Kupffer cell pyroptosis mediated by METTL3 contributes to the progression of alcoholic steatohepatitis.

Chronic alcohol consumption is a major risk factor for alcoholic steatohepatitis (ASH). Previous studies have shown that direct injury of hepatocytes is the key factor in its occurrence and development. However, our study shows that the role of Kupffer cells in ASH cannot be ignored. We isolated Kupffer cells from the livers of ASH mice and found that alcohol consumption induced Kupffer cell pyroptosis and increased the release of interleukin-1ß (IL-1ß). Furthermore, we screened the related m6A enzyme methyltransferase-like 3 (METTL3) from liver Kupffer cells, and found that silencing METTL3 alleviated inflammatory cytokine eruption by Kupffer cell pyroptosis in ASH mice. In vitro, we silenced METTL3 with lentivirus in BMDMs and RAW264.7 cells and confirmed that METTL3 could reduce pyroptosis by influencing the splicing of pri-miR-34A. Together, our results revealed a critical role of KC pyroptosis in ASH and highlighted the mechanism by which METLL3 relieves cell pyroptosis, which could be a promising therapeutic strategy for ASH.

Immunopathogenesis of Immune Checkpoint Inhibitor Induced Myocarditis: Insights from Experimental Models and Treatment Implications.

Despite the extraordinary success of immune checkpoint inhibitors (ICIs) in cancer treatment, their use is associated with a high incidence of immune-related adverse events (IRAEs), resulting from therapy-related autoimmunity against various target organs. ICI-induced myocarditis is one of the most severe forms of IRAE, which is associated with risk of hemodynamic compromise and mortality. Despite increasing recognition and prompt treatment by clinicians, there remain significant gaps in knowledge regarding the pathophysiology, diagnosis and treatment of ICI-induced myocarditis. As the newly emerged disease entity is relatively rare, it is challenging for researchers to perform studies involving patients at scale. Alternatively, mouse models have been developed to facilitate research understanding of the pathogenesis of ICI-induced myocarditis and drug discovery. Transgenic mice with immune checkpoint genes knocked out allow induction of myocarditis in a highly reproducible manner. On the other hand, it has not been possible to induce ICI-induced myocarditis in wild type mice by injecting ICIs monotherapy alone. Additional interventions such as combinational ICI, tumor inoculation, cardiac sarcomere immunization, or cardiac irradiation are necessary to mimic the underlying pathophysiology in human cancer patients and to induce ICI-induced myocarditis successfully. This review focuses on the immunopathogenesis of ICI-induced myocarditis, drawing insights from human studies and animal models, and discusses the potential implications for treatment.

Acid-sensitive ion channel 1a regulates TNF-α expression in LPS-induced acute lung injury via ERS-CHOP-C/EBPα signaling pathway.

BACKGROUND: Acute lung injury (ALI) is the local inflammatory response of the lungs involved in a variety of inflammatory cells. Macrophages are immune cells and inflammatory cells widely distributed in the body. Acid-sensitive ion channel 1a (ASIC1a) is involved in the occurrence of ALI, but the mechanism is still unclear. METHODS: Kunming mouse were stimulated by Lipopolysaccharides (LPS) to establish ALI model in vivo, and RAW264.7 cells were stimulated by LPS to establish inflammatory model in vitro. Amiloride was used as a blocker of ASIC1a to treat mice, and dexamethasone was used as a positive drug for ALI. After blockers and RNAi blocked or silenced the expression of ASIC1a, the expressions of ASIC1a, endoplasmic reticulum-related proteins GRP78, CHOP, C/EBPα and TNF-α were detected. The Ca2+ concentration was measured by a laser confocal microscope. The interaction between CHOP and C/EBPα and the effect of C/EBPα on the activity of TNF-α promoter were detected by immunoprecipitation and luciferase reporter. RESULTS: The expressions of ASIC1a and TNF-α were increased significantly in LPS group. After the blocker and RNAi blocked or silenced ASIC1a, the expressions of TNF-α, GRP78, CHOP were reduced, and the intracellular Ca2+ influx was weakened. The results of immunoprecipitation showed that CHOP and C/EBPα interacted in the macrophages. After silencing CHOP, C/EBPα expression was increased, and TNF-α expression was decreased. The results of the luciferase reporter indicated that C/EBPα directly binds to TNF-α. CONCLUSION: ASIC1a regulates the expression of TNF-α in LPS-induced acute lung injury via ERS-CHOP-C/EBPα signaling pathway.

