Immuno-related cardio-vascular adverse events associated with immuno-oncological treatments: an under-estimated threat for cancer patients.

Immunotherapy represents an emergent and heterogeneous group of anticancer treatments harnessing the human immune-surveillance system, including immune-checkpoint inhibitor monoclonal antibodies (mAbs), Chimeric Antigen Receptor T Cells (CAR-T) therapy, cancer vaccines and lymphocyte activation gene-3 (LAG-3) therapy. While remarkably effective against several malignancies, these therapies, often in combination with other cancer treatments, have showed unforeseen toxicity, including cardiovascular complications. The occurrence of immuno-mediated adverse (irAEs) events has been progressively reported in the last 10 years. These irAEs present an extended range of severity, from self-limiting to life-threatening conditions. Although recent guidelines in CardioOncology have provided important evidence in managing cancer treatments, they often encompass general approaches. However, a specific focus is required due to the particular etiology, unique risk factors, and associated side effects of immunotherapy. This review aims to deepen the understanding of the prevalence and nature of cardiovascular issues in patients undergoing immunotherapy, offering insights into strategies for risk stratification and management.

Challenge of concomitant thymoma resection and myocardial revascularization: A Case Report.

Myocardial revascularization in patients presenting with an anterior mediastinal mass poses considerable challenges. In this report, we outline two cases involving patients with anterior mediastinal masses who underwent surgical resection alongside concurrent myocardial revascularization. One patient underwent coronary artery bypass graft surgery, while the other was treated by percutaneous coronary intervention with drug-eluting stent placement. Both patients fully recovered from the relative procedures and were discharged within two weeks post-surgery, ultimately diagnosed with thymoma. The concomitant intervention offered the advantage of promptly addressing both conditions, and it was performed safely through a collaborative multidisciplinary effort.

Effects of sacubitril-valsartan on aging-related cardiac dysfunction.

Heart failure (HF) remains a huge medical burden worldwide, with aging representing a major risk factor. Here, we report the effects of sacubitril/valsartan, an approved drug for HF with reduced EF, in an experimental model of aging-related HF with preserved ejection fraction (HFpEF). Eighteen-month-old female Fisher 344 rats were treated for 12 weeks with sacubitril/valsartan (60 mg/kg/day) or with valsartan (30 mg/kg/day). Three-month-old rats were used as control. No differential action of sacubitril/valsartan versus valsartan alone, either positive or negative, was observed. The positive effects of both sacubitril/valsartan and valsartan on cardiac hypertrophy was evidenced by a significant reduction of wall thickness and myocyte cross-sectional area. Contrarily, myocardial fibrosis in aging heart was not reduced by any treatment. Doppler echocardiography and left ventricular catheterization evidenced diastolic dysfunction in untreated and treated old rats. In aging rats, both classical and non-classical renin-angiotensin-aldosterone system (RAAS) were modulated. In particular, with respect to untreated animals, both sacubitril/valsartan and valsartan showed a partial restoration of cardioprotective non-classical RAAS. In conclusion, this study evidenced the favorable effects, by both treatments, on age-related cardiac hypertrophy. The attenuation of cardiomyocyte size and hypertrophic response may be linked to a shift towards cardioprotective RAAS signaling. However, diastolic dysfunction and cardiac fibrosis persisted despite of treatment and were accompanied by myocardial inflammation, endothelial activation, and oxidative stress.

Full-Moon Coronary Calcification as Detected With Computed Tomography Angiography in Chronic Total Occlusion Percutaneous Coronary Intervention.

