Cardiac Progenitor Cells Research Articles

Human cardiomyocyte-derived exosomes induce cardiac gene expressions in mesenchymal stromal cells within 3D hyaluronic acid hydrogels and in dose-dependent manner

Accomplishing a reliable lineage-specific differentiation of stem cells is vital in tissue engineering applications, however, this need remained unmet. Extracellular nanovesicles (particularly exosomes) have previously been shown to have this potential owing to their rich biochemical content including proteins, nucleic acids and metabolites. In this work, the potential of human cardiomyocytes-derived exosomes to induce in vitro cardiac gene expressions in human mesenchymal stem cells (hMSCs) was evaluated. Cardiac exosomes (CExo) were integrated with hyaluronic acid (HA) hydrogel, which was functionalized with tyramine (HA-Tyr) to enable the development of 3D (three dimensional), robust and bioactive hybrid cell culture construct through oxidative coupling. In HA-Tyr/CExo 3D hybrid hydrogels, hMSCs exhibited good viability and proliferation behaviours. Real time quantitative polymerase chain reaction (RT-qPCR) results demonstrated that cells incubated within HA-Tyr/CExo expressed early cardiac progenitor cell markers (GATA4, Nkx2.5 and Tbx5), but not cTnT, which is expressed in the late stages of cardiac differentiation and development. The expressions of cardiac genes were remarkably increased with increasing CExo concentration, signifying a dose-dependent induction of hMSCs. This report, to some extent, explains the potential of tissue-specific exosomes to induce lineage-specific differentiation. However, the strategy requires further mechanistic explanations so that it can be utilized in translational medicine.

Oxygen-rich Environment Ameliorates Cell Therapy Outcomes of Cardiac Progenitor Cells for Myocardial Infarction

To some extent, cell therapy for myocardial infarction (MI) has supported the idea of cardiac repair; however, further optimizations are inevitable. Combined approaches that comprise suitable cell sources and supporting molecules considerably improved its effect. Here, we devised a strategy of simultaneous transplantation of human cardiac progenitor cells (CPCs) and an optimized oxygen generating microparticles (MPs) embedded in fibrin hydrogel, which was injected into a left anterior descending artery (LAD) ligating-based rat model of acute myocardial infarction (AMI). Functional parameters of the heart, particularly left ventricular systolic function, markedly improved and reached pre-AMI levels. This functional restoration was well correlated with substantially lower fibrotic tissue formation and greater vascular density in the infarct area. Our novel approach promoted CPCs retention and differentiation into cardiovascular lineages. We propose this novel co-transplantation strategy for more efficient cell therapy of AMI which may function by providing an oxygen-rich microenvironment, and thus regulate cell survival and differentiation.

Increased prostaglandin-D2 in male STAT3-deficient hearts shifts cardiac progenitor cells from endothelial to white adipocyte differentiation.

