CARDIAC MUSCLE CELLS Bmi1 Is a Key Epigenetic Barrier to Direct Cardiac Reprogramming Scientists screened for epigenetic regulators of induced cardiomyocyte (iCM) reprogramming and found that reducing levels of the polycomb complex gene Bmi1 significantly enhanced induction of beating iCMs from neonatal and adult mouse fibroblasts. [Cell Stem Cell] Abstract | Graphical Abstract | Press Release Fibroblasts Rendered Antifibrotic, Antiapoptotic, and Angiogenic by Priming with Cardiosphere-Derived Extracellular Membrane Vesicles Researchers sought to investigate the effect of cardiosphere-derived extracellular membrane vesicles (CSp-EMVs) on fibroblasts in vitro and tested whether priming with CSp-EMVs could confer salutary properties on fibroblasts in vivo. [J Am Coll Cardiol] Abstract | Press Release Rationally Engineered Troponin C Modulates In Vivo Cardiac Function and Performance in Health and Disease Investigators developed a protein engineering approach to directly tune in vivo cardiac contractility by tailoring the ability of the heart to respond to the Ca2+ signal. In a myocardial infarction (MI) model of heart failure, expression of Ca2+-sensitizing Troponin C before the MI preserved cardiac function and performance. [Nat Commun] Full Article | Press Release Influence of Aging on the Quantity and Quality of Human Cardiac Stem Cells Scientists examined whether aging affected the quantity and quality of cardiac stem cells using cells obtained from 26 patients of various ages. They investigated growth rate, senescence, DNA damage, and the growth factor production of cardiosphere-derived cells. [Sci Rep] Full Article Systemic Injection of AAV9 Carrying a Periostin Promoter Targets Gene Expression to a Myofibroblast-Like Lineage in Mouse Hearts after Reperfused Myocardial Infarction Scientists constructed expression cassettes using a modified periostin promoter to drive gene expression in a cardiac myofibroblast-like lineage, with only occasional spillover into cardiomyocyte-like cells. [Gene Ther] Abstract SKELETAL MUSCLE CELLS Nfix Regulates Temporal Progression of Muscle Regeneration through Modulation of Myostatin Expression Investigators previously showed a pivotal role for Nfix in regulating the transcriptional switch from embryonic to fetal myogenesis. In this study, they showed that Nfix directly represses the Myostatin promoter, thus controlling the proper timing of satellite cell differentiation and muscle regeneration. [Cell Rep] Full Article | Graphical Abstract KLF7 Regulates Satellite Cell Quiescence in Response to Extracellular Signaling The authors report that KLF7 functioned as a key mediator involved in low-level TGF-β signaling and canonical Notch signaling-induced satellite cell (SC) quiescence and myoblast arrest. The data obtained showed that KLF7 was upregulated in quiescent SCs and non-proliferating myoblasts. [Stem Cells] Abstract Induction of CCAAT/Enhancer-Binding Protein β Expression with the Phosphodiesterase Inhibitor Isobutylmethylxanthine Improves Myoblast Engraftment into Dystrophic Muscle Scientists demonstrated that induction of the transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) using the cyclic adenosine monophosphate phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) results in enhanced myoblast expansion in culture and increased satellite cell marker expression. [Stem Cells Transl Med] Abstract Tumor Necrosis Factor-α Impairs Adiponectin Signaling, Mitochondrial Biogenesis and Myogenesis in Primary Human Myotubes Cultures Researchers aimed to examine the impact of adiponectin receptor 1 deficiency and TNF-α treatment on adiponectin signaling, proliferative capacity, myogenic differentiation and mitochondrial biogenesis in primary human skeletal muscle cells. [Am J Physiol Heart Circ Physiol] Abstract SMOOTH MUSCLE CELLS Nuclear PTEN Functions as an Essential Regulator of SRF-Dependent Transcription to Control Smooth Muscle Differentiation Scientists report that the lipid and protein phosphatase, PTEN, has a novel role in the nucleus by functioning as an indispensable regulator with serum response factor (SRF) to maintain the differentiated smooth muscle phenotype. [Nat Commun] Full Article Hyperinsulinemia Adversely Affects Lung Structure and Function Scientists demonstrated that insulin can adversely affect respiratory health. Insulin treatment significantly increased the proliferation of primary human airway smooth muscle cells and induced collagen release. [Am J Physiol Lung Cell Mol Physiol] Abstract |