Developmental pathways that orchestrate the fleeting transition of endothelial cells into haematopoietic stem cells remain undefined. Here we demonstrate a tractable approach for fully reprogramming ...adult mouse endothelial cells to haematopoietic stem cells (rEC-HSCs) through transient expression of the transcription-factor-encoding genes Fosb, Gfi1, Runx1, and Spi1 (collectively denoted hereafter as FGRS) and vascular-niche-derived angiocrine factors. The induction phase (days 0-8) of conversion is initiated by expression of FGRS in mature endothelial cells, which results in endogenous Runx1 expression. During the specification phase (days 8-20), RUNX1
FGRS-transduced endothelial cells commit to a haematopoietic fate, yielding rEC-HSCs that no longer require FGRS expression. The vascular niche drives a robust self-renewal and expansion phase of rEC-HSCs (days 20-28). rEC-HSCs have a transcriptome and long-term self-renewal capacity similar to those of adult haematopoietic stem cells, and can be used for clonal engraftment and serial primary and secondary multi-lineage reconstitution, including antigen-dependent adaptive immune function. Inhibition of TGFβ and CXCR7 or activation of BMP and CXCR4 signalling enhanced generation of rEC-HSCs. Pluripotency-independent conversion of endothelial cells into autologous authentic engraftable haematopoietic stem cells could aid treatment of haematological disorders.
RATIONALE:Autologous bone marrow–derived or cardiac-derived stem cell therapy for heart disease has demonstrated safety and efficacy in clinical trials, but functional improvements have been limited. ...Finding the optimal stem cell type best suited for cardiac regeneration is the key toward improving clinical outcomes.
OBJECTIVE:To determine the mechanism by which novel bone-derived stem cells support the injured heart.
METHODS AND RESULTS:Cortical bone–derived stem cells (CBSCs) and cardiac-derived stem cells were isolated from enhanced green fluorescent protein (EGFP+) transgenic mice and were shown to express c-kit and Sca-1 as well as 8 paracrine factors involved in cardioprotection, angiogenesis, and stem cell function. Wild-type C57BL/6 mice underwent sham operation (n=21) or myocardial infarction with injection of CBSCs (n=67), cardiac-derived stem cells (n=36), or saline (n=60). Cardiac function was monitored using echocardiography. Only 2/8 paracrine factors were detected in EGFP+ CBSCs in vivo (basic fibroblast growth factor and vascular endothelial growth factor), and this expression was associated with increased neovascularization of the infarct border zone. CBSC therapy improved survival, cardiac function, regional strain, attenuated remodeling, and decreased infarct size relative to cardiac-derived stem cells– or saline-treated myocardial infarction controls. By 6 weeks, EGFP+ cardiomyocytes, vascular smooth muscle, and endothelial cells could be identified in CBSC-treated, but not in cardiac-derived stem cells–treated, animals. EGFP+ CBSC-derived isolated myocytes were smaller and more frequently mononucleated, but were functionally indistinguishable from EGFP− myocytes.
CONCLUSIONS:CBSCs improve survival, cardiac function, and attenuate remodeling through the following 2 mechanisms(1) secretion of proangiogenic factors that stimulate endogenous neovascularization, and (2) differentiation into functional adult myocytes and vascular cells.
The natriuretic peptides play a vital role in normal physiology and as counter-regulatory hormones in heart failure (HF). Clinical assessment of their levels (for B-type natriuretic peptide BNP, ...N-terminal proBNP, and the midregion of N-terminal pro-atrial natriuretic peptide) have become valuable tools in diagnosing patients with HF as well as risk stratifying and guiding therapy. Their roles have further expanded beyond HF to other cardiovascular conditions and for risk stratification in asymptomatic individuals. Understanding the clinical use of these hormones is vital to achieving their full potential.
Although increased neuropeptides are often detected in lungs that exhibit respiratory distress, whether they contribute to the condition is unknown. Here, we show in a mouse model of neuroendocrine ...cell hyperplasia of infancy, a pediatric disease with increased pulmonary neuroendocrine cells (PNECs), excess PNEC-derived neuropeptides are responsible for pulmonary manifestations including hypoxemia. In mouse postnatal lung, prolonged signaling from elevated neuropeptides such as calcitonin gene-related peptide (CGRP) activate receptors enriched on endothelial cells, leading to reduced cellular junction gene expression, increased endothelium permeability, excess lung fluid, and hypoxemia. Excess fluid and hypoxemia were effectively attenuated by either prevention of PNEC formation, inactivation of CGRP gene, endothelium-specific inactivation of CGRP receptor gene, or treatment with CGRP receptor antagonist. Neuropeptides were increased in human lung diseases with excess fluid such as acute respiratory distress syndrome. Our findings suggest that restricting neuropeptide function may limit fluid and improve gas exchange in these conditions.
