Publications
366 results found
Ferrini A, Skaalure S, Furtado MB, et al., 2020, 4D ECHOCARDIOGRAPHY AND MYOCARDIAL MECHANICS ASSESSMENT FOLLOWING INJECTION OF A THERMORESPONSIVE HYDROGEL FOR HEART FAILURE TREATMENT, Publisher: SPRINGER, Pages: 282-282
Forte E, Skelly DA, Chen M, et al., 2020, Dynamic interstitial cell response during myocardial infarction predicts resilience to rupture in genetically diverse mice, Cell Reports, Vol: 30, Pages: 3149-3163.e6, ISSN: 2211-1247
Cardiac ischemia leads to the loss of myocardial tissue and the activation of a repair process that culminates in the formation of a scar whose structural characteristics dictate propensity to favorable healing or detrimental cardiac wall rupture. To elucidate the cellular processes underlying scar formation, here we perform unbiased single-cell mRNA sequencing of interstitial cells isolated from infarcted mouse hearts carrying a genetic tracer that labels epicardial-derived cells. Sixteen interstitial cell clusters are revealed, five of which were of epicardial origin. Focusing on stromal cells, we define 11 sub-clusters, including diverse cell states of epicardial- and endocardial-derived fibroblasts. Comparing transcript profiles from post-infarction hearts in C57BL/6J and 129S1/SvImJ inbred mice, which displays a marked divergence in the frequency of cardiac rupture, uncovers an early increase in activated myofibroblasts, enhanced collagen deposition, and persistent acute phase response in 129S1/SvImJ mouse hearts, defining a crucial time window of pathological remodeling that predicts disease outcome.
Sattler S, Baxan N, Chowdhury R, et al., 2019, Characterization of acute TLR-7 agonist-induced hemorrhagic myocarditis in mice by multi-parametric quantitative cardiac MRI, Disease Models & Mechanisms, Vol: 12, Pages: 1-10, ISSN: 1754-8403
Hemorrhagic myocarditis is a potentially fatal complication of excessive levels of systemic inflammation. It has been reported in viral infection, but is also possible in systemic autoimmunity. Epicutaneous treatment of mice with the TLR-7 agonist Resiquimod induces auto-antibodies and systemic tissue damage including in the heart, and is used as an inducible mouse model of Systemic Lupus Erythematosus (SLE).Here, we show that over-activation of the TLR-7 pathway of viral recognition by Resiquimod-treatment of CFN mice induces severe thrombocytopenia and internal bleeding which manifests most prominently as hemorrhagic myocarditis. We optimized a cardiac magnetic resonance (CMR) tissue mapping approach for the in vivo detection of diffuse infiltration, fibrosis and hemorrhages using a combination of T1, T2 and T2* relaxation times, and compared results to ex vivo histopathology of cardiac sections corresponding to CMR tissue maps. This allowed a detailed correlation between in vivo CMR parameters and ex vivo histopathology, and confirmed the need to include T2* measurements to detect tissue iron for accurate interpretation of pathology associated with CMR parameter changes.In summary, we provide detailed histological and in vivo imaging-based characterization of acute hemorrhagic myocarditis as acute cardiac complication in the mouse model of Resiquimod-induced SLE, and a refined CMR protocol to allow non-invasive longitudinal in vivo studies of heart involvement in acute inflammation. We propose that adding T2* mapping to CMR protocols for myocarditis diagnosis will improve interpretation of disease mechanisms and diagnostic sensitivity.
Ascenzi F, Barberi L, Dobrowolny G, et al., 2019, Effects of IGF-1 isoforms on muscle growth and sarcopenia, Aging Cell, Vol: 18, ISSN: 1474-9718
The decline in skeletal muscle mass and strength occurring in aging, referred as sarcopenia, is the result of many factors including an imbalance between protein synthesis and degradation, changes in metabolic/hormonal status, and in circulating levels of inflammatory mediators. Thus, factors that increase muscle mass and promote anabolic pathways might be of therapeutic benefit to counteract sarcopenia. Among these, the insulin‐like growth factor‐1 (IGF‐1) has been implicated in many anabolic pathways in skeletal muscle. IGF‐1 exists in different isoforms that might exert different role in skeletal muscle. Here we study the effects of two full propeptides IGF‐1Ea and IGF‐1Eb in skeletal muscle, with the aim to define whether and through which mechanisms their overexpression impacts muscle aging. We report that only IGF‐1Ea expression promotes a pronounced hypertrophic phenotype in young mice, which is maintained in aged mice. Nevertheless, examination of aged transgenic mice revealed that the local expression of either IGF‐1Ea or IGF‐1Eb transgenes was protective against age‐related loss of muscle mass and force. At molecular level, both isoforms activate the autophagy/lysosome system, normally altered during aging, and increase PGC1‐α expression, modulating mitochondrial function, ROS detoxification, and the basal inflammatory state occurring at old age. Moreover, morphological integrity of neuromuscular junctions was maintained and preserved in both MLC/IGF‐1Ea and MLC/IGF‐1Eb mice during aging. These data suggest that IGF‐1 is a promising therapeutic agent in staving off advancing muscle weakness.
