Generation of induced pluripotent stem cells from adult rhesus monkey fibroblasts

Generation and characterization of giant panda induced pluripotent stem cells

The giant panda (Ailuropoda melanoleuca) stands as a flagship and umbrella species, symbolizing global biodiversity. While traditional assisted reproductive technology faces constraints in safeguarding the genetic diversity of giant pandas, induced pluripotent stem cells (iPSCs) known for their capacity to differentiate into diverse cells types, including germ cells, present a transformative potential for conservation of endangered animals. In this study, primary fibroblast cells were isolated from the giant panda, and giant panda iPSCs (GPiPSCs) were generated using a non-integrating episomal vector reprogramming method. Characterization of these GPiPSCs revealed their state of primed pluripotency and demonstrated their potential for differentiation. Furthermore, we innovatively formulated a species-specific chemically defined FACL medium and unraveled the intricate signaling pathway networks responsible for maintaining the pluripotency and fostering cell proliferation of GPiPSCs. This study provides key insights into rare species iPSCs, offering materials for panda characteristics research and laying the groundwork for in vitro giant panda gamete generation, potentially aiding endangered species conservation.

CHIR99021 and Brdu Are Critical in Chicken iPSC Reprogramming via Small-Molecule Screening

Background/Objectives: Induced pluripotent stem cells (iPSCs) reprogrammed from somatic cells into cells with most of the ESC (embryonic stem cell) characteristics show promise toward solving ethical problems currently facing stem cell research and eventually yield clinical grade pluripotent stem cells for therapies and regenerative medicine. In recent years, an increasing body of research suggests that the chemical induction of pluripotency (CIP) method can yield iPSCs in vitro, yet its application in avian species remains unreported. Methods: Herein, we successfully obtained stably growing chicken embryonic fibroblasts (CEFs) using the tissue block adherence method and employed 12 small-molecule compounds to induce chicken iPSC formation. Results: The final optimized iPSC induction system was bFGF (10 ng/mL), CHIR99021 (3 μM), RepSox (5 μM), DZNep (0.05 μM), BrdU (10 μM), BMP4 (10 ng/mL), vitamin C (50 μg/mL), EPZ-5676 (5 μM), and VPA (0.1 mM). Optimization of the induction system revealed that the highest number of clones was induced with 8 × 104 cells per well and at 1.5 times the original concentration. Upon characterization, these clones exhibited iPSC characteristics, leading to the development of a stable compound combination for iPSC generation in chickens. Concurrently, employing a deletion strategy to investigate the functionality of small-molecule compounds during induction, we identified CHIR99021 and BrdU as critical factors for inducing chicken iPSC formation. Conclusions: In conclusion, this study provides a reference method for utilizing small-molecule combinations in avian species to reprogram cells and establish a network of cell fate determination mechanisms.

Role of small molecules as drug candidates for reprogramming somatic cells into induced pluripotent stem cells: A comprehensive review

With the use of specific genetic factors and recent developments in cellular reprogramming, it is now possible to generate lineage-committed cells or induced pluripotent stem cells (iPSCs) from readily available and common somatic cell types. However, there are still significant doubts regarding the safety and effectiveness of the current genetic methods for reprogramming cells, as well as the conventional culture methods for maintaining stem cells. Small molecules that target specific epigenetic processes, signaling pathways, and other cellular processes can be used as a complementary approach to manipulate cell fate to achieve a desired objective. It has been discovered that a growing number of small molecules can support lineage differentiation, maintain stem cell self-renewal potential, and facilitate reprogramming by either increasing the efficiency of reprogramming or acting as a genetic reprogramming factor substitute. However, ongoing challenges include improving reprogramming efficiency, ensuring the safety of small molecules, and addressing issues with incomplete epigenetic resetting. Small molecule iPSCs have significant clinical applications in regenerative medicine and personalized therapies. This review emphasizes the versatility and potential safety benefits of small molecules in overcoming challenges associated with the iPSCs reprogramming process.

Cell-cell communication in stem cells and cancer: Alone but in touch

BACKGROUND

Cellular communication and signaling pathways are fundamental regulators of stem cell and cancer cell behaviors. This review explores the intricate interplay of these pathways in governing cellular behaviors, focusing on their implications for diseases, particularly cancer.