Attenuation of Myocardial Dysfunction in Hypertensive Cardiomyopathy Using Non-R-Wave-Synchronized Cardiac Shock Wave Therapy.

Cardiac shock wave therapy (CSWT) is a novel therapeutic procedure for patients with angina that is refractory to conventional therapy. We investigated the potential mechanism and therapeutic efficacy of non-R-wave-triggered CSWT to attenuate myocardial dysfunction in a large animal model of hypertensive cardiomyopathy. Sustained elevated blood pressure (BP) was induced in adult pigs using a combination of angiotensin-II and deoxycorticosterone acetate (DOCA). Two sessions of non-R-wave-triggered CSWT were performed at 11 and 16 weeks. At 10 weeks, systolic and diastolic blood pressure, LV posterior wall thickness and intraventricular septum thickness significantly increased in both the hypertension and CSWT groups. At 20 weeks, +dP/dt and end-systolic pressure-volume relationship (ESPVR) decreased significantly in the hypertension group but not the CSWT group, as compared with week 10. A significant improvement in end-diastolic pressure-volume relationship (EDPVR) was observed in the CSWT group. The CSWT group exhibited significantly increased microvascular density and vascular endothelial growth factor (VEGF) expression in the myocardium. Cytokine array demonstrated that the CSWT group had significantly reduced inflammation compared with the hypertension group. Our results demonstrate that non-R-wave-triggered CSWT is safe and can attenuate LV systolic and diastolic dysfunction via enhancement of myocardial neovascularization and anti-inflammatory effect in a large animal model of hypertensive cardiomyopathy.

Identification of energy metabolism-related biomarkers for risk prediction of heart failure patients using random forest algorithm.

Objective: Energy metabolism plays a crucial role in the improvement of heart dysfunction as well as the development of heart failure (HF). The current study is designed to identify energy metabolism-related diagnostic biomarkers for predicting the risk of HF due to myocardial infarction. Methods: Transcriptome sequencing data of HF patients and non-heart failure (NF) people (GSE66360 and GSE59867) were obtained from gene expression omnibus (GEO) database. Energy metabolism-related differentially expressed genes (DEGs) were screened between HF and NF samples. The subtyping consistency analysis was performed to enable the samples to be grouped. The immune infiltration level among subtypes was assessed by single sample gene set enrichment analysis (ssGSEA). Random forest algorithm (RF) and support vector machine (SVM) were applied to identify diagnostic biomarkers, and the receiver operating characteristic curves (ROC) was plotted to validate the accuracy. Predictive nomogram was constructed and validated based on the result of the RF. Drug screening and gene-miRNA network were analyzed to predict the energy metabolism-related drugs and potential molecular mechanism. Results: A total of 22 energy metabolism-related DEGs were identified between HF and NF patients. The clustering analysis showed that HF patients could be classified into two subtypes based on the energy metabolism-related genes, and functional analyses demonstrated that the identified DEGs among two clusters were mainly involved in immune response regulating signaling pathway and lipid and atherosclerosis. ssGSEA analysis revealed that there were significant differences in the infiltration levels of immune cells between two subtypes of HF patients. Random-forest and support vector machine algorithm eventually identified ten diagnostic markers (MEF2D, RXRA, PPARA, FOXO1, PPARD, PPP3CB, MAPK14, CREB1, MEF2A, PRMT1) for risk prediction of HF patients, and the proposed nomogram resulted in good predictive performance (GSE66360, AUC = 0.91; GSE59867, AUC = 0.84) and the clinical usefulness in HF patients. More importantly, 10 drugs and 15 miRNA were predicted as drug target and hub miRNA that associated with energy metabolism-related genes, providing further information on clinical HF treatment. Conclusion: This study identified ten energy metabolism-related diagnostic markers using random forest algorithm, which may help optimize risk stratification and clinical treatment in HF patients.

