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Breast cancer is the most common invasive cancer in women, affecting more than 10% of women worldwide. Microscopic analysis of a biopsy remains one of the most important methods to diagnose the type of breast cancer. This requires specialized analysis by pathologists, in a task that i) is highly time- and cost-consuming and ii) often leads to nonconsensual results. The relevance and potential of automatic classification algorithms using hematoxylin-eosin stained histopathological images has already been demonstrated, but the reported results are still sub-optimal for clinical use. With the goal of advancing the state-of-the-art in automatic classification, the Grand Challenge on BreAst Cancer Histology images (BACH) was organized in conjunction with the 15th International Conference on Image Analysis and Recognition (ICIAR 2018). A large annotated dataset, composed of both microscopy and whole-slide images, was specifically compiled and made publicly available for the BACH challenge. Following a positive response from the scientific community, a total of 64 submissions, out of 677 registrations, effectively entered the competition. From the submitted algorithms it was possible to push forward the state-of-the-art in terms of accuracy (87%) in automatic classification of breast cancer with histopathological images. Convolutional neuronal networks were the most successful methodology in the BACH challenge. Detailed analysis of the collective results allowed the identification of remaining challenges in the field and recommendations for future developments. The BACH dataset remains publically available as to promote further improvements to the field of automatic classification in digital pathology., Accepted for publication at Medical Image Analysis (Elsevier). Publication licensed under the Creative Commons CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

Summary: Patient-derived tumor organoids (TOs) are emerging as high-fidelity models to study cancer biology and develop novel precision medicine therapeutics. However, utilizing TOs for systems-biology-based approaches has been limited by a lack of scalable and reproducible methods to develop and profile these models. We describe a robust pan-cancer TO platform with chemically defined media optimized on cultures acquired from over 1,000 patients. Crucially, we demonstrate tumor genetic and transcriptomic concordance utilizing this approach and further optimize defined minimal media for organoid initiation and propagation. Additionally, we demonstrate a neural-network-based high-throughput approach for label-free, light-microscopy-based drug assays capable of predicting patient-specific heterogeneity in drug responses with applicability across solid cancers. The pan-cancer platform, molecular data, and neural-network-based drug assay serve as resources to accelerate the broad implementation of organoid models in precision medicine research and personalized therapeutic profiling programs.

© 2016 American College of Cardiology Foundation Background Brugada syndrome (BrS), a disorder associated with characteristic electrocardiogram precordial ST-segment elevation, predisposes afflicted patients to ventricular fibrillation and sudden cardiac death. Despite marked achievements in outlining the organ level pathophysiology of the disorder, the understanding of human cellular phenotype has lagged due to a lack of adequate human cellular models of the disorder. Objectives The objective of this study was to examine single cell mechanism of Brugada syndrome using induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs). Methods This study recruited 2 patients with type 1 BrS carrying 2 different sodium voltage-gated channel alpha subunit 5 variants as well as 2 healthy control subjects. We generated iPSCs from their skin fibroblasts by using integration-free Sendai virus. We used directed differentiation to create purified populations of iPSC-CMs. Results BrS iPSC-CMs showed reductions in inward sodium current density and reduced maximal upstroke velocity of action potential compared with healthy control iPSC-CMs. Furthermore, BrS iPSC-CMs demonstrated increased burden of triggered activity, abnormal calcium (Ca2+) transients, and beating interval variation. Correction of the causative variant by genome editing was performed, and resultant iPSC-CMs showed resolution of triggered activity and abnormal Ca2+ transients. Gene expression profiling of iPSC-CMs showed clustering of BrS compared with control subjects. Furthermore, BrS iPSC-CM gene expression correlated with gene expression from BrS human cardiac tissue gene expression. Conclusions Patient-specific iPSC-CMs were able to recapitulate single-cell phenotype features of BrS, including blunted inward sodium current, increased triggered activity, and abnormal Ca2+handling. This novel human cellular model creates future opportunities to further elucidate the cellular disease mechanism and identify novel therapeutic targets.

Background Patient derived tumor organoids (TOs) are emerging as potential models to elucidate mechanisms of tumor biology and therapeutic response. Here, we establish pan-cancer metrics for validation of genetic and transcriptomic recapitulation, and concordance of an organoid to its native tumor. Methods/Results We sequenced 50 tumor/TO pairs from 12 cancer types using the Tempus xT DNAseq panel and transcriptome RNAseq platforms. Concordance metrics between tumors and TOs were derived for genomic variants called by the DNA xT platform and comparative ratios were calculated for all detected somatic variants. Across all sequenced pairs, somatic variant detection concordance between any mutation identified in primary tissues and tumor organoids resulted in a mean value of 88.1%. Somatic primary tumor variant recapitulation, the percent of somatic variants identified in the primary tumors that were also detected in the TO, averaged 96.3%. In addition to genetic concordance, DNAseq can identify and track clonal and subclonal diversity from source material to TO. In particular, we observed that >90% of source tumor/TO pairs harbor variants with allelic fractions TOs and primary tumor transcriptomic profiles were compared by dimensionality reduction approaches (i.e. Uniform Manifold Approximation and Projection (UMAP), and Principal Components Analysis (PCA)) as well as differential expression analysis between cancer types. Overall, TOs recapitulated expected transcriptional programs of their tumor type as evidenced by UMAP and PCA as well as upregulation of defining pathways, such as estrogen receptor pathways in breast cancer TOs (ssGSEA p-values ranging from 0.004 to 5 × 10−5 for 5 gene ontology estrogen response pathways when compared to non-breast cancer TOs). Conclusion Determining genomic and transcriptomic concordance of TOs to source tumors is essential to confirm the validity of a given patient derived model. Our approach establishes metrics through key genomic features identified from routine next-generation sequencing data and can be extended beyond model validation to tracking clonal evolution over time in the presence or absence of therapeutic selection pressures. Our metrics may also serve as a critical quality control step if TOs are utilized in the clinical setting for personalized medicine. Citation Format: Brandon L. Mapes, Joshua SK Bell, Lee F. Langer, Robert Huether, Catherine Igartua, Veronica Sanchez-Freire, Robert Tell, Jeffrey A. Borgia, Ashiq Masood, Ameen A. Salahudeen. Universal genetic and transcriptomic concordance metrics to validate patient-derived tumor organoid models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3908.

