Cobalt (Co) and chromium (Cr) are widely used in medical implants due to their strength and biocompatibility. However, implant wear and corrosion can lead to systemic release of these metals, raising concerns about cardiotoxic effects, especially with long-term exposure. This review summarizes current data on the potential cardiotoxicity of implant-derived Co and Cr, focusing on molecular mechanisms, inflammatory responses, and clinical observations. Case reports and clinical studies document considerable variability in serum Co and Cr concentrations postimplantation, influenced by implant type, material composition, and patient-specific factors. While extreme elevations are strongly associated with cardiomyopathy and fibrosis, moderate increases also correlate with subclinical changes such as ventricular dilatation and impaired strain. Nonetheless, many studies fail to find a direct relationship between ion levels and cardiac dysfunction, highlighting the complexity and interindividual variability of toxic responses and underlying pathomechanisms. Existing experimental data suggest that Co and Cr ions interfere with calcium and magnesium handling, impair mitochondrial respiration, and promote the generation of reactive oxygen species. Additionally, both metals can induce inflammatory responses, including cytokine release that results in DNA damage, apoptosis, and impaired cardiomyocyte physiology. Although Co and Cr implants offer substantial clinical benefits, emerging evidence indicates that they may contribute to cardiotoxicity in susceptible individuals. Current findings emphasize the importance of personalized monitoring, including serum ion concentration assessments and advanced imaging techniques. Given the absence of universally accepted toxicity thresholds, further mechanistic and longitudinal clinical studies are essential to define risk stratification strategies, establish safe exposure limits, and improve the cardiovascular safety of patients with metal implants.

Background/Objectives: This study aimed to compare changes in functional and strain parameters in young and old mice using cardiac MRI before and shortly after myocardial infarction. Methods: In this prospective experimental study, 7 young mice and 10 old mice underwent a cardiac MRI 5 days before and 2 days after myocardial infarction by LAD ligation. Functional parameters such as EDV, ESV, EF, SV, and Strain were determined. Results: EDV in the young mice before LAD ligation was significantly lower than in the old mice (p-value 0.002). EDV significantly increased after infarction in both groups. ESV was significantly lower in young mice before infarction than in old mice (9.7 ± 2.6 vs. 13.8 ± 3.9 [µL], p = 0.029). After infarction, the mean value was still lower but no longer significant. There was no significant difference between young and old mice either before or after infarction for the EF. But again, the decrease was significant for both groups (old: p < 0.0001 and young: p = 0.0009). Each global strain showed deterioration after infarction. This difference was significant in both subgroups for young mice and old mice for each strain. There were no differences either before or after infarction between the young and old mice. Conclusions: There were differences in functional parameters between young and old mice in EDV, SV, and CO. Changes in strain parameters in the acute phase post-myocardial infarction did not differ significantly between young and old mice, while there was a clear deterioration in strain parameters after infarction in both groups.

Group A Streptococcus (GAS) exploits the host fibrinolytic system by activating plasminogen via streptokinase, promoting clot degradation, tissue invasion, and immune evasion. Tranexamic acid (TXA), a clinically used antifibrinolytic agent, inhibits fibrinolysis, but its impact on GAS virulence and host immune responses remains incompletely understood. We investigated whether clinically relevant concentrations of TXA or ϵ-aminocaproic acid (AHA) inhibit GAS-induced fibrinolysis, affect bacterial survival in blood, and modulate host immune responses. In vitro plasma clot lysis assays, D-dimer quantification, and bacterial escape experiments were used to assess fibrinolytic activity. Western blots and substrate assays evaluated plasminogen and fibrinogen binding and plasmin activity. Bacterial survival and immune phenotypes were analyzed in human blood, and in vivo responses were assessed in a murine intranasal infection model. TXA at therapeutic concentrations (10–50 µg/ml) blocked streptokinase- and GAS-induced fibrinolysis, reduced D-dimer release, and prevented bacterial escape from clots in vitro. It impaired GAS survival in whole human blood without affecting growth in plasma or culture medium, suggesting a host-mediated effect. TXA affected plasminogen interaction with the bacterial surface and reduced fibrinogen degradation, suggesting interference in GAS-driven fibrinolysis. In infected blood, TXA partially restored CD169 and CD66b expression, consistent with preserved monocyte and neutrophil activation. In vivo, TXA lowered lung IL1β and shifted cardiac macrophage polarization toward more M1 and fewer M2 cells. These findings indicate that TXA not only inhibits GAS-induced fibrinolysis but also enhances innate immune responses, exerting both antifibrinolytic and immunomodulatory effects during infection.