ASIC1a induces mitochondrial apoptotic responses in acute lung injury.

AIM: This study aimed to investigate the promoting effect of acid-sensing ion channel 1a (ASIC1a) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and its mechanisms. METHODS: In this experiment, the ALI rat model was induced by intratracheal injection of LPS, and the ASIC1a specific blocker psalmotoxin-1 (PcTx-1) was injected into the tail vein before LPS administration once. Western blot, immunofluorescence, immunohistochemistry and real-time PCR methods were used to detect ASIC1a and apoptosis-related proteins expressions in lung tissue and RLE-6TN rat type II alveolar epithelial cells. Confocal Laser Scanning Microscopy was used to detect Ca2+ fluorescence intensity in RLE-6TN cells. RESULTS: PcTx-1 pretreatment not only inhibited the pathological changes of LPS-induced ALI in lung tissue, but also inhibited lung dysfunction. PcTx-1 also reduced the increased levels of the apoptosis-related proteins B-cell lymphoma-2-associated X (Bax) and cleaved cysteinyl aspartate specific proteinase 3 (Cleaved caspase-3) and increased the decreased level of B-cell lymphoma-2 (Bcl-2) in the lung tissue of the model group. LPS-induced changes in mitochondrial membrane potential and calcium influx in alveolar epithelial cells were also reversed by PcTx-1. CONCLUSION: ASIC1a induces an apoptotic response in ALI through mitochondrial apoptosis.

Repeated intravenous administration of hiPSC-MSCs enhance the efficacy of cell-based therapy in tissue regeneration.

We seek to demonstrate whether therapeutic efficacy can be improved by combination of repeated intravenous administration and local transplantation of human induced pluripotential stem cell derived MSCs (hiPSC-MSCs). In this study, mice model of hind-limb ischemia is established by ligation of left femoral artery. hiPSC-MSCs (5 × 105) is intravenously administrated immediately after induction of hind limb ischemia with or without following intravenous administration of hiPSC-MSCs every week or every 3 days. Intramuscular transplantation of hiPSC-MSCs (3 × 106) is performed one week after induction of hind-limb ischemia. We compare the therapeutic efficacy and cell survival of intramuscular transplantation of hiPSC-MSCs with or without a single or repeated intravenous administration of hiPSC-MSCs. Repeated intravenous administration of hiPSC-MSCs can increase splenic regulatory T cells (Tregs) activation, decrease splenic natural killer (NK) cells expression, promote the polarization of M2 macrophages in the ischemic area and improved blood perfusion in the ischemic limbs. The improved therapeutic efficacy of MSC-based therapy is due to both increased engraftment of intramuscular transplanted hiPSC-MSCs and intravenous infused hiPSC-MSCs. In conclusion, our study support a combination of repeated systemic infusion and local transplantation of hiPSC-MSCs for cardiovascular disease.

Mesenchymal stromal cell-derived exosomes in cardiac regeneration and repair.

Mesenchymal stromal cell (MSC)-derived exosomes play a promising role in regenerative medicine. Their trophic and immunomodulatory potential has made them a promising candidate for cardiac regeneration and repair. Numerous studies have demonstrated that MSC-derived exosomes can replicate the anti-inflammatory, anti-apoptotic, and pro-angiogenic and anti-fibrotic effects of their parent cells and are considered a substitute for cell-based therapies. In addition, their lower tumorigenic risk, superior immune tolerance, and superior stability compared with their parent stem cells make them an attractive option in regenerative medicine. The therapeutic effects of MSC-derived exosomes have consequently been evaluated for application in cardiac regeneration and repair. In this review, we summarize the potential mechanisms and therapeutic effects of MSC-derived exosomes in cardiac regeneration and repair and provide evidence to support their clinical application.