Cardiac levels of the signal transducer and activator of transcription factor-3 (STAT3) decline with age, and male but not female mice with a cardiomyocyte-specific STAT3 deficiency conditional knockout (CKO) display premature age-related heart failure associated with reduced cardiac capillary density. In the present study, isolated male and female CKO-cardiomyocytes exhibit increased prostaglandin (PG)-generating cyclooxygenase-2 (COX-2) expression. The PG-degrading hydroxyprostaglandin-dehydrogenase-15 (HPGD) expression is only reduced in male cardiomyocytes, which is associated with increased prostaglandin D2 (PGD2) secretion from isolated male but not female CKO-cardiomyocytes. Reduced HPGD expression in male cardiomyocytes derive from impaired androgen receptor (AR)-signaling due to loss of its cofactor STAT3. Elevated PGD2 secretion in males is associated with increased white adipocyte accumulation in aged male but not female hearts. Adipocyte differentiation is enhanced in isolated stem cell antigen-1 (SCA-1)+ cardiac progenitor cells (CPC) from young male CKO-mice compared with the adipocyte differentiation of male wild-type (WT)-CPC and CPC isolated from female mice. Epigenetic analysis in freshly isolated male CKO-CPC display hypermethylation in pro-angiogenic genes (Fgfr2, Epas1) and hypomethylation in the white adipocyte differentiation gene Zfp423 associated with up-regulated ZFP423 expression and a shift from endothelial to white adipocyte differentiation compared with WT-CPC. The expression of the histone-methyltransferase EZH2 is reduced in male CKO-CPC compared with male WT-CPC, whereas no differences in the EZH2 expression in female CPC were observed. Clonally expanded CPC can differentiate into endothelial cells or into adipocytes depending on the differentiation conditions. ZFP423 overexpression is sufficient to induce white adipocyte differentiation of clonal CPC. In isolated WT-CPC, PGD2 stimulation reduces the expression of EZH2, thereby up-regulating ZFP423 expression and promoting white adipocyte differentiation. The treatment of young male CKO mice with the COX inhibitor Ibuprofen or the PGD2 receptor (DP)2 receptor antagonist BAY-u 3405 in vivo increased EZH2 expression and reduced ZFP423 expression and adipocyte differentiation in CKO-CPC. Thus, cardiomyocyte STAT3 deficiency leads to age-related and sex-specific cardiac remodeling and failure in part due to sex-specific alterations in PGD2 secretion and subsequent epigenetic impairment of the differentiation potential of CPC. Causally involved is the impaired AR signaling in absence of STAT3, which reduces the expression of the PG-degrading enzyme HPGD.

Development of Biomimetic Alginate/Gelatin/Elastin Sponges with Recognition Properties toward Bioactive Peptides for Cardiac Tissue Engineering.

In recent years, there has been an increasing interest toward the covalent binding of bioactive peptides from extracellular matrix proteins on scaffolds as a promising functionalization strategy in the development of biomimetic matrices for tissue engineering. A totally new approach for scaffold functionalization with peptides is based on Molecular Imprinting technology. In this work, imprinted particles with recognition properties toward laminin and fibronectin bioactive moieties were synthetized and used for the functionalization of biomimetic sponges, which were based on a blend of alginate, gelatin, and elastin. Functionalized sponges underwent a complete morphological, physicochemical, mechanical, functional, and biological characterization. Micrographs of functionalized sponges showed a highly porous structure and a quite homogeneous distribution of imprinted particles on their surface. Infrared and thermal analyses pointed out the presence of interactions between blend components. Biodegradation and mechanical properties appeared adequate for the aimed application. The results of recognition tests showed that the deposition on sponges did not alter the specific recognition and binding behavior of imprinted particles. In vitro biological characterization with cardiac progenitor cells showed that early cell adherence was promoted. In vivo analysis showed that developed scaffolds improved cardiac progenitor cell adhesion and differentiation toward myocardial phenotypes.

Generation of a human iPSC line GIBHi002-A-2 with a dual-reporter for NKX2-5 using TALENs.

The human transcription factor NKX2-5 plays an important role in cardiac formation and development, and thus it can be used for isolation of cardiomyocytes (CMs) differentiated from human pluripotent stem cells (hPSCs). Here, we knocked-in enhanced GFP (eGFP) and Pac (a puromycin resistant gene; PuroR) into the exon 1 coding region of NKX2-5 from a human iPSC line iPSN0003 using TALENs. The generated GIBHi002-A-2 enables us to monitor and optimize cardiac differentiation procedures via the cardiac progenitor cells (CPCs), as well as to isolate iPSC-derived CMs for drug screening.

