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1. Proteomic Profiling Reveals Roles of Stress Response, Ca 2+ Transient Dysregulation, and Novel Signaling Pathways in Alcohol‐Induced Cardiotoxicity

   https://doi.org/10.1111/acer.14471  

   Liu, Rui ; Sun, Fangxu ; Forghani, Parvin ; Armand, Lawrence C. ; Rampoldi, Antonio ; Li, Dong ; Wu, Ronghu ; Xu, Chunhui ( October 2020 , Alcoholism: Clinical and Experimental Research)

   Alcohol use in pregnancy increases the risk of abnormal cardiac development, and excessive alcohol consumption in adults can induce cardiomyopathy, contractile dysfunction, and arrhythmias. Understanding molecular mechanisms underlying alcohol‐induced cardiac toxicity could provide guidance in the development of therapeutic strategies.

   We have performed proteomic and bioinformatic analysis to examine protein alterations globally and quantitatively in cardiomyocytes derived from human‐induced pluripotent stem cells (hiPSC‐CMs) treated with ethanol (EtOH). Proteins in both cell lysates and extracellular culture media were systematically quantitated.

   Treatment with EtOH caused severe detrimental effects on hiPSC‐CMs as indicated by significant cell death and deranged Ca²⁺handling. Treatment of hiPSC‐CMs with EtOH significantly affected proteins responsible for stress response (e.g., GPX1 and HSPs), ion channel‐related proteins (e.g. ATP1A2), myofibril structure proteins (e.g., MYL2/3), and those involved in focal adhesion and extracellular matrix (e.g., ILK and PXN). Proteins involved in the TNF receptor‐associated factor 2 signaling (e.g., CPNE1 and TNIK) were also affected by EtOH treatment.

   The observed changes in protein expression highlight the involvement of oxidative stress and dysregulation of Ca²⁺handling and contraction while also implicating potential novel targets in alcohol‐induced cardiotoxicity. These findings facilitate further exploration of potential mechanisms, discovery of novel biomarkers, and development of targeted therapeutics against EtOH‐induced cardiotoxicity.

    

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2. An intrinsic, label-free signal for identifying stem cell-derived cardiomyocyte subtype

   https://doi.org/10.1002/stem.3127  

   Chang, Che-Wei ; Kao, Hillary K. J. ; Yechikov, Sergey ; Lieu, Deborah K. ; Chan, James W. ( December 2019 , Stem Cells)

   Human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes have many promising applications, including the regeneration of injured heart muscles, cardiovascular disease modeling, and drug cardiotoxicity screening. Current differentiation protocols yield a heterogeneous cell population that includes pluripotent stem cells and different cardiac subtypes (pacemaking and contractile cells). The ability to purify these cells and obtain well-defined, controlled cell compositions is important for many downstream applications; however, there is currently no established and reliable method to identify hiPSC-derived cardiomyocytes and their subtypes. Here, we demonstrate that second harmonic generation (SHG) signals generated directly from the myosin rod bundles can be a label-free, intrinsic optical marker for identifying hiPSC-derived cardiomyocytes. A direct correlation between SHG signal intensity and cardiac subtype is observed, with pacemaker-like cells typically exhibiting ~70% less signal strength than atrial- and ventricular-like cardiomyocytes. These findings suggest that pacemaker-like cells can be separated from the heterogeneous population by choosing an SHG intensity threshold criteria. This work lays the foundation for developing an SHG-based high-throughput flow sorter for purifying hiPSC-derived cardiomyocytes and their subtypes.

   The structural and functional maturation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is essential for pharmaceutical testing, disease modeling, and ultimately therapeutic use. Multicellular 3D-tissue platforms have improved the functional maturation of hiPSC-CMs, but probing cardiac contractile properties in a 3D environment remains challenging, especially at depth and in live tissues. Using small-angle X-ray scattering (SAXS) imaging, we show that hiPSC-CMs matured and examined in a 3D environment exhibit a periodic spatial arrangement of the myofilament lattice, which has not been previously detected in hiPSC-CMs. The contractile force is found to correlate with both the scattering intensity (R² = 0.44) and lattice spacing (R² = 0.46). The scattering intensity also correlates with lattice spacing (R² = 0.81), suggestive of lower noise in our structural measurement than in the functional measurement. Notably, we observed decreased myofilament ordering in tissues with a myofilament mutation known to lead to hypertrophic cardiomyopathy (HCM). Our results highlight the progress of human cardiac tissue engineering and enable unprecedented study of structural maturation in hiPSC-CMs.