Streptococcus pyogenes (group A Streptococcus [GAS]) is a human pathogen that causes local and systemic infections of the skin and mucous membranes. However, GAS is also found asymptomatically in the nasopharynx of infants. GAS infections, including pharyngitis and invasive pneumosepsis, pose significant public health concerns. Streptokinase, a key virulence factor of GAS, activates human plasminogen, facilitating bacterial dissemination. Plasminogen, traditionally known for its role in fibrinolysis, may also modulate host immune responses. We therefore aim to investigate systemic and cardiac immune cell responses during pneumonia and pneumosepsis with GAS in a murine infection model. The interaction of streptokinase with human plasminogen is species specific, so the murine pneumosepsis model was developed in a transgenic mouse strain that produces human plasminogen. The data show a critical role of human plasminogen for GAS colonization and systemic spread via the nasopharynx. Because of pneumosepsis, blood immune cell profiles and plasma protein concentrations are significantly altered, indicating potential biomarkers for distinguishing local from systemic infection. In the hearts of animals with invasive infection, proinflammatory immune cells significantly increased and likely displaced resident healing macrophages. The established pneumosepsis model is useful to study the pathophysiological mechanisms underlying local and invasive pneumonia caused by GAS and to investigate new therapeutic options.

Angiogenesis is crucial in myocardial healing after myocardial infarction (MI). The αvβ3-integrin, a key regulator of angiogenesis, is targeted by RGD-based PET tracers like [68Ga]Ga-NODAGA-RGD. Yet, angiogenesis imaging using RGD-based tracers is seriously hampered by the lack of true specificity of the αvβ3-integrin for angiogenic cells. Therefore, our study aimed to identify the cell type with the highest αvβ3-integrin expression in the process of myocardial healing in order to determine the actual value of the PET tracer [68Ga]Ga-NODAGA-RGD for imaging post-MI angiogenesis. Cardiac magnetic resonance imaging (CMR) was used to assess cardiac function and morphology after 28 days in two groups: permanent ligation (PL) of the left anterior descending coronary artery and transient occlusion for 30 min (I/R). Following these measurements, hearts were excised for histological and immunohistological examinations to evaluate scar formation, capillary density, and cellular composition. PET imaging with [68Ga]Ga-NODAGA-RGD was conducted on day 5 and day 7 post-MI. Single-nucleus transcriptomics were performed to identify cell clusters expressing αvβ3-integrin. Both infarct models induced scar formation, with the PL group developing large infarcts accompanied by massive left ventricular dilation and hypertrophy of cardiomyocytes, while the I/R group exhibited small intramural scars without significant changes in LV geometry or function. PET imaging revealed significantly higher tracer accumulation in the infarct area of the PL group compared to the I/R group. Single-nucleus transcriptomics performed 5 days post-MI revealed that angiogenesis markers were enriched in the I/R group, while the highest αvβ3-integrin mRNA expression was identified in the fibroblast cluster, indicating an activated phenotype. Activated fibroblasts are the primary target cells of [68Ga]Ga-NODAGA-RGD, rather than angiogenic cells. In this regard, [68Ga]Ga-NODAGA-RGD is most probably not a valid tracer for imaging angiogenesis during the first days post-MI.