"Full moon" is a central calcification that occludes the entire vessel on coronary computed tomography angiography (CCTA). We examined the association of full moon calcification as identified by CCTA, on clinical and procedural outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). We studied patients who underwent elective CTO-PCI in 2 European centers and had preprocedural CCTA. The primary end point was the inability to cross the lesion and/or the need for extensive debulking techniques. Secondary end points were procedural success, in-hospital cardiac mortality, the need for extensive debulking techniques, myocardial infarction, major adverse cardiac events (defined as in-hospital death, myocardial infarction, and clinically driven target vessel revascularization), and stent thrombosis. Secondary procedural end points included procedural time, fluoroscopy time, number of guidewires and balloons, stent length, number and diameter, and contrast volume. Multivariable logistic regression analysis was performed, identifying potential covariates related to the primary outcome according to knowledge and previous studies. Subsequently, a stepwise selection approach was performed to select factors with the greatest predictive value. Of 140 patients included, 28 (20%) had a full moon calcified CTO plaque. Patients in the full moon group were older and had more cardiovascular risk factors. There was not significant difference in the need for retrograde approach and anterograde dissection and reentry techniques between the full moon group and the other groups (32.1% vs 37.5%, p = 0.59 and 0% vs 1.7%, p = 0.47, respectively). Patients in the full moon group had greater incidence of the primary outcome than did those who did not have full moon morphology (53.5% vs 12.5%, p <0.001). On multivariable analysis that included chronic kidney failure and previous coronary artery bypass surgery, full moon calcification was associated with greater incidence of the primary end point (odds ratio 6.5, 95% confidence interval 2.1 to 20.5, p = 0.001). Moreover, less procedural success (71.4% vs 87.5%, p = 0.03), greater incidence of coronary perforations (14.2% vs 3.5%, p <0.02), and greater procedural (172.5 [118.0 to 237.5] vs 144.0 [108.50 to 174.75], p = 0.02) and fluoroscopic time (62.6 [38.1 to 83.0] vs 42.8 [29.5 to 65.7], p = 0.03) were observed in the full moon group. Overall major adverse cardiac events did not differ between the 2 groups (1 patient in the full moon group vs 1 patient in the non-full moon group; 3.5% vs 0.8%, p = 0.29). In conclusion, full moon calcification on CCTA was independently associated with procedural complexity and adverse outcomes in CTO-PCI.

Polarizing Macrophage Functional Phenotype to Foster Cardiac Regeneration.

There is an increasing interest in understanding the connection between the immune and cardiovascular systems, which are highly integrated and communicate through finely regulated cross-talking mechanisms. Recent evidence has demonstrated that the immune system does indeed have a key role in the response to cardiac injury and in cardiac regeneration. Among the immune cells, macrophages appear to have a prominent role in this context, with different subtypes described so far that each have a specific influence on cardiac remodeling and repair. Similarly, there are significant differences in how the innate and adaptive immune systems affect the response to cardiac damage. Understanding all these mechanisms may have relevant clinical implications. Several studies have already demonstrated that stem cell-based therapies support myocardial repair. However, the exact role that cardiac macrophages and their modulation may have in this setting is still unclear. The current need to decipher the dual role of immunity in boosting both heart injury and repair is due, at least for a significant part, to unresolved questions related to the complexity of cardiac macrophage phenotypes. The aim of this review is to provide an overview on the role of the immune system, and of macrophages in particular, in the response to cardiac injury and to outline, through the modulation of the immune response, potential novel therapeutic strategies for cardiac regeneration.

Adult Multipotent Cardiac Progenitor-Derived Spheroids: A Reproducible Model of In Vitro Cardiomyocyte Commitment and Specification.

BACKGROUND: Three-dimensional cell culture systems hold great promise for bridging the gap between in vitro cell-based model systems and small animal models to study tissue biology and disease. Among 3D cell culture systems, stem-cell-derived spheroids have attracted significant interest as a strategy to better mimic in vivo conditions. Cardiac stem cell/progenitor (CSC)-derived spheroids (CSs) provide a relevant platform for cardiac regeneration. METHODS: We compared three different cell culture scaffold-free systems, (i) ultra-low attachment plates, (ii) hanging drops (both requiring a 2D/3D switch), and (iii) agarose micro-molds (entirely 3D), for CSC-derived CS formation and their cardiomyocyte commitment in vitro. RESULTS: The switch from a 2D to a 3D culture microenvironment per se guides cell plasticity and myogenic differentiation within CS and is necessary for robust cardiomyocyte differentiation. On the contrary, 2D monolayer CSC cultures show a significant reduced cardiomyocyte differentiation potential compared to 3D CS culture. Forced aggregation into spheroids using hanging drop improves CS myogenic differentiation when compared to ultra-low attachment plates. Performing CS formation and myogenic differentiation exclusively in 3D culture using agarose micro-molds maximizes the cardiomyocyte yield. CONCLUSIONS: A 3D culture system instructs CS myogenic differentiation, thus representing a valid model that can be used to study adult cardiac regenerative biology.