Stem-cell-based therapies hold considerable promise for regenerative medicine. However, acute donor-cell death within several weeks after cell delivery remains a critical hurdle for clinical translation. Co-transplantation of stem cells with pro-survival factors can improve cell engraftment, but this strategy has been hampered by the typically short half-lives of the factors and by the use of Matrigel and other scaffolds that are not chemically defined. Here, we report a collagen–dendrimer biomaterial crosslinked with pro-survival peptide analogues that adheres to the extracellular matrix and slowly releases the peptides, significantly prolonging stem cell survival in mouse models of ischaemic injury. The biomaterial can serve as a generic delivery system to improve functional outcomes in cell-replacement therapy.

Cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSCs) are being increasingly used to model human heart diseases. hiPSC-CMs generated by earlier aggregation-based methods (i.e., embryoid body) often lack functional sarcoplasmic reticulum (SR) Ca stores characteristic of mature mammalian CMs. Newer monolayer-based cardiac differentiation methods (i.e., Matrigel sandwich or small molecule-based differentiation) produce hiPSC-CMs of high purity and yield, but their Ca handling has not been comprehensively investigated. Here, we studied Ca handling and cytosolic Ca buffering properties of hiPSC-CMs generated independently from multiple hiPSC lines at Stanford University, Vanderbilt University and University of Wisconsin-Madison. hiPSC-CMs were cryopreserved at each university. Frozen aliquots were shipped, recovered from cryopreservation, plated at low density and compared 3–5days after plating with acutely-isolated adult rabbit and mouse ventricular CMs. Although hiPSC-CM cell volume was significantly smaller, cell capacitance to cell volume ratio and cytoplasmic Ca buffering were not different from rabbit-CMs. hiPSC-CMs from all three laboratories exhibited robust L-type Ca currents, twitch Ca transients and caffeine-releasable SR Ca stores comparable to adult CMs. Ca transport by sarcoendoplasmic reticulum Ca ATPase (SERCA) and Na/Ca exchanger (NCX) was similar in all hiPSC-CM lines, but slower compared to rabbit-CMs. However, the relative contribution of SERCA and NCX to Ca transport of hiPSC-CMs was comparable to rabbit-CMs. Ca handling maturity of hiPSC-CMs increased from 15 to 21days post-induction. We conclude that hiPSC-CMs generated independently from multiple iPSC lines using monolayer-based methods can be reproducibly recovered from cryopreservation and exhibit comparable and functional SR Ca handling.

Summary There is growing interest in using embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) derivatives for tissue regeneration. However, an increased understanding of human immune responses to stem cell-derived allografts is necessary for maintaining long-term graft persistence. To model this alloimmunity, humanized mice engrafted with human hematopoietic and immune cells could prove to be useful. In this study, an in-depth analysis of graft-infiltrating human lymphocytes and splenocytes revealed that humanized mice incompletely model human immune responses toward allogeneic stem cells and their derivatives. Furthermore, using an “allogenized” mouse model, we show the feasibility of reconstituting immunodeficient mice with a functional mouse immune system and describe a key role of innate immune cells in the rejection of mouse stem cell allografts., Graphical Abstract, Highlights • Innate immunity is crucial in rejection of minor HA mismatched grafts • Stem cell alloimmune responses modeled with an “allogenized mouse” • Humanized mice are unable to fully model immune responses to stem cell allografts • Splenocytes and graft-infiltrating lymphocytes display an exhausted phenotype, Kooreman et al. use various types of humanized mice for the modeling of pluripotent stem cell alloimmunity. They report the development of a wasting disease-like syndrome within these mice over time, limiting their functionality, and provide ways to address this by using an immune reconstituted “allogenized” mouse model.

Restoring pluripotency using chemical compounds alone would be a major step forward in developing clinical-grade pluripotent stem cells, but this has not yet been reported in human cells. We previously demonstrated that VPA_ AFS cells, human amniocytes cultivated with valproic acid (VPA) acquired functional pluripotency while remaining distinct from human embryonic stem cells (hESCs), questioning the relationship between the modulation of cell fate and molecular regulation of the pluripotency network. Here, we used single-cell analysis and functional assays to reveal that VPA treatment resulted in a homogeneous population of self-renewing non-transformed cells that fulfill the hallmarks of pluripotency, i.e., a short G1 phase, a dependence on glycolytic metabolism, expression of epigenetic modifications on histones 3 and 4, and reactivation of endogenous OCT4 and downstream targets at a lower level than that observed in hESCs. Mechanistic insights into the process of VPA-induced reprogramming revealed that it was dependent on OCT4 promoter activation, which was achieved independently of the PI3K (phosphatidylinositol 3-kinase)/ AKT/ mTOR (mammalian target of rapamycin) pathway or GSK3 beta inhibition but was concomitant with the presence of acetylated histones H3K9 and H3K56, which promote pluripotency. Our data identify, for the first time, the pluripotent transcriptional and molecular signature and metabolic status of human chemically induced pluripotent stem cells.