Ferrini A, Stevens MM, Sattler S, et al., 2019, Toward regeneration of the heart: Bioengineering strategies for immunomodulation, Frontiers in Cardiovascular Medicine, Vol: 6, ISSN: 2297-055X
Myocardial Infarction (MI) is the most common cardiovascular disease. An average-sized MI causes the loss of up to 1 billion cardiomyocytes and the adult heart lacks the capacity to replace them. Although post-MI treatment has dramatically improved survival rates over the last few decades, more than 20% of patients affected by MI will subsequently develop heart failure (HF), an incurable condition where the contracting myocardium is transformed into an akinetic, fibrotic scar, unable to meet the body's need for blood supply. Excessive inflammation and persistent immune auto-reactivity have been suggested to contribute to post-MI tissue damage and exacerbate HF development. Two newly emerging fields of biomedical research, immunomodulatory therapies and cardiac bioengineering, provide potential options to target the causative mechanisms underlying HF development. Combining these two fields to develop biomaterials for delivery of immunomodulatory bioactive molecules holds great promise for HF therapy. Specifically, minimally invasive delivery of injectable hydrogels, loaded with bioactive factors with angiogenic, proliferative, anti-apoptotic and immunomodulatory functions, is a promising route for influencing the cascade of immune events post-MI, preventing adverse left ventricular remodeling, and offering protection from early inflammation to fibrosis. Here we provide an updated overview on the main injectable hydrogel systems and bioactive factors that have been tested in animal models with promising results and discuss the challenges to be addressed for accelerating the development of these novel therapeutic strategies.
Sintou A, Rifai SE, Mansfield C, et al., 2019, Persistent anti-heart autoimmunity causes cardiomyocyte damage in chronic heart failure, Publisher: bioRxiv
Although clinicians and researchers have long appreciated the detrimental effects of excessive acute inflammation after myocardial infarction (MI), less is known about the role of the adaptive immune system in MI complications including heart failure. Yet, abundant cardiac self-antigens released from necrotic cardiomyocytes in a highly inflammatory environment are likely to overwhelm peripheral mechanisms of immunological self-tolerance and adaptive auto-reactivity against the heart may cause ongoing tissue destruction and exacerbate progression to chronic heart failure (CHF). Here, we confirm that the adaptive immune system is indeed persistently active in CHF due to ischemic heart disease triggered by MI in rats. Heart draining mediastinal lymph nodes contain active secondary follicles with mature class-switched IgG2a positive cells, and mature anti-heart auto-antibodies binding to cardiac epitopes are still present in serum as late as 16 weeks after MI. When applied to healthy cardiomyocytes in vitro, humoral factors present in CHF serum promoted apoptosis, cytotoxicity and signs of hypertrophy. These findings directly implicate post-MI autoimmunity as an integral feature of CHF progression, constituting a roadblock to effective regeneration and a promising target for therapeutic intervention.
Salimova E, Nowak KJ, Estrada AC, et al., 2019, Variable outcomes of human heart attack recapitulated in genetically diverse mice, npj Regenerative Medicine, Vol: 4, Pages: 1-15, ISSN: 2057-3995
Clinical variation in patient responses to myocardial infarction (MI) has been difficult to model in laboratory animals. To assess the genetic basis of variation in outcomes after heart attack, we characterized responses to acute MI in the Collaborative Cross (CC), a multi-parental panel of genetically diverse mouse strains. Striking differences in post-MI functional, morphological, and myocardial scar features were detected across 32 CC founder and recombinant inbred strains. Transcriptomic analyses revealed a plausible link between increased intrinsic cardiac oxidative phosphorylation levels and MI-induced heart failure. The emergence of significant quantitative trait loci for several post-MI traits indicates that utilizing CC strains is a valid approach for gene network discovery in cardiovascular disease, enabling more accurate clinical risk assessment and prediction.
