress prostacyclin protect vascular cells.

Prostacyclin (PGI2) is a potent vasodilator and important mediator of vascular homeostasis; however, its clinical use is limited because of its short (<2-min) half-life. Thus, we hypothesize that the use of engineered endothelial progenitor cells (EPCs) that constitutively secrete high levels of PGI2 may overcome this limitation of PGI2 therapy. A cDNA encoding COX-1-10aa-PGIS, which links human cyclooxygenase-1 (COX-1) to prostacyclin synthase (PGIS), was delivered via nucleofection into outgrowth EPCs derived from rat bone marrow mononuclear cells. PGI2-secreting strains (PGI2-EPCs) were established by continuous subculturing of transfected cells under G418 selection. Genomic PCR, RT-PCR, and Western blot analyses confirmed the overexpression of COX-1-10aa-PGIS in PGI2-EPCs. PGI2-EPCs secreted significantly higher levels of PGI2 in vitro than native EPCs (P < 0.05) and showed higher intrinsic angiogenic capability; conditioned medium (CM) from PGI2-EPCs promoted better tube formation than CM from native EPCs (P < 0.05). Cell- and paracrine-mediated in vitro angiogenesis was attenuated when COX-1-10aa-PGIS protein expression was knocked down. Whole-cell patch-clamp studies showed that 4-aminopyridine-sensitive K(+) current density was increased significantly in rat smooth muscle cells (rSMCs) cocultured under hypoxia with PGI2-EPCs (7.50 ± 1.59 pA/pF; P < 0.05) compared with rSMCs cocultured with native EPCs (3.99 ± 1.26 pA/pF). In conclusion, we successfully created EPC strains that overexpress an active novel enzyme resulting in consistent secretion of PGI2. PGI2-EPCs showed enhanced intrinsic proangiogenic properties and provided favorable paracrine-mediated cellular protections, including promoting in vitro angiogenesis of native EPCs and hyperpolarization of SMCs under hypoxia.

Impact of family history of coronary artery disease on clinical outcomes in Takotsubo cardiomyopathy.

Family history of coronary artery disease (FHxCAD) is a critical risk factor for CAD, underscoring the contribution of genetic factors to disease pathogenesis and susceptibility. Takotsubo cardiomyopathy (TCM) simulates the clinical features of and frequently coexists with CAD. However, the association between FHxCAD and TCM is unclear. Here, we retrospectively examined the impact of FHxCAD on in-hospital outcomes of patients with TCM. Using the National Inpatient Sample database (2016-2018), we identified 4733 patients admitted to hospital with a primary diagnosis of TCM. We compared in-hospital outcomes and complications between TCM patients with (n=646, 13.7%) and without FHxCAD (n=646) in the unmatched and in a propensity-score matched cohort (1:1 ratio). TCM with FHxCAD patients had a reduced incidence of cardiogenic shock, acute kidney injury (AKI), and acute respiratory failure (ARF); lower mortality rates; shorter length of stay (LOS); and decreased total charge compared with TCM without FHxCAD patients (p<0.05). In the matched cohort, TCM with FHxCAD patients (vs TCM without FHxCAD patients) had a lower incidence of cardiogenic shock (2.2% vs 6.3%, p<0.001; OR 0.33, 95% CI 0.18 to 0.61), AKI (5.1% vs 8.7%, p=0.016; OR 0.57, 95% CI 0.36 to 0.88), and ARF (5.7% vs 12.7%, p<0.001; OR 0.42, 95% CI 0.28 to 0.63); decreased in-hospital mortality (<11% vs 3.1%, p=0.002; OR 0.2, 95% CI 0.07 to 0.57); shorter LOS (2.66±1.96 days vs 3.40±3.05 days, p<0.001); and a reduced total charge (p=0.001), respectively. FHxCAD was associated with favorable outcomes in both unmatched and propensity-matched cohorts.

A machine learning model to estimate myocardial stiffness from EDPVR.

