Efficient differentiation of cardiomyocytes and generation of calcium-sensor reporter lines from nonhuman primate iPSCs

Long-term engraftment and maturation of autologous iPSC-derived cardiomyocytes in two rhesus macaques

Cellular therapies with cardiomyocytes produced from induced pluripotent stem cells (iPSC-CMs) offer a potential route to cardiac regeneration as a treatment for chronic ischemic heart disease. Here, we report successful long-term engraftment and in vivo maturation of autologous iPSC-CMs in two rhesus macaques with small, subclinical chronic myocardial infarctions, all without immunosuppression. Longitudinal positron emission tomography imaging using the sodium/iodide symporter (NIS) reporter gene revealed stable grafts for over 6 and 12 months, with no teratoma formation. Histological analyses suggested capability of the transplanted iPSC-CMs to mature and integrate with endogenous myocardium, with no sign of immune cell infiltration or rejection. By contrast, allogeneic iPSC-CMs were rejected within 8 weeks of transplantation. This study provides the longest-term safety and maturation data to date in any large animal model, addresses concerns regarding neoantigen immunoreactivity of autologous iPSC therapies, and suggests that autologous iPSC-CMs would similarly engraft and mature in human hearts.

Chemical Hypoxic Preconditioning Improves Survival and Proliferation of Mesenchymal Stem Cells

Increasing evidence has demonstrated that mesenchymal stem cells (MSCs) have been linked to tissue regeneration both in vitro and in vivo. However, poor engraftment and low survival rate of transplanted MSCs are still a major concern. It has been found that the proliferation, survival, and migration of MSCs are all increased by hypoxic preconditioning. However, the molecular mechanism through which hypoxic preconditioning enhances these beneficial properties of MSCs remains to be fully investigated. Therefore, the present study is aimed to investigate the mechanism by which hypoxic preconditioning enhances the survival of MSCs. We used proteomic analysis to explore the molecules that may contribute to the survival and proliferation of hypoxic preconditioned (HP) MSCs. The analysis revealed a higher expression of prelamin A/C (Lmna), glutamate dehydrogenase 1(Glud1), Actin, cytoplasmic 1(Actb), Alpha-enolase (Eno1), Glucose-6-phosphate 1-dehydrogenase (G6pd), Protein disulfide-isomerase A3 (Pdia3), Malate dehydrogenase (Mdh1), Peroxiredoxin-6 (Prdx6), Superoxide dismutase (Sod1), and Annexin A2 (Anxa2) in HP-MSCs. These proteins are possibly involved in cellular survival and proliferation through various cellular pathways. This research could aid in understanding the processes involved in hypoxic preconditioning of MSCs and designing of cell-based therapeutic strategies for tissue regeneration.

Cardiac differentiation of chimpanzee induced pluripotent stem cell lines with different subspecies backgrounds

The comparative analysis between humans and non-human primates is an instrumental approach for elucidating the evolutional traits and disease propensity of humans. However, in primates, cross-species analyses of their developmental events have encountered constraints because of the ethical and technical limitations in available sample collection, sequential monitoring, and manipulations. In an endeavor to surmount these challenges, in recent years, induced pluripotent stem cells (iPSCs) have garnered escalating interest as an in vitro tool for cross-species analyses between humans and non-human primates. Meanwhile, compared to humans, there is less information on in vitro differentiation of non-human primate iPSCs, and their genetic diversity including subspecies may cause different eligibility to in vitro differentiation methods. Therefore, antecedent to embarking on a comparative analysis to humans, it is a prerequisite to develop the efficacious methodologies for in vitro differentiation regardless of the intraspecies genetic background in non-human primates. In this study, we executed the in vitro differentiation of cardiomyocytes from four chimpanzee iPSC lines with different subspecies and individual backgrounds. To induce cardiomyocytes from chimpanzee iPSCs, we evaluated our methodology for in vitro cardiac differentiation of human iPSCs. Eventually, with minor alterations, our cardiac differentiation method was applicable to all chimpanzee iPSC lines tested as assessed by the expression of cardiac marker genes and the beating ability. Hence, our in vitro differentiation method will advance iPSC-based research of chimpanzee cardiac development and also hold possible utility to cross-species analyses among primate species.