Brito L, Mylonaki I, Moroz E, et al., 2019, Epicardial cell transfection with cationic polymeric nanocomplexes, British-Society-for-Gene-and-Cell-Therapy Autumn Conference, Publisher: MARY ANN LIEBERT, INC, Pages: A9-A9, ISSN: 1043-0342
Paracrine signalling has been shown to contribute to heart regeneration after myocardial infarction (MI). As an important signalling regulatory centre, the epicardium is crucial for the heart development. Moreover, it is re-activated after MI, indicating its involvement in the response to this injury. This project aims to accomplish in situ transfection of the epicardium to stimulate the regenerative signalling pathways after MI.Here an in vitro proof of concept of epicardial cell transfection with nanocomplexes is presented. pABOL polyplexes, resulting from complexation of a bioreducible polymer with a GFP gene plasmid (pCAG-GFP), were able to transfect epicardial cells when added in suspension to the culture. The pCAG-GFP-pABOL polyplexes formulation was the most suitable when compared to Lipofectamine, Fugene or naked plasmid, revealing 45.9±9.7% of cell viability and 39.4±6.4% of transfection efficiency. Moreover, the freeze-drying of the pABOL polyplexes was tested. pABOL polyplexes formed in water and in the different sugar/surfactants HEPES buffers. The ζ-potential of these polyplexes ranged between +20 and +30mV. After the freeze-drying, pABOL polyplexes only maintained their transfection activity when formed in sugar-containing buffers.These preliminary results indicate for the first time the advantage of using pABOL polymer in comparison with standard transfection reagents for epicardial cells transfection and the possibility of retaining transfection activity of pABOL polyplexes when freeze-dried. Our final aim is to use nanoneedles, which can transfer substances to the epicardial layer alone, to deliver these polyplexes.
Wilmanns JC, Pandey R, Hon O, et al., 2019, Metformin intervention prevents cardiac dysfunction in a murine model of adult congenital heart disease, Molecular Metabolism, Vol: 20, Pages: 102-114, ISSN: 2212-8778
OBJECTIVE: Congenital heart disease (CHD) is the most frequent birth defect worldwide. The number of adult patients with CHD, now referred to as ACHD, is increasing with improved surgical and treatment interventions. However the mechanisms whereby ACHD predisposes patients to heart dysfunction are still unclear. ACHD is strongly associated with metabolic syndrome, but how ACHD interacts with poor modern lifestyle choices and other comorbidities, such as hypertension, obesity, and diabetes, is mostly unknown. METHODS: We used a newly characterized mouse genetic model of ACHD to investigate the consequences and the mechanisms associated with combined obesity and ACHD predisposition. Metformin intervention was used to further evaluate potential therapeutic amelioration of cardiac dysfunction in this model. RESULTS: ACHD mice placed under metabolic stress (high fat diet) displayed decreased left ventricular ejection fraction. Comprehensive physiological, biochemical, and molecular analysis showed that ACHD hearts exhibited early changes in energy metabolism with increased glucose dependence as main cardiac energy source. These changes preceded cardiac dysfunction mediated by exposure to high fat diet and were associated with increased disease severity. Restoration of metabolic balance by metformin administration prevented the development of heart dysfunction in ACHD predisposed mice. CONCLUSIONS: This study reveals that early metabolic impairment reinforces heart dysfunction in ACHD predisposed individuals and diet or pharmacological interventions can be used to modulate heart function and attenuate heart failure. Our study suggests that interactions between genetic and metabolic disturbances ultimately lead to the clinical presentation of heart failure in patients with ACHD. Early manipulation of energy metabolism may be an important avenue for intervention in ACHD patients to prevent or delay onset of heart failure and secondary comorbidities. These interactions raise
Costa MW, Hasham MG, Rosenthal N, 2019, Molecular Tools in Cancer Research, Abeloff’s Clinical Oncology, Pages: 2-23, ISBN: 9780323476744
Our understanding and treatment of cancer have always relied heavily on parallel developments in biologic research. Molecular biology provides the basic tools to study genes involved with cancer growth patterns and tumor suppression. An advanced understanding of the molecular processes governing cell growth and differentiation has revolutionized the diagnosis, prognosis, and treatment of malignant disorders. This introductory chapter relates basic principles of molecular biology to emerging perspectives on the origin and progression of cancer, and explains newly developed laboratory techniques, including whole genome analysis, expression profiling, and refined genetic manipulation in and use of genetically diverse animal models, providing the conceptual and technical background necessary to grasp the central principles and new methods of current cancer research.
