Molecular mechanism underlying increased ischemic damage in the ALDH2*2 genetic polymorphism using a human iPSC model system
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ABSTRACT: We investigated the ALDH2*2 genetic polymorphism and its underlying mechanisms for the first time in a human model system of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from individuals carrying the most common heterozygous form of the ALDH2*2 genotype. We showed that the ALDH2*2 mutation confers elevated levels of reactive oxygen species (ROS) and toxic aldehydes such as 4HNE, thereby inducing cell cycle arrest and activation of apoptotic signaling pathways, especially during ischemic injury. ALDH2 exerts control of cell survival decisions via modulation of oxidative stress levels. This regulatory circuitry was found to be dysfunctional in the loss-of-function ALDH2*2 genotype, causing upregulation of apoptosis in cardiomyocytes following ischemic insult. These results reveal a novel function of the metabolic enzyme ALDH2 in modulation of cell survival decisions. Molecular mechanism of increased ischemic damage in cardiomyocytes of ALDH2*2 genotype.
Project description:We investigated the ALDH2*2 genetic polymorphism and its underlying mechanisms for the first time in a human model system of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from individuals carrying the most common heterozygous form of the ALDH2*2 genotype. We showed that the ALDH2*2 mutation confers elevated levels of reactive oxygen species (ROS) and toxic aldehydes such as 4HNE, thereby inducing cell cycle arrest and activation of apoptotic signaling pathways, especially during ischemic injury. ALDH2 exerts control of cell survival decisions via modulation of oxidative stress levels. This regulatory circuitry was found to be dysfunctional in the loss-of-function ALDH2*2 genotype, causing upregulation of apoptosis in cardiomyocytes following ischemic insult. These results reveal a novel function of the metabolic enzyme ALDH2 in modulation of cell survival decisions.
Project description:Genome-wide gene expression analysis of new cardiomyocytes (CMs) derived from resident c-kitpos endogenous cardiac stem cells (eCSCs) after myocardial injury by Isoproterenol (ISO) in mice. These data show that of new CMs derived from resident c-kitpos eCSCs have a gene expression profile that closely resembles the specific gene expression of adult cardiomyocytes. This result supports a role of c-kitpos eCSCs in the regeneration and repair of myocardial damage. To test the identity and the degree of differentiation of new cardiomyocytes (CMs) derived from resident c-kitpos endogenous cardiac stem cells (eCSCs) after myocardial injury by Isoproterenol (ISO) in mice. Global gene expression profiles by microarray was obtained in c-kitpos eCSCs, c-kitpos eCSC-derived YFPpos CMs and normal adult CMs. c-kitposCD45neg eCSCs were isolated from B6.129X1-Gt(ROSA)26Sortm1(EYFP)Cos/J mice and harvested at 4th passage (n=3). YFPpos cardiomyocytes were FACS sorted from left ventricle apex of Lentirius-c-kit/cre recombined B6.129X1-Gt(ROSA)26Sortm1(EYFP)Cos/J mice 28 days after ISO (N=3). Normal adult CMs were isolated from B6.129X1-Gt(ROSA)26Sortm1(EYFP)Cos/J mice (n=3).
Project description:Pluripotent stem cell-derived cardiomyocytes (PSC-CMs) were transplanted into rats for one month to determine the change in morphology, structure, and function. Single cell RNA seq analysis was performed to compared the transcriptome of in vivo matured PSC-CMs to adult rat cardiomyocytes and in vitro cultured PSC-CMs.
Project description:The generation of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) offers an unlimited source of patient-specific human cardiomyocytes. However, the use of iPSC-CM in vitro-models to guide the clinic selection of particular drugs for individual patients remains a vision. A major limitation represents the immature phenotype of iPSC-CMs, which alters their sensitivity towards physiological and pathophysiological stimuli, cardioactive drugs or toxic substances, in comparison to adult cardiomyocytes (CMs). In this study, we aim to generate iPSC-CMs with an advanced maturation state by combining the use of MM with the alignment of the cells on nanopatterned surfaces (NP) and induction of an increased contractile workload by electrical stimulation (ES). Under the combined influence of MM, NP and ES, iPSC-CMs develop a more complex cellular structure, increased mitochondrial content and enhanced electrophysiological properties. Furthermore, the response of iPSC-CMs matured under influence of MM, NP and ES to isoprenaline as well as verapamil differs to less mature iPSC-CMs cultured in B27-medium. Taken together, our results reveal that the combination of MM, NP and ES strongly improves the maturation state of iPSC-CMs and that this advanced maturation state critically affects the cell behavior in functional studies as well as response to cardioactive drugs.