Immunomodulation by systemic administration of human-induced pluripotent stem cell-derived mesenchymal stromal cells to enhance the therapeutic efficacy of cell-based therapy for treatment of myocardial infarction.

Rationale: Poor survival and engraftment are major hurdles of stem cell therapy in the treatment of myocardial infarction (MI). We sought to determine whether pre-transplantation systemic intravenous administration of human induced pluripotent stem cell (hiPSC)-derived mesenchymal stromal cells (hiPSC-MSCs) could improve the survival of hiPSC-MSCs or hiPSC-derived cardiomyocytes (hiPSC-CMs) following direct intramyocardial transplantation in a mouse model of MI. Methods: Mice were randomized to undergo intravenous administration of saline or 5×105 hiPSC-MSCs one week prior to MI, induced by ligation of the left anterior descending coronary artery. Mice were further assigned to undergo direct intramyocardial transplantation of hiPSC-MSCs (1×106) or hiPSC-CMs (1×106) 10 minutes following MI. Echocardiographic and invasive hemodynamic assessment were performed to determine cardiac function. In-vivo fluorescent imaging analysis, immunofluorescence staining and polymerase chain reaction were performed to detect cell engraftment. Flow cytometry of splenic regulatory T cells (Tregs) and natural killer (NK) cells was performed to assess the immunomodulatory effects. Results: Pre-transplantation systemic administration of hiPSC-MSCs increased systemic Tregs activation, decreased the number of splenic NK cells and inflammation, and enhanced survival of transplanted hiPSC-MSCs and hiPSC-CMs. These improvements were associated with increased neovascularization and decreased myocardial inflammation and apoptosis at the peri-infract zone with consequent improved left ventricular function four weeks later. Co-culture of splenic CD4 cells with hiPSC-MSCs also modulated their cytokine expression profile with a decreased level of interferon-γ, tumor necrosis factor-α, and interleukin (IL)-17A, but not IL-2, IL-6 and IL-10. Conclusion: Pre-transplantation systemic intravenous administration of hiPSC-MSCs induced immunomodulation and facilitated the survival of intramyocardially transplanted cells to improve cardiac function in MI.

Myocardial repair of bioengineered cardiac patches with decellularized placental scaffold and human-induced pluripotent stem cells in a rat model of myocardial infarction.

BACKGROUND: The creation of a bioengineered cardiac patch (BCP) is a potential novel strategy for myocardial repair. Nevertheless, the ideal scaffold for BCP is unknown. OBJECTIVE: We investigated whether the decellularized placenta (DP) could serve as natural scaffold material to create a BCP for myocardial repair. METHODS AND RESULTS: A BCP was created by seeding human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs; 1 × 106/cm2) onto DP. The functional and electrophysiological properties of the BCP were first characterized by in vitro analysis and optical mapping. Next, in vivo therapeutic efficacy of the BCP was evaluated in a rat model of myocardial infarction (MI), created by left descending coronary artery ligation (MI + BCP group), and compared with MI alone (MI group), transplantation of DP (MI + DP group), and hiPSC-CMs (MI + CM group). Cytokine profiling demonstrated that the BCP contained multiple growth and angiogenic factors, including vascular endothelial growth factor, platelet-derived growth factor, insulin-like growth factor-1, basic fibroblast growth factor, angiogenin, and angiopoietin-2. In vitro optical mapping showed that the BCP exhibited organized mechanical contraction and synchronized electrical propagation. RNA sequencing showed that DP enhanced the maturation of hiPSC-CMs compared with the monolayer of cultured hiPSC-CMs. At 4 weeks follow-up, the BCP significantly improved left ventricular (LV) function, as determined by LV ejection fraction, fractional shortening, + dP/dtmax, and end-systolic pressure-volume relationship, compared with the MI, MI + DP, and MI + CM groups. Moreover, histological examination revealed that engraftment of the BCP at the infarct zone decreased infarct size and increased cell retention and neovascularization compared with the MI, MI + DP, and MI + CM groups. CONCLUSIONS: Our results demonstrate that a DP scaffold contains multiple growth and angiogenic factors that enhance the maturation and survival of seeded hiPSC-CMs. Transplantation of a BCP is superior to DP or hiPSC-CMs alone in reducing infarct size and improving cell retention and neovascularization, thus providing a novel therapy for myocardial repair following MI.

Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment.

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major causes of mortality and morbidity around the world. Cell-based therapies for cardiac repair and improvement of left ventricular function after MI have attracted considerable attention. Accordingly, the safety and efficacy of these cell transplantations should be tested in a preclinical large animal model of HF prior to clinical use. Pigs are widely used for cardiovascular disease research due to their similarity to humans in terms of heart size and coronary anatomy. Therefore, we sought to present an effective protocol for the establishment of a porcine chronic HF model using closed-chest coronary balloon occlusion of the left circumflex artery (LCX), followed by rapid ventricular pacing induced with pacemaker implantation. Eight weeks later, the stem cells were administered by intramyocardial injection in the peri-infarct area. Then the infarct size, cell survival, and left ventricular function (including echocardiography, hemodynamic parameters, and electrophysiology) were evaluated. This study helps establish a stable preclinical large animal HF model for stem cell treatment.

Catheter-Based Splanchnic Denervation for Treatment of Hypertensive Cardiomyopathy.

Emerging preclinical data suggest that splanchnic sympathetic nerve activation may play an important role in the pathophysiology of hypertension. We sought to determine the potential therapeutic application of catheter-based splanchnic denervation in a clinically relevant large animal model of hypertensive cardiomyopathy (hCMP). Sustained elevated blood pressure was induced in adult pigs using a combination of intravenous infusion of Ang II (angiotensin II) and subcutaneous implantation of deoxycorticosterone acetate pellets to establish a large animal model of hCMP. Serial changes in cardiac echocardiographic and invasive hemodynamic parameters and neurohumoral biomarkers were investigated in animals with hypertension alone (n=9) and hypertension with catheter-based splanchnic denervation (n=6). Another 6 pigs without hypertension induction served as controls. At 10 weeks, hypertensive animals developed sustained elevated blood pressure and phenotype of hCMP with significant systolic and diastolic dysfunction, and left ventricular remodeling and hypertrophy as determined by invasive hemodynamic and echocardiogram assessments, respectively, and increased venoarterial norepinephrine gradient over the myocardium, kidneys, and splanchnic organs compared with baseline. Catheter-based splanchnic denervation decreased the venoarterial norepinephrine gradient over the splanchnic organs associated with the reduced splenic sympathetic nerve innervation; attenuated the elevated blood pressure, left ventricular remodeling, and hypertrophy; and preserved left ventricular systolic and diastolic function at 20 weeks in pigs with hCMP. Our results provide novel mechanistic insight into the role of splenic sympathetic nerve innervation in hypertension and important proof-of-principle data for the therapeutic application of catheter-based splanchnic denervation in a large animal model of hCMP.

Potent immunomodulation and angiogenic effects of mesenchymal stem cells versus cardiomyocytes derived from pluripotent stem cells for treatment of heart failure.

BACKGROUND: Optimal cell type as cell-based therapies for heart failure (HF) remains unclear. We sought to compare the safety and efficacy of direct intramyocardial transplantation of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and human induced pluripotent stem cell-derived mesenchymal stem cells (hiPSC-MSCs) in a porcine model of HF. METHODS: Eight weeks after induction of HF with myocardial infarction (MI) and rapid pacing, animals with impaired left ventricular ejection fraction (LVEF) were randomly assigned to receive direct intramyocardial injection of saline (MI group), 2 × 108 hESC-CMs (hESC-CM group), or 2 × 108 hiPSC-MSCs (hiPSC-MSC group). The hearts were harvested for immunohistochemical evaluation after serial echocardiography and hemodynamic evaluation and ventricular tachyarrhythmia (VT) induction by in vivo programmed electrical stimulation. RESULTS: At 8 weeks post-transplantation, LVEF, left ventricular maximal positive pressure derivative, and end systolic pressure-volume relationship were significantly higher in the hiPSC-MSC group but not in the hESC-CM group compared with the MI group. The incidence of early spontaneous ventricular tachyarrhythmia (VT) episodes was higher in the hESC-CM group but the incidence of inducible VT was similar among the different groups. Histological examination showed no tumor formation but hiPSC-MSCs exhibited a stronger survival capacity by activating regulatory T cells and reducing the inflammatory cells. In vitro study showed that hiPSC-MSCs were insensitive to pro-inflammatory interferon-gamma-induced human leukocyte antigen class II expression compared with hESC-CMs. Moreover, hiPSC-MSCs also significantly enhanced angiogenesis compared with other groups via increasing expression of distinct angiogenic factors. CONCLUSIONS: Our results demonstrate that transplantation of hiPSC-MSCs is safe and does not increase proarrhythmia or tumor formation and superior to hESC-CMs for the improvement of cardiac function in HF. This is due to their immunomodulation that improves in vivo survival and enhanced angiogenesis via paracrine effects.