Endurance training before the induction of a myocardial infarction (MI) limits scar formation, wall thinning and adverse remodeling after an MI in rodents. The few existing studies have been conducted on young animals, leaving a significant gap in evidence regarding older specimens. However, myocardial infarctions will occur predominantly in aged individuals despite optimal primary prevention. Regular endurance training, even when initiated later in life, may have the potential to reduce functional decline following an MI. The goal of this study was to assess the effect of endurance training in aged mice (20 months) on left ventricular remodeling by multimodal in-vivo imaging after 4 weeks. The exercise group (EX-MI, n=11) underwent treadmill running sessions of 30 minutes at a speed of 18 cm/s, 5 days per week for 6 weeks. The sedentary control group (SED-MI, n=12) received no training. Myocardial infarction was induced by permanent ligation of the left anterior descending (LAD) artery in 20-month-old C57BL6 mice. Cardiac MRI was performed on day 28 to assess cardiac morphology and function in detail, followed by FDG-PET scans on day 29 to evaluate glucose metabolism in subgroups. While left ventricular (LV) dilation was similar in both groups, contractile function—measured by left ventricular ejection fraction (LVEF), stroke volume (SV), and cardiac output (CO)—was significantly higher in the exercised group. Left ventricular mass was also significantly greater in the EX-MI group. Infarct scars were smaller and thicker in the EX-MI group. Additionally, exercise led to higher global strain rates, including global circumferential strain (GCS), global longitudinal strain (GLS), and global radial strain (GRS). Wall thickening within the scar was also greater in the EX-MI group. Deformation analysis of the scar revealed higher GCS and GRS in this group. The remote myocardium was thicker and showed higher values of radial deformation in the EX-MI group. FDG-PET imaging on day 29 demonstrated similar uptake within the scar but reduced uptake in the remote myocardium in the EX-MI group. Our study shows that commencing endurance training, even at an advanced age, reduces left ventricular remodeling, scar size, and scar thinning. Myocardial contractility in both the remote and infarct areas is preserved by endurance training, suggesting a higher compensatory capacity in the exercised group. Higher FDG uptake on day 29 after MI in the SED-MI group reflects increased rates of glycolysis, a typical metabolic characteristic of the failing heart. Further studies are needed to determine the optimal dose of exercise required to achieve the protective phenotype. However, our data suggest that the intensity should be sufficient to induce left ventricular hypertrophy.

There is considerable evidence that action potentials are accompanied by "intrinsic optical signals", such as a nanometer-scale motion of the cell membrane. Here we present ChiSCAT, a technically simple imaging scheme that detects such signals with interferometric sensitivity. ChiSCAT combines illumination by a chaotic speckle pattern and interferometric scattering microscopy (iSCAT) to sensitively detect motion in any direction. The technique features reflective high-NA illumination, common-path suppression of vibrations, and a large field of view. This approach maximizes sensitivity to motion, but does not produce a visually interpretable image. We show that unsupervised learning based on matched filtering and motif discovery can recover underlying motion patterns and detect action potentials. We demonstrate these claims in an experiment on blebbistatin-paralyzed cardiomyocytes. ChiSCAT opens the door to action potential measurement in scattering tissue, including a living brain.

Background and objective: The primary cilium is a small protrusion found on most mammalian cells. It acts as a cellular antenna, being involved in various cell signaling pathways. The length of the primary cilium affects its function. To study the impact of physical or chemical stimuli on cilia, their lengths must be determined easily and reproducibly. Methods: We have developed and evaluated an open-source R package called detectCilia to detect and measure primary cilia automatically. As a case study to demonstrate the capability of our tool, we compared the influence of 4 different cell culture media compositions on the lengths of primary cilia in human chondrocytes. These media compositions include (1) insulin-transferrin-selenium (ITS); (2) ITS and dexamethasone (Dexa); (3) ITS, Dexa, insulin-like growth factor 1 (IGF-1), and transforming growth factor beta 1 (TGF-β1); and (4) fetal bovine serum (FBS). Results: The assessment of detectCilia included a comparison with 2 similar tools: ACDC (Automated Cilia Detection in Cells) and CiliaQ. Several differences and advantages of our package make it a valuable addition to these tools. In the case study, we have observed variations in the ciliary lengths associated with using different media compositions. Conclusions: We conclude that detectCilia can automatically and reproducibly detect and measure primary cilia in confocal microscopy images with low false-positive rates without requiring extensive user interaction.

