Cycling Cardiomyocytes: Scarce but Important in Recovery From Heart Infarction?

Polyploidy Promotes Hypertranscription, Apoptosis Resistance, and Ciliogenesis in Cancer Cells and Mesenchymal Stem Cells of Various Origins: Comparative Transcriptome In Silico Study

Mesenchymal stem cells (MSC) attract an increasing amount of attention due to their unique therapeutic properties. Yet, MSC can undergo undesirable genetic and epigenetic changes during their propagation in vitro. In this study, we investigated whether polyploidy can compromise MSC oncological safety and therapeutic properties. For this purpose, we compared the impact of polyploidy on the transcriptome of cancer cells and MSC of various origins (bone marrow, placenta, and heart). First, we identified genes that are consistently ploidy-induced or ploidy-repressed through all comparisons. Then, we selected the master regulators using the protein interaction enrichment analysis (PIEA). The obtained ploidy-related gene signatures were verified using the data gained from polyploid and diploid populations of early cardiomyocytes (CARD) originating from iPSC. The multistep bioinformatic analysis applied to the cancer cells, MSC, and CARD indicated that polyploidy plays a pivotal role in driving the cell into hypertranscription. It was evident from the upregulation of gene modules implicated in housekeeping functions, stemness, unicellularity, DNA repair, and chromatin opening by means of histone acetylation operating via DNA damage associated with the NUA4/TIP60 complex. These features were complemented by the activation of the pathways implicated in centrosome maintenance and ciliogenesis and by the impairment of the pathways related to apoptosis, the circadian clock, and immunity. Overall, our findings suggest that, although polyploidy does not induce oncologic transformation of MSC, it might compromise their therapeutic properties because of global epigenetic changes and alterations in fundamental biological processes. The obtained results can contribute to the development and implementation of approaches enhancing the therapeutic properties of MSC by removing polyploid cells from the cell population.

Single-cell transcriptional landscape of long non-coding RNAs orchestrating mouse heart development

Long non-coding RNAs (lncRNAs) comprise the most representative transcriptional units of the mammalian genome. They are associated with organ development linked with the emergence of cardiovascular diseases. We used bioinformatic approaches, machine learning algorithms, systems biology analyses, and statistical techniques to define co-expression modules linked to heart development and cardiovascular diseases. We also uncovered differentially expressed transcripts in subpopulations of cardiomyocytes. Finally, from this work, we were able to identify eight cardiac cell-types; several new coding, lncRNA, and pcRNA markers; two cardiomyocyte subpopulations at four different time points (ventricle E9.5, left ventricle E11.5, right ventricle E14.5 and left atrium P0) that harbored co-expressed gene modules enriched in mitochondrial, heart development and cardiovascular diseases. Our results evidence the role of particular lncRNAs in heart development and highlight the usage of co-expression modular approaches in the cell-type functional definition.

Cre-loxP-mediated genetic lineage tracing: Unraveling cell fate and origin in the developing heart

The Cre-loxP-mediated genetic lineage tracing system is essential for constructing the fate mapping of single-cell progeny or cell populations. Understanding the structural hierarchy of cardiac progenitor cells facilitates unraveling cell fate and origin issues in cardiac development. Several prospective Cre-loxP-based lineage-tracing systems have been used to analyze precisely the fate determination and developmental characteristics of endocardial cells (ECs), epicardial cells, and cardiomyocytes. Therefore, emerging lineage-tracing techniques advance the study of cardiovascular-related cellular plasticity. In this review, we illustrate the principles and methods of the emerging Cre-loxP-based genetic lineage tracing technology for trajectory monitoring of distinct cell lineages in the heart. The comprehensive demonstration of the differentiation process of single-cell progeny using genetic lineage tracing technology has made outstanding contributions to cardiac development and homeostasis, providing new therapeutic strategies for tissue regeneration in congenital and cardiovascular diseases (CVDs).

Cellular Heterogeneity of the Heart

Recent advances in technology such as the introduction of high throughput multidimensional tools like single cell sequencing help to characterize the cellular composition of the human heart. The diversity of cell types that has been uncovered by such approaches is by far greater than ever expected before. Accurate identification of the cellular variety and dynamics will not only facilitate a much deeper understanding of cardiac physiology but also provide important insights into mechanisms underlying its pathological transformation. Distinct cellular patterns of cardiac cell clusters may allow differentiation between a healthy heart and a sick heart while potentially predicting future disease at much earlier stages than currently possible. These advances have already extensively improved and will ultimately revolutionize our knowledge of the mechanisms underlying cardiovascular disease as such. In this review, we will provide an overview of the cells present in the human and rodent heart as well as genes that may be used for their identification.

Baoyuan decoction (BYD) attenuates cardiac hypertrophy through ANKRD1-ERK/GATA4 pathway in heart failure after acute myocardial infarction

BACKGROUND

The pathological cardiac functions of ankyrin repeat domain 1 (ANKRD1) in left ventricle can directly aggravate cardiac hypertrophy (CH) and fibrosis through the activation of extracellular signal-regulated kinase (ERK)/ transcription factor GATA binding protein 4 (GATA4) pathway, and subsequently contribute to heart failure (HF). Baoyuan Decoction (BYD), which is a famous classic Chinese medicinal formulation, has shown impressive cardioprotective effects clinically and experimentally. However, the knowledge is still limited in its underlying mechanisms against HF.

PURPOSE

To explore whether BYD plays a protective role against HF by attenuating CH via the ANKRD1-ERK/GATA4 pathway.

METHODS

In vivo, HF rat models were prepared using left anterior descending coronary artery (LADCA) ligation. Rats in the BYD group were administered a dosage of 2.57 g/kg of BYD for 28 days, while in the positive control group rats were given 4.67 mg/kg of Fosinopril. In vitro, a hypertrophic model was constructed by stimulating H9C2 cells with 1 uM Ang II. An ANKRD1-overexpressing cell model was established through transient transfection of ANKRD1 plasmid into H9C2 cells. Subsequently, BYD intervention was performed on the cell models to further elucidate its effects and underlying mechanism.

RESULTS

In vivo results showed that BYD significantly improved cardiac function and inhibited pathological hypertrophy and fibrosis in a rat model of HF post-acute myocardial infarction (AMI). Noticeably, label-free proteomic analysis demonstrated that BYD could reverse the CH-related biological turbulences, mainly through ANKRD1-ERK/GATA4 pathway. Further in vitro results validated that the hypertrophy was attenuated by BYD through suppression of AT1R, ANKRD1, Calpain1, p-ERK1/2 and p-GATA4. The results of in vitro model indicated that BYD could reverse the outcome of transfected over-expression of ANKRD1, including down-regulated expressions of ANKRD1, p-ERK1/2 and p-GATA4.

CONCLUSION

BYD ameliorates CH and improves HF through the ANKRD1-ERK/GATA4 pathway, providing a novel therapeutic option for the treatment of HF.