Abstract 14080: A Phase II Randomized, Double-blind, Controlled Trial of Combined Mesenchymal Stromal Cells and C-kit+ Cardiac Progenitor Cells in Ischemic Heart Failure: The CCTRN CONCERT-HF Trial

Introduction: Although preclinical studies of cell delivery in models of ischemic heart failure (HF) suggest a beneficial interaction between mesenchymal stromal cells (MSCs) and c-kit+ cardiac progenitor cells (CPCs) resulting in additive therapeutic effects, no clinical trial has examined a combination of different cell types in ischemic HF. Furthermore, comparative studies of different cell products in humans are rare. CONCERT-HF (NCT02501811) is an NHLBI-sponsored, randomized, double-blind, placebo-controlled, Phase II trial of the Cardiovascular Cell Therapy Research Network (CCTRN) investigating feasibility, safety, and efficacy of MSCs and CPCs, alone and in combination, in patients with chronic ischemic HF. Objectives: To address the following questions: Is combined treatment with MSCs and CPCs feasible and safe in patients with ischemic HF? Do MSCs and CPCs, given alone or in combination, alleviate LV dysfunction, reduce scar size, improve quality of life, and/or augment functional capacity? Is either cell type more effective than the other? Is the combination of MSCs and CPCs more efficacious than MSCs alone or CPCs alone? Methods: Patients were randomized (1:1:1:1) to receive i) the combination of autologous bone marrow-derived MSCs and autologous CPCs, ii) MSCs alone, iii) CPCs alone, or iv) placebo. Target doses were 150 x 10 6 MSCs and 5 x 10 6 CPCs. All patients underwent bone marrow aspiration and right heart catheterization. Endomyocardial biopsy was performed only in the MSC + CPC and CPC alone groups; a “sham biopsy” was performed in the MSC alone and placebo groups. All patients underwent study product injection using the NOGA ® XP Mapping System and were followed for 12 months. Results: A total of 125 patients (116 M, 9 F), 62.5 ± 8.9 years old, were enrolled at 7 CCTRN centers between Nov 2016 and Oct 2018. Baseline LVEF (cardiac MRI) was 28.6 ± 6.1% with a mean scar size of 31.8 ± 10.9 g and NYHA class II (80%) or class III (15.2%). Conclusions: CONCERT-HF is the first cell therapy trial to assess a combination of different cell types and to directly compare two different cell products in patients with HF. All patients will complete follow-up by the end of June and final primary (12-month) safety and outcomes data will be available in August 2020.

Abstract 16733: Immune Response Following Allogenic Cardiac Progenitor Cells Transplantation in Rat Myocardial Infarction Model

Cardiac progenitor cells (CPCs) are well-characterized stem cell type shown to potentiate cardiac regeneration in myocardial infarct (MI) model. However, auto and allo immune response to transplanted adult CPCs (aCPCs) reduces cell retention and MI recovery. We aimed to increase the regenerative potential of aCPCs by reducing immune response directed to the transplanted aCPCs using cyclosporine A (CsA). Adult CPCs isolated from Wister Kyoto rat was transplanted into Brown Norway MI rats. MI rats transplanted with aCPCs+CsA demonstrated significant increase in MI recovery and cell retention compared to MI rats with aCPCs, CsA and Iscove Modified Dulbecco Media controls (p<0.05). MI rats transplanted with aCPCs showed increased infiltration of CD68 + cells and apoptotic cells in the infarcted myocardium compared to aCPCs+CsA group (p<0.05) analyzed by immunohistochemistry. Sera collected on day 2 and 7 of aCPCs group showed increased inflammatory cytokines (IL-2, IL-17, IFN-γ, TGF-β), antibodies to cardiac SAgs (Troponin-T and Myosin) allo antigens (RT1A, RT1B and RT1D) and reduced anti-inflammatory cytokines (IL-10). In contrast MI rats transplanted with aCPCs+CsA showed reduced inflammatory cytokines, abs to SAgs, allo antigens and increased anti-inflammatory cytokine IL-10 (p<0.05). In conclusion, MI rats transplanted with allogeneic aCPCs with immune suppressant CsA showed increased cell retention, reduced inflammatory cells and cytokines compared to aCPCs, CsA and IMDM control. Therefore, CsA reduces auto and allo immune response and increases regeneration potential by increased transplanted aCPCs retention that resulted in enhanced myocardial recovery.