Thermoresponsive M1 macrophage-derived hybrid nanovesicles for improved in vivo tumor targeting.

Despite the efforts and advances done in the last few decades, cancer still remains one of the main leading causes of death worldwide. Nanomedicine and in particular extracellular vesicles are one of the most potent tools to improve the effectiveness of anticancer therapies. In these attempts, the aim of this work is to realize a hybrid nanosystem through the fusion between the M1 macrophages-derived extracellular vesicles (EVs-M1) and thermoresponsive liposomes, in order to obtain a drug delivery system able to exploit the intrinsic tumor targeting capability of immune cells reflected on EVs and thermoresponsiveness of synthetic nanovesicles. The obtained nanocarrier has been physicochemically characterized, and the hybridization process has been validated by cytofluorimetric analysis, while the thermoresponsiveness was in vitro confirmed through the use of a fluorescent probe. Tumor targeting features of hybrid nanovesicles were in vivo investigated on melanoma-induced mice model monitoring the accumulation in tumor site through live imaging and confirmed by cytofluorimetric analysis, showing higher targeting properties of hybrid nanosystem compared to both liposomes and native EVs. These promising results confirmed the ability of this nanosystem to combine the advantages of both nanotechnologies, also highlighting their potential use as effective and safe personalized anticancer nanomedicine.

Initial Phase of Anthracycline Cardiotoxicity Involves Cardiac Fibroblasts Activation and Metabolic Switch.

The application of doxorubicin (DOX) is hampered by cardiotoxicity, with diastolic dysfunction as the earliest manifestation. Fibrosis leads to impaired relaxation, but the mechanisms that operate shortly after DOX exposure are not clear. We asked whether the activation of cardiac fibroblasts (CFs) anticipates myocardial dysfunction and evaluated the effects of DOX on CF metabolism. CFs were isolated from the hearts of rats after the first injection of DOX. In another experiment, CFs were exposed to DOX in vitro. Cell phenotype and metabolism were determined. Early effects of DOX consisted of diastolic dysfunction and unchanged ejection fraction. Markers of pro-fibrotic remodeling and evidence of CF transformation were present immediately after treatment completion. Oxygen consumption rate and extracellular acidification revealed an increased metabolic activity of CFs and a switch to glycolytic energy production. These effects were consistent in CFs isolated from the hearts of DOX-treated animals and in naïve CFs exposed to DOX in vitro. The metabolic switch was paralleled with the phenotype change of CFs that upregulated markers of myofibroblast differentiation and the activation of pro-fibrotic signaling. In conclusion, the metabolic switch and activation of CFs anticipate DOX-induced damage and represent a novel target in the early phase of anthracycline cardiomyopathy.

Mitochondrial a Kinase Anchor Proteins in Cardiovascular Health and Disease: A Review Article on Behalf of the Working Group on Cellular and Molecular Biology of the Heart of the Italian Society of Cardiology.

Second messenger cyclic adenosine monophosphate (cAMP) has been found to regulate multiple mitochondrial functions, including respiration, dynamics, reactive oxygen species production, cell survival and death through the activation of cAMP-dependent protein kinase A (PKA) and other effectors. Several members of the large family of A kinase anchor proteins (AKAPs) have been previously shown to locally amplify cAMP/PKA signaling to mitochondria, promoting the assembly of signalosomes, regulating multiple cardiac functions under both physiological and pathological conditions. In this review, we will discuss roles and regulation of major mitochondria-targeted AKAPs, along with opportunities and challenges to modulate their functions for translational purposes in the cardiovascular system.

Ammonium Glycyrrhizinate and Bergamot Essential Oil Co-Loaded Ultradeformable Nanocarriers: An Effective Natural Nanomedicine for In Vivo Anti-Inflammatory Topical Therapies.