Conformal phased surfaces for wireless powering of bioelectronic microdevices.

Wireless powering could enable the long-term operation of advanced bioelectronic devices within the human body. Although both enhanced powering depth and device miniaturization can be achieved by shaping the field pattern within the body, existing electromagnetic structures do not provide the spatial phase control required to synthesize such patterns. Here, we describe the design and operation of conformal electromagnetic structures, termed phased surfaces, that interface with non-planar body surfaces and optimally modulate the phase response to enhance the performance of wireless powering. We demonstrate that the phased surfaces can wirelessly transfer energy across anatomically heterogeneous tissues in large animal models, powering miniaturized semiconductor devices (<12 mm3) deep within the body (>4 cm). As an illustration of in vivo operation, we wirelessly regulated cardiac rhythm by powering miniaturized stimulators at multiple endocardial sites in a porcine animal model.

High-performance wireless powering for peripheral nerve neuromodulation systems.

Neuromodulation of peripheral nerves with bioelectronic devices is a promising approach for treating a wide range of disorders. Wireless powering could enable long-term operation of these devices, but achieving high performance for miniaturized and deeply placed devices remains a technological challenge. We report the miniaturized integration of a wireless powering system in soft neuromodulation device (15 mm length, 2.7 mm diameter) and demonstrate high performance (about 10%) during in vivo wireless stimulation of the vagus nerve in a porcine animal model. The increased performance is enabled by the generation of a focused and circularly polarized field that enhances efficiency and provides immunity to polarization misalignment. These performance characteristics establish the clinical potential of wireless powering for emerging therapies based on neuromodulation.

Elevated plasma interleukin-37 playing an important role in acute coronary syndrome through suppression of ROCK activation.

OBJECTIVE: The plasma level of interleukin-37 is elevated in patients with acute coronary syndrome, however, its function during the onset and progress of the disease remains unclear. This study aimed to investigate the clinical significance of IL-37 in acute coronary syndrome and its underlying mechanism. METHODS: 124 patients with acute coronary syndrome and 40 healthy controls were recruited in this study. Plasma interleukin-37 levels were measured in 41 patients with ST elevation myocardial infarction (STEMI), 41 patients with non-STEMI, 42 patients with unstable angina, and 40 controls. Mortality was defined as an event. RESULTS: In this study, the mean follow-up period was 824±306 days (2-1077 days). 22% (n=27) of patients died. The mortality rate was significantly lower in patients with interleukin-37 serum levels below the median (6.4 pg/mL) than those with interleukin-37 serum levels above 6.4 pg/mL at 36-month follow-up (16% vs. 24%, p=0.02, log rank X2=5.39). Highly concentration of the anti-inflammatory interleukin-37 exerted a protective effect by suppressing the activated Rho Kinase (ROCK) activity in the peripheral blood mononuclear cells in vivo and in vitro after ischemia/reperfusion injury and stimulation of the Rho activator, calpeptin. CONCLUSIONS: The interleukin-37 level is significantly increased in acute coronary syndrome. Elevated baseline interleukin-37 levels in patients on admission are associated with poor outcomes. Thus, we propose that interleukin-37 could be a biomarker predictive of mortality in acute coronary syndrome. Moreover, this study reveals that the protective effect of interleukin-37 against atherosclerosis may involve the inhibition of ROCK activity.