BackgroundCardiac arrhythmias have markedly increased in recent decades, highlighting the urgent need for appropriate test systems to evaluate the efficacy and safety of new pharmaceuticals and the potential side effects of established drugs.MethodsThe Microelectrode Array (MEA) system may be a suitable option, as it provides both real-time and non-invasive monitoring of cellular networks of spontaneously active cells. However, there is currently no commercially available cell source to apply this technology in the context of the cardiac conduction system (CCS). In response to this problem, our group has previously developed a protocol for the generation of pure functional cardiac pacemaker cells from mouse embryonic stem cells (ESCs). In addition, we compared the hanging drop method, which was previously utilized, with spherical plate-derived embryoid bodies (EBs) and the pacemaker cells that are differentiated from these.ResultsWe described the application of these pacemaker cells on the MEA platform, which required a number of crucial optimization steps in terms of coating, dissociation, and cell density. As a result, we were able to generate a monolayer of pure pacemaker cells on an MEA surface that is viable and electromechanically active for weeks. Furthermore, we introduced spherical plates as a convenient and scalable method to be applied for the production of induced sinoatrial bodies.ConclusionWe provide a tool to transfer modeling and analysis of cardiac rhythm diseases to the cell culture dish. Our system allows answering CCS-related queries within a cellular network, both under baseline conditions and post-drug exposure in a reliable and affordable manner. Ultimately, our approach may provide valuable guidance not only for cardiac pacemaker cells but also for the generation of an MEA test platform using other sensitive non-proliferating cell types.

Background The initial idea of functional tissue replacement has shifted to the concept that injected cells positively modulate myocardial healing by a non-specific immune response of the transplanted cells within the target tissue. This alleged local modification of the scar requires assessment of regional properties of the left ventricular wall in addition to commonly applied measures of global morphological and functional parameters. Hence, we aimed at investigating the effect of cardiac cell therapy with cardiovascular progenitor cells, so-called cardiac induced cells, on both global and regional properties of the left ventricle by a multimodal imaging approach in a mouse model. Methods Myocardial infarction was induced in mice by ligation of the left anterior descending artery, the therapy group received an intramyocardial injection of 1 × 10 6 cardiac induced cells suspended in matrigel, the control group received matrigel only. [ 18 F]FDG positron emission tomography imaging was performed after 17 days, to assess regional glucose metabolism. Three weeks after myocardial infarction, cardiac magnetic resonance imaging was performed for morphological and functional assessment of the left ventricle. Following these measurements, hearts were excised for histological examinations. Results Cell therapy had no significant effect on global morphological parameters. Similarly, there was no difference in scar size and capillary density between therapy and control group. However, there was a significant improvement in contractile function of the left ventricle – left ventricular ejection fraction, stroke volume and cardiac output. Regional analysis of the left ventricle identified changes of wall properties in the scar area as the putative mechanism. Cell therapy reduced the thinning of the scar and significantly improved its radial contractility. Furthermore, the metabolic defect, assessed by [ 18 F]FDG, was significantly reduced by the cell therapy. Conclusion Our data support the relevance of extending the assessment of global left ventricular parameters by a structured regional wall analysis for the evaluation of therapies targeting at modulation of healing myocardium. This approach will enable a deeper understanding of mechanisms underlying the effect of experimental regenerative therapies, thus paving the way for a successful translation into clinical application.

Advances in cancer therapeutics have improved patient survival rates. However, cancer survivors may suffer from adverse events either at the time of therapy or later in life. Cardiovascular diseases (CVD) represent a clinically important, but mechanistically understudied complication, which interfere with the continuation of best-possible care, induce life-threatening risks, and/or lead to long-term morbidity. These concerns are exacerbated by the fact that targeted therapies and immunotherapies are frequently combined with radiotherapy, which induces durable inflammatory and immunogenic responses, thereby providing a fertile ground for the development of cardiovascular diseases (CVDs). Stressed and dying irradiated cells produce ‘danger’ signals including, but not limited to, major histocompatibility complexes, cell-adhesion molecules, proinflammatory cytokines, and damage-associated molecular patterns. These factors activate intercellular signaling pathways which have potentially detrimental effects on the heart tissue homeostasis. Herein, we present the clinical crosstalk between cancer and heart diseases, describe how it is potentiated by cancer therapies, and highlight the multifactorial nature of the underlying mechanisms. We particularly focus on radiotherapy, as a case known to often induce cardiovascular complications even decades after treatment. We provide evidence that the secretome of irradiated tumors entails factors that exert systemic, remote effects on the cardiac tissue, potentially predisposing it to CVDs. We suggest how diverse disciplines can utilize pertinent state-of-the-art methods in feasible experimental workflows, to shed light on the molecular mechanisms of radiotherapy-related cardiotoxicity at the organismal level and untangle the desirable immunogenic properties of cancer therapies from their detrimental effects on heart tissue. Results of such highly collaborative efforts hold promise to be translated to next-generation regimens that maximize tumor control, minimize cardiovascular complications, and support quality of life in cancer survivors.