Abstract 16769: Intravenous Injection of Neonatal Cardiac Mesenchymal Stem Cells is a Viable Alternative Route to Treat Acute Myocardial Infarction

Introduction: Cardiovascular disease is major cause of morbidity and mortality around the world and major health care burden indeed. Ischemic heart disease (IHD) and myocardial ischemia (MI) are most devastating cardiovascular disease. Multiple stem cell/ cardiac progenitor cell therapy has been reported previously to treat cardiovascular disease safely. However randomized clinical trials with adult cardiac progenitor cells or cardiosphere-derived cells unable to show long-term efficacy. We have our unique source of human neonatal cardiac tissue derived neonatal cardiac mesenchymal stem cells (nMSCs). Systemic administration is preferred route of stem cell delivery in order to consecutive dosage for most of the clinical trials. We hypothesized that nMSCs have unique proteome profile, which supports their survival, migration and homing. They home to the injured myocardium when administered intravenously (IV) to a wild type male rat subjected to MI. Methods: This model was created in 6-week-old Brown-Norway Rats. Rats were subjected to an anterior myocardial Infraction (MI) by permanent LAD ligation. The rats were treated with nMSCs (1^10 6 cells/Kg, 5^10 6 cells/Kg and 10^10 6 cells/Kg) along with placebo and sham, which are delivered intravenously by tail vein injection. Rats are once again treated with nMSCs/placebo 4 days after MI. Baseline echocardiography is performed 24 hours after MI. Results: LVEF was significantly higher in the nMSC-treated group than in the placebo group. Other parameters, including fractional shortening (FS) and decreased end-systolic volume (ESV), were also significantly improved when compared with the placebo group, and other LV functional parameter, including cardiac output/body weight and posterior wall thickness tended towards improvement of remodeled heart. Conclusions: Twice intravenous administration of nMSCs for MI attenuate the progressive deterioration of left ventricle and adverse remodeling of rat heart.

Abstract 17087: Mesenchymal Stem Cell-Derived Extracellular Vesicle Therapy Delivered in a Hydrogel Preserves Hemodynamic Function Following Myocardial Infarction

Introduction: Mesenchymal Stem Cell (MSC)-derived Extracellular Vesicles (EVs) are an emerging regenerative therapy for treatment of ischemic cardiomyopathy. In this study, we determine the efficacy of MSC-EV therapy in a shear-thinning hydrogel (STG) delivered via intramyocardial injection to the border zone of rat hearts following myocardial infarction (MI). Hypothesis: MSC EV-loaded STGs will preserve hemodynamic function and minimize ventricular scar formation in a rat model of acute MI. Methods: EVs were isolated from MSCs by PEG precipitation, and the EV proteome was characterized by MaxQuant 1.5.1.2 and Metacore analysis software. Varying concentrations of EVs were administered to rats following induction of acute MI by ligation of the left anterior descending artery. EVs were delivered in either sterile phosphate buffered saline (PBS) or STG for sustained EV release. Chronic injury was assessed at 4 weeks post-MI through transthoracic echocardiography, intraventricular pressure-volume loop displacement, and histology. Results: MSC EV proteomic analysis highlighted upregulation of VEGF angiogenic cascades and ILK-mediated proliferative pathways. The mean left ventricle ejection fraction (LVEF) for each treatment group at four weeks is displayed in Table 1. A 20 ug dose of MSC EVs in STG improved LVEF by 19.12% (p<0.05) compared to PBS, with a 90 ug dose of MSC EVs in STG increasing LVEF by 23.56% (p<0.01) (Fig. 1). Conclusions: Intramyocardial injection of MSC EVs in STG post-MI showed concentration dependent improvements in hemodynamics. These findings show that high doses of MSC EV in STG may have potential as a therapy for ischemic cardiomyopathy. Proteomic analysis revealed that angiogenesis, recruitment of cardiac progenitor cells, and immune modulation may be mechanistic drivers of MSC-EV therapy.

The Noncoding Side of Cardiac Differentiation and Regeneration.