Display omitted
•Increased PNECs are responsible for poor gas exchange in a NEHI mouse model•Increased PNECs and CGRP led to impaired endothelial barrier and excess fluid•Antagonizing CGRP signaling improved barrier and oxygenation in NEHI mouse mutants•Increased neuropeptides and reduced endothelial junctions were found in ARDS lungs
Xu et al. show that increased pulmonary neuroendocrine cells (PNECs), and secreted neuropeptides can cause poor gas exchange. In neuroendocrine hyperplasia of infancy (NEHI) mice, increased CGRP from PNECs causes vessel leakage, excess fluid, and poor oxygenation. These findings suggest neuropeptides as therapeutic targets for conditions with excess lung fluid.
All muscle contraction occurs due to the cyclical interaction between sarcomeric thin and thick filament proteins within the myocyte. The thin filament consists of the proteins actin, tropomyosin, ...Troponin C, Troponin I, and Troponin T. Mutations in these proteins can result in various forms of cardiomyopathy, including hypertrophic, restrictive, and dilated phenotypes and account for as many as 30% of all cases of inherited cardiomyopathy. There is significant evidence that thin filament mutations contribute to dysregulation of Ca
2+
within the sarcomere and may have a distinct pathomechanism of disease from cardiomyopathy associated with thick filament mutations. A number of distinct clinical findings appear to be correlated with thin-filament mutations: greater degrees of restrictive cardiomyopathy and relatively less left ventricular (LV) hypertrophy and LV outflow tract obstruction than that seen with thick filament mutations, increased morbidity associated with heart failure, increased arrhythmia burden and potentially higher mortality. Most therapies that improve outcomes in heart failure blunt the neurohormonal pathways involved in cardiac remodeling, while most therapies for hypertrophic cardiomyopathy involve use of negative inotropes to reduce LV hypertrophy or septal reduction therapies to reduce LV outflow tract obstruction. None of these therapies directly address the underlying sarcomeric dysfunction associated with thin-filament mutations. With mounting evidence that thin filament cardiomyopathies occur through a distinct mechanism, there is need for therapies targeting the unique, underlying mechanisms tailored for each patient depending on a given mutation.
SARS-CoV-2 infection-induced aggravation of host innate immune response not only causes tissue damage and multiorgan failure in COVID-19 patients but also induces host genome damage and activates DNA ...damage response pathways. To test whether the compromised DNA repair capacity of individuals modulates the severity of COVID-19 infection, we analyze DNA repair gene expression in publicly available patient datasets and observe a lower level of the DNA glycosylase NEIL2 in the lungs of severely infected COVID-19 patients. This observation of lower NEIL2 levels is further validated in infected patients, hamsters and ACE2 receptor-expressing human A549 (A549-ACE2) cells. Furthermore, delivery of recombinant NEIL2 in A549-ACE2 cells shows decreased expression of proinflammatory genes and viral E-gene, as well as lowers the yield of viral progeny compared to mock-treated cells. Mechanistically, NEIL2 cooperatively binds to the 5'-UTR of SARS-CoV-2 genomic RNA to block viral protein synthesis. Collectively, these data strongly suggest that the maintenance of basal NEIL2 levels is critical for the protective response of hosts to viral infection and disease.
Childhood exposure to potentially traumatic events and adversity is highly prevalent and linked to adverse outcomes. Many children suffering from symptoms related to traumatic stress are not ...identified or do not receive appropriate trauma-focused treatment, including evidence-based treatments. Trauma screening is a promising strategy to improve identification, but many child-serving staff members have concerns about asking youth and caregivers about trauma. This study aimed to describe staff perceptions about the feasibility, utility, and potential for distress associated with trauma screening. Between 2014 and 2019, the Child Trauma Screen was used in 1,272 trauma screenings completed by juvenile probation officers or mental health clinicians as part of routine practice with youth in the juvenile justice system. Further, 1,190 caregiver reports about youth trauma were completed for youth in the juvenile justice system. Staff completed a brief postscreening survey about the feasibility and utility of the screening and the perceived level of child or caregiver distress. Across staff roles, trauma screening was deemed to be feasible and worthwhile to practice, with very few staff members reporting that children or caregivers appeared very uncomfortable as a result of screening, although some differences in feasibility and utility by staff role did occur. Trauma screening measures appear to be useful and practical in juvenile justice settings when appropriate support is provided, including when administered by nonclinical staff. Nonclinical staff may benefit from additional training, consultation, or support with trauma screening.