BackgroundHuman-induced pluripotent stem cells (iPSCs) are a potentially unlimited source for generation of cardiomyocytes (iPSC-CMs). However, current protocols for iPSC-CM derivation face several challenges, including variability in somatic cell sources and inconsistencies in cardiac differentiation efficiency.ObjectivesThis study aimed to assess the effect of epigenetic memory on differentiation and function of iPSC-CMs generated from somatic cell sources of cardiac versus noncardiac origins.MethodsCardiac progenitor cells (CPCs) and skin fibroblasts from the same donors were reprogrammed into iPSCs and differentiated into iPSC-CMs via embryoid body and monolayer-based differentiation protocols.ResultsDifferentiation efficiency was found to be higher in CPC-derived iPSC-CMs (CPC-iPSC-CMs) than in fibroblast-derived iPSC-CMs (Fib-iPSC-CMs). Gene expression analysis during cardiac differentiation demonstrated up-regulation of cardiac transcription factors in CPC-iPSC-CMs, including NKX2-5, MESP1, ISL1, HAND2, MYOCD, MEF2C, and GATA4. Epigenetic assessment revealed higher methylation in the promoter region of NKX2-5 in Fib-iPSC-CMs compared with CPC-iPSC-CMs. Epigenetic differences were found to dissipate with increased cell passaging, and a battery of in vitro assays revealed no significant differences in their morphological and electrophysiological properties at early passage. Finally, cell delivery into a small animal myocardial infarction model indicated that CPC-iPSC-CMs and Fib-iPSC-CMs possess comparable therapeutic capabilities in improving functional recovery in vivo.ConclusionsThis is the first study to compare differentiation of iPSC-CMs from human CPCs versus human fibroblasts from the same donors. The authors demonstrate that although epigenetic memory improves differentiation efficiency of cardiac versus noncardiac somatic cell sources in vitro, it does not contribute to improved functional outcome in vivo.

Background— Cardiotoxicity is a leading cause for drug attrition during pharmaceutical development and has resulted in numerous preventable patient deaths. Incidents of adverse cardiac drug reactions are more common in patients with preexisting heart disease than the general population. Here we generated a library of human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) from patients with various hereditary cardiac disorders to model differences in cardiac drug toxicity susceptibility for patients of different genetic backgrounds. Methods and Results— Action potential duration and drug-induced arrhythmia were measured at the single cell level in hiPSC-CMs derived from healthy subjects and patients with hereditary long QT syndrome, familial hypertrophic cardiomyopathy, and familial dilated cardiomyopathy. Disease phenotypes were verified in long QT syndrome, hypertrophic cardiomyopathy, and dilated cardiomyopathy hiPSC-CMs by immunostaining and single cell patch clamp. Human embryonic stem cell–derived cardiomyocytes (hESC-CMs) and the human ether-a-go-go –related gene expressing human embryonic kidney cells were used as controls. Single cell PCR confirmed expression of all cardiac ion channels in patient-specific hiPSC-CMs as well as hESC-CMs, but not in human embryonic kidney cells. Disease-specific hiPSC-CMs demonstrated increased susceptibility to known cardiotoxic drugs as measured by action potential duration and quantification of drug-induced arrhythmias such as early afterdepolarizations and delayed afterdepolarizations. Conclusions— We have recapitulated drug-induced cardiotoxicity profiles for healthy subjects, long QT syndrome, hypertrophic cardiomyopathy, and dilated cardiomyopathy patients at the single cell level for the first time. Our data indicate that healthy and diseased individuals exhibit different susceptibilities to cardiotoxic drugs and that use of disease-specific hiPSC-CMs may predict adverse drug responses more accurately than the standard human ether-a-go-go –related gene test or healthy control hiPSC-CM/hESC-CM screening assays.

Defects in urothelial integrity resulting in leakage and activation of underlying sensory nerves are potential causative factors of bladder pain syndrome, a clinical syndrome of pelvic pain and urinary urgency/frequency in the absence of a specific cause. Herein, we identified the microRNA miR-199a-5p as an important regulator of intercellular junctions. On overexpression in urothelial cells, it impairs correct tight junction formation and leads to increased permeability. miR-199a-5p directly targets mRNAs encoding LIN7C, ARHGAP12, PALS1, RND1, and PVRL1 and attenuates their expression levels to a similar extent. Using laser microdissection, we showed that miR-199a-5p is predominantly expressed in bladder smooth muscle but that it is also detected in mature bladder urothelium and primary urothelial cultures. In the urothelium, its expression can be up-regulated after activation of cAMP signaling pathways. While validating miR-199a-5p targets, we delineated novel functions of LIN7C and ARHGAP12 in urothelial integrity and confirmed the essential role of PALS1 in establishing and maintaining urothelial polarity and junction assembly. The present results point to a possible link between miR-199a-5p expression and the control of urothelial permeability in bladder pain syndrome. Up-regulation of miR-199a-5p and concomitant down-regulation of its multiple targets might be detrimental to the establishment of a tight urothelial barrier, leading to chronic pain.