Bergamot essential oil (BEO) and Ammonium glycyrrhizinate (AG), naturally derived compounds, have remarkable anti-inflammatory properties, thus making them suitable candidates for the treatment of skin disorders. Despite this, their inadequate physicochemical properties strongly compromise their topical application. Ultradeformable nanocarriers containing both BEO and AG were used to allow their passage through the skin, thus maximizing their therapeutic activity. Physicochemical characterization studies were performed using Zetasizer Nano ZS and Turbiscan Lab®. The dialysis method was used to investigate the release profile of the active compounds. In vivo studies were performed on human healthy volunteers through the X-Rite spectrophotometer. The nanosystems showed suitable features for topical cutaneous administration in terms of mean size, surface charge, size distribution, and long-term stability/storability. The co-delivery of BEO and AG in the deformable systems improved both the release profile kinetic of ammonium glycyrrhizinate and deformability properties of the resulting nanosystems. The topical cutaneous administration on human volunteers confirmed the efficacy of the nanosystems. In detail, BEO and AG-co-loaded ultradeformable vesicles showed a superior activity compared to that recorded from the ones containing AG as a single agent. These results are promising and strongly encourage a potential topical application of AG/BEO co-loaded nanocarriers for anti-inflammatory therapies.

Iron Administration Overcomes Resistance to Erastin-Mediated Ferroptosis in Ovarian Cancer Cells.

Objectives: Developing novel therapeutic approaches to defeat chemoresistance is the major goal of ovarian cancer research. Induction of ferroptosis has shown promising antitumor effects in ovarian cancer cells, but the existence of still undefined genetic and metabolic determinants of susceptibility has so far limited the application of ferroptosis inducers in vivo. Methods: Erastin and/or the iron compound ferlixit were used to trigger ferroptosis in HEY, COV318, PEO4, and A2780CP ovarian cancer cell lines. Cell viability and cell death were measured by MTT and PI flow cytometry assay, respectively. The "ballooning" phenotype was tested as ferroptosis specific morphological feature. Mitochondrial dysfunction was evaluated based on ultrastructural changes, mitochondrial ROS, and mitochondrial membrane polarization. Lipid peroxidation was tested through both C11-BODIPY and malondialdehyde assays. VDAC2 and GPX4 protein levels were quantified as additional putative indicators of mitochondrial dysfunction or lipid peroxidation, respectively. The effect of erastin/ferlixit treatments on iron metabolism was analyzed by measuring intracellular labile iron pool and ROS. FtH and NCOA4 were measured as biomarkers of ferritinophagy. Results: Here, we provide evidence that erastin is unable to induce ferroptosis in a series of ovarian cancer cell lines. In HEY cells, provided with a high intracellular labile iron pool, erastin treatment is accompanied by NCOA4-mediated ferritinophagy and mitochondrial dysfunction, thus triggering ferroptosis. In agreement, iron chelation counteracts erastin-induced ferroptosis in these cells. COV318 cells, with low baseline intracellular labile iron pool, appear resistant to erastin treatment. Notably, the use of ferlixit sensitizes COV318 cells to erastin through a NCOA4-independent intracellular iron accumulation and mitochondrial dysfunction. Ferlixit alone mimics erastin effects and promotes ferroptosis in HEY cells. Conclusion: This study proposes both the baseline and the induced intracellular free iron level as a significant determinant of ferroptosis sensitivity and discusses the potential use of ferlixit in combination with erastin to overcome ferroptosis chemoresistance in ovarian cancer.

Diabetes-Induced Cellular Senescence and Senescence-Associated Secretory Phenotype Impair Cardiac Regeneration and Function Independently of Age.

