Mammals have evolutionarily sacrificed their cardiac regenerative capacity in order to maintain high-output contractile function. This developmental trade-off involves integrated metabolic and epigenetic regulation, as well as microenvironmental maturation, all of which contribute to the withdrawal of cardiomyocytes from the cell-cycle. Reactivating juvenile regulatory networks—through the induction of transcription factors, metabolic reprogramming, and modulation of the cellular niche—may offer a strategy to restore proliferative potential in adult cardiomyocytes. Notably, cardiac aging appears to recapitulate the disruption of these regulatory mechanisms. Therefore, we propose that reprogramming strategies capable of reversing the developmental barriers to regeneration may represent a promising approach to counteract cardiac senescence.

Dilated cardiomyopathy (DCM) is a leading cause of heart failure and the primary indication for heart transplantation. The intricate and poorly elucidated pathogenesis of genetic DCM, coupled with the paucity of effective therapeutic options, imposes a substantial burden on both patients and their families. In this study, we identified a novel MYBPC3 mutation (c.194C > T) in a patient diagnosed with DCM and established a patient-specific human induced pluripotent stem cell (hiPSC) model. Cardiomyocytes derived from these patient-specific hiPSCs (hiPSC-CMs) exhibited hallmark features of DCM, including cell enlargement, aberrant distribution of sarcomeric α-actinin, and dysregulated calcium ion homeostasis, as compared to control hiPSC-CMs derived from a healthy individual. RNA sequencing analysis revealed a significant upregulation of CASQ2, which encodes calsequestrin, a protein that binds to Ryanodine receptor 2 (RyR2). Notably, treatment with the RyR2 inhibitor ryanodine effectively restored the abnormal calcium transients observed in DCM-hiPSC-CMs. In summary, our findings provide compelling evidence that the c.194 C > T mutation of MYBPC3 plays a definitive pathogenic role in DCM, and that modulation of the RyR2 receptor may alleviate calcium dysregulation in affected cardiomyocytes. These insights enhance our understanding of the molecular mechanisms underlying DCM and offer a promising therapeutic strategy for patients with calcium ion dysregulation associated with this condition. Cardiomyocytes differentiated from patient-specific induced pluripotent stem cells (hiPSCs) reproduce enlargement and sarcomeric disorganization. A novel c.194C>T mutation in MYBPC3 results in abnormal calcium transients in hiPSC-derived cardiomyocytes. c.194C>T mutation of MYBPC3 leads to a significant increase in the expression of calsequestrin that binds to the ryanodine receptor 2 (RyR2). Treatment with RyR2 inhibitor markedly improves the ability of calcium handling in DCM-hiPSC-cardiomyocytes.

Thermogenic adipocytes hold significant therapeutic promise for combating obesity and metabolic diseases due to their capacity to dissipate energy as heat. However, the transcriptional regulatory mechanisms underlying thermogenic adipocyte activation remain incompletely understood. Here, we identified RUNX1 and RUNX2 as key transcriptional barriers to thermogenic adipocyte differentiation and activation. RUNX1/2 expression is dynamically suppressed by thermal stress and positively associated with adverse metabolic traits. Genetic deletion of RUNX1 or RUNX2 in adipocytes enhances beige fat formation but differentially influences systemic metabolism in male mice. Conversely, enforced RUNX1/2 expression suppresses thermogenic gene programs and blunts thermogenic adipocyte activation. Mechanistically, RUNX1 recruits HDAC1 to enforce epigenetic silencing of thermogenic loci, whereas RUNX2 governs thermogenic cell fate through phase-separation-dependent repression. Notably, pharmacological inhibition of RUNX1/2 enhances adipose thermogenesis and improves energy metabolism. Our findings unveil an unrecognized role for RUNX in adipose thermogenesis, highlighting their potential as therapeutic targets for metabolic disease intervention.