Rosenthal N, Kress M, Gruss P, et al., 2019, BK Viral enhancer element and a human cellular homolog, Biotechnology and Biological Frontiers, Pages: 351-364, ISBN: 9780367020460
Identification of elements that control the initiation of transcription is a crucial step in understanding the regulation of eukaryotic gene expression. Approaches to the problem of transcriptional control with animal viruses as a model system have recently uncovered transcriptional regulatory elements, called enhancers. This chapter utilizes the human papovavirus BKV as a viral model of eukaryotic transcriptional control. The 68-bp BKV triplication functions as an enhancer element for gene expression in a number of cell types without a pronounced host cell preference. To investigate the possibility that viral enhancers may have cellular homologs, we screened a human genomic λ library for sequences related to the BKV tandem triplication with the 216-bp BKV Hae III fragment as a probe. The sequence length and arrangement of the human genomic tandem repeats is different from that of the BKV enhancer, certain similarities such as the core region and the glycoprotein-rich hexanucleotides are impressive.
Lavine KJ, Pinto AR, Epelman S, et al., 2018, The macrophage in cardiac homeostasis and disease JACC macrophage in CVD series (Part 4), Journal of the American College of Cardiology, Vol: 72, Pages: 2213-2230, ISSN: 0735-1097
Macrophages are integral components of cardiac tissue and exert profound effects on the healthy and diseased heart. Paradigm shifting studies using advanced molecular techniques have revealed significant complexity within these macrophage populations that reside in the heart. In this final of a 4-part review series covering the macrophage in cardiovascular disease, the authors review the origins, dynamics, cell surface markers, and respective functions of each cardiac macrophage subset identified to date, including in the specific scenarios of myocarditis and after myocardial infarction. Looking ahead, a deeper understanding of the diverse and often dichotomous functions of cardiac macrophages will be essential for the development of targeted therapies to mitigate injury and orchestrate recovery of the diseased heart. Moreover, as macrophages are critical for cardiac healing, they are an emerging focus for therapeutic strategies aimed at minimizing cardiomyocyte death, ameliorating pathological cardiac remodeling, and for treating heart failure and after myocardial infarction.
Forte E, Furtado MB, Rosenthal N, 2018, The interstitium in cardiac repair: role of the immune-stromal cell interplay, Nature Reviews Cardiology, Vol: 15, Pages: 601-616, ISSN: 1759-5002
Cardiac regeneration, that is, restoration of the original structure and function in a damaged heart, differs from tissue repair, in which collagen deposition and scar formation often lead to functional impairment. In both scenarios, the early-onset inflammatory response is essential to clear damaged cardiac cells and initiate organ repair, but the quality and extent of the immune response vary. Immune cells embedded in the damaged heart tissue sense and modulate inflammation through a dynamic interplay with stromal cells in the cardiac interstitium, which either leads to recapitulation of cardiac morphology by rebuilding functional scaffolds to support muscle regrowth in regenerative organisms or fails to resolve the inflammatory response and produces fibrotic scar tissue in adult mammals. Current investigation into the mechanistic basis of homeostasis and restoration of cardiac function has increasingly shifted focus away from stem cell-mediated cardiac repair towards a dynamic interplay of cells composing the less-studied interstitial compartment of the heart, offering unexpected insights into the immunoregulatory functions of cardiac interstitial components and the complex network of cell interactions that must be considered for clinical intervention in heart diseases.
Panahi M, Papanikolaou A, Torabi A, et al., 2018, Immunomodulatory interventions in myocardial infarction and heart failure: a systematic review of clinical trials and meta-analysis of IL-1 inhibition, Cardiovascular Research, Vol: 114, Pages: 1445-1461, ISSN: 1755-3245
Following a myocardial infarction (MI), the immune system helps to repair ischaemic damage and restore tissue integrity, but excessive inflammation has been implicated in adverse cardiac remodelling and development towards heart failure (HF). Pre-clinical studies suggest that timely resolution of inflammation may help prevent HF development and progression. Therapeutic attempts to prevent excessive post-MI inflammation in patients have included pharmacological interventions ranging from broad immunosuppression to immunomodulatory approaches targeting specific cell types or factors with the aim to maintain beneficial aspects of the early post-MI immune response. These include the blockade of early initiators of inflammation including reactive oxygen species and complement, inhibition of mast cell degranulation and leucocyte infiltration, blockade of inflammatory cytokines, and inhibition of adaptive B and T-lymphocytes. Herein, we provide a systematic review on post-MI immunomodulation trials and a meta-analysis of studies targeting the inflammatory cytokine Interleukin-1. Despite an enormous effort into a significant number of clinical trials on a variety of targets, a striking heterogeneity in study population, timing and type of treatment, and highly variable endpoints limits the possibility for meaningful meta-analyses. To conclude, we highlight critical considerations for future studies including (i) the therapeutic window of opportunity, (ii) immunological effects of routine post-MI medication, (iii) stratification of the highly diverse post-MI patient population, (iv) the potential benefits of combining immunomodulatory with regenerative therapies, and at last (v) the potential side effects of immunotherapies.