Large scale projects such as FANTOM and ENCODE led to a revolution in our comprehension of the mammalian transcriptomes by revealing that ~53% of the produced RNAs do not encode for proteins. These transcripts, defined as noncoding RNAs (ncRNAs), constitute a heterogeneous group of molecules which can be categorized in two main classes, namely small and long, according to their length. In animals, the first-class includes Piwi-interacting RNAs (piRNAs), small interfering RNAs (siRNAs) and microRNAs (miRNAs). Among them, the best-characterized subgroup is represented by miRNAs, which are known to regulate gene expression largely at the post-transcriptional level. In contrast, long noncoding RNAs (lncRNAs) represent a more heterogeneous group of > 200 nucleotides long transcripts, that act through a variety of mechanisms at both transcriptional and posttranscriptional level. Here, we discuss how miRNAs and lncRNAs are emerging as pivotal regulators of cardiac muscle development and how the alteration of ncRNA expression was seen to disturb the physiology of all the different cell types forming the cardiac tissue. Particular emphasis is given to those species that are expressed and are known to regulate the capacity of cardiac progenitor cells (CPCs), currently used in regenerative medicine protocols, to proliferate and differentiate. Understanding how the ncRNAmediated circuitries regulate heart homeostasis is one of the research areas expected to have a high impact, improving the therapeutic efficacy of stem/progenitor-cells treatments for translation into clinical applications.

Vascular endothelial growth factor sustained delivery augmented cell therapy outcomes of cardiac progenitor cells for myocardial infarction.

Cell therapy has become a novel promising approach for improvement of cardiac functional capacity in the instances of ventricular remodeling and fibrosis caused by episodes of coronary artery occlusion and hypoxia. The challenge toward enhancing cell engraftment as well as formation of functional tissue, however, necessitated combinatorial approaches. Here, we complemented human embryonic stem cell-derived cardiac progenitor cell (hESC-CPC) therapy by heparin-conjugated, vascular endothelial growth factor (VEGF)-loaded fibrin hydrogel as VEGF delivery system. Transplantation of these cardiac committed cells along with sustained VEGF release could surpass the cardiac repair effects of each constituent alone in a rat model of acute myocardial infarction. The histological sections of rat hearts revealed improved vascularization as well as inclusion of hESC-CPC-derived cardiomyocytes, endothelial, and smooth muscle cells in host myocardium. Thus, co-transplantation of hESC-CPC and proangiogenic factor by a suitable delivery rate may resolve the shortcomings of conventional cell therapy.

Lysophosphatidic Acid Receptor 4 Is Transiently Expressed during Cardiac Differentiation and Critical for Repair of the Damaged Heart

Efficient differentiation of pluripotent stem cells (PSCs) into cardiac cells is essential for the development of new therapeutic modalities to repair damaged heart tissue. We identified a novel cell surface marker, the G protein-coupled receptor lysophosphatidic acid receptor 4 (LPAR4), specific to cardiac progenitor cells (CPCs) and determined its functional significance and therapeutic potential. During in vitro differentiation of mouse and human PSCs toward cardiac lineage, LPAR4 expression peaked after 3−7 days of differentiation in cardiac progenitors and then declined. In vivo, LPAR4 was specifically expressed in the early stage of embryonal heart development, and as development progressed, LPAR4 expression decreased and was non-specifically distributed. We identified the effective agonist octadecenyl phosphate and a p38 MAPK blocker as the downstream signal blocker. Sequential stimulation and inhibition of LPAR4 using these agents enhanced the in vitro efficiency of cardiac differentiation from mouse and human PSCs. Importantly, in vivo, this sequential stimulation and inhibition of LPAR4 reduced the infarct size and rescued heart dysfunction in mice. In conclusion, LPAR4 is a novel CPC marker transiently expressed only in heart during embryo development. Modulation of LPAR4-positive cells may be a promising strategy for repairing myocardium after myocardial infarction.