Humoral immunological memory mediated by memory B cells (MBCs) and long-lived plasma cells (LLPCs) is critical for sustained protection following infection or vaccination. LLPCs protect the hosts by secreting protective neutralizing antibodies over extended periods. However, the mechanism regulating their survival and thus the durability of protective antibodies remains unclear. Here, we showed in human and mouse models that intermittent fasting impaired humoral immunological memory by accelerating antibody decay. Fasting selectively depleted LLPCs while sparing MBCs in mice. Mechanistically, this effect was mediated by increased extracellular β-hydroxybutyrate, a ketone body produced during fasting, which acted through the hydroxycarboxylic acid receptor 2 (HCAR2) on plasma cells. Activation of the HCAR2-Gαi-adenylate cyclase-cAMP axis by β-hydroxybutyrate downregulated CXCR4, leading plasma cells to exit their bone marrow niche and undergo apoptosis in the periphery. These findings reveal that fasting-induced metabolic signals regulate humoral immunity duration and suggest that diet and lifestyle could influence vaccine effectiveness.

Triple-negative breast cancer (TNBC) poses significant therapeutic challenges due to its aggressive nature and resistance to hormone therapies and human epidermal growth factor receptor 2 (HER2)-targeted treatments. Paclitaxel is a first-line chemotherapy for TNBC. Its nanoformulation, Abraxane (Abx), has gained widespread clinical use. However, the efficacy of Abx is often limited by poor colloidal stability and a lack of active targeting capability. In this study, we aimed to address these limitations through a dual-modification strategy by complexing Abx with spermidine-conjugated dextran (spm-DEX) and coating it with homologous tumor membranes. The resulting nanoformulation, Abx/spm@4T1, displayed a core-shell structure, enhanced colloidal stability, and preserved the integrity of the membrane proteins. Additionally, Abx/spm@4T1 leveraged the homotypic targeting ability of membrane proteins and the cationic charge of spm-DEX to enhance cellular uptake and tumor accumulation. In vitro studies demonstrated superior cytotoxicity, induction of apoptosis, and inhibition of migration and invasion in tumor cells. In vivo, Abx/spm@4T1 exhibited enhanced tumor-targeting efficiency, suppressed primary tumor growth and lung metastasis, while maintaining favorable biosafety with minimal systemic toxicity. This study underscores the potential of combining biomimetic membrane coatings with modifications of cationic spermidine conjugates to overcome the limitations of conventional nanotherapeutics, providing a promising strategy for targeted therapy in TNBC.

The restricted regenerative potential of adult hearts poses a significant barrier to effective repair following injury. In contrast to numerous vertebrates, mammalian hearts exhibit only transient neonatal renewal capacity during the initial days of life. Beyond cardiomyocytes, understanding the diverse compositions of non-cardiomyocytes (non-CMs) is imperative for maintaining heart microenvironment homeostasis during neonatal heart regeneration. Here, we conduct single-cell ATAC sequencing on neonatal hearts at varying time points post-apical resection to profile the epigenetic landscape. Intriguingly, fibroblasts and endothelial cells, as the most abundant populations in the heart, exhibit the most dynamic chromatin remodeling upon injury. Furthermore, we reveal CEBPD and AP-1 family transcriptional factors as pivotal trans-regulators orchestrating these alterations, governing beneficial fibroblast activation and endothelial cell angiogenesis crucial for cardiac regeneration, respectively. Collectively, our study delineates the cellular identity of non-CMs at the epigenome level using single-cell approaches, offering insights into cell type-targeted interventions for heart regeneration.