Improvement of Myocardial Function Following Catheter-Based Renal Denervation in Heart Failure.

Renal denervation (RD) is a potential novel nonpharmacological therapy for heart failure (HF). We performed bilateral catheter-based RD in 10 adult pigs and compared them with 10 control subjects after induction of HF to investigate the long-term beneficial effects of RD on left ventricular (LV) function and regional norepinephrine gradient after conventional HF pharmacological therapy. Compared with control subjects, animals treated with RD demonstrated an improvement in LV function and reduction of norepinephrine gradients over the myocardium and kidney at 10-week follow-up. Our results demonstrated that effective bilateral RD decrease regional norepinephrine gradients and improve LV contractile function compared with medical therapy alone.

iPSC-MSCs with High Intrinsic MIRO1 and Sensitivity to TNF-α Yield Efficacious Mitochondrial Transfer to Rescue Anthracycline-Induced Cardiomyopathy.

Mesenchymal stem cells (MSCs) can donate mitochondria and rescue anthracycline-induced cardiomyocyte (CM) damage, although the underlying mechanisms remain elusive. We determined that the superior efficiency of mitochondrial transfer by human induced-pluripotent-stem-cell-derived MSCs (iPSC-MSCs) compared with bone marrow-derived MSCs (BM-MSCs) is due to high expression of intrinsic Rho GTPase 1 (MIRO1). Further, due to a higher level of TNFαIP2 expression, iPSC-MSCs are more responsive to tumor necrosis factor alpha (TNF-α)-induced tunneling nanotube (TNT) formation for mitochondrial transfer to CMs, which is regulated via the TNF-α/NF-κB/TNFαIP2 signaling pathway. Inhibition of TNFαIP2 or MIRO1 in iPSC-MSCs reduced the efficiency of mitochondrial transfer and decreased CMs protection. Compared with BM-MSCs, transplantation of iPSC-MSCs into a mouse model of anthracycline-induced cardiomyopathy resulted in more human mitochondrial retention and bioenergetic preservation in heart tissue. Efficacious transfer of mitochondria from iPSC-MSCs to CMs, due to higher MIRO1 expression and responsiveness to TNF-α-induced nanotube formation, effectively attenuates anthracycline-induced CM damage.

Generation of Induced Cardiospheres via Reprogramming of Skin Fibroblasts for Myocardial Regeneration.

Recent pre-clinical and clinical studies have suggested that endogenous cardiospheres (eCS) are potentially safe and effective for cardiac regeneration following myocardial infarction (MI). Nevertheless the preparation of autologous eCS requires invasive myocardial biopsy with limited yield. We describe a novel approach to generate induced cardiospheres (iCS) from adult skin fibroblasts via somatic reprogramming. After infection with Sox2, Klf4, and Oct4, iCS were generated from mouse adult skin fibroblasts treated with Gsk3ß inhibitor-(2'Z,3'E)- 6-Bromoindirubin-3'-oxime and Oncostatin M. They resembled eCS, but contained a higher percentage of cells expressing Mesp1, Isl1, and Nkx2.5. They were differentiated into functional cardiomyocytes in vitro with similar electrophysiological properties, calcium transient and contractile function to eCS and mouse embryonic stem cell-derived cardiomyocytes. Transplantation of iCS (1 × 106 cells) into mouse myocardium following MI had similar effects to transplantation of eCS but significantly better than saline or fibroblast in improving left ventricular ejection fraction, increasing anterior/septal ventricular wall thickness and capillary density in the infarcted region 4 weeks after transplantation. No tumor formation was observed. iCS generated from adult skin fibroblasts by somatic reprogramming and a cocktail of Gsk3ß inhibitor-6-Bromoindirubin-3'-oxime and Oncostatin M may represent a novel source for cell therapy in MI. Stem Cells 2016;34:2693-2706.