Comparison of One and Three Intraventricular Injections of Cardiac Progenitor Cells in a Murine Model of Chronic Ischemic Cardiomyopathy.

Repeated doses of c-kit+ cardiac progenitor cells (CPCs) are superior to a single dose in improving LV function in rats with old myocardial infarction (MI). However, this concept needs testing in different species to determine whether it is generalizable. We used a new murine model of chronic ischemic cardiomyopathy whose unique feature is that cell therapy was started late (3months) after MI. Mice received three echo-guided intraventricular infusions, 5weeks apart, of vehicle, CPCs × 1, or CPCs × 3. Echocardiography demonstrated that the single-dose group exhibited improved LV ejection fraction (EF) after the 1st infusion (CPCs), but not after the 2nd and 3rd (vehicle). In contrast, in the multiple-dose group LVEF continued to improve, so that the final value was greater than in vehicle or single-dose groups (P < 0.05). Hemodynamic studies showed that compared with vehicle, both preload-dependent and preload-independent functional parameters were significantly increased in the multiple-dose group but not in the single-dose group. Thus, two independent methods of functional assessment (echocardiography and hemodynamic studies) consistently demonstrated the superiority of three doses of CPCs vs. one dose. Compared with the single-dose group, the multiple-dose group exhibited less LV hypertrophy, as evidenced by a greater reduction in LV/body weight ratio and cardiomyocyte cross-sectional area. Furthermore, unlike the single dose, three CPC doses reduced myocardial inflammatory cells in the risk region. This is the first study of echo-guided intraventricular infusion of CPCs in mice with chronic ischemic cardiomyopathy. The results demonstrate that the beneficial effects of three CPC doses are greater than those of one dose, supporting the concept that multiple treatments are necessary to properly evaluate cell therapy. Our findings indicate that this concept applies not only to rat models but also to murine models. The generalizability of this strategy greatly enhances its importance and provides a rationale for large animal studies. Graphical abstract.

The Future of Direct Cardiac Reprogramming: Any GMT Cocktail Variety?

Direct cardiac reprogramming has emerged as a novel therapeutic approach to treat and regenerate injured hearts through the direct conversion of fibroblasts into cardiac cells. Most studies have focused on the reprogramming of fibroblasts into induced cardiomyocytes (iCMs). The first study in which this technology was described, showed that at least a combination of three transcription factors, GATA4, MEF2C and TBX5 (GMT cocktail), was required for the reprogramming into iCMs in vitro using mouse cells. However, this was later demonstrated to be insufficient for the reprogramming of human cells and additional factors were required. Thereafter, most studies have focused on implementing reprogramming efficiency and obtaining fully reprogrammed and functional iCMs, by the incorporation of other transcription factors, microRNAs or small molecules to the original GMT cocktail. In this respect, great advances have been made in recent years. However, there is still no consensus on which of these GMT-based varieties is best, and robust and highly reproducible protocols are still urgently required, especially in the case of human cells. On the other hand, apart from CMs, other cells such as endothelial and smooth muscle cells to form new blood vessels will be fundamental for the correct reconstruction of damaged cardiac tissue. With this aim, several studies have centered on the direct reprogramming of fibroblasts into induced cardiac progenitor cells (iCPCs) able to give rise to all myocardial cell lineages. Especially interesting are reports in which multipotent and highly expandable mouse iCPCs have been obtained, suggesting that clinically relevant amounts of these cells could be created. However, as of yet, this has not been achieved with human iCPCs, and exactly what stage of maturity is appropriate for a cell therapy product remains an open question. Nonetheless, the major concern in regenerative medicine is the poor retention, survival, and engraftment of transplanted cells in the cardiac tissue. To circumvent this issue, several cell pre-conditioning approaches are currently being explored. As an alternative to cell injection, in vivo reprogramming may face fewer barriers for its translation to the clinic. This approach has achieved better results in terms of efficiency and iCMs maturity in mouse models, indicating that the heart environment can favor this process. In this context, in recent years some studies have focused on the development of safer delivery systems such as Sendai virus, Adenovirus, chemical cocktails or nanoparticles. This article provides an in-depth review of the in vitro and in vivo cardiac reprograming technology used in mouse and human cells to obtain iCMs and iCPCs, and discusses what challenges still lie ahead and what hurdles are to be overcome before results from this field can be transferred to the clinical settings.