Integration-free induced pluripotent stem cells from three endangered Southeast Asian non-human primate species

Advanced molecular and cellular technologies provide promising tools for wildlife and biodiversity conservation. Induced pluripotent stem cell (iPSC) technology offers an easily accessible and infinite source of pluripotent stem cells, and have been derived from many threatened wildlife species. This paper describes the first successful integration-free reprogramming of adult somatic cells to iPSCs, and their differentiation, from three endangered Southeast Asian primates: the Celebes Crested Macaque (Macaca nigra), the Lar Gibbon (Hylobates lar), and the Siamang (Symphalangus syndactylus). iPSCs were also generated from the Proboscis Monkey (Nasalis larvatus). Differences in mechanisms could elicit new discoveries regarding primate evolution and development. iPSCs from endangered species provides a safety net in conservation efforts and allows for sustainable sampling for research and conservation, all while providing a platform for the development of further in vitro models of disease.

iPSC-Derived Glioblastoma Cells Have Enhanced Stemness Wnt/β-Catenin Activity Which Is Negatively Regulated by Wnt Antagonist sFRP4

Growing evidence indicates that cancer stem cells (CSCs) endow the tumor with stem-like properties. Recently, induced pluripotent stem cells (iPSCs) have gained increased attention because of their easy derivation and availability and their potential to differentiate into any cell type. A CSC model derived from iPSCs of human origin would help understand the driving force of tumor initiation and early progression. We report the efficient generation of feeder-free SSEA4, TRA-1-60 and TRA-1-81 positive iPSCs from amniotic membrane-derived mesenchymal stem cells (AMMSCs), which successfully differentiated into three germ layers. We then developed human iPSC-derived glioblastoma multiforme (GBM) model using conditioned media (CM) from U87MG cell line and CSCs derived from U87MG, which confer iPSCs with GBM and GSC-like phenotypes within five days. Both cell types overexpress MGMT and GLI2, but only GSCs overexpress CD133, CD44, ABCG2 and ABCC2. We also observed overexpression of LEF1 and β-catenin in both cell types. Down-regulation of Wnt antagonist secreted frizzled-related protein 4 (sFRP4) in GBM and GSCs, indicating activation of the Wnt/β-catenin pathway, which could be involved in the conversion of iPSCs to CSCs. From future perspectives, our study will help in the creation of a rapid cell-based platform for understanding the complexity of GBM.

Sympathetic Neurons Regulate Cardiomyocyte Maturation in Culture

Embryos devoid of autonomic innervation suffer sudden cardiac death. However, whether autonomic neurons have a role in heart development is poorly understood. To investigate if sympathetic neurons impact cardiomyocyte maturation, we co-cultured phenotypically immature cardiomyocytes derived from human induced pluripotent stem cells with mouse sympathetic ganglion neurons. We found that 1) multiple cardiac structure and ion channel genes related to cardiomyocyte maturation were up-regulated when co-cultured with sympathetic neurons; 2) sarcomere organization and connexin-43 gap junctions increased; 3) calcium imaging showed greater transient amplitudes. However, sarcomere spacing, relaxation time, and level of sarcoplasmic reticulum calcium did not show matured phenotypes. We further found that addition of endothelial and epicardial support cells did not enhance maturation to a greater extent beyond sympathetic neurons, while administration of isoproterenol alone was insufficient to induce changes in gene expression. These results demonstrate that sympathetic neurons have a significant and complex role in regulating cardiomyocyte development.

Retinal organoids derived from rhesus macaque iPSCs undergo accelerated differentiation compared to human stem cells

Purpose

To compare the timing and efficiency of the development of Macaca mulatta, a nonhuman primate (NHP), induced pluripotent stem cell (rhiPSC) derived retinal organoids to those derived from human embryonic stem cells (hESCs).

Results

Generation of retinal organoids was achieved from both human and several NHP pluripotent stem cell lines. All rhiPSC lines resulted in retinal differentiation with the formation of optic vesicle‐like structures similar to what has been observed in hESC retinal organoids. NHP retinal organoids had laminated structure and were composed of mature retinal cell types including cone and rod photoreceptors. Single‐cell RNA sequencing was conducted at two time points; this allowed identification of cell types and developmental trajectory characterization of the developing organoids. Important differences between rhesus and human cells were measured regarding the timing and efficiency of retinal organoid differentiation. While the culture of NHP‐derived iPSCs is relatively difficult compared to that of human stem cells, the generation of retinal organoids from NHP iPSCs is feasible and may be less time‐consuming due to an intrinsically faster timing of retinal differentiation.