Summary Familial hypertrophic cardiomyopathy (HCM) is a prevalent hereditary cardiac disorder linked to arrhythmia and sudden cardiac death. While the causes of HCM have been identified as genetic mutations in the cardiac sarcomere, the pathways by which sarcomeric mutations engender myocyte hypertrophy and electrophysiological abnormalities are not understood. To elucidate the mechanisms underlying HCM development, we generated patient-specific induced pluripotent stem cell cardiomyocytes (iPSC-CMs) from a ten-member family cohort carrying a hereditary HCM missense mutation (Arg663His) in the MYH7 gene. Diseased iPSC-CMs recapitulated numerous aspects of the HCM phenotype including cellular enlargement and contractile arrhythmia at the single-cell level. Calcium (Ca 2+ ) imaging indicated dysregulation of Ca 2+ cycling and elevation in intracellular Ca 2+ ([Ca 2+ ] i ) are central mechanisms for disease pathogenesis. Pharmacological restoration of Ca 2+ homeostasis prevented development of hypertrophy and electrophysiological irregularities. We anticipate that these findings will help elucidate the mechanisms underlying HCM development and identify novel therapies for the disease.

Human pluripotent stem cells, including human embryonic stem cells (hESCs) and human induced PSCs (hiPSCs), have great potential as an unlimited donor source for cell-based therapeutics. The risk of teratoma formation from residual undifferentiated cells, however, remains a critical barrier to the clinical application of these cells. Herein, we describe external beam radiation therapy (EBRT) as an attractive option for the treatment of this iatrogenic growth. We present evidence that EBRT is effective in arresting growth of hESC-derived teratomas in vivo at day 28 post-implantation by using a microCT irradiator capable of targeted treatment in small animals. Within several days of irradiation, teratomas derived from injection of undifferentiated hESCs and hiPSCs demonstrated complete growth arrest lasting several months. In addition, EBRT reduced reseeding potential of teratoma cells during serial transplantation experiments, requiring irradiated teratomas to be seeded at 1 × 103 higher doses to form new teratomas. We demonstrate that irradiation induces teratoma cell apoptosis, senescence, and growth arrest, similar to established radiobiology mechanisms. Taken together, these results provide proof of concept for the use of EBRT in the treatment of existing teratomas and highlight a strategy to increase the safety of stem cell-based therapies.

We have investigated cardiac myocytes derived from human-induced pluripotent stem cells (iPSC-CMs) from two normal control and two family members expressing a mutant cardiac troponin T (cTnT-R173W) linked to dilated cardiomyopathy (DCM). cTnT is a regulatory protein of the sarcomeric thin filament. The loss of this basic charge, which is strategically located to control tension, has consequences leading to progressive DCM. iPSC-CMs serve as a valuable platform for understanding clinically relevant mutations in sarcomeric proteins; however, there are important questions to be addressed with regard to myocyte adaptation that we model here by plating iPSC-CMs on softer substrates (100 kPa) to create a more physiologic environment during recovery and maturation of iPSC-CMs after thawing from cryopreservation. During the first week of culture of the iPSC-CMs, we have determined structural and functional characteristics as well as actin assembly dynamics. Shortening, actin content, and actin assembly dynamics were depressed in CMs from the severely affected mutant at 1 wk of culture, but by 2 wk differences were less apparent. Sarcomeric troponin and myosin isoform composition were fetal/neonatal. Furthermore, the troponin complex, reconstituted with wild-type cTnT or recombinant cTnT-R173W, depressed the entry of cross-bridges into the force-generating state, which can be reversed by the myosin activator omecamtiv mecarbil. Therapeutic doses of this drug increased both contractility and the content of F-actin in the mutant iPSC-CMs. Collectively, our data suggest the use of a myosin activation reagent to restore function within patient-specific iPSC-CMs may aid in understanding and treating this familial DCM.