Derivation of proliferative islet1-positive cells during metamorphosis and wound response in Xenopus.

In mammalian hearts, cardiomyocytes retain a transient capacity to proliferate and regenerate following injury before birth, whereas they lose proliferative capacity immediately after birth. It has also been known that cardiac progenitor cells including islet1-positive cells do not contribute to the cardiac repair and regeneration in mammals. In contrast, hearts of zebrafish, amphibians and reptiles maintain a regenerative ability throughout life. Here, we analyzed proliferative capacity of cardiac cells during cardiac development and post-ventricular resection using Xenopus laevis, especially focusing on islet1. Immunohistochemical examination showed that islet1-positive cells were present in a wide range of the ventricle and maintained high dividing ability after metamorphosis. Interestingly, the islet1-positive cells were preserved even at 1year after metamorphosis, some of which showed tropomyosin expression. To assess the possibility of islet1-positive cells as a cellular resource, islet1 response to cardiac resection was analyzed, using adult hearts of 3months after metamorphosis. Transient gene activation of islet1 in apical region was detected within 1day after amputation. Histological analyses revealed that islet1-positive cells appeared in the vicinity of resection plane at 1day post-amputation (dpa) and increased at 3 dpa in both tropomyosin-positive and tropomyosin-negative regions. Vascular labeling analysis by biotinylated dextran amine (BDA) indicated that the islet1-positive cells in a tropomyosin-negative region were closely associated with cardiac vessels. Moreover, dividing ability at this time point was peaked. The resected region was healed with tropomyosin-positive cardiomyocytes until 3months post-amputation. These results suggest a role of islet1-positive cells as a cellular resource for vascularization and cardiogenesis in Xenopus laevis.

Hematopoietic Stem Cell Transcription Factors in Cardiovascular Pathology.

Transcription factors as multifaceted modulators of gene expression that play a central role in cell proliferation, differentiation, lineage commitment, and disease progression. They interact among themselves and create complex spatiotemporal gene regulatory networks that modulate hematopoiesis, cardiogenesis, and conditional differentiation of hematopoietic stem cells into cells of cardiovascular lineage. Additionally, bone marrow-derived stem cells potentially contribute to the cardiovascular cell population and have shown potential as a therapeutic approach to treat cardiovascular diseases. However, the underlying regulatory mechanisms are currently debatable. This review focuses on some key transcription factors and associated epigenetic modifications that modulate the maintenance and differentiation of hematopoietic stem cells and cardiac progenitor cells. In addition to this, we aim to summarize different potential clinical therapeutic approaches in cardiac regeneration therapy and recent discoveries in stem cell-based transplantation.

Trophoblast Stem-Cell-Derived Exosomes Improve Doxorubicin-Induced Dilated Cardiomyopathy by Modulating the let-7i/YAP Pathway

Trophoblast stem cells (TSCs) have been confirmed to play a cardioprotective role in heart failure. However, whether TSC-derived exosomes (TSC-exos) can protect against cardiac injury remains unclear. In the present study, TSC-exos were isolated from the supernatant of TSCs using the ultracentrifugation method and characterized by transmission electron microscopy and western blotting. Utilizing the public Gene Expression Omnibus (GEO) database, we found that let-7i and Yes-associated protein 1 (YAP) could participate in the development of heart failure. In vitro, AC16 cardiomyocytes subjected to doxorubicin (DOX) were treated with TSC-exos or let-7i mimic. Flow cytometry showed that TSC-exos and let-7i both decreased cardiomyocyte apoptosis. In vivo, mice that were intraperitoneally injected into DOX received either PBS, TSC-exos, or AAV9-let7iup for let-7i overexpression. Mice receiving TSC-exos and AAV9-let7iup showed improved cardiac function and decreased inflammatory responses, accompanied by downregulated YAP signaling. Mechanistically, TSC-exos could transfer let-7i to cardiomyocytes and silence the YAP signaling pathway. In conclusion, TSC-exos could alleviate DOX-induced cardiac injury via the let-7i/YAP pathway, which sheds new light on the application of TSC-exos as a potential therapeutic tool for heart failure.