Conclusions

Retinal organoids produced from rhesus monkey iPSCs using established protocols differentiate through the stages of organoid development faster than those derived from human stem cells. The production of NHP retinal organoids may be advantageous to reduce experimental time for basic biology studies in retinogenesis as well as for preclinical trials in NHPs studying retinal allograft transplantation.

Generation of macrophages with altered viral sensitivity from genome-edited rhesus macaque iPSCs to model human disease

Because of their close biological similarity to humans, non-human primate (NHP) models are very useful for the development of induced pluripotent stem cell (iPSC)-based cell and regenerative organ transplantation therapies. However, knowledge on the establishment, differentiation, and genetic modification of NHP-iPSCs, especially rhesus macaque iPSCs, is limited. We succeeded in establishing iPSCs from the peripheral blood of rhesus macaques (Rh-iPSCs) by combining the Yamanaka reprograming factors and two inhibitors (GSK-3 inhibitor [CHIR 99021] and MEK1/2 inhibitor [PD0325901]) and differentiated the cells into functional macrophages through hematopoietic progenitor cells. To confirm feasibility of the Rh-iPSC-derived macrophages as a platform for bioassays to model diseases, we knocked out TRIM5 gene in Rh-iPSCs by CRISPR-Cas9, which is a species-specific HIV resistance factor. TRIM5 knockout (KO) iPSCs had the same differentiation potential to macrophages as did Rh-iPSCs, but the differentiated macrophages showed a gain of sensitivity to HIV infection in vitro. Our reprogramming, gene editing, and differentiation protocols used to obtain Rh-iPSC-derived macrophages can be applied to other gene mutations, expanding the number of NHP gene therapy models.

Sepsis and the evolution of human increased sensitivity to lipopolysaccharide

Among mammals, humans are exquisitely sensitive to lipopolysaccharide (LPS), an environmentally pervasive bacterial cell membrane component. Very small doses of LPS trigger powerful immune responses in humans and can even initiate symptoms of sepsis. Close evolutionary relatives such as African and Asian monkeys require doses that are an order of magnitude higher to do the same. Why humans have evolved such an energetically expensive antimicrobial strategy is a question that biological anthropologists are positioned to help address. Here we compare LPS sensitivity in primate/mammalian models and propose that human high sensitivity to LPS is adaptive, linked to multiple immune tactics against pathogens, and part of multi-faceted anti-microbial strategy that strongly overlaps with that of other mammals. We support a notion that LPS sensitivity in humans has been driven by microorganisms that constitutively live on us, and has been informed by human behavioral changes over our species' evolution (e.g., meat eating, agricultural practices, and smoking).

Engineering and Assessing Cardiac Tissue Complexity

Cardiac tissue engineering is very much in a current focus of regenerative medicine research as it represents a promising strategy for cardiac disease modelling, cardiotoxicity testing and cardiovascular repair. Advances in this field over the last two decades have enabled the generation of human engineered cardiac tissue constructs with progressively increased functional capabilities. However, reproducing tissue-like properties is still a pending issue, as constructs generated to date remain immature relative to native adult heart. Moreover, there is a high degree of heterogeneity in the methodologies used to assess the functionality and cardiac maturation state of engineered cardiac tissue constructs, which further complicates the comparison of constructs generated in different ways. Here, we present an overview of the general approaches developed to generate functional cardiac tissues, discussing the different cell sources, biomaterials, and types of engineering strategies utilized to date. Moreover, we discuss the main functional assays used to evaluate the cardiac maturation state of the constructs, both at the cellular and the tissue levels. We trust that researchers interested in developing engineered cardiac tissue constructs will find the information reviewed here useful. Furthermore, we believe that providing a unified framework for comparison will further the development of human engineered cardiac tissue constructs displaying the specific properties best suited for each particular application.