What’s known on the subject? and What does the study add? In this paper we established the mRNA expression profiles of selected genes involved in bladder contractility and epithelial permeability in the bladder dome and trigone in order to evaluate the use of cold cut biopsies for comparative quantitative studies reflecting the anatomical differences between the bladder regions. Using QPCR and immunofluorescence we demonstrated differences in the amount of smooth muscle and the structure of urothelium of the dome and trigon. Our mRNA and immunofluorescence data show that cold cut biopsies from the bladder dome have a higher relative SM content compared to the trigone, reflecting a well-developed network of sub-urothelial myofibroblasts and muscularis mucosae present in the bladder dome. An up-regulation of the genes encoding the tight junction proteins in the bladder trigone is independent of the urothelium content, and might imply further discrepancy between these regions. OBJECTIVE • To establish the mRNA expression profiles of selected genes involved in bladder contractility and epithelial permeability in the bladder dome and trigone in order to evaluate the use of cold-cut biopsies for comparative quantitative studies into the anatomical differences between these two bladder regions. PATIENTS AND METHODS • After informed consent, cold-cut biopsies from the bladder dome and trigone were obtained from eight asymptomatic subjects. • RNA was extracted from muscle biopsies, and the expression levels of selected genes were analysed using TaqMan real-time PCR-based gene expression assays. • Protein levels and localization were investigated by immunofluorescence. RESULTS • mRNA levels of NK2 receptor, P2X1, ASIC1a and muscarinic cholinergic receptors M2, and M3 were significantly higher in the dome than in the trigone (P < 0.05). In contrast, the mRNA levels of cellular adhesion and tight junction proteins were up-regulated in the trigone. • There were no significant differences in expression levels of NK1R, and TRPV1 between the dome and trigone. • Although the mRNA levels of uroplakin UP2 were similar in both sample groups, the smooth muscle (SM) markers were up-regulated in the dome biopsies, indicating the higher SM content of these biopsies. • Consistent with these observations, when normalizing for the SM content, there were no significant differences in the levels of SM-specific markers between the two sample groups. In contrast, occludin, junctional adhesion molecule 1, claudins 1 and 4, γ-catenin and E-cadherin were up-regulated in the trigone. • These observations were confirmed by immunofluorescence labelling, showing differences in the amount of SM and in the structure of urothelium of the dome and trigone. CONCLUSIONS • Our mRNA and immunofluorescence data show that cold-cut biopsies from the bladder dome have a higher relative SM content compared with the trigone, reflecting a well-developed network of suburothelial myofibroblasts and muscularis mucosae present in the bladder dome. • An up-regulation of the genes encoding the tight junction proteins in the bladder trigone is independent of the urothelium content, and might imply further discrepancy between these regions.

PURPOSE We examined the possible role of H(+) activated acid sensing ion channels in pain perception. We characterized expression in bladder dome biopsies from patients with bladder pain syndrome and controls in cultured human urothelium and in urothelial TEU 2 cells. MATERIALS AND METHODS Cold cut biopsies from the bladder dome were obtained in 8 asymptomatic controls and 28 patients with bladder pain syndrome symptoms. Acid sensing ion channel expression was analyzed by quantitative real time polymerase chain reaction and immunofluorescence. Channel function was measured by electrophysiology. RESULTS Acid sensing ion channel 1a 2a and 3 mRNA was detected in the human bladder. Similar amounts of acid sensing ion channel 1a and 3 were detected in detrusor smooth muscle while in urothelium acid sensing ion channel 3 levels were higher than levels of acid sensing ion channel 1a. Acid sensing ion channel 2a mRNA levels were lower than acid sensing ion channel 1a and 3 levels in each layer. Acid sensing ion channel currents were measured in TEU 2 cells and in primary cultures of human urothelium. Activated acid sensing ion channel expression was confirmed by quantitative real time polymerase chain reaction. TEU 2 cell differentiation caused acid sensing ion channel 2a and 3 mRNA up regulation and acid sensing ion channel 1a mRNA down regulation. Patients with bladder pain syndrome showed up regulation of acid sensing ion channel 2a and 3 mRNA but acid sensing ion channel 1a remained unchanged. In contrast transient receptor potential vanilloid 1 mRNA was down regulated during bladder pain syndrome. All differences were statistically significant (p

In skeletal muscle of patients with clinically diagnosed statin-associated myopathy, discrete signs of structural damage predominantly localize to the T-tubular region and are suggestive of a calcium leak. The impact of statins on skeletal muscle of non-myopathic patients is not known. We analyzed the expression of selected genes implicated in the molecular regulation of calcium and membrane repair, in lipid homeostasis, myocyte remodeling and mitochondrial function. Microscopic and gene expression analyses were performed using validated TaqMan custom arrays on skeletal muscle biopsies of 72 age-matched subjects who were receiving statin therapy (n = 38), who had discontinued therapy due to statin-associated myopathy (n = 14), and who had never undergone statin treatment (n = 20). In skeletal muscle, obtained from statin-treated, non-myopathic patients, statins caused extensive changes in the expression of genes of the calcium regulatory and the membrane repair machinery, whereas the expression of genes responsible for mitochondrial function or myocyte remodeling was unaffected. Discontinuation of treatment due to myopathic symptoms led to a normalization of gene expression levels, the genes encoding the ryanodine receptor 3, calpain 3, and dystrophin being the most notable exceptions. Hence, even in clinically asymptomatic (non-myopathic) patients, statin therapy leads to an upregulation in the expression of genes that are concerned with skeletal muscle regulation and membrane repair.

Background: Many patients taking statins often complain of muscle pain and weakness. The extent to which muscle pain reflects muscle injury is unknown. Methods: We obtained biopsy samples from the vastus lateralis muscle of 83 patients. Of the 44 patients with clinically diagnosed statin-associated myopathy, 29 were currently taking a statin, and 15 had discontinued statin therapy before the biopsy (minimal duration of discontinuation 3 weeks). We also included 19 patients who were taking statins and had no myopathy, and 20 patients who had never taken statins and had no myopathy. We classified the muscles as injured if 2% or more of the muscle fibres in a biopsy sample showed damage. Using reverse transcriptase polymerase chain reaction, we evaluated the expression levels of candidate genes potentially related to myocyte injury. Results: Muscle injury was observed in 25 (of 44) patients with myopathy and in 1 patient without myopathy. Only 1 patient with structural injury had a circulating level of creatine phosphokinase that was elevated more than 1950 U/L (10× the upper limit of normal). Expression of ryanodine receptor 3 was significantly upregulated in patients with biopsy evidence of structural damage (1.7, standard error of the mean 0.3). Interpretation: Persistent myopathy in patients taking statins reflects structural muscle damage. A lack of elevated levels of circulating creatine phosphokinase does not rule out structural muscle injury. Upregulation of the expression of ryanodine receptor 3 is suggestive of an intracellular calcium leak.