Tichy ED, Sidibe DK, Greer CD, et al., 2018, A robust Pax7EGFP mouse that enables the visualization of dynamic behaviors of muscle stem cells, SKELETAL MUSCLE, Vol: 8, ISSN: 2044-5040
BackgroundPax7 is a transcription factor involved in the specification and maintenance of muscle stem cells (MuSCs). Upon injury, MuSCs leave their quiescent state, downregulate Pax7 and differentiate, contributing to skeletal muscle regeneration. In the majority of regeneration studies, MuSCs are isolated by fluorescence-activated sorting (FACS), based on cell surface markers. It is known that MuSCs are a heterogeneous population and only a small percentage of isolated cells are true stem cells that are able to self-renew. A strong Pax7 reporter line would be valuable to study the in vivo behavior of Pax7-expressing stem cells.MethodsWe generated and characterized the muscle properties of a new transgenic Pax7EGFP mouse. Utilizing traditional immunofluorescence assays, we analyzed whole embryos and muscle sections by fluorescence microscopy, in addition to whole skeletal muscles by 2-photon microscopy, to detect the specificity of EGFP expression. Skeletal muscles from Pax7EGFP mice were also evaluated in steady state and under injury conditions. Finally, MuSCs-derived from Pax7EGFP and control mice were sorted and analyzed by FACS and their myogenic activity was comparatively examined.ResultsOur studies provide a new Pax7 reporter line with robust EGFP expression, detectable by both flow cytometry and fluorescence microscopy. Pax7EGFP-derived MuSCs have identical properties to that of wild-type MuSCs, both in vitro and in vivo, excluding any positional effect due to the transgene insertion. Furthermore, we demonstrated high specificity of EGFP to label MuSCs in a temporal manner that recapitulates the reported Pax7 expression pattern. Interestingly, immunofluorescence analysis showed that the robust expression of EGFP marks cells in the satellite cell position of adult muscles in fixed and live tissues.ConclusionsThis mouse could be an invaluable tool for the study of a variety of questions related to MuSC biology, including but not limited to population heterogen
Panahi M, Papanikolaou A, Khan H, et al., 2018, A systematic review and meta-analysis of anti-cytokine therapies targeting IL-1 and TNF- A in myocardial infarction and heart failure, European-Society-of-Cardiology Congress, Publisher: European Society of Cardiology, Pages: 599-599, ISSN: 0195-668X
Yucel N, Chang AC, Day JW, et al., 2018, Humanizing the mdx mouse model of DMD: the long and the short of it, npj Regenerative Medicine, Vol: 3, Pages: 1-11, ISSN: 2057-3995
Duchenne muscular dystrophy (DMD) is a common fatal heritable myopathy, with cardiorespiratory failure occurring by the third decade of life. There is no specific treatment for DMD cardiomyopathy, in large part due to a lack of understanding of the mechanisms underlying the cardiac failure. Mdx mice, which have the same dystrophin mutation as human patients, are of limited use, as they do not develop early dilated cardiomyopathy as seen in patients. Here we summarize the usefulness of the various commonly used DMD mouse models, highlight a model with shortened telomeres like humans, and identify directions that warrant further investigation.