Fluorescent PSC-Derived Cardiomyocyte Reporter Lines: Generation Approaches and Their Applications in Cardiovascular Medicine

Recent advances have made pluripotent stem cell (PSC)-derived cardiomyocytes an attractive option to model both normal and diseased cardiac function at the single-cell level. However, in vitro differentiation yields heterogeneous populations of cardiomyocytes and other cell types, potentially confounding phenotypic analyses. Fluorescent PSC-derived cardiomyocyte reporter systems allow specific cell lineages to be labelled, facilitating cell isolation for downstream applications including drug testing, disease modelling and cardiac regeneration. In this review, the different genetic strategies used to generate such reporter lines are presented with an emphasis on their relative technical advantages and disadvantages. Next, we explore how the fluorescent reporter lines have provided insights into cardiac development and cardiomyocyte physiology. Finally, we discuss how exciting new approaches using PSC-derived cardiomyocyte reporter lines are contributing to progress in cardiac cell therapy with respect to both graft adaptation and clinical safety.

CRISPR/Cas9-mediated introduction of the sodium/iodide symporter gene enables noninvasive in vivo tracking of induced pluripotent stem cell-derived cardiomyocytes

Techniques that enable longitudinal tracking of cell fate after myocardial delivery are imperative for optimizing the efficacy of cell‐based cardiac therapies. However, these approaches have been underutilized in preclinical models and clinical trials, and there is considerable demand for site‐specific strategies achieving long‐term expression of reporter genes compatible with safe noninvasive imaging. In this study, the rhesus sodium/iodide symporter (NIS) gene was incorporated into rhesus macaque induced pluripotent stem cells (RhiPSCs) via CRISPR/Cas9. Cardiomyocytes derived from NIS‐RhiPSCs (NIS‐RhiPSC‐CMs) exhibited overall similar morphological and electrophysiological characteristics compared to parental control RhiPSC‐CMs at baseline and with exposure to physiological levels of sodium iodide. Mice were injected intramyocardially with 2 million NIS‐RhiPSC‐CMs immediately following myocardial infarction, and serial positron emission tomography/computed tomography was performed with ¹⁸F‐tetrafluoroborate to monitor transplanted cells in vivo. NIS‐RhiPSC‐CMs could be detected until study conclusion at 8 to 10 weeks postinjection. This NIS‐based molecular imaging platform, with optimal safety and sensitivity characteristics, is primed for translation into large‐animal preclinical models and clinical trials.

Fluorescence-based actin turnover dynamics of stem cells as a profiling method for stem cell functional evolution, heterogeneity and phenotypic lineage parsing

Stem cells are widely explored in regenerative medicine as a source to produce diverse cell types. Despite the wide usage of stem cells like mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs), there is a lack of robust methods to rapidly discern the phenotypic and functional heterogeneity of stem cells. The organization of actin cytoskeleton has been previously used to discern divergent stem cell differentiation pathways. In this paper, we highlight the versatility of a cell profiling method for actin turnover dynamics. Actin filaments in live stem cells are labeled using SiR-actin, a cell permeable fluorogenic probe, to determine the endogenous actin turnover. Live MSC imaging after days of induction successfully demonstrated lineage specific change in actin turnover. Next, we highlighted the differences in the cellular heterogeneity of actin dynamics during adipogenic or osteogenic MSC differentiation. Next, we applied the method to differentiating iPSCs in culture, and detected a progressive slowdown in actin turnover during differentiation upon stimulation with neural or cardiac media. Finally, as a proof of concept, the actin dynamic profiling was used to isolate MSCs via flow cytometry prior to sorting into three distinct sub-populations with low, intermediate or high actin dynamics. A greater fraction of MSCs with more rapid actin dynamics demonstrated increased inclination for adipogenesis, whereas, slower actin dynamics correlated with increased osteogenesis. Together, these results show that actin turnover can serve as a versatile biomarker to not only track cellular phenotypic heterogeneity but also harvest live cells with potential for differential phenotypic fates.