OBJECTIVES

This comprehensive review aims to elucidate the significance of cellular signaling pathways in regulating the behavior of stem cells and cancer cells. It delves into the alterations in these pathways, their impact on cell fate, and their implications for developing diseases, notably cancer. The objective is to underscore the importance of understanding these signaling pathways for developing targeted therapeutic strategies.

METHODS

The review critically analyzes existing literature and research findings concerning the roles of signaling pathways in stem cell behavior regulation, emphasizing their parallels and disparities in cancer cells. It synthesizes information on both direct and indirect modes of cell communication to delineate the complexity of signaling networks.

RESULTS

Direct and indirect modes of cell communication intricately regulate the complex signaling pathways governing stem cell behaviors, influencing differentiation potential and tissue regeneration. Alterations in these pathways significantly impact stem cell fate, contributing to disease pathogenesis, including cancer. Understanding these signaling cascades offers insights into developing targeted therapies, particularly cancer treatment.

CONCLUSION

Understanding the regulation of signaling pathways in stem cells and the specialized subset of cancer stem cells holds promise for innovative therapeutic approaches. By targeting aberrant signaling pathways, tailored interventions may improve treatment outcomes. This review underscores the critical role of signaling pathways in cellular behaviors, offering a pathway toward developing novel, more effective therapies for diverse diseases and disorders.

Development of rhesus macaque astrocyte cell lines supporting infection with a panel of viruses

Non-human primate (NHP)-based model systems are highly relevant for biomedical research. However, only few NHP cell lines are available and the generation of additional cell lines is an urgent need to help in the refinement and replacement of these models. Using lentiviral transduction of c-Fos, we established cell lines from the brain of rhesus macaques (Macaca mulatta). Transcriptome analysis revealed that these cell lines are closely related to astrocytes, which was confirmed by immunoblot and immunofluorescence microscopy detecting expression of the astrocyte marker glial fibrillary acidic protein (GFAP). Quantitative real-time PCR (qRT-PCR) demonstrated that major pathways of the interferon (IFN) system are intact. Using retroviral pseudotypes we found that the cell lines are susceptible to entry driven by the glycoproteins of vesicular stomatitis virus (VSV), lymphocytic choriomeningitis virus (LCMV) and to a lesser extent influenza A virus (IAV). Finally, these cells supported growth of Zika virus (ZIKV) and Papiine alphaherpesvirus 2 (PaHV2). In summary, we developed IFN-responsive cell lines from the rhesus macaque brain that allowed entry driven by several viral glycoproteins and were permissive to infection with ZIKV and a primate simplexvirus. These cell lines will be useful for efforts to analyze neurotropic viral infections in rhesus macaque models.

Long-term in vivo chimeric cells tracking in non-human primate

Non-human primates (NHPs) are increasingly used in preclinical trials to test the safety and efficacy of biotechnology therapies. Nonetheless, given the ethical issues and costs associated with this model, it would be highly advantageous to use NHP cellular models in clinical studies. However, developing and maintaining the naïve state of primate pluripotent stem cells (PSCs) remains difficult as does in vivo detection of PSCs, thus limiting biotechnology application in the cynomolgus monkey. Here, we report a chemically defined, xeno-free culture system for culturing and deriving monkey PSCs in vitro. The cells display global gene expression and genome-wide hypomethylation patterns distinct from monkey-primed cells. We also found expression of signaling pathways components that may increase the potential for chimera formation. Crucially for biomedical applications, we were also able to integrate bioluminescent reporter genes into monkey PSCs and track them in chimeric embryos in vivo and in vitro. The engineered cells retained embryonic and extra-embryonic developmental potential. Meanwhile, we generated a chimeric monkey carrying bioluminescent cells, which were able to track chimeric cells for more than 2 years in living animals. Our study could have broad utility in primate stem cell engineering and in utilizing chimeric monkey models for clinical studies.

An expedition in the jungle of pluripotent stem cells of non-human primates

For nearly three decades, more than 80 embryonic stem cell lines and more than 100 induced pluripotent stem cell lines have been derived from New World monkeys, Old World monkeys, and great apes. In this comprehensive review, we examine these cell lines originating from marmoset, cynomolgus macaque, rhesus macaque, pig-tailed macaque, Japanese macaque, African green monkey, baboon, chimpanzee, bonobo, gorilla, and orangutan. We outline the methodologies implemented for their establishment, the culture protocols for their long-term maintenance, and their basic molecular characterization. Further, we spotlight any cell lines that express fluorescent reporters. Additionally, we compare these cell lines with human pluripotent stem cell lines, and we discuss cell lines reprogrammed into a pluripotent naive state, detailing the processes used to attain this. Last, we present the findings from the application of these cell lines in two emerging fields: intra- and interspecies embryonic chimeras and blastoids.