In-vivo estimation of mechanical properties of the myocardium is essential for patient-specific diagnosis and prognosis of cardiac disease involving myocardial remodeling, including myocardial infarction and heart failure with preserved ejection fraction. Current approaches use time-consuming finite-element (FE) inverse methods that involve reconstructing and meshing the heart geometry, imposing measured loading, and conducting computationally expensive iterative FE simulations. In this paper, we propose a machine learning (ML) model that feasibly and accurately predicts passive myocardial properties directly from select geometric, architectural, and hemodynamic measures, thus bypassing exhaustive steps commonly required in cardiac FE inverse problems. Geometric and fiber-orientation features were chosen to be readily obtainable from standard cardiac imaging protocols. The end-diastolic pressure-volume relationship (EDPVR), which can be obtained using a single-point pressure-volume measurement, was used as a hemodynamic (loading) feature. A comprehensive ML training dataset in the geometry-architecture-loading space was generated, including a wide variety of partially synthesized rodent heart geometry and myofiber helicity possibilities, and a broad range of EDPVRs obtained using forward FE simulations. Latin hypercube sampling was used to create 2500 examples for training, validation, and testing. A multi-layer feed-forward neural network (MFNN) was used as a deep learning agent to train the ML model. The model showed excellent performance in predicting stiffness parameters [Formula: see text] and [Formula: see text] associated with fiber direction ([Formula: see text] and [Formula: see text]). After conducting permutation feature importance analysis, the ML performance further improved for [Formula: see text] ([Formula: see text]), and the left ventricular volume and endocardial area were found to be the most critical geometric features for accurate predictions. The ML model predictions were evaluated further in two cases: (i) rat-specific stiffness data measured using ex-vivo mechanical testing, and (ii) patient-specific estimation using FE inverse modeling. Excellent agreements with ML predictions were found for both cases. The trained ML model offers a feasible technology to estimate patient-specific myocardial properties, thus, bridging the gap between EDPVR, as a confounded organ-level metric for tissue stiffness, and intrinsic tissue-level properties. These properties provide incremental information relative to traditional organ-level indices for cardiac function, improving the clinical assessment and prognosis of cardiac diseases.

Takotsubo syndrome and respiratory diseases: a systematic review.

Takotsubo syndrome (TTS) is a rare cardiovascular condition characterized by reversible ventricular dysfunction and a presentation resembling that of acute myocardial infarction. An increasing number of studies has shown the association of respiratory diseases with TTS. Here, we comprehensively reviewed the literature and examined the available evidence for this association. After searching PubMed, EMBASE, and Cochrane Library databases, two investigators independently reviewed 3117 studies published through May 2021. Of these studies, 99 met the inclusion criteria (n = 108 patients). In patients with coexisting respiratory disease and TTS, the most common TTS symptom was dyspnoea (70.48%), followed by chest pain (24.76%) and syncope (2.86%). The most common type of TTS was apical, accounting for 81.13% of cases, followed by the midventricular (8.49%), basal (8.49%), and biventricular (1.89%) types. Among the TTS cases, 39.82% were associated with obstructive lung disease and 38.89% were associated with pneumonia. Coronavirus disease 2019 (COVID-19), which has been increasingly reported in patients with TTS, was identified in 29 of 42 (69.05%) patients with pneumonia. The overall mortality rate for patients admitted for respiratory disease complicated by TTS was 12.50%. Obstructive lung disease and pneumonia are the most frequently identified respiratory triggers of TTS. Medications and invasive procedures utilized in managing respiratory diseases may also contribute to the development of TTS. Furthermore, the diagnosis of TTS triggered by these conditions can be challenging due to its atypical presentation. Future prospective studies are needed to establish appropriate guidelines for managing respiratory disease with concurrent TTS.

Synthesis and evaluation of an anti-MLC1 × anti-CD90 bispecific antibody for targeting and retaining bone-marrow-derived multipotent stromal cells in infarcted myocardium.

A key issue regarding the use of stem cells in cardiovascular regenerative medicine is their retention in target tissues. Here, we have generated and assessed a bispecific antibody heterodimer designed to improve the retention of bone-marrow-derived multipotent stromal cells (BMMSC) in cardiac tissue damaged by myocardial infarction. The heterodimer comprises an anti-human CD90 monoclonal antibody (mAb) (clone 5E10) and an anti-myosin light chain 1 (MLC1) mAb (clone MLM508) covalently cross-linked by a bis-arylhydrazone. We modified the anti-CD90 antibody with a pegylated-4-formylbenzamide moiety to a molar substitution ratio (MSR) of 2.6 and the anti-MLC1 antibody with a 6-hydrazinonicotinamide moiety to a MSR of 0.9. The covalent modifications had no significant deleterious effect on mAb epitope binding. Furthermore, the binding of anti-CD90 antibody to BMMSCs did not prevent their differentiation into adipo-, chondro-, or osteogenic lineages. Modified antibodies were combined under mild conditions (room temperature, pH 6, 1 h) in the presence of a catalyst (aniline) to allow for rapid generation of the covalent bis-arylhydrazone, which was monitored at A(354). We evaluated epitope immunoreactivity for each mAb in the construct. Flow cytometry demonstrated binding of the bispecific construct to BMMSCs that was competed by free anti-CD90 mAb, verifying that modification and cross-linking were not detrimental to the anti-CD90 complementarity-determining region. Similarly, ELISA-based assays demonstrated bispecific antibody binding to plastic-immobilized recombinant MLC1. Excess anti-MLC1 mAb competed for bispecific antibody binding. Finally, the anti-CD90 × anti-MLC1 bispecific antibody construct induced BMMSC adhesion to plastic-immobilized MLC1 that was resistant to shear stress, as measured in parallel-plate flow chamber assays. We used mAbs that bind both human antigens and the respective pig homologues. Thus, the anti-CD90 × anti-MLC1 bispecific antibody may be used in large animal studies of acute myocardial infarction and may provide a starting point for clinical studies.

