Uncovering the molecular identity of cardiosphere-derived cells (CDCs) by single-cell RNA sequencing

Closer to The Heart: Harnessing the Power of Targeted Extracellular Vesicle Therapies

Extracellular vesicles (EVs) have emerged as novel diagnostic and therapeutic approaches for cardiovascular diseases. EVs derived from various origins exhibit distinct effects on the cardiovascular system. However, the application of native EVs is constrained due to their poor stabilities and limited targeting capabilities. Currently, targeted modification of EVs primarily involves genetic engineering, chemical modification (covalent, non-covalent), cell membrane modification, and biomaterial encapsulation. These techniques enhance the stability, biological activity, target-binding capacity, and controlled release of EVs at specific cells and tissues. The diverse origins of cardioprotective EVs are covered, and the applications of cardiac-targeting EV delivery systems in protecting against cardiovascular diseases are discussed. This review summarizes the current stage of research on the potential of EV-based targeted therapies for addressing cardiovascular disorders.

Circulating GDF11 exacerbates myocardial injury in mice and associates with increased infarct size in humans

AIMS

The heart rejuvenating effects of circulating growth differentiation factor 11 (GDF11), a transforming growth factor-β superfamily member that shares 90% homology with myostatin (MSTN), remains controversial. Here, we aimed to probe the role of GDF11 in acute myocardial infarction (MI), a frequent cause of heart failure and premature death during ageing.

METHODS AND RESULTS

In contrast to endogenous Mstn, myocardial Gdf11 declined during the course of ageing and was particularly reduced following ischaemia/reperfusion (I/R) injury, suggesting a therapeutic potential of GDF11 signalling in MI. Unexpectedly, boosting systemic Gdf11 by recombinant GDF11 delivery (0.1 mg/kg body weight over 30 days) prior to myocardial I/R augmented myocardial infarct size in C57BL/6 mice irrespective of their age, predominantly by accelerating pro-apoptotic signalling. While intrinsic cardioprotective signalling pathways remained unaffected by high circulating GDF11, targeted transcriptomics and immunomapping studies focusing on GDF11-associated downstream targets revealed attenuated Nkx2-5 expression confined to CD105-expressing cells, with pro-apoptotic activity, as assessed by caspase-3 levels, being particularly pronounced in adjacent cells, suggesting an indirect effect. By harnessing a highly specific and validated liquid chromatography-tandem mass spectrometry-based assay, we show that in prospectively recruited patients with MI circulating GDF11 but not MSTN levels incline with age. Moreover, GDF11 levels were particularly elevated in those at high risk for adverse outcomes following the acute event, with circulating GDF11 emerging as an independent predictor of myocardial infarct size, as estimated by standardized peak creatine kinase-MB levels.

CONCLUSION

Our data challenge the initially reported heart rejuvenating effects of circulating GDF11 and suggest that high levels of systemic GDF11 exacerbate myocardial injury in mice and humans alike. Persistently high GDF11 levels during ageing may contribute to the age-dependent loss of cardioprotective mechanisms and thus poor outcomes of elderly patients following acute MI.

Paracrine Responses of Cardiosphere-Derived Cells to Cytokines and TLR Ligands: A Comparative Analysis

Cardiosphere-derived cells (CDCs) are currently being evaluated in clinical trials as a potential therapeutic tool for regenerative medicine. The effectiveness of transplanted CDCs is largely attributed to their ability to release beneficial soluble factors to enhance therapeutic effects. An emerging area of research is the pretreatment of stem cells, including CDCs, with various cytokines to improve their therapeutic properties. This strategy aims to enhance their survival, proliferation, differentiation, and paracrine activities after transplantation. In our study, we investigated the differential effects of various cytokines and TLR ligands on the secretory phenotype of human CDCs. Using a magnetic bead-based immunoassay, we analyzed the CDCs-conditioned media for 41 cytokines and growth factors and detected the presence of 21 cytokines. We found that CDC incubation with lipopolysaccharide, a TLR4 ligand, and the cytokine combination of TNF/IFN significantly increased the secretion of most of the cytokines detected. Specifically, we observed an increased secretion and gene expression of IP10, MCP3, IL8, and VEGFA. In contrast, the TLR3 ligand polyinosinic-polycytidylic acid and TGF-beta had minimal effects on CDC cytokine secretion. Additionally, TNF/IFN, but not LPS, enhanced ICAM1 expression. Our findings offer new insights into the role of cytokines in potentially modulating the biology and regenerative potential of CDCs.