BACKGROUND:The immune response is a crucial factor for mediating the benefit of cardiac cell therapies. Our previous research showed that cardiomyocyte transplantation alters the cardiac immune response and, when combined with short-term pharmacological CCR2 inhibition, resulted in diminished functional benefit. However, the specific role of innate immune cells, especially CCR2 macrophages on the outcome of cardiomyocyte transplantation, is unclear.METHODS:We compared the cellular, molecular, and functional outcome following cardiomyocyte transplantation in wildtype and T cell- and B cell-deficient Rag2del mice. The cardiac inflammatory response was assessed using flow cytometry. Gene expression profile was assessed using single-cell and bulk RNA sequencing. Cardiac function and morphology were determined using magnetic resonance tomography and immunohistochemistry respectively.RESULTS:Compared to wildtype mice, Rag2del mice show an increased innate immune response at steady state and disparate macrophage response after MI. Subsequent single-cell analyses after MI showed differences in macrophage development and a lower prevalence of CCR2 expressing macrophages. Cardiomyocyte transplantation increased NK cells and monocytes, while reducing CCR2-MHC-IIlo macrophages. Consequently, it led to increased mRNA levels of genes involved in extracellular remodelling, poor graft survival, and no functional improvement. Using machine learning-based feature selection, Mfge8 and Ccl7 were identified as the primary targets underlying these effects in the heart.CONCLUSIONS:Our results demonstrate that the improved functional outcome following cardiomyocyte transplantation is dependent on a specific CCR2 macrophage response. This work highlights the need to study the role of the immune response for cardiomyocyte cell therapy for successful clinical translation.

Investigating native human cardiac tissue with preserved 3D macro- and microarchitecture is fundamental for clinical and basic research. Unfortunately, the low accessibility of the human myocardium continues to limit scientific progress. To overcome this issue, utilizing atrial appendages of the human heart may become highly beneficial. Atrial appendages are often removed during open-heart surgery and can be preserved ex vivo as living tissue with varying durability depending on the culture method. In this study, we prepared living thin myocardial slices from left atrial appendages that were cultured using an air-liquid interface system for overall 10 days. Metabolic activity of the cultured slices was assessed using a conventional methyl thiazolyl tetrazolium (MTT) assay. To monitor the structural integrity of cardiomyocytes within the tissue, we implemented our recently described super-resolution microscopy approach that allows both qualitative and quantitative in-depth evaluation of sarcomere network based on parameters such as overall sarcomere content, filament size and orientation. Additionally, expression of mRNAs coding for key structural and functional proteins was analyzed by real-time reverse transcription polymerase chain reaction (qRT-PCR). Our findings demonstrate highly significant disassembly of contractile apparatus represented by degradation of [Formula: see text]-actinin filaments detected after three days in culture, while metabolic activity was constantly rising and remained high for up to seven days. However, gene expression of crucial cardiac markers strongly decreased after the first day in culture indicating an early destructive response to ex vivo conditions. Therefore, we suggest static cultivation of living myocardial slices derived from left atrial appendage and prepared according to our protocol only for short-termed experiments (e.g. medicinal drug testing), while introduction of electro-mechanical stimulation protocols may offer the possibility for long-term integrity of such constructs.