    

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3. AMPK activator-treated human cardiac spheres enhance maturation and enable pathological modeling

   https://doi.org/10.1186/s13287-023-03554-7  

   Li, Dong ; Armand, Lawrence C. ; Sun, Fangxu ; Hwang, Hyun ; Wolfson, David ; Rampoldi, Antonio ; Liu, Rui ; Forghani, Parvin ; Hu, Xin ; Yu, Wen-Mei ; et al ( December 2023 , Stem Cell Research & Therapy)

   Cardiac pathological outcome of metabolic remodeling is difficult to model using cardiomyocytes derived from human-induced pluripotent stem cells (hiPSC-CMs) due to low metabolic maturation.

   hiPSC-CM spheres were treated with AMP-activated protein kinase (AMPK) activators and examined for hiPSC-CM maturation features, molecular changes and the response to pathological stimuli.

   Treatment of hiPSC-CMs with AMPK activators increased ATP content, mitochondrial membrane potential and content, mitochondrial DNA, mitochondrial function and fatty acid uptake, indicating increased metabolic maturation. Conversely, the knockdown of AMPK inhibited mitochondrial maturation of hiPSC-CMs. In addition, AMPK activator-treated hiPSC-CMs had improved structural development and functional features—including enhanced Ca²⁺transient kinetics and increased contraction. Transcriptomic, proteomic and metabolomic profiling identified differential levels of expression of genes, proteins and metabolites associated with a molecular signature of mature cardiomyocytes in AMPK activator-treated hiPSC-CMs. In response to pathological stimuli, AMPK activator-treated hiPSC-CMs had increased glycolysis, and other pathological outcomes compared to untreated cells.

   AMPK activator-treated cardiac spheres could serve as a valuable model to gain novel insights into cardiac diseases.

    

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4. Integrated modeling framework reveals co-regulation of transcription factors, miRNAs and lncRNAs on cardiac developmental dynamics

   https://doi.org/10.1186/s13287-023-03442-0  

   Li, Shumin ; Yan, Bin ; Wu, Binbin ; Su, Junhao ; Lu, Jianliang ; Lam, Tak-Wah ; Boheler, Kenneth R. ; Poon, Ellen Ngar-Yun ; Luo, Ruibang ( September 2023 , Stem Cell Research & Therapy)

   Dissecting complex interactions among transcription factors (TFs), microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are central for understanding heart development and function. Although computational approaches and platforms have been described to infer relationships among regulatory factors and genes, current approaches do not adequately account for how highly diverse, interacting regulators that include noncoding RNAs (ncRNAs) control cardiac gene expression dynamics over time.

   To overcome this limitation, we devised an integrated framework, cardiac gene regulatory modeling (CGRM) that integrates LogicTRN and regulatory component analysis bioinformatics modeling platforms to infer complex regulatory mechanisms. We then used CGRM to identify and compare the TF-ncRNA gene regulatory networks that govern early- and late-stage cardiomyocytes (CMs) generated by in vitro differentiation of human pluripotent stem cells (hPSC) and ventricular and atrial CMs isolated during in vivo human cardiac development.

   Comparisons of in vitro versus in vivo derived CMs revealed conserved regulatory networks among TFs and ncRNAs in early cells that significantly diverged in late staged cells. We report that cardiac genes (“heart targets”) expressed in early-stage hPSC-CMs are primarily regulated by MESP1, miR-1, miR-23, lncRNAs NEAT1 and MALAT1, while GATA6, HAND2, miR-200c, NEAT1 and MALAT1 are critical for late hPSC-CMs. The inferred TF-miRNA-lncRNA networks regulating heart development and contraction were similar among early-stage CMs, among individual hPSC-CM datasets and between in vitro and in vivo samples. However, genes related to apoptosis, cell cycle and proliferation, and transmembrane transport showed a high degree of divergence between in vitro and in vivo derived late-stage CMs. Overall, late-, but not early-stage CMs diverged greatly in the expression of “heart target” transcripts and their regulatory mechanisms.

   In conclusion, we find that hPSC-CMs are regulated in a cell autonomous manner during early development that diverges significantly as a function of time when compared to in vivo derived CMs. These findings demonstrate the feasibility of using CGRM to reveal dynamic and complex transcriptional and posttranscriptional regulatory interactions that underlie cell directed versus environment-dependent CM development. These results with in vitro versus in vivo derived CMs thus establish this approach for detailed analyses of heart disease and for the analysis of cell regulatory systems in other biomedical fields.

    

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