Diabetes mellitus (DM) affects the biology of multipotent cardiac stem/progenitor cells (CSCs) and adult myocardial regeneration. We assessed the hypothesis that senescence and senescence-associated secretory phenotype (SASP) are main mechanisms of cardiac degenerative defect in DM. Accordingly, we tested whether ablation of senescent CSCs would rescue the cardiac regenerative/reparative defect imposed by DM. We obtained cardiac tissue from nonaged (50- to 64-year-old) patients with type 2 diabetes mellitus (T2DM) and without DM (NDM) and postinfarct cardiomyopathy undergoing cardiac surgery. A higher reactive oxygen species production in T2DM was associated with an increased number of senescent/dysfunctional T2DM-human CSCs (hCSCs) with reduced proliferation, clonogenesis/spherogenesis, and myogenic differentiation versus NDM-hCSCs in vitro. T2DM-hCSCs showed a defined pathologic SASP. A combination of two senolytics, dasatinib (D) and quercetin (Q), cleared senescent T2DM-hCSCs in vitro, restoring their expansion and myogenic differentiation capacities. In a T2DM model in young mice, diabetic status per se (independently of ischemia and age) caused CSC senescence coupled with myocardial pathologic remodeling and cardiac dysfunction. D + Q treatment efficiently eliminated senescent cells, rescuing CSC function, which resulted in functional myocardial repair/regeneration, improving cardiac function in murine DM. In conclusion, DM hampers CSC biology, inhibiting CSCs' regenerative potential through the induction of cellular senescence and SASP independently from aging. Senolytics clear senescence, abrogating the SASP and restoring a fully proliferative/differentiation-competent hCSC pool in T2DM with normalization of cardiac function.

Physical Exercise and Cardiac Repair: The Potential Role of Nitric Oxide in Boosting Stem Cell Regenerative Biology.

Over the years strong evidence has been accumulated showing that aerobic physical exercise exerts beneficial effects on the prevention and reduction of cardiovascular risk. Exercise in healthy subjects fosters physiological remodeling of the adult heart. Concurrently, physical training can significantly slow-down or even reverse the maladaptive pathologic cardiac remodeling in cardiac diseases, improving heart function. The underlying cellular and molecular mechanisms of the beneficial effects of physical exercise on the heart are still a subject of intensive study. Aerobic activity increases cardiovascular nitric oxide (NO) released mainly through nitric oxidase synthase 3 activity, promoting endothelium-dependent vasodilation, reducing vascular resistance, and lowering blood pressure. On the reverse, an imbalance between increasing free radical production and decreased NO generation characterizes pathologic remodeling, which has been termed the "nitroso-redox imbalance". Besides these classical evidence on the role of NO in cardiac physiology and pathology, accumulating data show that NO regulate different aspects of stem cell biology, including survival, proliferation, migration, differentiation, and secretion of pro-regenerative factors. Concurrently, it has been shown that physical exercise generates physiological remodeling while antagonizes pathologic remodeling also by fostering cardiac regeneration, including new cardiomyocyte formation. This review is therefore focused on the possible link between physical exercise, NO, and stem cell biology in the cardiac regenerative/reparative response to physiological or pathological load. Cellular and molecular mechanisms that generate an exercise-induced cardioprotective phenotype are discussed in regards with myocardial repair and regeneration. Aerobic training can benefit cells implicated in cardiovascular homeostasis and response to damage by NO-mediated pathways that protect stem cells in the hostile environment, enhance their activation and differentiation and, in turn, translate to more efficient myocardial tissue regeneration. Moreover, stem cell preconditioning by and/or local potentiation of NO signaling can be envisioned as promising approaches to improve the post-transplantation stem cell survival and the efficacy of cardiac stem cell therapy.

Reparative cell therapy for the heart: critical internal appraisal of the field in response to recent controversies.

The concept that cell-based repair of myocardial injury might be possible was introduced almost two decades ago; however, the field of cardiovascular reparative medicine has been criticized as translation to clinically effective approaches has been slow. The recent retraction of a series of papers has further impacted perception of this area of research. As researchers, clinicians, and teachers in this field, we felt it incumbent to critically appraise the current state of cardiac cell repair, determine what can be learned from past mistakes, and formulate best practices for future work. This special communication summarizes an introspective assessment of what has fallen short, how to prevent similar issues, and how the field might best move forward in the service of science and patients.

Combined lymphocyte/monocyte count, D-dimer and iron status predict COVID-19 course and outcome in a long-term care facility.