Backgound Aims: This meta-analysis aims at summarizing the whole body of research on cell therapies for acute myocardial infarction (MI) in the mouse model to bring forward ongoing research in this field of regenerative medicine. Despite rather modest effects in clinical trials, pre-clinical studies continue to report beneficial effects of cardiac cell therapies for cardiac repair following acute ischemic injury. Results: The authors' meta-analysis of data from 166 mouse studies comprising 257 experimental groups demonstrated a significant improvement in left ventricular ejection fraction of 10.21% after cell therapy compared with control animals. Subgroup analysis indicated that second-generation cell therapies such as cardiac progenitor cells and pluripotent stem cell derivatives had the highest therapeutic potential for minimizing myocardial damage post-MI. Conclusions: Whereas the vision of functional tissue replacement has been replaced by the concept of regional scar modulation in most of the investigated studies, rather basic methods for assessing cardiac function were most frequently used. Hence, future studies will highly benefit from integrating methods for assessment of regional wall properties to evolve a deeper understanding of how to modulate cardiac healing after acute MI.

Long-living individuals (LLIs) escape age-related cardiovascular complications until the very last stage of life. Previous studies have shown that a Longevity-Associated Variant (LAV) of the BPI Fold Containing Family B Member 4 (BPIFB4) gene correlates with an extraordinarily prolonged life span. Moreover, delivery of the LAV-BPIFB4 gene exerted therapeutic action in murine models of atherosclerosis, limb ischemia, diabetic cardiomyopathy, and aging. We hypothesize that downregulation of BPIFB4 expression marks the severity of coronary artery disease (CAD) in human subjects, and supplementation of the LAV-BPIFB4 protects the heart from ischemia. In an elderly cohort with acute myocardial infarction (MI), patients with three-vessel CAD were characterized by lower levels of the natural logarithm (Ln) of peripheral blood BPIFB4 (p = 0.0077). The inverse association between Ln BPIFB4 and three-vessel CAD was confirmed by logistic regression adjusting for confounders (Odds Ratio = 0.81, p = 0.0054). Moreover, in infarcted mice, a single administration of LAV-BPIFB4 rescued cardiac function and vascularization. In vitro studies showed that LAV-BPIFB4 protein supplementation exerted chronotropic and inotropic actions on induced pluripotent stem cell (iPSC)-derived cardiomyocytes. In addition, LAV-BPIFB4 inhibited the pro-fibrotic phenotype in human cardiac fibroblasts. These findings provide a strong rationale and proof of concept evidence for treating CAD with the longevity BPIFB4 gene/protein.

Cardiovascular diseases have a high mortality due to a very limited regenerative potential of lost cardiomyocytes and therefore are one of the leading causes of death in developed countries [...]

Cardiovascular diseases are the leading cause of death in industrialized nations. Due to the high number of patients and expensive treatments, according to the Federal Statistical Office (2017) in Germany, cardiovascular diseases account for around 15% of total health costs. Advanced coronary artery disease is mainly the result of chronic disorders such as high blood pressure, diabetes, and dyslipidemia. In the modern obesogenic environment, many people are at greater risk of being overweight or obese. The hemodynamic load on the heart is influenced by extreme obesity, which often leads to myocardial infarction (MI), cardiac arrhythmias, and heart failure. In addition, obesity leads to a chronic inflammatory state and negatively affects the wound-healing process. It has been known for many years that lifestyle interventions such as exercise, healthy nutrition, and smoking cessation drastically reduce cardiovascular risk and have a preventive effect against disorders in the healing process. However, little is known about the underlying mechanisms, and there is significantly less high-quality evidence compared to pharmacological intervention studies. Due to the immense potential of prevention in heart research, the cardiologic societies are calling for research work to be intensified, from basic understanding to clinical application. The topicality and high relevance of this research area are also evident from the fact that in March 2018, a one-week conference on this topic with contributions from top international scientists took place as part of the renowned "Keystone Symposia" ("New Insights into the Biology of Exercise"). Consistent with the link between obesity, exercise, and cardiovascular disease, this review attempts to draw lessons from stem-cell transplantation and preventive exercise. The application of state-of-the-art techniques for transcriptome analysis has opened new avenues for tailoring targeted interventions to very individual risk factors.