A Guide to Understanding "State-of-the-Art" Basic Research Techniques in Anesthesiology

Perioperative medicine is changing from a "protocol-based" approach to a progressively personalized care model. New molecular techniques and comprehensive perioperative medical records allow for detection of patient-specific phenotypes that may better explain, or even predict, a patient's response to perioperative stress and anesthetic care. Basic science technology has significantly evolved in recent years with the advent of powerful approaches that have translational relevance. It is incumbent on us as a primarily clinical specialty to have an in-depth understanding of rapidly evolving underlying basic science techniques to incorporate such approaches into our own research, critically interpret the literature, and improve future anesthesia patient care. This review focuses on 3 important and most likely practice-changing basic science techniques: next-generation sequencing (NGS), clustered regularly interspaced short palindromic repeat (CRISPR) modulations, and inducible pluripotent stem cells (iPSCs). Each technique will be described, potential advantages and limitations discussed, open questions and challenges addressed, and future developments outlined. We hope to provide insight for practicing physicians when confronted with basic science articles and encourage investigators to apply "state-of-the-art" technology to their future experiments.

Gene therapy for cardiovascular diseases in China: basic research

Cardiovascular disease has become a major disease affecting health in the whole world. Gene therapy, delivering foreign normal genes into target cells to repair damages caused by defects and abnormal genes, shows broad prospects in treating different kinds of cardiovascular diseases. China has achieved great progress of basic gene therapy researches and pathogenesis of cardiovascular diseases in recent years. This review will summarize the latest research about gene therapy of proteins, epigenetics, including noncoding RNAs and genome-editing technology in myocardial infarction, cardiac ischemia-reperfusion injury, atherosclerosis, muscle atrophy, and so on in China. We wish to highlight some important findings about the essential roles of basic gene therapy in this field, which might be helpful for searching potential therapeutic targets for cardiovascular disease.

Metabolic changes in human brain evolution

Because the human brain is considerably larger than those of other primates, it is not surprising that its energy requirements would far exceed that of any of the species within the order. Recently, the development of stem cell technologies and single-cell transcriptomics provides novel ways to address the question of what specific genomic changes underlie the human brain's unique phenotype. In this review, we consider what is currently known about human brain metabolism using a variety of methods from brain imaging and stereology to transcriptomics. Next, we examine novel opportunities that stem cell technologies and single-cell transcriptomics provide to further our knowledge of human brain energetics. These new experimental approaches provide the ability to elucidate the functional effects of changes in genetic sequence and expression levels that potentially had a profound impact on the evolution of the human brain.

Intracellular toxic advanced glycation end-products in cardiomyocytes may cause cardiovascular disease

Cardiovascular disease (CVD) is a lifestyle-related disease (LSRD) and one of the largest public health issues. Risk factors for CVD correlate with an excessive intake of glucose and/or fructose, which has been shown to induce the production of advanced glycation end-products (AGEs). We previously identified AGEs derived from glyceraldehyde and named them toxic AGEs (TAGE) due to their cytotoxicities and relationship with LSRD. We also reported that extracellular TAGE in the vascular system may promote CVD and that serum TAGE levels are associated with risk factors for CVD. The mechanisms responsible for the onset and/or progression of CVD by extracellular TAGE or the above risk factors involve vascular disorders. In the present study, we revealed that rat primary cultured cardiomyocytes generated intracellular TAGE, which decreased beating rates and induced cell death. LC3-II/LC3-I, a factor of autophagy, also decreased. Although intracellular TAGE may be targets of degradation as cytotoxic proteins via autophagy, they may inhibit autophagy. Furthermore, the mechanisms by which intracellular TAGE decrease beating rates and induce cell death may involve the suppression of autophagy. The present results suggest that intracellular TAGE are generated in cardiomyocytes and directly damage them, resulting in CVD.

Combining Optical Approaches with Human Inducible Pluripotent Stem Cells in G Protein-Coupled Receptor Drug Screening and Development

Drug discovery for G protein-coupled receptors (GPCRs) stands at an interesting juncture. Screening programs are slowly moving away from model heterologous cell systems such as human embryonic kidney (HEK) 293 cells to more relevant cellular, tissue and whole animal platforms. Investigators are now developing analytical approaches as means to undertake different aspects of drug discovery by scaling into increasingly more relevant models all the way down to the single cell level. Such approaches include cellular, tissue slice and whole animal models where biosensors that track signaling events and receptor conformational profiles can be used. Here, we review aspects of biosensor-based imaging approaches that might be used in inducible pluripotent stem cell (iPSC) and organoid models, and focus on how such models must be characterized in order to apply them in drug screening.