Familial hypertrophic cardiomyopathy (HCM) is the leading cause of sudden cardiac death in the young, and is the most common inherited heart defect affecting 1 in 500 individuals worldwide. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) have been demonstrated to model aspects of HCM, but only one iPSC model has been reported for a single HCM mutation in one gene. Here we compare disease phenotypes across a library of patient-specific HCM iPSC-CMs carrying distinct mutations to assess the range of phenotypes that may present in iPSC-CMs derived from different patient cohorts. iPSCs were generated from three patient cohorts carrying known hereditary mutations for HCM in TNNI3, TNNT2, and MYH7 and family-matched controls. Disease phenotypes in patient-specific iPSC-CMs were modeled using immunostaining, Ca2+ imaging, multielectrode array, and video analysis of contractile motion. HCM iPSC-CMs displayed a range of disease phenotypes as assessed by cell size, Ca2+ homeostasis, electrophysiology, and contractile arrhythmia. Different HCM mutations resulted in distinct disease phenotype presentation. Importantly, identical mutations demonstrated similar readouts across multiple lines and clones whereas distinct mutations exhibited differential disease phenotypes. These findings indicate disease-specific iPSC-CMs present with a range of phenotypes for HCM that vary by specific mutation and that iPSC libraries are important for cellular characterization of diseases such as HCM. Figure 1. Derivation and disease phenotype modeling of iPSC-CMs generated from patients carrying distinct familial HCM mutations and family-matched controls.

We are thankful for the interest and comments of Li and Hong concerning our recent findings demonstrating that exogenous administration of hypoxia-inducible factor-1 (HIF-1) could modulate the ischemic microenvironment, rendering it more favorable for the survival of transplanted stem cells, effects that are partially mediated by exosomal transfer of miR-126 and miR-210.! Indeed, the role of exosomes in cardiovascular diseases and cardiac regeneration is being explored actively, and exosomes have been demonstrated to possess both physiological and pathophysiological effects in this context.2 …

Background— Although single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) has improved the diagnosis and risk stratification of patients with suspected coronary artery disease, it remains a primary source of low-dose radiation exposure for cardiac patients. To determine the biological effects of low-dose radiation from SPECT MPI, we measured the activation of the DNA damage response pathways using quantitative flow cytometry and single-cell gene expression profiling. Methods and Results— Blood samples were collected from patients before and after SPECT MPI (n=63). Overall, analysis of all recruited patients showed no marked differences in the phosphorylation of proteins (H2AX, protein 53, and ataxia telangiectasia mutated) after SPECT. The majority of patients also had either downregulated or unchanged expression in DNA damage response genes at both 24 and 48 hours post-SPECT. Interestingly, a small subset of patients with increased phosphorylation had significant upregulation of genes associated with DNA damage, whereas those with no changes in phosphorylation had significant downregulation or no difference, suggesting that some patients may potentially be more sensitive to low-dose radiation exposure. Conclusions— Our findings showed that SPECT MPI resulted in a variable activation of the DNA damage response pathways. Although only a small subset of patients had increased protein phosphorylation and elevated gene expression postimaging, continued care should be taken to reduce radiation exposure to both the patients and operators.

Background— Despite the promise shown by stem cells for restoration of cardiac function after myocardial infarction, the poor survival of transplanted cells has been a major issue. Hypoxia-inducible factor-1 (HIF1) is a transcription factor that mediates adaptive responses to ischemia. Here, we hypothesize that codelivery of cardiac progenitor cells (CPCs) with a nonviral minicircle plasmid carrying HIF1 (MC-HIF1) into the ischemic myocardium can improve the survival of transplanted CPCs. Methods and Results— After myocardial infarction, CPCs were codelivered intramyocardially into adult NOD/SCID mice with saline, MC-green fluorescent protein, or MC-HIF1 versus MC-HIF1 alone (n=10 per group). Bioluminescence imaging demonstrated better survival when CPCs were codelivered with MC-HIF1. Importantly, echocardiography showed mice injected with CPCs+MC-HIF1 had the highest ejection fraction 6 weeks after myocardial infarction (57.1±2.6%; P =0.002) followed by MC-HIF1 alone (48.5±2.6%; P =0.04), with no significant protection for CPCs+MC-green fluorescent protein (44.8±3.3%; P =NS) when compared with saline control (38.7±3.2%). In vitro mechanistic studies confirmed that cardiac endothelial cells produced exosomes that were actively internalized by recipient CPCs. Exosomes purified from endothelial cells overexpressing HIF1 had higher contents of miR-126 and miR-210. These microRNAs activated prosurvival kinases and induced a glycolytic switch in recipient CPCs, giving them increased tolerance when subjected to in vitro hypoxic stress. Inhibiting both of these miRs blocked the protective effects of the exosomes. Conclusions— In summary, HIF1 can be used to modulate the host microenvironment for improving survival of transplanted cells. The exosomal transfer of miRs from host cells to transplanted cells represents a unique mechanism that can be potentially targeted for improving survival of transplanted cells.

