Neuregulin-1, a potential therapeutic target for cardiac repair

Cell cycle arrest of cardiomyocytes in the context of cardiac regeneration

The limited capacity of adult mammalian cardiomyocytes to undergo cell division and proliferation is one of the key factors contributing to heart failure. In newborn mice, cardiac proliferation occurs during a brief window, but this proliferative capacity diminishes by 7 days after birth. Current studies on cardiac regeneration focused on elucidating changes in regulatory factors within the heart before and after this proliferative window, aiming to determine whether potential association between these factors and cell cycle arrest in cardiomyocytes. Facilitating the re-entry of cardiomyocytes into the cell cycle or reversing their exit from it represents a critical strategy for cardiac regeneration. This paper provides an overview of the role of cell cycle arrest in cardiac regeneration, briefly describes cardiomyocyte proliferation and cardiac regeneration, and systematically summarizes the regulation of the cell cycle arrest in cardiomyocytes, and the potential metabolic mechanisms underlying cardiomyocyte cycle arrest. Additionally, we highlight the development of cardiovascular disease drugs targeting cardiomyocyte cell cycle regulation and their status in clinical treatment. Our goal is to outline strategies for promoting cardiac regeneration and repair following cardiac injury, while also pointing toward future research directions that may offer new technologies and prospects for treating cardiovascular diseases, such as myocardial infarction, arrhythmia and heart failure.

Developments in Extracellular Matrix-Based Angiogenesis Therapy for Ischemic Heart Disease: A Review of Current Strategies, Methodologies and Future Directions

Ischemic heart disease (IHD) is the leading cause of mortality worldwide, underscoring the urgent need for innovative therapeutic strategies. The cardiac extracellular matrix (ECM) undergoes extreme transformations during IHD, adversely influencing the heart's structure, mechanics, and cellular signaling. Researchers investigating the regenerative capacity of the diseased heart have turned their attention to exploring the modulation of ECM to improve therapeutic outcomes. In this review, we thoroughly examine the current state of knowledge regarding the cardiac ECM and its therapeutic potential in the ischemic myocardium. We begin by providing an overview of the fundamentals of cardiac ECM, focusing on the structural, functional, and regulatory mechanisms that drive its modulation. Subsequently, we examine the ECM's interactions within both chronically ischemic and acutely infarcted myocardium, emphasizing key ECM components and their roles in modulating angiogenesis. Finally, we discuss recent ECM-based approaches in biomedical engineering, focusing on different types of scaffolds as delivery tools and their compositions, and conclude with future directions for therapeutic research. By harnessing the potential of these emerging ECM-based therapies, we aim to contribute to the development of novel therapeutic modalities for IHD.

Protective role of Tongxinluo in mitigating myocardial fibrosis in mice with acute myocardial infarction via neuregulin-1 upregulation and Inhibition of endothelium-interstitial transition

Acute myocardial infarction (AMI) is a leading cause of heart failure, often accompanied by myocardial fibrosis (MF), characterized by excessive extracellular matrix accumulation. Endothelial-to-mesenchymal transition (EndMT) plays a key role in MF progression post-AMI. Neuregulin-1 (NRG-1), a growth factor with cardioprotective properties, has emerged as a potential therapeutic target. Tongxinluo (TXL), a traditional Chinese medicine, mitigates MF by upregulating NRG-1. This study elucidates the mechanisms underlying the protective effects of NRG-1 and TXL against MF following AMI. Left anterior descending artery ligation established a model for mice with AMI. Adeno-associated virus was used to modulate NRG-1 expression in the myocardium. Echocardiography assessed cardiac function, and histological staining was used to evaluate MF. Expression levels of markers for myofibroblasts (α-SMA, FSP-1) and endothelial cells (CD31, VE-cadherin) were analysed to investigate EndMT. The involvement of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signalling pathway in NRG-1's protective mechanism was validated using biochemical methods. Tongxinluo was administered to mice with AMI via gavage for 4 weeks, and its effects on cardiac function, MF and EndMT were assessed. Overexpression of NRG-1 in mice with AMI ameliorated cardiac dysfunction and reduced interstitial and perivascular fibrosis, whereas NRG-1 deficiency exacerbated these effects. NRG-1 protected against EndMT, as evidenced by changes in myofibroblast and endothelial cell markers. The PI3K/AKT signalling pathway was involved in NRG-1's protective mechanism against MF. The administration of TXL to mice with AMI improved cardiac function and reduced MF by activating NRG-1. Furthermore, TXL inhibited EndMT post-AMI through the NRG-1/PI3K/AKT pathway. NRG-1 and TXL protect against MF post-AMI by mitigating EndMT through the PI3K/AKT pathway. These findings suggest that targeting NRG-1 or using TXL may be promising therapeutic strategies for MF following AMI.