Multiple regulatory layers influence allele-specific expression (ASE), particularly through sequence-dependent and parent-of-origin-dependent mechanisms at the transcriptional level. However, little is known about ASE regulation at the post-transcriptional level. The most prevalent post-transcriptional mRNA modification, N6-methyladenosine (m6A), plays important roles in regulating gene expression. Here, we conduct transcriptome-wide analysis of allele-specific m6A in mice. Using early postnatal tissues from reciprocal crosses of two divergent mouse strains, we measured allelic m6A differences at single-base resolution. Our study reveals widespread sequence-dependent allelic imbalance in m6A methylation, identifying thousands of allele-specific m6A (ASm6A) sites with statistically significant and reproducible allelic methylation differences. We find evidence of potential cis-regulatory variants within 50-nt flanking regions of ASm6As. Intriguingly, we detect parental effects on allelic methylation across m6As exhibiting parent-of-origin-dependent ASE. For both sequence- and parent-of-origin-dependent m6As, we observe opposing allelic preferences between methylation and expression, suggesting a potential role of ASm6A in regulating ASE through negative effects on gene expression. Overall, our findings reveal that both cis-acting and parent-of-origin effects influence ASm6A, offering new insights into post-transcriptional mechanisms of ASE regulation.

The distribution of m6A across various RNA isoforms and its heterogeneity within single cells are still not well understood. Here, we develop m6A-isoSC-seq, which employs both Oxford Nanopore long-read and Illumina short-read sequencing on the same 10x Genomics single-cell cDNA library with APOBEC1-YTH induced C-to-U mutations near m6A sites. Through m6A-isoSC-seq on a pooled sample of three cell line origins, we unveil a profound degree of m6A heterogeneity at both the isoform and single-cell levels. Through comparisons across single cells, we identify widespread specific m6A methylation on certain RNA isoforms, usually those misprocessed RNA isoforms. Compared to the coding isoforms of the same genes, the expression of highly methylated misprocessed RNA isoforms is more sensitive to METTL3 depletion. These misprocessed RNAs tend to have excessive m6A sites in coding regions, which are targets of CDS-m6A decay (CMD). This study offers undocumented insights into the role of m6A in RNA surveillance.

Dilated cardiomyopathy (DCM) is a leading cause of heart failure and the primary indication for heart transplantation. The intricate and poorly elucidated pathogenesis of genetic DCM, coupled with the paucity of effective therapeutic options, imposes a substantial burden on both patients and their families. In this study, we identified a novel MYBPC3 mutation (c.194C>T) in a patient diagnosed with DCM and established a patient-specific human induced pluripotent stem cell (hiPSC) model. Cardiomyocytes derived from these patient-specific hiPSCs (hiPSC-CMs) exhibited hallmark features of DCM, including hypertrophic cell size, aberrant distribution of sarcomeric α-actinin, and dysregulated calcium ion homeostasis, as compared to control hiPSC-CMs derived from a healthy individual. RNA sequencing analysis revealed a significant upregulation of CASQ2, which encodes calsequestrin, a protein that binds to Ryanodine receptor 2 (RyR2). Notably, treatment with the RyR2 inhibitor ryanodine effectively restored the abnormal calcium transients observed in DCM-hiPSC-CMs. In summary, our findings provide compelling evidence that the c.194C>T mutation of MYBPC3 plays a definitive pathogenic role in DCM, and that modulation of the RyR2 receptor may alleviate calcium dysregulation in affected cardiomyocytes. These insights enhance our understanding of the molecular mechanisms underlying DCM and offer a promising therapeutic strategy for patients with calcium ion dysregulation associated with this condition. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was funded by the National Natural Science Foundation of China (82470367, 82272164), the Natural Science Foundation of Guangdong Province (2024A1515013135). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Medical Ethics Committee of Sun Yat-Sen Memorial Hospital I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript

Here, we present a protocol for the differentiation of human pluripotent stem cells (hPSCs) into definitive endoderm (DE) lineage. We describe steps for the resuscitation, passaging, and plating of hPSCs. We then detail procedures for culturing cells followed by immunostaining, imaging, and analysis. This chemically defined, small-molecule-based, recombinant protein-free system offers a cost-effective and scalable platform for generating endodermal derivatives, demonstrating efficiency for applications in drug screening, disease modeling, and regenerative medicine. For complete details on the use and execution of this protocol, please refer to Zhao et al.1.