Project description:In this study we have compared functional and molecular properties of highly purified murine induced pluripotent stem (iPS) cell- and embryonic stem (ES) cell-derived cardiomyocytes (CM). In order to obtain large amounts of purified CM, we have generated a transgenic murine iPS cell line, which expresses puromycin resistance protein N-acetyltransferase and EGFP under the control of the cardiomyocyte-specific α-myosin heavy chain promoter (alphaMHC-Puro-IRES-GFP, aPiG). We demonstrate that murine aPIG-iPS and aPIG-ES cells differentiate into spontaneously beating CM at comparable efficiencies. When selected with puromycin both cell types yielded more than 97% pure population of CMs. Both aPIG-iPS and aPIG-ES cell-derived CM express typical cardiac transcripts and structural proteins and possess similar sarcomeric organization. Action potential recordings revealed that iPS- and ES cell-derived CM respond to beta-adrenergic and muscarinic receptor modulation, express functional voltage-gated sodium, calcium and potassium channels and possess comparable current densities. Comparison of global gene expression profiles of CM generated from iPS and ES cells revealed that both cell types cluster close to each other but are highly distant to undifferentiated ES or iPS cells as well as unpurified iPS and ES cell-derived embryoid bodies (EB). Both iPS and ES cell-derived CMs express genes and functional categories typical for CM. They are enriched in genes involved in transcription and genes coding for structural proteins involved in cardiac muscle contraction and relaxation. They also express genes involved in heart and muscle developmental processes, ion export and ion binding processes and various metabolic processes for ATP synthesis. These CMs downregulate genes involved in immune response, cell cycle and cell division, thus demonstrating the CMs population is mitotically inactive. Most surface signaling pathways are also downregulated. Thus, a transgenic aPiG-iPS cell line can provide a robust supply of highly purified and functional CMs for future in vitro and in vivo studies. Seven different experimental groups were included into analysis: undifferentiated murine ES cells (1) and undifferentiated murine iPS cells (2), murine ES cell-derived embyroid bodies (3) and murine iPS cell-derived embryoid bodies at day 16 of differentiation (4), murine ES cell-derived cardiomyocytes (5) and murine iPS cell-derived cardiomyocytes (6) at day 16 of differentiation (they were generated by puromycin selection for 7 days prior to RNA isolation). Adult mouse tail tip fibroblasts (7) were used as a control for iPS cells. Total RNA samples were prepared from three independent biological replicates in groups 1-6. In group 7, single RNA probes were analyzed as three technical replicates.
Project description:The ischemic borderzone (BZ) is a geographically complex and biologically enigmatic interface separating poorly perfused infarct zones (IZ) from comparatively healthy remote zones (RZ). BZ cellular and molecular mechanisms are not well understood because efforts to dissect it inevitably include RZ and IZ in uncontrolled proportions. Here, we use single-cell/nuclei RNA-sequencing, spatial transcriptomics, and multiplexed RNA fluorescence in situ hybridization (mFISH) to identify BZ cardiomyocytes (CMs) subsets. BZ1 (Nppa+Xirp2-) forms a hundreds-of-microns-thick transitional layer adjacent to RZ, while BZ2 (Nppa+Xirp2+) forms a tens-of-microns-thick layer that the IZ edge. BZ2 CMs have reduced CM cell contact; colocalize with matricellular-protein-expressing myofibroblasts; and upregulate focal adhesion-, sarcomere-, and cytoskeletal-genes. Surprisingly, the transcriptional BZ emerges within an hour of injury and is inducible by non-ischemic fine-needle-trauma. We suggest that mechanical instability and “loss of neighbor” at the BZ edge are the dominant inducers of the BZ transcriptional response.