Exercise Training After Myocardial Infarction Enhances Endothelial Progenitor Cells Function via NRG-1 Signaling

Vascular regeneration after myocardial infarction (MI) is essential to improve myocardial ischemia, delay post-infarction ventricular remodeling, and improve the long-term prognosis of MI. Endothelial progenitor cells (EPCs) play important roles in the functional repair and homeostatic maintenance of the vascular endothelium. Exercise training stimulates EPC mobilization and increases the number of circulating EPCs, which has beneficial effects on the restoration of vascular integrity and hemodynamic reconstitution. After post-MI exercise training, cardiac function, the myocardial infarct area, and capillary density in the peri-infarct zone were measured. Bone marrow-derived EPCs were isolated from mice to measure the proliferation, migration, and in vitro angiogenesis of EPCs after myocardial infarction exercise. The expression of NRG-1/ErbB4 signaling factor and related proteins in downstream PI3K/AKT signaling pathway were detected, and the level of autocrine NRG-1 in EPCs was detected. Post-MI resistance training, aerobic exercise training, and combined exercise training increased EPC mobilization and proliferation, migration, and tube-forming capacity, promoted myocardial vascular regeneration, improved cardiac function, and reduced infarct size. Exercise training upregulated NRG-1 expression in EPCs, and NRG-1/ErbB4 signaling activated the downstream PI3K/Akt signaling pathway. Moreover, EPCs may have a positive feedback autocrine loop with NRG-1 to improve the function of EPCs and promote vascular repair and regeneration in mice with MI. Exercise training after MI promotes the function of bone marrow-derived EPCs through NRG-1/ErbB4/PI3K/AKT signaling, thus exerting a role in angiogenesis.

Geroscience in heart failure: the search for therapeutic targets in the shared pathobiology of human aging and heart failure

Age is a major risk factor for heart failure, but one that has been historically viewed as non-modifiable. Emerging evidence suggests that the biology of aging is malleable, and can potentially be intervened upon to treat age-associated chronic diseases, such as heart failure. While aging biology represents a new frontier for therapeutic target discovery in heart failure, the challenges of translating Geroscience research to the clinic are multifold. In this review, we propose a strategy that prioritizes initial target discovery in human biology. We review the rationale for starting with human omics, which has generated important insights into the shared (patho)biology of human aging and heart failure. We then discuss how this knowledge can be leveraged to identify the mechanisms of aging biology most relevant to heart failure. Lastly, we provide examples of how this human-first Geroscience approach, when paired with rigorous functional assessments in preclinical models, is leading to early-stage clinical development of gerotherapeutic approaches for heart failure.

Small-molecule-induced ERBB4 activation to treat heart failure

Heart failure is a common and deadly disease requiring new treatments. The neuregulin-1/ERBB4 pathway offers cardioprotective benefits, but using recombinant neuregulin-1 as therapy has limitations due to the need for intravenous delivery and lack of receptor specificity. We hypothesize that small-molecule activation of ERBB4 could protect against heart damage and fibrosis. To test this, we conduct a screening of 10,240 compounds and identify eight structurally similar ones (EF-1 to EF-8) that induce ERBB4 dimerization, with EF-1 being the most effective. EF-1 reduces cell death and hypertrophy in cardiomyocytes and decreases collagen production in cardiac fibroblasts in an ERBB4-dependent manner. In wild-type mice, EF-1 inhibits angiotensin-II-induced fibrosis in males and females and reduces heart damage caused by doxorubicin and myocardial infarction in females, but not in Erbb4-null mice. This study shows that small-molecule ERBB4 activation is feasible and may lead to a novel class of drugs for treating heart failure.