Padron-Barthe L, Villalba-Orero M, Gomez-Salinero JM, et al., 2018, Activation of Serine One-Carbon Metabolism by Calcineurin A beta 1 Reduces Myocardial Hypertrophy and Improves Ventricular Function, JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, Vol: 71, Pages: 654-667, ISSN: 0735-1097
BackgroundIn response to pressure overload, the heart develops ventricular hypertrophy that progressively decompensates and leads to heart failure. This pathological hypertrophy is mediated, among others, by the phosphatase calcineurin and is characterized by metabolic changes that impair energy production by mitochondria.ObjectivesThe authors aimed to determine the role of the calcineurin splicing variant CnAβ1 in the context of cardiac hypertrophy and its mechanism of action.MethodsTransgenic mice overexpressing CnAβ1 specifically in cardiomyocytes and mice lacking the unique C-terminal domain in CnAβ1 (CnAβ1Δi12 mice) were used. Pressure overload hypertrophy was induced by transaortic constriction. Cardiac function was measured by echocardiography. Mice were characterized using various molecular analyses.ResultsIn contrast to other calcineurin isoforms, the authors show here that cardiac-specific overexpression of CnAβ1 in transgenic mice reduces cardiac hypertrophy and improves cardiac function. This effect is mediated by activation of serine and one-carbon metabolism, and the production of antioxidant mediators that prevent mitochondrial protein oxidation and preserve ATP production. The induction of enzymes involved in this metabolic pathway by CnAβ1 is dependent on mTOR activity. Inhibition of serine and one-carbon metabolism blocks the beneficial effects of CnAβ1. CnAβ1Δi12 mice show increased cardiac hypertrophy and declined contractility.ConclusionsThe metabolic reprogramming induced by CnAβ1 redefines the role of calcineurin in the heart and shows for the first time that activation of the serine and one-carbon pathway has beneficial effects on cardiac hypertrophy and function, paving the way for new therapeutic approaches.
Skelly DA, Squiers GT, McLellan MA, et al., 2018, Single-cell transcriptional profiling reveals cellular diversity and intercommunication in the mouse heart, Cell Reports, Vol: 22, Pages: 600-610, ISSN: 2211-1247
Characterization of the cardiac cellulome, the network of cells that form the heart, is essential for understanding cardiac development and normal organ function and for formulating precise therapeutic strategies to combat heart disease. Recent studies have reshaped our understanding of cardiac cellular composition and highlighted important functional roles for non-myocyte cell types. In this study, we characterized single-cell transcriptional profiles of the murine non-myocyte cardiac cellular landscape using single-cell RNA sequencing (scRNA-seq). Detailed molecular analyses revealed the diversity of the cardiac cellulome and facilitated the development of techniques to isolate understudied cardiac cell populations, such as mural cells and glia. Our analyses also revealed extensive networks of intercellular communication and suggested prevalent sexual dimorphism in gene expression in the heart. This study offers insights into the structure and function of the mammalian cardiac cellulome and provides an important resource that will stimulate studies in cardiac cell biology.
Hasham M, Baxan N, Dent O, et al., 2017, Heart disease in systemic autoimmunity; an inducible mouse model to study regenerative processes and therapies under inflammatory conditions, Annual Conference of the British-Society-for-Gene-and-Cell-Therapy / Joint UK-Regenerative-Medicine-Platform Meeting, Publisher: MARY ANN LIEBERT, INC, Pages: A20-A21, ISSN: 1043-0342
Godwin JW, Debuque R, Salimova E, et al., 2017, Heart regeneration in the salamander relies on macrophage-mediated control of fibroblast activation and the extracellular landscape, npj Regenerative Medicine, Vol: 2, ISSN: 2057-3995
In dramatic contrast to the poor repair outcomes for humans and rodent models such as mice, salamanders and some fish species are able to completely regenerate heart tissue following tissue injury, at any life stage. This capacity for complete cardiac repair provides a template for understanding the process of regeneration and for developing strategies to improve human cardiac repair outcomes. Using a cardiac cryo-injury model we show that heart regeneration is dependent on the innate immune system, as macrophage depletion during early time points post-injury results in regeneration failure. In contrast to the transient extracellular matrix that normally accompanies regeneration, this intervention resulted in a permanent, highly cross-linked extracellular matrix scar derived from alternative fibroblast activation and lysyl-oxidase enzyme synthesis. The activation of cardiomyocyte proliferation was not affected by macrophage depletion, indicating that cardiomyocyte replacement is an independent feature of the regenerative process, and is not sufficient to prevent fibrotic progression. These findings highlight the interplay between macrophages and fibroblasts as an important component of cardiac regeneration, and the prevention of fibrosis as a key therapeutic target in the promotion of cardiac repair in mammals.