Dynamic transcriptome profiling toward understanding the development of the human embryonic heart during different Carnegie stages

Transcriptional regulation participates in heart development. However, the transcriptomes of human embryonic hearts during Carnegie stage (CS)10-CS16 have not been elucidated. Here, we found marked changes in the morphology and transcriptome of the human embryonic heart from CS10 to CS11. At CS12-CS14, the embryonic heart undergoes hypoxia-to-aerobic transformation. At CS14-CS16, transcriptome functions were related to energy metabolism, regulation of cholesterol, and processes related to inorganic substances. Moreover, the transcriptomes of cardiac progenitor cells derived from human embryonic stem cells (hESCs) most overlapped with those of human embryonic hearts at CS10. Cardiomyocytes derived from hESCs considerably overlapped with embryonic hearts at CS14-CS16. Overall, these results provide a new perspective into the characteristics of human embryonic heart development.

Differences in Mitochondrial Membrane Potential Identify Distinct Populations of Human Cardiac Mesenchymal Progenitor Cells.

Adult human cardiac mesenchymal progenitor cells (hCmPC) are multipotent resident populations involved in cardiac homeostasis and heart repair. Even if the mechanisms have not yet been fully elucidated, the stem cell differentiation is guided by the mitochondrial metabolism; however, mitochondrial approaches to identify hCmPC with enhanced stemness and/or differentiation capability for cellular therapy are not established. Here we demonstrated that hCmPCs sorted for low and high mitochondrial membrane potential (using a lipophilic cationic dye tetramethylrhodamine methyl ester, TMRM), presented differences in energy metabolism from preferential glycolysis to oxidative rates. TMRM-high cells are highly efficient in terms of oxygen consumption rate, basal and maximal respiration, and spare respiratory capacity compared to TMRM-low cells. TMRM-high cells showed characteristics of pre-committed cells and were associated with higher in vitro differentiation capacity through endothelial, cardiac-like, and, to a lesser extent, adipogenic and chondro/osteogenic cell lineage, when compared with TMRM-low cells. Conversely, TMRM-low showed higher self-renewal potential. To conclude, we identified two hCmPC populations with different metabolic profile, stemness maturity, and differentiation potential. Our findings suggest that metabolic sorting can isolate cells with higher regenerative capacity and/or long-term survival. This metabolism-based strategy to select cells may be broadly applicable to therapies.

12-O-Tetradecanoylphorbol-13-acetate increases cardiomyogenesis through PKC/ERK signaling

12-O-Tetradecanoylphorbol-13-acetate (TPA) is the most widely used diacylglycerol (DAG) mimetic agent and inducer of protein kinase C (PKC)-mediated cellular response in biomedical studies. TPA has been proposed as a pluripotent cell differentiation factor, but results obtained have been inconsistent. In the present study we show that TPA can be applied as a cardiomyogenesis-promoting factor for the differentiation of mouse embryonic stem (mES) cells in vitro. The mechanism of TPA action is mediated by the induction of extracellular signal-regulated kinase (ERK) activity and the subsequent phosphorylation of GATA4 transcription factor. Interestingly, general mitogens (FGF, EGF, VEGF and serum) or canonical WNT signalling did not mimic the effect of TPA. Moreover, on the basis of our results, we postulate that a TPA-sensitive population of cardiac progenitor cells exists at a certain time point (after days 6–8 of the differentiation protocol) and that the proposed treatment can be used to increase the multiplication of ES cell-derived cardiomyocytes.