The Complex Connection Between Myocardial Dysfunction and Cancer Beyond Cardiotoxicity: Shared Risk Factors and Common Molecular Pathways

Cardiovascular diseases and cancer represent the largest disease burden worldwide. Previously, these two conditions were considered independent, except in terms of cardiotoxicity, which links cancer treatment to subsequent cardiovascular issues. However, recent studies suggest that there are further connections between cancer and heart disease beyond cardiotoxicity. It has been revealed that myocardial dysfunction may promote carcinogenesis, indicating that additional common pathophysiological mechanisms might be involved in the relationship between cardiology and oncology, rather than simply a connection through cardiotoxic effects. These mechanisms may include shared risk factors and common molecular pathways, such as persistent inflammation and neurohormonal activation. This review explores the connection between myocardial dysfunction and cancer, emphasizing their shared risk factors, similar biological mechanisms, and causative factors like cardiotoxicity, along with their clinical implications.

A region on chromosome 16 is associated with Doberman Pinscher dilated cardiomyopathy

Doberman Pinschers are known for their increased susceptibility to dilated cardiomyopathy (DCM) relative to other domestic dogs. This makes the Doberman Pinscher a key model for gene-disease investigations. We conducted a genome-wide association study (GWAS) leveraging a database of genetic profiles obtained through collaboration with the Doberman Diversity Project (DDP). We worked in parallel to increase the depth and power of the DDP database. We exchanged direct correspondences with listed breeders and owners to establish health updates for participant dogs. In total, our study included data on 216, 184 single nucleotide polymorphisms (SNPs) in 46 cases and 3226 population control Doberman Pinschers. Using a generalized linear mixed model and saddlepoint approximation to correct for unbalanced group sizes, we identified a cluster of SNPs associated with DCM on chromosome 16.

Recent Insights into Endogenous Mammalian Cardiac Regeneration Post-Myocardial Infarction

Myocardial infarction (MI) is a critical global health issue and a leading cause of heart failure. Indeed, while neonatal mammals can regenerate cardiac tissue mainly through cardiomyocyte proliferation, this ability is lost shortly after birth, resulting in the adult heart's inability to regenerate after injury effectively. In adult mammals, the adverse cardiac remodelling, which compensates for the loss of cardiac cells, impairs cardiac function due to the non-contractile nature of fibrotic tissue. Moreover, the neovascularisation after MI is inadequate to restore blood flow to the infarcted myocardium. This review aims to synthesise the most recent insights into the molecular and cellular players involved in endogenous myocardial and vascular regeneration, facilitating the identification of mechanisms that could be targeted to trigger cardiac regeneration, reduce fibrosis, and improve functional recovery post-MI. Reprogramming adult cardiomyocytes to regain their proliferative potential, along with the modulation of target cells responsible for neovascularisation, represents promising therapeutic strategies. An updated overview of endogenous mechanisms that regulate both myocardial and coronary vasculature regeneration-including stem and progenitor cells, growth factors, cell cycle regulators, and key signalling pathways-could help identify new critical intervention points for therapeutic applications.

The role and mechanism of NRG1/ErbB4 in inducing the differentiation of induced pluripotent stem cells into cardiomyocytes

BACKGROUND

We aimed to investigate the effect and potential mechanism of enhancing Neuregulin1 (NRG1)/v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ErbB4) expression on the differentiation of induced pluripotent stem cells (iPSCs) into cardiomyocytes.

METHODS

We utilized CRISPR-CAS9 technology to knock in ErbB4 and obtained a single-cell clone IPSN-AAVS1-CMV-ErbB4 (iPSCs-ErbB4). Subsequently, we induced the differentiation of iPSCs into cardiomyocytes and quantified the number of beating embryoid bodies. Furthermore, quantitative real-time PCR assessed the expression of cardiomyocyte markers, including ANP (atrial natriuretic peptide), Nkx2.5 (NK2 transcription factor related locus 5), and GATA4 (GATA binding protein 4). On the 14th day of differentiation, we observed the α-MHC (α-myosin heavy chain)-positive area using immunofluorescent staining and conducted western blotting to detect the expression of cTnT (cardiac troponin) protein and PI3K/Akt signaling pathway-related proteins. Additionally, we intervened the iPSCs-ErbB4 + NRG1 group with the PI3K/Akt inhibitor LY294002 and observed alterations in the expression of cardiomyocyte differentiation-related genes.