Breast cancer is the most common malignancy in females and remains the leading cause of cancer-related deaths for women worldwide. The cellular and molecular basis of breast tumorigenesis is not completely understood partly due to the lack of human research models which simulate the development of breast cancer. Here, we developed a method for generating functional mammary-like cells (MCs) from human-induced pluripotent stem cells (iPSCs). The iPSC-MCs closely resemble human primary MCs at cellular, transcriptional, and functional levels. Using this method, a breast cancer model was generated using patient-derived iPSCs harboring germline BRCA1 mutation. The patient iPSC-MCs recapitulated the transcriptome, clinical genomic alteration, and tumorigenic ability of breast cancer cells. We also identified S100P as an oncogene downstream of mutated BRCA1 that promotes cancer cell stemness and tumorigenesis. Our study establishes a promising system of breast cancer for studying the mechanism of tumorigenesis and identifying potential therapeutic targets.

Definitive endoderm (DE) derived from human pluripotent stem cells (hPSCs) holds great promise for cell-based therapies and drug discovery. However, current DE differentiation methods required undefined components and/or expensive recombinant proteins, limiting their scalable manufacture and clinical use. Homogeneous DE differentiation in defined and recombinant protein-free conditions remains a major challenge. Here, by systematic optimization and high-throughput screening, we report a chemically defined, small-molecule-based defined system that contains only four components (4C), enabling highly efficient and cost-effective DE specification of hPSCs in the absence of recombinant proteins. 4C-induced DE can differentiate into functional hepatocytes, lung epithelium, and pancreatic β cells in vitro and multiple DE derivatives in vivo. Genomic accessibility analysis reveals that 4C reconfigures chromatin architecture to allow key DE transcription factor binding while identifying TEAD3 as a novel key regulator of the process. This system may facilitate mass production of DE derivatives for drug discovery, disease modeling, and cell therapy.

Group 3 innate lymphoid cells (ILC3s) regulate inflammation and tissue repair at mucosal sites, but whether these functions pertain to other tissues—like the kidneys—remains unclear. Here, we observed that renal fibrosis in humans was associated with increased ILC3s in the kidneys and blood. In mice, we showed that CXCR6+ ILC3s rapidly migrated from the intestinal mucosa and accumulated in the kidney via CXCL16 released from the injured tubules. Within the fibrotic kidney, ILC3s increased the expression of programmed cell death-1 (PD-1) and subsequent IL-17A production to directly activate myofibroblasts and fibrotic niche formation. ILC3 expression of PD-1 inhibited IL-23R endocytosis and consequently amplified the JAK2/STAT3/RORγt/IL-17A pathway that was essential for the pro-fibrogenic effect of ILC3s. Thus, we reveal a hitherto unrecognized migration pathway of ILC3s from the intestine to the kidney and the PD-1-dependent function of ILC3s in promoting renal fibrosis.

Induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) therapy has emerged as a highly promising field of heart repair. Lin et al.1 presented compelling evidence on the long-term engraftment and maturation of autologous iPSC-CMs in two rhesus macaques, demonstrating unprecedented cardiac autografting data in large animal models without the need of immunosuppressants.

Preservation of mitochondrial functionality is essential for heart hemostasis and cardiovascular diseases treatment. However, the current nanomedicines including liposomes, polymers and inorganic nanomaterials are severely hindered by poor stability, high manufacturing costs and potential biotoxicity. In this research, we present novel polyphenolic nanoparticles (NPs) derived from naturally occurring pomegranate peel (PP, labelled as PPP NPs), which exhibit potent antioxidative and anti-inflammatory properties, serving as a modulator of mitochondrial function. PPP NPs have been identified to improve survival rates in models of mitochondrial depletion through enhancement of cardiomyocyte proliferation and the reduction of DNA damage. Moreover, PPP NPs can effectively inhibit the production of reactive oxygen species and inflammatory mediators in lipopolysaccharide (LPS)-induced mitochondrial damage. Utilizing human engineered heart tissue and mice models, PPP NPs were found to significantly improve contractile function and alleviate inflammation activities after LPS treatment. Mechanically, PPP NPs regulated inflammatory responses via a m6A dependent manner, as determined using RNA-seq and MeRIP-seq analyses. Collectively, these insights underscore the potential of PPP NPs as a novel therapeutic approach for mitochondrial dysfunction. PPP NPs revealed multiple functions with identified molecular mechanisms including ROS clearance and m6A modification regulation in alleviating damages and presenting therapeutic roles in mitochondrial and sepsis-induced cardiomyopathy.