BACKGROUND: The Sars-CoV-2 can cause severe pneumonia with multiorgan disease; thus, the identification of clinical and laboratory predictors of the progression towards severe and fatal forms of this illness is needed. Here, we retrospectively evaluated and integrated laboratory parameters of 45 elderly subjects from a long-term care facility with Sars-CoV-2 outbreak and spread, to identify potential common patterns of systemic response able to better stratify patients' clinical course and outcome. METHODS: Baseline white blood cells, granulocytes', lymphocytes', and platelets' counts, hemoglobin, total iron, ferritin, D-dimer, and interleukin-6 concentration were used to generate a principal component analysis. Statistical analysis was performed by using R statistical package version 4.0. RESULTS: We identified 3 laboratory patterns of response, renamed as low-risk, intermediate-risk, and high-risk, strongly associated with patients' survival (p < 0.01). D-dimer, iron status, lymphocyte/monocyte count represented the main markers discriminating high- and low-risk groups. Patients belonging to the high-risk group presented a significantly longer time to ferritin decrease (p: 0.047). Iron-to-ferritin-ratio (IFR) significantly segregated recovered and dead patients in the intermediate-risk group (p: 0.012). CONCLUSIONS: Our data suggest that a combination of few laboratory parameters, i.e. iron status, D-dimer and lymphocyte/monocyte count at admission and during the hospital stay, can predict clinical progression in COVID-19.

Statins Stimulate New Myocyte Formation After Myocardial Infarction by Activating Growth and Differentiation of the Endogenous Cardiac Stem Cells.

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) exert pleiotropic effects on cardiac cell biology which are not yet fully understood. Here we tested whether statin treatment affects resident endogenous cardiac stem/progenitor cell (CSC) activation in vitro and in vivo after myocardial infarction (MI). Statins (Rosuvastatin, Simvastatin and Pravastatin) significantly increased CSC expansion in vitro as measured by both BrdU incorporation and cell growth curve. Additionally, statins increased CSC clonal expansion and cardiosphere formation. The effects of statins on CSC growth and differentiation depended on Akt phosphorylation. Twenty-eight days after myocardial infarction by permanent coronary ligation in rats, the number of endogenous CSCs in the infarct border zone was significantly increased by Rosuvastatin-treatment as compared to untreated controls. Additionally, commitment of the activated CSCs into the myogenic lineage (c-kitpos/Gata4pos CSCs) was increased by Rosuvastatin administration. Accordingly, Rosuvastatin fostered new cardiomyocyte formation after MI. Finally, Rosuvastatin treatment reversed the cardiomyogenic defects of CSCs in c-kit haploinsufficient mice, increasing new cardiomyocyte formation by endogenous CSCs in these mice after myocardial infarction. In summary, statins, by sustaining Akt activation, foster CSC growth and differentiation in vitro and in vivo. The activation and differentiation of the endogenous CSC pool and consequent new myocyte formation by statins improve myocardial remodeling after coronary occlusion in rodents. Similar effects might contribute to the beneficial effects of statins on human cardiovascular diseases.

Unravelling the Biology of Adult Cardiac Stem Cell-Derived Exosomes to Foster Endogenous Cardiac Regeneration and Repair.

Cardiac remuscularization has been the stated goal of the field of regenerative cardiology since its inception. Along with the refreshment of lost and dysfunctional cardiac muscle cells, the field of cell therapy has expanded in scope encompassing also the potential of the injected cells as cardioprotective and cardio-reparative agents for cardiovascular diseases. The latter has been the result of the findings that cell therapies so far tested in clinical trials exert their beneficial effects through paracrine mechanisms acting on the endogenous myocardial reparative/regenerative potential. The endogenous regenerative potential of the adult heart is still highly debated. While it has been widely accepted that adult cardiomyocytes (CMs) are renewed throughout life either in response to wear and tear and after injury, the rate and origin of this phenomenon are yet to be clarified. The adult heart harbors resident cardiac/stem progenitor cells (CSCs/CPCs), whose discovery and characterization were initially sufficient to explain CM renewal in response to physiological and pathological stresses, when also considering that adult CMs are terminally differentiated cells. The role of CSCs in CM formation in the adult heart has been however questioned by some recent genetic fate map studies, which have been proved to have serious limitations. Nevertheless, uncontested evidence shows that clonal CSCs are effective transplantable regenerative agents either for their direct myogenic differentiation and for their paracrine effects in the allogeneic setting. In particular, the paracrine potential of CSCs has been the focus of the recent investigation, whereby CSC-derived exosomes appear to harbor relevant regenerative and reparative signals underlying the beneficial effects of CSC transplantation. This review focuses on recent advances in our knowledge about the biological role of exosomes in heart tissue homeostasis and repair with the idea to use them as tools for new therapeutic biotechnologies for "cell-less" effective cardiac regeneration approaches.