Tumor Necrosis Factor-Alpha Induces Proangiogenic Profiling of Cardiosphere-Derived Cell Secretome and Increases Its Ability to Stimulate Angiogenic Properties of Endothelial Cells

Ischemic heart disease and its complications, such as myocardial infarction and heart failure, are the leading causes of death in modern society. The adult heart innately lacks the capacity to regenerate the damaged myocardium after ischemic injury. Multiple lines of evidence indicated that stem-cell-based transplantation is one of the most promising treatments for damaged myocardial tissue. Different kinds of stem cells have their advantages for treating ischemic heart disease. One facet of their mechanism is the paracrine effect of the transplanted cells. Particularly promising are stem cells derived from cardiac tissue per se, referred to as cardiosphere-derived cells (CDCs), whose therapeutic effect is mediated by the paracrine mechanism through secretion of multiple bioactive molecules providing immunomodulatory, angiogenic, anti-fibrotic, and anti-inflammatory effects. Although secretome-based therapies are increasingly being used to treat various cardiac pathologies, many obstacles remain because of population heterogeneity, insufficient understanding of potential modulating compounds, and the principles of secretome regulation, which greatly limit the feasibility of this technology. In addition, components of the inflammatory microenvironment in ischemic myocardium may influence the secretome content of transplanted CDCs, thus altering the efficacy of cell therapy. In this work, we studied how Tumor necrosis factor alpha (TNFa), as a key component of the pro-inflammatory microenvironment in damaged myocardium from ischemic injury and heart failure, may affect the secretome content of CDCs and their angiogenic properties. We have shown for the first time that TNFa may act as a promising compound modulating the CDC secretome, which induces its profiling to enhance proangiogenic effects on endothelial cells. These results allow us to elucidate the underlying mechanisms of the impact of the inflammatory microenvironment on transplanted CDCs and may contribute to the optimization of CDC efficiency and the development of the technology for producing the CDC secretome with enhanced proangiogenic properties for cell-free therapy.

Single-cell RNA sequencing to identify cellular heterogeneity and targets in cardiovascular diseases: from bench to bedside

The mechanisms of cardiovascular diseases (CVDs) remain incompletely elucidated. Single-cell RNA sequencing (scRNA-seq) has enabled the profiling of single-cell transcriptomes at unprecedented resolution and throughput, which is critical for deciphering cardiovascular cellular heterogeneity and underlying disease mechanisms, thereby facilitating the development of therapeutic strategies. In this review, we summarize cellular heterogeneity in cardiovascular homeostasis and diseases as well as the discovery of potential disease targets based on scRNA-seq, and yield new insights into the promise of scRNA-seq technology in precision medicine and clinical application.

Inflammatory biomarkers after an exercise intervention in childhood acute lymphoblastic leukemia survivors

Cancer survivors show increased risk for non-communicable diseases and chronic low-grade inflammation characterizes the development of such diseases. We investigated inflammatory plasma protein profiles of survivors of childhood acute lymphoblastic leukemia (ALL) in comparison to healthy controls and after an intervention with a home-based exercise program. Survivors of childhood ALL aged 16-30 years (n = 21) with a median age at diagnosis 4.9 (1.6-12.9) years and a median time of 15.9 years from diagnosis, and sex- and age-matched healthy controls (n = 21) were studied. Stored plasma samples were analyzed with Olink's 92-protein-wide Inflammation panel in 21 ALL long-term survivors at baseline, after a previous 16-week home-based exercise intervention (n = 17) and in 21 age- and sex-matched controls at baseline. Protein expression levels were compared between the groups. Inflammatory protein levels did not differ between the survivors and controls at baseline. Significantly reduced levels after the intervention were found in 11 proteins related to either vascular inflammation, insulin resistance, or both: tumor necrosis factor superfamily member 14 (TNFSF14), oncostatin M (OSM), monocyte chemoattractant protein 1 (MCP-1), MCP-2, fibroblast growth factor 21 (FGF-21), chemokine (C-C motif) ligand 4 (CCL4), transforming growth factor alpha (TGF-α), tumor necrosis factor-related apoptosis-inducing ligand 10 (TRAIL), adenosine deaminase (ADA), chemokine (C-X-C motif) ligand 6 (CXCL6), and latency-associated peptide transforming growth factor beta 1 (LAP TGF-β1). The ALL survivors were not significantly more affected by inflammation than controls at baseline. The survivors' 16-week exercise intervention led to significant reduction in inflammatory protein levels. Physical exercise should be promoted for survivors of childhood cancer.