RESULTS

The number of beating embryoid bodies increased after promoting the expression of NRG1/ErbB4 compared to the iPSCs control group. Cardiomyocyte markers ANP, Nkx2.5, and GATA4 significantly increased on day 14 of differentiation, and the positive area of α-MHC was three times that of the iPSCs control group. Moreover, there was a marked increase in cTnT protein expression. However, there was no significant difference in cardiomyocyte differentiation between the iPSCs-ErbB4 group and the iPSCs control group. Akt phosphorylation was significantly increased in the iPSCs-ErbB4 + NRG1 group. LY294002 significantly reversed the enhancing effect of NRG1/ErbB4 overexpression on Akt phosphorylation as well as the increase in α-MHC and cTnT expression.

CONCLUSIONS

In conclusion, promoting the expression of NRG1/ErbB4 induced the differentiation of iPSC into cardiomyocytes, possibly through modulation of the PI3K/Akt signaling pathway.

NRG1 secreted by cancer-associated fibroblasts contributes to enzalutamide resistance in prostate cancer cells

While androgen deprivation therapy (ADT) continues to be a fundamental aspect of prostate cancer treatment, the development of castration-resistant prostate cancer (CRPC) emphasizes the necessity for a more profound understanding of the tumor microenvironment (TME). Normal fibroblasts (NFs) and cancer-associated fibroblasts (CAFs) were isolated and characterized from normal control and prostate cancer specimens, respectively. PC3 and DU145 cells, and the corresponding enzalutamide resistant counterparts, PC3-EnzR and DU145-EnzR, were co-cultured with NFs or CAFs to evaluate the effects of TME in driving enzalutamide resistance. Cell viability of prostate cancer cells was examined by MTT assay. The study also utilized recombinant human neuregulin-1 (NRG1) protein and siRNA to modulate NRG1 expression in CAFs. RT-qPCR, Western blot, and ELISA were employed to assess gene and protein expressions related to the NRG1-HER3 signaling pathway and its association with enzalutamide resistance. CAFs significantly promoted cell growth and enzalutamide resistance of PC3-EnzR and DU145-EnzR cells through substantial increased secretion of NRG1 by CAFs. Co-culturing enzalutamide-resistant prostate cancer cells (PC3-EnzR and DU145-EnzR) with CAFs further enhanced enzalutamide resistance, as evidenced by elevated IC50 values. Inhibition of NRG1 in CAFs attenuated their impact on enzalutamide resistance, providing insight into the role of NRG1 in mediating the crosstalk between CAFs and prostate cancer in the context of enzalutamide resistance. This study elucidates the pivotal role of CAF-secreted NRG1 in promoting enzalutamide resistance in prostate cancer, providing valuable insights for developing targeted therapeutic strategies to overcome resistance in advanced prostate cancer.

Blood Growth Factor Levels in Patients with Systemic Lupus Erythematosus: High Neuregulin-1 Is Associated with Comorbid Cardiovascular Pathology

Patients with systemic lupus erythematosus (SLE) are known to frequently suffer from comorbid cardiovascular diseases (CVDs). There are abundant data on cytokine levels and their role in the pathogenesis of SLE, while growth factors have received much less attention. The aim of this study was to analyze growth factor levels in SLE patients and their association with the presence of comorbid CVDs. The serum concentrations for the granulocyte-macrophage colony-stimulating factor (GM-CSF), nerve growth factor β (NGFβ), glial cell line-derived neurotrophic factor (GDNF), and neuregulin-1 β (NRG-1β) were determined in the SLE patients (n = 35) and healthy individuals (n = 38) by a Luminex multiplex assay. The NGFβ and NRG-1β concentrations were shown to be significantly higher in the total group of SLE patients (median [Q1-Q3]: 3.6 [1.3-4.5] and 52.5 [8.5-148], respectively) compared with the healthy individuals (2.9 [1.3-3.4] and 13.7 [4.4-42] ng/mL, respectively). The GM-CSF and GDNF levels did not differ. Interestingly, elevated NRG-1β levels were associated with the presence of CVDs, as SLE patients with CVDs had significantly higher NRG-1β levels (99 [22-242]) compared with the controls (13.7 [4.4-42]) and patients without CVDs (19 [9-80] ng/mL). The model for the binary classification of SLE patients with and without CVDs based on the NRG-1β level had an average predictive ability (AUC = 0.67). Thus, altered levels of growth factors may be associated with comorbid CVDs in SLE patients.