RATIONALE:Sorafenib is an effective treatment for renal cell carcinoma, but recent clinical reports have documented its cardiotoxicity through an unknown mechanism.
OBJECTIVE:Determining the ...mechanism of sorafenib-mediated cardiotoxicity.
METHODS AND RESULTS:Mice treated with sorafenib or vehicle for 3 weeks underwent induced myocardial infarction (MI) after 1 week of treatment. Sorafenib markedly decreased 2-week survival relative to vehicle-treated controls, but echocardiography at 1 and 2 weeks post MI detected no differences in cardiac function. Sorafenib-treated hearts had significantly smaller diastolic and systolic volumes and reduced heart weights. High doses of sorafenib induced necrotic death of isolated myocytes in vitro, but lower doses did not induce myocyte death or affect inotropy. Histological analysis documented increased myocyte cross-sectional area despite smaller heart sizes after sorafenib treatment, further suggesting myocyte loss. Sorafenib caused apoptotic cell death of cardiac- and bone-derived c-kit+ stem cells in vitro and decreased the number of BrdU+ (5-bromo-2’-deoxyuridine+) myocytes detected at the infarct border zone in fixed tissues. Sorafenib had no effect on infarct size, fibrosis, or post-MI neovascularization. When sorafenib-treated animals received metoprolol treatment post MI, the sorafenib-induced increase in post-MI mortality was eliminated, cardiac function was improved, and myocyte loss was ameliorated.
CONCLUSIONS:Sorafenib cardiotoxicity results from myocyte necrosis rather than from any direct effect on myocyte function. Surviving myocytes undergo pathological hypertrophy. Inhibition of c-kit+ stem cell proliferation by inducing apoptosis exacerbates damage by decreasing endogenous cardiac repair. In the setting of MI, which also causes large-scale cell loss, sorafenib cardiotoxicity dramatically increases mortality.
Purpose of Review
The advent of induced pluripotent stem cells (iPSC) has paved the way for new in vitro models of human cardiomyopathy. Herein, we will review existing models of disease as well as ...strengths and limitations of the system.
Recent Findings
Preclinical studies have now demonstrated that iPSCs generated from patients with both acquired or heritable genetic diseases retain properties of the disease in vitro and can be used as a model to study novel therapeutics. iPSCs can be differentiated in vitro into the cardiomyocyte lineage into cells resembling adult ventricular myocytes that retain properties of cardiovascular disease from their respective donor. iPSC pluripotency allows for them to be frozen, stored, and continually used to generate iPSC-derived myocytes for future experiments without need for invasive procedures or repeat myocyte isolations to obtain animal or human cardiac tissues.
Summary
While not without their limitations, iPSC models offer new ways for studying patient-specific cardiomyopathies. iPSCs offer a high-throughput avenue for drug development, modeling of disease pathophysiology in vitro, and enabling experimental repair strategies without need for invasive procedures to obtain cardiac tissues.
Neutrophils can function and survive in injured and infected tissues, where oxygen and metabolic substrates are limited. Using radioactive flux assays and LC-MS tracing with U-13C glucose, glutamine, ...and pyruvate, we observe that neutrophils require the generation of intracellular glycogen stores by gluconeogenesis and glycogenesis for effective survival and bacterial killing. These metabolic adaptations are dynamic, with net increases in glycogen stores observed following LPS challenge or altitude-induced hypoxia. Neutrophils from patients with chronic obstructive pulmonary disease have reduced glycogen cycling, resulting in impaired function. Metabolic specialization of neutrophils may therefore underpin disease pathology and allow selective therapeutic targeting.
Display omitted
•Neutrophils utilize gluconeogenesis (GNG) to generate glycogen stores•Glycogenesis is essential for neutrophil survival and function•Defective glycogen cycling impairs neutrophil function in COPD•Glycogen cycling underpins the metabolic specialization of neutrophils
Neutrophils are required to meet their energy demands at inflamed sites where nutrients may be limited. Sadiku et al. provide evidence of a specialized metabolism that enables neutrophils to utilize glycogen cycling for energy production. This is essential for neutrophil function and survival, and dysregulation is associated with chronic disease states.
PDF