Here, we present a protocol for the quantitative assessment of rat and mouse cardiomyocyte proliferation both in vitro and in vivo. For the in vivo approach, we describe steps for the isolation of neonatal rat cardiomyocytes and the employment of various indicators to quantify cell proliferation. We then detail in vivo procedures that incorporate comprehensive assays and a genetic lineage tracing strategy to evaluate endogenous cardiomyocyte proliferation. This protocol can be modified to investigate other mammalian cardiomyocyte proliferation.For complete details on the use and execution of this protocol, please refer to Ji et al.1

Utilization of lipids as energy substrates after birth causes cardiomyocyte (CM) cell-cycle arrest and loss of regenerative capacity in mammalian hearts. Beyond energy provision, proper management of lipid composition is crucial for cellular and organismal health, but its role in heart regeneration remains unclear. Here, we demonstrate widespread sphingolipid metabolism remodeling in neonatal hearts after injury and find that SphK1 and SphK2, isoenzymes producing the same sphingolipid metabolite sphingosine-1-phosphate (S1P), differently regulate cardiac regeneration. SphK2 is downregulated during heart development and determines CM proliferation via nuclear S1P-dependent modulation of histone acetylation. Reactivation of SphK2 induces adult CM cell-cycle re-entry and cytokinesis, thereby enhancing regeneration. Conversely, SphK1 is upregulated during development and promotes fibrosis through an S1P autocrine mechanism in cardiac fibroblasts. By fine-tuning the activity of each SphK isoform, we develop a therapy that simultaneously promotes myocardial repair and restricts fibrotic scarring to regenerate the infarcted adult hearts.

Promoting endogenous cardiomyocyte proliferation is crucial for repairing infarcted hearts. Implantation of human pluripotent stem cell-derived cardiovascular progenitor cells (hCVPCs) promotes healing of infarcted hearts. However, little is known regarding their impact on host cardiomyocyte proliferation. Here, we revealed that hCVPC implantation into mouse infarcted hearts induced dedifferentiation and cell cycle re-entry of host cardiomyocytes, which was further confirmed in vitro by hCVPC-conditioned medium. Mechanistically, the PI3K/Akt signaling pathway mediated hCVPC-induced cardiomyocyte cell cycle re-entry. The findings reveal the novel function of hCVPCs in triggering cardiomyocyte dedifferentiation and cell cycle activation and highlight a strategy utilizing cells at early developmental stages to rejuvenate adult cardiomyocytes.

BACKGROUND:Cardiomyocyte growth and differentiation rely on precise gene expression regulation, with epigenetic modifications emerging as key players in this intricate process. Among these modifications, N6-methyladenosine (m6A) stands out as one of the most prevalent modifications on mRNA, exerting influence over mRNA metabolism and gene expression. However, the specific function of m6A in cardiomyocyte differentiation remains poorly understood.RESULTS:We investigated the relationship between m6A modification and cardiomyocyte differentiation by conducting a comprehensive profiling of m6A dynamics during the transition from pluripotent stem cells to cardiomyocytes. Our findings reveal that while the overall m6A modification level remains relatively stable, the m6A levels of individual genes undergo significant changes throughout cardiomyocyte differentiation. We discovered the correlation between alterations in chromatin accessibility and the binding capabilities of m6A writers, erasers, and readers. The changes in chromatin accessibility influence the recruitment and activity of m6A regulatory proteins, thereby impacting the levels of m6A modification on specific mRNA transcripts.CONCLUSION:Our data demonstrate that the coordinated dynamics of m6A modification and chromatin accessibility are prominent during the cardiomyocyte differentiation.