The exact nature of the immune response elicited by autologous induced pluripotent stem cell (iPSC) progeny is still not well understood. Here we show in murine models that autologous iPSC-derived endothelial cells (iECs) elicit an immune response that resembles the one against a comparable somatic cell, the aortic endothelial cell (AEC). These cells exhibit long-term survival in vivo and prompt a tolerogenic contexture of intra-graft characterized by elevated IL-10 expression. In contrast, undifferentiated iPSCs elicit a very different immune response with high lymphocytic infiltration and elevated IFN-γ, granzyme-B, and perforin intra-graft. Furthermore, the clonal structure of infiltrating T cells from iEC grafts is statistically indistinguishable from that of AECs, but is different from that of undifferentiated iPSC grafts. Taken together, our results indicate that the differentiation of iPSCs results in a loss of immunogenicity and leads to the induction of tolerance, despite expected antigen expression differences between iPSC-derived versus original somatic cells.

Rationale: Human embryonic stem cell (hESC) derivatives are attractive candidates for therapeutic use. The engraftment and survival of hESC derivatives as xenografts or allografts require effective immunosuppression to prevent immune cell infiltration and graft destruction. Objective: To test the hypothesis that a short-course, dual-agent regimen of two costimulation-adhesion blockade agents can induce better engraftment of hESC derivatives compared to current immunosuppressive agents. Methods and Results: We transduced hESCs with a double fusion reporter gene construct expressing firefly luciferase (Fluc) and enhanced green fluorescent protein, and differentiated these cells to endothelial cells (hESC-ECs). Reporter gene expression enabled longitudinal assessment of cell engraftment by bioluminescence imaging. Costimulation-adhesion therapy resulted in superior hESC-EC and mouse EC engraftment compared to cyclosporine therapy in a hind limb model. Costimulation-adhesion therapy also promoted robust hESC-EC and hESC-derived cardiomyocyte survival in an ischemic myocardial injury model. Improved hESC-EC engraftment had a cardioprotective effect after myocardial injury, as assessed by magnetic resonance imaging. Mechanistically, costimulation-adhesion therapy is associated with systemic and intragraft upregulation of T-cell immunoglobulin and mucin domain 3 (TIM3) and a reduced proinflammatory cytokine profile. Conclusions: Costimulation-adhesion therapy is a superior alternative to current clinical immunosuppressive strategies for preventing the post-transplant rejection of hESC derivatives. By extending the window for cellular engraftment, costimulation-adhesion therapy enhances functional preservation following ischemic injury. This regimen may function through a TIM3-dependent mechanism.

Background— Drug-induced arrhythmia is one of the most common causes of drug development failure and withdrawal from market. This study tested whether human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) combined with a low-impedance microelectrode array (MEA) system could improve on industry-standard preclinical cardiotoxicity screening methods, identify the effects of well-characterized drugs, and elucidate underlying risk factors for drug-induced arrhythmia. hiPSC-CMs may be advantageous over immortalized cell lines because they possess similar functional characteristics as primary human cardiomyocytes and can be generated in unlimited quantities. Methods and Results— Pharmacological responses of beating embryoid bodies exposed to a comprehensive panel of drugs at 65 to 95 days postinduction were determined. Responses of hiPSC-CMs to drugs were qualitatively and quantitatively consistent with the reported drug effects in literature. Torsadogenic hERG blockers, such as sotalol and quinidine, produced statistically and physiologically significant effects, consistent with patch-clamp studies, on human embryonic stem cell–derived cardiomyocytes hESC-CMs. False-negative and false-positive hERG blockers were identified accurately. Consistent with published studies using animal models, early afterdepolarizations and ectopic beats were observed in 33% and 40% of embryoid bodies treated with sotalol and quinidine, respectively, compared with negligible early afterdepolarizations and ectopic beats in untreated controls. Conclusions— We found that drug-induced arrhythmias can be recapitulated in hiPSC-CMs and documented with low impedance MEA. Our data indicate that the MEA/hiPSC-CM assay is a sensitive, robust, and efficient platform for testing drug effectiveness and for arrhythmia screening. This system may hold great potential for reducing drug development costs and may provide significant advantages over current industry standard assays that use immortalized cell lines or animal models.

Characterized by ventricular dilatation, systolic dysfunction, and progressive heart failure, dilated cardiomyopathy (DCM) is the most common form of cardiomyopathy in patients. DCM is the most common diagnosis leading to heart transplantation and places a significant burden on healthcare worldwide. The advent of induced pluripotent stem cells (iPSCs) offers an exceptional opportunity for creating disease-specific cellular models, investigating underlying mechanisms, and optimizing therapy. Here, we generated cardiomyocytes from iPSCs derived from patients in a DCM family carrying a point mutation (R173W) in the gene encoding sarcomeric protein cardiac troponin T. Compared to control healthy individuals in the same family cohort, cardiomyocytes derived from iPSCs from DCM patients exhibited altered regulation of calcium ion (Ca(2+)), decreased contractility, and abnormal distribution of sarcomeric α-actinin. When stimulated with a β-adrenergic agonist, DCM iPSC-derived cardiomyocytes showed characteristics of cellular stress such as reduced beating rates, compromised contraction, and a greater number of cells with abnormal sarcomeric α-actinin distribution. Treatment with β-adrenergic blockers or overexpression of sarcoplasmic reticulum Ca(2+) adenosine triphosphatase (Serca2a) improved the function of iPSC-derived cardiomyocytes from DCM patients. Thus, iPSC-derived cardiomyocytes from DCM patients recapitulate to some extent the morphological and functional phenotypes of DCM and may serve as a useful platform for exploring disease mechanisms and for drug screening.