Autoimmune Rheumatic Diseases: An Update on the Role of Atherogenic Electronegative LDL and Potential Therapeutic Strategies.

Atherosclerosis has been linked with an increased risk of atherosclerotic cardiovascular disease (ASCVD). Autoimmune rheumatic diseases (AIRDs) are associated with accelerated atherosclerosis and ASCVD. However, the mechanisms underlying the high ASCVD burden in patients with AIRDs cannot be explained only by conventional risk factors despite disease-specific factors and chronic inflammation. Nevertheless, the normal levels of plasma low-density lipoprotein (LDL) cholesterol observed in most patients with AIRDs do not exclude the possibility of increased LDL atherogenicity. By using anion-exchange chromatography, human LDL can be divided into five increasingly electronegative subfractions, L1 to L5, or into electropositive and electronegative counterparts, LDL (+) and LDL (-). Electronegative L5 and LDL (-) have similar chemical compositions and can induce adverse inflammatory reactions in vascular cells. Notably, the percentage of L5 or LDL (-) in total LDL is increased in normolipidemic patients with AIRDs. Electronegative L5 and LDL (-) are not recognized by the normal LDL receptor but instead signal through the lectin-like oxidized LDL receptor 1 (LOX-1) to activate inflammasomes involving interleukin 1ß (IL-1ß). Here, we describe the detailed mechanisms of AIRD-related ASCVD mediated by L5 or LDL (-) and discuss the potential targeting of LOX-1 or IL-1ß signaling as new therapeutic modalities for these diseases.

Identification of Phenotypes Among COVID-19 Patients in the United States Using Latent Class Analysis.

BACKGROUND: Coronavirus disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or COVID-19) is a heterogeneous disorder with a complex pathogenesis. Recent studies from Spain and France have indicated that underlying phenotypes may exist among patients admitted to the hospital with COVID-19. Whether those same phenotypes exist in the United States (US) remains unclear. Using latent class analysis (LCA), we sought to determine whether clinical phenotypes exist among patients admitted for COVID-19. METHODS: We reviewed the charts of adult patients who were hospitalized primarily for COVID-19 at Greenwich Hospital and performed LCA using variables based on patient demographics and comorbidities. To further examine the reliability and replicability of the clustering results, we repeated LCA on the cohort of patients who died during hospitalization for COVID-19. RESULTS: Two phenotypes were identified in patients admitted for COVID-19 (N = 483). According to phenotype, patients were designated as cluster 1 (C1) or cluster 2 (C2). C1 (n = 193) consisted of older individuals with more comorbidities and a higher mortality rate (25.4% vs 8.97%, p < 0.001) than patients in C2. C2 (n = 290) consisted of younger individuals who were more likely to be obese, male, and nonwhite, with higher levels of the inflammatory markers C-reactive protein and alanine aminotransferase. When we performed LCA on the cohort of patients who died during hospitalization for COVID-19 (n = 75), we found that the distribution of patient baseline characteristics and comorbidities was similar to that of the entire cohort of patients admitted for COVID-19. CONCLUSION: Using LCA, we identified two clinical phenotypes of patients who were admitted to our hospital for COVID-19. These findings may reflect different pathophysiologic processes that lead to moderate to severe COVID-19 and may be useful for identifying treatment targets and selecting patients with severe COVID-19 disease for future clinical trials.

Prognostic factors of Takotsubo cardiomyopathy: a systematic review.

Takotsubo cardiomyopathy (TCM), characterized by reversible ventricular dysfunction, has similar mortality to acute coronary syndrome. With the growing interest in the diagnosis of and interventions for TCM, many risk factors had been found to affect the prognosis of TCM patients, such as age, sex, and pre-existing diseases. Because of the incomplete understanding of the pathophysiologic mechanism in TCM, evidence-based medical therapy for this condition is lacking. Early intervention on risk factors may improve the outcomes of TCM. In this review, we sought to provide up-to-date evidence on risk factors and medical therapies that affect TCM outcome. We found that male sex, physical triggers, and certain comorbidities such as chronic kidney disease, malignant disease, higher body mass index, sepsis, chronic obstructive pulmonary disease, and anaemia were associated with poor TCM prognosis. In contrast, race, hyperlipidaemia, diabetes mellitus, and mood disorders were not clearly associated with TCM prognosis. We also reviewed the effect of medical therapies on TCM outcome, including angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, ß-blockers, calcium channel blockers, and statins. The evidence that these medications confer a survival benefit on TCM patients is limited. Understanding these prognostic factors could help develop risk-stratification tools for TCM and establish effective prevention and interventions for this not-so-benign condition. Further multicentre clinical studies with large samples and meta-analyses of findings from previous studies are needed to address the inconsistent findings among the many potential risk factors for TCM.