Screening and identification of key biomarkers associated with endometriosis using bioinformatics and next-generation sequencing data analysis

Background

Endometriosis is a common cause of endometrial-type mucosa outside the uterine cavity with symptoms such as painful periods, chronic pelvic pain, pain with intercourse and infertility. However, the early diagnosis of endometriosis is still restricted. The purpose of this investigation is to identify and validate the key biomarkers of endometriosis.

Methods

Next-generation sequencing dataset GSE243039 was obtained from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) between endometriosis and normal control samples were identified. After screening of DEGs, gene ontology (GO) and REACTOME pathway enrichment analyses were performed. Furthermore, a protein–protein interaction (PPI) network was constructed and modules were analyzed using the Human Integrated Protein–Protein Interaction rEference database and Cytoscape software, and hub genes were identified. Subsequently, a network between miRNAs and hub genes, and network between TFs and hub genes were constructed using the miRNet and NetworkAnalyst tool, and possible key miRNAs and TFs were predicted. Finally, receiver operating characteristic curve analysis was used to validate the hub genes.

Results

A total of 958 DEGs, including 479 upregulated genes and 479 downregulated genes, were screened between endometriosis and normal control samples. GO and REACTOME pathway enrichment analyses of the 958 DEGs showed that they were mainly involved in multicellular organismal process, developmental process, signaling by GPCR and muscle contraction. Further analysis of the PPI network and modules identified 10 hub genes, including vcam1, snca, prkcb, adrb2, foxq1, mdfi, actbl2, prkd1, dapk1 and actc1. Possible target miRNAs, including hsa-mir-3143 and hsa-mir-2110, and target TFs, including tcf3 (transcription factor 3) and clock (clock circadian regulator), were predicted by constructing a miRNA-hub gene regulatory network and TF-hub gene regulatory network.

Conclusions

This investigation used bioinformatics techniques to explore the potential and novel biomarkers. These biomarkers might provide new ideas and methods for the early diagnosis, treatment and monitoring of endometriosis.

Demonstration of the Protective Effect of Vinpocetine in Diabetic Cardiomyopathy

Background: Diabetic cardiomyopathy (DCM) poses a significant risk for heart failure in individuals with diabetes, yet its underlying mechanisms remain incompletely understood. Elevated blood sugar levels initiate harmful processes, including apoptosis, collagen accumulation, and fibrosis in the heart. Vinpocetine, a derivative of Vinca minor L., has demonstrated diverse pharmacological effects, including vasodilation, anti-inflammatory properties, and enhanced cellular metabolism. This study aims to investigate Vinpocetine's protective and remodeling effects in diabetic cardiomyopathy by evaluating biochemical and histopathological parameters. Methods: Twenty-one adult male Wistar rats were induced with diabetes using streptozocin and divided into Diabetes and Diabetes + Vinpocetine groups. Histopathological analyses, TGF-β1 immunoexpression, and measurements of plasma markers (TGF-β, pro-BNP, Troponin T) were performed. Biochemical analyses included HIF-1 alpha and neuregulin-1β quantification and evaluation of lipid peroxidation. Results: Vinpocetine significantly reduced cardiac muscle thickness, TGF-β1 expression, and plasma in diabetic rats. HIF-1 alpha and neuregulin-1β levels increased with Vinpocetine treatment. Histopathological observations confirmed reduced fibrosis and structural abnormalities in Vinpocetine-treated hearts. Conclusions: This study provides comprehensive evidence supporting the protective effects of Vinpocetine against diabetic cardiomyopathy. Vinpocetine treatment improved cardiac morphology, immunohistochemistry, and modulation of biochemical markers, suggesting its potential as a therapeutic intervention to attenuate the negative impact of diabetes on heart function.