Project description:Inter-organelle contact and communication between mitochondria (Mito) and endoplasmic reticulum (ER), also known as sarcoplasmic reticulum (SR) in cardiomyocytes (CM), play vital roles in the maintenance of Mito and SR properties and cellular homeostasis. Here, we tested the hypothesis that the formin, Diaphanous-1 (DIAPH1), which regulates actin dynamics and signal transduction, contributes to these processes. Mice bearing CM-specific deletion of Diaph1 displayed reduced injury and superior functional recovery after the induction of cardiac ischemia and reperfusion (I/R). Studies in DIAPH1-silenced human induced pluripotent stem cell-derived CMs (HiPSC-CMs) and murine hearts devoid of CM-Diaph1 revealed that DIAPH1 interacts directly with Mitofusin-2 (MFN2) to regulate Mito-SR contact, Mito turnover, mitophagy, and oxidative stress. Ischemic murine hearts and human heart biopsies revealed more robust DIAPH1-MFN2 interaction vs. that observed in non-ischemic hearts. Solution structure studies affirm this interaction and reveal strong pH-dependent interaction between the Diaphanous Inhibitory Domain (DID) and the cytosolic GTPase domain of MFN2. In HiPSC-CMs, introduction of synthetic linkers, which reduce the Mito-SR distance, mitigated the cardioprotective benefits of Diaph1 deletion. Finally, DIAPH1 binding to the cytoplasmic domain of receptor for advanced glycation endproduct (RAGE) supports signal transduction and contributes to I/R injury in the heart; in HiPSC-CMs, small molecule antagonism of RAGE-DIAPH1 reduced DIAPH1-MFN2 interaction and increased Mito-SR distance. This work establishes fundamental roles for DIAPH1-MFN2 interaction in the regulation of Mito-SR contact networks that control responses to ischemic stress. Targeting pathways that regulate DIAPH1-MFN2 may facilitate recovery from cardiac ischemic injury.
Project description:Human pluripotent stem cell-derived cardiomyocytes (CMs) are a promising tool for cardiac cell therapy. To optimize graft cells for cardiac reconstruction, we compared the engraftment efficiency of intramyocardially-injected undifferentiated-induced pluripotent stem cells (iPSCs), day4 mesodermal cells, and day8, day20, and day30 purified iPSC-CMs after initial differentiation by tracing the engraftment ratio (ER) using in vivo bioluminescence imaging. This analysis revealed the ER of day20 CMs was significantly higher compared to other cells. Transplantation of day20 CMs into the infarcted hearts of immunodeficient mice showed significant functional improvement. Moreover, the imaging signal and ratio of Ki67-positive CMs at 3 months post injection indicated engrafted CMs proliferated in the host heart. Although this graft growth reached a plateau at 3 months, histological analysis confirmed progressive maturation from 3 to 6 months. These results suggested that day20 CMs had very high engraftment, proliferation, and therapeutic potential in host mouse hearts. Differentiated cells, N=10 Undifferentiated pluripotent stem cells, N=1 Heart samples, N=6
Project description:ABSTRACT Background: Viral myocarditis is a life-threatening illness that may lead to heart failure or cardiac arrhythmias. This study examined whether human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) could be used to model the pathogenic processes of coxsackievirus-induced viral myocarditis and to screen antiviral therapeutics for efficacy. Methods and Results: Human iPSC-CMs were infected with a luciferase-expressing mutant of the coxsackievirus B3 strain (CVB3-Luc). Brightfield microscopy, immunofluorescence, and calcium imaging were used to characterize virally infected hiPSC-CMs. Viral proliferation on hiPSC-CMs was subsequently quantified using bioluminescence imaging. For drug screening, select antiviral compounds including interferon beta 1 (IFNβ1), ribavirin, pyrrolidine dithiocarbamate (PDTC), and fluoxetine were tested for their capacity to abrogate CVB3-Luc proliferation in hiPSC-CMs in vitro. The ability of some of these compounds to reduce CVB3-Luc proliferation in hiPSC-CMs was consistent with the reported drug effects in previous studies. Finally, mechanistic analyses via gene expression profiling of hiPSC-CMs infected with CVB3-Luc revealed an activation of viral RNA and protein clearance pathways within these hiPSC-CMs after IFNβ1 treatment. Conclusions: This study demonstrates that hiPSC-CMs express the coxsackievirus and adenovirus receptor, are susceptible to coxsackievirus infection, and can be used to confirm antiviral drug efficacy. Our results suggest that the hiPSC-CM/CVB3-Luc assay is a sensitive platform that could be used to screen novel antiviral therapeutics for their effectiveness in a high-throughput fashion. For this experiment, human induced pluripotent stem cell derived cardiomyocytes were infected with coxsackievirus at multiplicity of infection (MOI) of 5 for 8 hours. Cells were treated with and without interferon beta 1 in order to determine if treatment activates antiviral response genes and/or viral clearance pathways. 4 total samples (2 for each condition) were analyzed