Atrial myxomas arise from multipotent cardiac stem cells.

AIMS: Cardiac myxomas usually develop in the atria and consist of an acid-mucopolysaccharide-rich myxoid matrix with polygonal stromal cells scattered throughout. These human benign tumours are a valuable research model because of the rarity of cardiac tumours, their clinical presentation and uncertain origin. Here, we assessed whether multipotent cardiac stem/progenitor cells (CSCs) give rise to atrial myxoma tissue. METHODS AND RESULTS: Twenty-three myxomas were collected and analysed for the presence of multipotent CSCs. We detected myxoma cells positive for c-kit (c-kitpos) but very rare Isl-1 positive cells. Most of the c-kitpos cells were blood lineage-committed CD45pos/CD31pos cells. However, c-kitpos/CD45neg/CD31neg cardiac myxoma cells expressed stemness and cardiac progenitor cell transcription factors. Approximately ≤10% of the c-kitpos/CD45neg/CD31neg myxoma cells also expressed calretinin, a characteristic of myxoma stromal cells. In vitro, the c-kitpos/CD45neg/CD31neg myxoma cells secrete chondroitin-6-sulfate and hyaluronic acid, which are the main components of gelatinous myxoma matrix in vivo. In vitro, c-kitpos/CD45neg/CD31neg myxoma cells have stem cell properties being clonogenic, self-renewing, and sphere forming while exhibiting an abortive cardiac differentiation potential. Myxoma-derived CSCs possess a mRNA and microRNA transcriptome overall similar to normal myocardium-derived c-kitpos/CD45neg/CD31negCSCs , yet showing a relatively small and relevant fraction of dysregulated mRNA/miRNAs (miR-126-3p and miR-335-5p, in particular). Importantly, myxoma-derived CSCs but not normal myocardium-derived CSCs, seed human myxoma tumours in xenograft's in immunodeficient NOD/SCID mice. CONCLUSION: Myxoma-derived c-kitpos/CD45neg/CD31neg CSCs fulfill the criteria expected of atrial myxoma-initiating stem cells. The transcriptome of these cells indicates that they belong to or are derived from the same lineage as the atrial multipotent c-kitpos/CD45neg/CD31neg CSCs. Taken together the data presented here suggest that human myxomas could be the first-described CSC-related human heart disease.

Heterogeneity of Adult Cardiac Stem Cells.

Cardiac biology and heart regeneration have been intensively investigated and debated in the last 15 years. Nowadays, the well-established and old dogma that the adult heart lacks of any myocyte-regenerative capacity has been firmly overturned by the evidence of cardiomyocyte renewal throughout the mammalian life as part of normal organ cell homeostasis, which is increased in response to injury. Concurrently, reproducible evidences from independent laboratories have convincingly shown that the adult heart possesses a pool of multipotent cardiac stem/progenitor cells (CSCs or CPCs) capable of sustaining cardiomyocyte and vascular tissue refreshment after injury. CSC transplantation in animal models displays an effective regenerative potential and may be helpful to treat chronic heart failure (CHF), obviating at the poor/modest results using non-cardiac cells in clinical trials. Nevertheless, the degree/significance of cardiomyocyte turnover in the adult heart, which is insufficient to regenerate extensive damage from ischemic and non-ischemic origin, remains strongly disputed. Concurrently, different methodologies used to detect CSCs in situ have created the paradox of the adult heart harboring more than seven different cardiac progenitor populations. The latter was likely secondary to the intrinsic heterogeneity of any regenerative cell agent in an adult tissue but also to the confusion created by the heterogeneity of the cell population identified by a single cell marker used to detect the CSCs in situ. On the other hand, some recent studies using genetic fate mapping strategies claimed that CSCs are an irrelevant endogenous source of new cardiomyocytes in the adult. On the basis of these contradictory findings, here we critically reviewed the available data on adult CSC biology and their role in myocardial cell homeostasis and repair.