To Repair a Broken Heart: Stem Cells in Ischemic Heart Disease

Despite improvements in contemporary medical and surgical therapies, cardiovascular disease (CVD) remains a significant cause of worldwide morbidity and mortality; more specifically, ischemic heart disease (IHD) may affect individuals as young as 20 years old. Typically managed with guideline-directed medical therapy, interventional or surgical methods, the incurred cardiomyocyte loss is not always completely reversible; however, recent research into various stem cell (SC) populations has highlighted their potential for the treatment and perhaps regeneration of injured cardiac tissue, either directly through cellular replacement or indirectly through local paracrine effects. Different stem cell (SC) types have been employed in studies of infarcted myocardium, both in animal models of myocardial infarction (MI) as well as in clinical studies of MI patients, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), Muse cells, multipotent stem cells such as bone marrow-derived cells, mesenchymal stem cells (MSCs) and cardiac stem and progenitor cells (CSC/CPCs). These have been delivered as is, in the form of cell therapies, or have been used to generate tissue-engineered (TE) constructs with variable results. In this text, we sought to perform a narrative review of experimental and clinical studies employing various stem cells (SC) for the treatment of infarcted myocardium within the last two decades, with an emphasis on therapies administered through thoracic incision or through percutaneous coronary interventions (PCI), to elucidate possible mechanisms of action and therapeutic effects of such cell therapies when employed in a surgical or interventional manner.

An update of new/potential cardiovascular markers: a narrative review

BACKGROUND

Cardiovascular and their associated disease (CVD) is a leading cause of death worldwide, in developed and developing countries, and its prevalence has increased over the past few decades, due to changes in the lifestyle of people. Biomarkers are important tools for diagnosing, analyzing, and providing evidence of pathological conditions of CVD and their associated diseases.

METHODS

This study reviews historical cardiovascular biomarkers used to diagnose various diseases, their uses, and limitations, as well as the importance of new and emerging biomarkers.

CONCLUSION

sST2, GDF-15, CD-40, IL-6, and Micro-RNA. Initial studies of the future of cardiac biomarkers are promising, but more research is needed to demonstrate that they are more effective biomarkers of risk factors for CVD development. They also lack the analytical foundation needed for adoption in the medical industry. It is also necessary to determine whether these biomarkers can be used for diagnosis.

Are There Hopeful Therapeutic Strategies to Regenerate the Infarcted Hearts?

Ischemic heart disease remains the primary cause of morbidity and mortality worldwide. Despite significant advancements in pharmacological and revascularization techniques in the late 20th century, heart failure prevalence after myocardial infarction has gradually increased over the last 2 decades. After ischemic injury, pathological remodeling results in cardiomyocytes (CMs) loss and fibrosis, which leads to impaired heart function. Unfortunately, there are no clinical therapies to regenerate CMs to date, and the adult heart's limited turnover rate of CMs hinders its ability to self-regenerate. In this review, we present novel therapeutic strategies to regenerate injured myocardium, including (1) reconstruction of cardiac niche microenvironment, (2) recruitment of functional CMs by promoting their proliferation or differentiation, and (3) organizing 3-dimensional tissue construct beyond the CMs. Additionally, we highlight recent mechanistic insights that govern these strategies and identify current challenges in translating these approaches to human patients.

Cartilage regeneration in zebrafish depends on Nrg1/ErbB signaling pathway

Objective: Cartilage, as the majority of adult mammalian tissues, has limited regeneration capacity. Cartilage degradation consecutive to joint injury or aging then leads to irreversible joint damage and diseases. In contrast, several vertebrate species such as the zebrafish have the remarkable capacity to spontaneously regenerate skeletal structures after severe injuries. The objective of our study was to test the regenerative capacity of Meckel's cartilage (MC) upon mechanical injury in zebrafish and to identify the mechanisms underlying this process. Methods and Results: Cartilage regenerative capacity in zebrafish larvae was investigated after mechanical injuries of the lower jaw MC in TgBAC(col2a1a:mCherry), to visualize the loss and recovery of cartilage. Confocal analysis revealed the formation of new chondrocytes and complete regeneration of MC at 14 days post-injury (dpi) via chondrocyte cell cycle re-entry and proliferation of pre-existing MC chondrocytes near the wound. Through expression analyses, we showed an increase of nrg1 expression in the regenerating lower jaw, which also expresses Nrg1 receptors, ErbB3 and ErbB2. Pharmacological inhibition of the ErbB pathway and specific knockdown of Nrg1 affected MC regeneration indicating the pivotal role of this pathway for cartilage regeneration. Finally, addition of exogenous NRG1 in an in vitro model of osteoarthritic (OA)-like chondrocytes induced by IL1β suggests that Nrg1/ErbB pathway is functional in mammalian chondrocytes and alleviates the increased expression of catabolic markers characteristic of OA-like chondrocytes. Conclusion: Our results show that the Nrg1/ErbB pathway is required for spontaneous cartilage regeneration in zebrafish and is of interest to design new therapeutic approaches to promote cartilage regeneration in mammals.