Rosenthal N, 2017, A Guardian of the Heartbeat, NEW ENGLAND JOURNAL OF MEDICINE, Vol: 377, Pages: 84-86, ISSN: 0028-4793
Sattler S, Fairchild P, Watt F, et al., 2017, The adaptive immune response to cardiac injury-the true roadblock to effective regenerative therapies?, npj Regenerative Medicine, Vol: 2, ISSN: 2057-3995
The regenerative capacity of adult human tissues and organs is limited, but recent developments have seen the advent of promising new technologies for regenerative therapy. The human heart is of particular interest for regenerative medicine, as cardiac tissue damage is repaired by the formation of rigid scar tissue, which causes inevitable structural changes and progressive functional decline leading to heart failure. Cardiac regenerative medicine aims to prevent scar formation or replace existing scars to halt or reverse adverse remodeling and therapeutic approaches include the use of biomaterials, gene therapies, delivery of growth factors and (stem) cell therapies. Regenerative therapies, however, face significant obstacles in a hostile microenvironment. While the early immune response to a myocardial infarct is essential to ensure tissue integrity and to avoid fatal cardiac rupture, excessive activation of endogenous repair mechanisms may lead to ongoing inflammation, fibrosis and sustained autoimmune-mediated tissue damage. Anti-cardiac auto-reactivity of the adaptive immune system has been suggested to be involved in structural remodeling, functional decline and the development of heart failure. It is, therefore, crucial to first understand the endogenous response to cardiac tissue damage and how to restore immune tolerance to cardiac tissue, before additional regenerative therapies can achieve their full potential.
Arumugam TV, Manzanero S, Furtado M, et al., 2017, An atypical role for the myeloid receptor Mincle in central nervous system injury, Journal of Cerebral Blood Flow and Metabolism, Vol: 37, Pages: 2098-2111, ISSN: 0271-678X
The C-type lectin Mincle is implicated in innate immune responses to sterile inflammation, but its contribution to associated pathologies is not well understood. Herein, we show that Mincle exacerbates neuronal loss following ischemic but not traumatic spinal cord injury. Loss of Mincle was beneficial in a model of transient middle cerebral artery occlusion but did not alter outcomes following heart or gut ischemia. High functional scores in Mincle KO animals using the focal cerebral ischemia model were accompanied by reduced lesion size, fewer infiltrating leukocytes and less neutrophil-derived cytokine production than isogenic controls. Bone marrow chimera experiments revealed that the presence of Mincle in the central nervous system, rather than recruited immune cells, was the critical regulator of a poor outcome following transient middle cerebral artery occlusion. There was no evidence for a direct role for Mincle in microglia or neural activation, but expression in a subset of macrophages resident in the perivascular niche provided new clues on Mincle's role in ischemic stroke.
Ta-Shma A, Zhang K, Salimova E, et al., 2017, Congenital valvular defects associated with deleterious mutations in the PLD1 gene, Journal of Medical Genetics, Vol: 54, Pages: 278-286, ISSN: 0022-2593
Background The underlying molecular aetiology of congenital heart defects is largely unknown. The aim of this study was to explore the genetic basis of non-syndromic severe congenital valve malformations in two unrelated families.Methods Whole-exome analysis was used to identify the mutations in five patients who suffered from severe valvular malformations involving the pulmonic, tricuspid and mitral valves. The significance of the findings was assessed by studying sporulation of yeast carrying a homologous Phospholipase D (PLD1) mutation, in situ hybridisation in chick embryo and echocardiography and histological examination of hearts of PLD1 knockout mice.Results Three mutations, p.His442Pro, p.Thr495fs32* and c.2882+2T>C, were identified in the PLD1 gene. The mutations affected highly conserved sites in the PLD1 protein and the p.His442Pro mutation produced a strong loss of function phenotype in yeast homologous mutant strain. Here we show that in chick embryos PLD1 expression is confined to the forming heart (E2–E8) and homogeneously expressed all over the heart during days E2–E3. Thereafter its expression decreases, remaining only adjacent to the atrioventricular valves and the right ventricular outflow tract. This pattern of expression follows the known dynamic patterning of apoptosis in the developing heart, consistent with the known role of PLD1 in the promotion of apoptosis. In hearts of PLD1 knockout mice, we detected marked tricuspid regurgitation, right atrial enlargement, and increased flow velocity, narrowing and thickened leaflets of the pulmonic valve.Conclusions The findings support a role for PLD1 in normal heart valvulogenesis.
Kennedy-Lydon T, Rosenthal N, 2017, Cardiac regeneration: All work and no repair?, Science Translational Medicine, Vol: 9, Pages: 1-5, ISSN: 1946-6234
Structural changes in the developing heart may influence the limited regenerative capacity of the adult heart. We examine how the workload exerted on the adult mammalian heart may limit regenerative capability and discuss recent therapies that demonstrate beneficial effects through unloading the heart.