Single-cell quantitative real-time PCR (qRT-PCR) combined with high-throughput arrays allows the analysis of gene expression profiles at a molecular level in approximately 11 h after cell sample collection. We present here a high-content microfluidic real-time platform as a powerful tool for comparatively investigating the regulation of developmental processes in single cells. This approach overcomes the limitations involving heterogeneous cell populations and sample amounts, and may shed light on differential regulation of gene expression in normal versus disease-related contexts. Furthermore, high-throughput single-cell qRT-PCR provides a standardized, comparative assay for in-depth analysis of the mechanisms underlying human pluripotent stem cell self-renewal and differentiation.

Human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) are promising candidate cell sources for regenerative medicine. However, despite the common ability of hiPSCs and hESCs to differentiate into all 3 germ layers, their functional equivalence at the single cell level remains to be demonstrated. Moreover, single cell heterogeneity amongst stem cell populations may underlie important cell fate decisions. Here, we used single cell analysis to resolve the gene expression profiles of 362 hiPSCs and hESCs for an array of 42 genes that characterize the pluripotent and differentiated states. Comparison between single hESCs and single hiPSCs revealed markedly more heterogeneity in gene expression levels in the hiPSCs, suggesting that hiPSCs occupy an alternate, less stable pluripotent state. hiPSCs also displayed slower growth kinetics and impaired directed differentiation as compared with hESCs. Our results suggest that caution should be exercised before assuming that hiPSCs occupy a pluripotent state equivalent to that of hESCs, particularly when producing differentiated cells for regenerative medicine aims.

Bladder pain syndrome (BPS) is a clinical syndrome of pelvic pain and urinary urgency-frequency in the absence of a specific cause. Investigating the expression levels of genes involved in the regulation of epithelial permeability, bladder contractility, and inflammation, we show that neurokinin (NK)1 and NK2 tachykinin receptors were significantly down-regulated in BPS patients. Tight junction proteins zona occludens-1, junctional adherins molecule -1, and occludin were similarly down-regulated, implicating increased urothelial permeability, whereas bradykinin B(1) receptor, cannabinoid receptor CB1 and muscarinic receptors M3-M5 were up-regulated. Using cell-based models, we show that prolonged exposure of NK1R to substance P caused a decrease of NK1R mRNA levels and a concomitant increase of regulatory micro(mi)RNAs miR-449b and miR-500. In the biopsies of BPS patients, the same miRNAs were significantly increased, suggesting that BPS promotes an attenuation of NK1R synthesis via activation of specific miRNAs. We confirm this hypothesis by identifying 31 differentially expressed miRNAs in BPS patients and demonstrate a direct correlation between miR-449b, miR-500, miR-328, and miR-320 and a down-regulation of NK1R mRNA and/or protein levels. Our findings further the knowledge of the molecular mechanisms of BPS, and have relevance for other clinical conditions involving the NK1 receptor.

A major concern about using cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) for human disease modeling is their "immature" phenotype which may result in substantial differences in their physiology when compared to native cardiomyocytes. Here we compare intracellular Ca buffering of hiPSC-CM derived from healthy humans to that of acutely-isolated adult rabbit ventricular CM. hiPSC-CM (21 days post cardiac induction) were plated at low density on matrigel-coated dishes and studied 3-5 days after plating. While hiPSC were significantly smaller than rabbit CM (cell capacity 19±2 pF vs 101±12 pF, p

Cardiomyocytes derived from human induced pluripotent stem cells (hIPS-CM) are useful to understand basic structural and functional characteristics of normal and diseased human heart cells. We investigated mechanical properties of hIPS-CM derived from unaffected and affected members of a family harboring a dilated cardiomyopathy (DCM) mutation in cardiac troponin T (cTnT), the tropomyosin binding unit of troponin. Patients with a cTnT point mutation (R173W) develop DCM, which commonly leads to diastolic and systolic dysfunction and progressive heart failure. To study the shortening and shortening velocity of normal and cTnT mutant hIPS-CM cells, cells were plated on substrates with a relatively soft stiffness (160 kPa) molded from polydimethylsiloxane and measured using a line scan method. Data were collected using a Zeiss 710 confocal microscope. Visual observation of cells after 5 days maturity on the PDMS substrates indicate a smaller percent of mutant (8%) compared to normal (87%) hIPS-CM were spontaneously beating. Immunohistochemistry showed that myofibril structure was better developed in normal compared to cTnT mutation cells. Day 5 line scans revealed normal hIPS-CM cells shorten more (0.47 μm) than mutant cTnT cells (0.32 μm); shortening velocity was faster in normal (1.42 μm/s) compared to mutant cTnT cells (0.67 μm/s). Acute treatment (1 dose with a 10 min activation dwell time) with omecamtiv mecarbil (200nM), a cardiac myosin activator, increased the shortening and shortening velocity of normal (0.78 μm at 1.85 μm/s) but not cTnT mutant (0.32 μm at 0.70 μm/s) hIPS-CM cells. Although more studies are necessary, these results suggest that cTnT may affect development of sarcomeres and the regulation of contractility. Furthermore, the myosin activator omecamtiv mecarbil may not be sufficient to rescue dysfunction in the cTnT mutation R173W. [Funding: NIH T32HL07692, PO1HL62426]