Furtado MB, Wilmanns JC, Chandran A, et al., 2017, Point mutations in murine Nkx2-5 phenocopy human congenital heart disease and induce pathogenic Wnt signaling, JCI insight, Vol: 2, ISSN: 2379-3708
Mutations in the Nkx2-5 gene are a main cause of congenital heart disease. Several studies haveaddressed the phenotypic consequences of disrupting the Nkx2-5 gene locus, although animalmodels to date failed to recapitulate the full spectrum of the human disease. Here, we describea new Nkx2-5 point mutation murine model, akin to its human counterpart disease–generatingmutation. Our model fully reproduces the morphological and physiological clinical presentationsof the disease and reveals an understudied aspect of Nkx2-5–driven pathology, a primary rightventricular dysfunction. We further describe the molecular consequences of disrupting thetranscriptional network regulated by Nkx2-5 in the heart and show that Nkx2-5–dependentperturbation of the Wnt signaling pathway promotes heart dysfunction through alteration ofcardiomyocyte metabolism. Our data provide mechanistic insights on how Nkx2-5 regulates heartfunction and metabolism, a link in the study of congenital heart disease, and confirms that ourmodels are the first murine genetic models to our knowledge to present all spectra of clinicallyrelevant adult congenital heart disease phenotypes generated by NKX2-5 mutations in patients.
McLellan MA, Rosenthal NA, Pinto AR, 2017, Cre-loxP-Mediated Recombination: General Principles and Experimental Considerations., Curr Protoc Mouse Biol, Vol: 7, Pages: 1-12
The cre-loxP-mediated recombination system (the "cre-loxP system") is an integral experimental tool for mammalian genetics and cell biology. Use of the system has greatly expanded our ability to precisely interrogate gene function in the mouse, providing both spatial and temporal control of gene expression. This has been largely due to the simplicity of its use and its adaptability to address diverse biological questions. While the use of the cre-loxP system is becoming increasingly widespread, in particular because of growing availability of conditional mouse mutants, many considerations need to be taken into account when utilizing the cre-loxP system. This review provides an overview of the cre-loxP system and its various permutations. It addresses the limitations of cre-loxP technology and related considerations for experimental design, and it discusses alternative strategies for site-specific genetic recombination and integration. © 2017 by John Wiley & Sons, Inc.
Hasham MG, Baxan N, Stuckey D, et al., 2017, Systemic autoimmunity induced by Toll-like receptor 7/8 agonist Resiquimod causes myocarditis and dilated cardiomyopathy: a new model of autoimmune heart disease, Disease Models & Mechanisms, Vol: 10, Pages: 259-270, ISSN: 1754-8411
Systemic autoimmune diseases such as Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA) show significant heart involvement and cardiovascular morbidity, which can be due to systemically increased levels of inflammation or direct autoreactivity targeting cardiac tissue. Despite high clinical relevance, cardiac damage secondary to systemic autoimmunity lacks inducible rodent models. Here we characterize immune-mediated cardiac tissue damage in a new model of SLE induced by topical application of the TLR-7/8 agonist Resiquimod. We observe a cardiac phenotype reminiscent of autoimmune-mediated dilated cardiomyopathy, and identify auto-antibodies as major contributors to cardiac tissue damage. Resiquimod-induced heart disease is a highly relevant mouse model for mechanistic and therapeutic studies aiming to protect the heart during autoimmunity.
Liu ET, Bolcun-Filas E, Grass DS, et al., 2017, Of mice and CRISPR: The post-CRISPR future of the mouse as a model system for the human condition, EMBO Reports, Vol: 18, Pages: 187-193, ISSN: 1469-221X
The usefulness of a specific technology often hits a ceiling based on technical limitations. Then, a single advance, frequently orthogonal to the core methodology, dramatically expands the utility of this technology. The effectiveness of early surgeons wielding a scalpel was severely limited by how much a patient could withstand the pain of an operation. Anesthesia was the core discovery that permitted surgery to become a consistently effective medical intervention. Molecular cloning was a powerful technology to understand the importance of genes in biology, but it had limited utility in population genetics and in medicine, because of the arduous requirements for cloning a single gene. The invention of polymerase chain reaction dramatically expanded the utility of molecular biology into high‐throughput sequencing, epidemiology, forensics, diagnostics, and gene therapy. We believe that the advent of powerful gene editing technologies such as the CRISPR/CAS system will be this transformative technology for murine genetics.
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