The evolution of aging and lifespan

Aging is a nearly inescapable trait among organisms yet lifespan varies tremendously across different species and spans several orders of magnitude in vertebrates alone. This vast phenotypic diversity is driven by distinct evolutionary trajectories and tradeoffs that are reflected in patterns of diversification and constraint in organismal genomes. Age-specific impacts of selection also shape allele frequencies in populations, thus impacting disease susceptibility and environment-specific mortality risk. Further, the mutational processes that spawn this genetic diversity in both germline and somatic cells are strongly influenced by age and life history. We discuss recent advances in our understanding of the evolution of aging and lifespan at organismal, population, and cellular scales, and highlight outstanding questions that remain unanswered.

Dopaminergic neurons derived from porcine induced pluripotent stem cell like cells function in the Lanyu pig model of Parkinson's disease

The induced pluripotent stem cells (iPSCs) are able to differentiate into dopaminergic neurons and execute the therapeutic effects for Parkinson's disease (PD). Here, we established a animal model of PD in Lanyu pigs by injecting 5 mg/kg of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP). Next, the porcine iPSC-like cells (piPSC-like cells) were differentiated into D18 neuronal progenitors (D18 NPs) that were transplanted into the striatum to evaluate their therapeutic effects of PD. We showed that after 8 weeks of cell transplantation, the behavior score was significantly ameliorated and fully recovered at the 14th week of cell transplantation. The number of dopaminergic neurons was also significantly improved at the end of the experiment although the number was still about 50% lower than that in the control group. Our findings suggest that piPSC-like cell-derived D18 NPs exhibit a potential for the treatment of PD in the Lanyu pig model.

Cloning in action: can embryo splitting, induced pluripotency and somatic cell nuclear transfer contribute to endangered species conservation?

The term 'cloning' refers to the production of genetically identical individuals but has meant different things throughout the history of science: a natural means of reproduction in bacteria, a routine procedure in horticulture, and an ever-evolving gamut of molecular technologies in vertebrates. Mammalian cloning can be achieved through embryo splitting, somatic cell nuclear transfer, and most recently, by the use of induced pluripotent stem cells. Several emerging biotechnologies also facilitate the propagation of genomes from one generation to the next whilst bypassing the conventional reproductive processes. In this review, we examine the state of the art of available cloning technologies and their progress in species other than humans and rodent models, in order to provide a critical overview of their readiness and relevance for application in endangered animal conservation.

Establishment of Skeletal Myogenic Progenitors from Non-Human Primate Induced Pluripotent Stem Cells

Pluripotent stem (PS) cells enable the scalable production of tissue-specific derivatives with therapeutic potential for various clinical applications, including muscular dystrophies. Given the similarity to human counterparts, the non-human primate (NHP) is an ideal preclinical model to evaluate several questions, including delivery, biodistribution, and immune response. While the generation of human-induced PS (iPS)-cell-derived myogenic progenitors is well established, there have been no data for NHP counterparts, probably due to the lack of an efficient system to differentiate NHP iPS cells towards the skeletal muscle lineage. Here, we report the generation of three independent Macaca fascicularis iPS cell lines and their myogenic differentiation using PAX7 conditional expression. The whole-transcriptome analysis confirmed the successful sequential induction of mesoderm, paraxial mesoderm, and myogenic lineages. NHP myogenic progenitors efficiently gave rise to myotubes under appropriate in vitro differentiation conditions and engrafted in vivo into the TA muscles of NSG and FKRP-NSG mice. Lastly, we explored the preclinical potential of these NHP myogenic progenitors in a single wild-type NHP recipient, demonstrating engraftment and characterizing the interaction with the host immune response. These studies establish an NHP model system through which iPS-cell-derived myogenic progenitors can be studied.

Establishment of Bactrian Camel Induced Pluripotent Stem Cells and Prediction of Their Unique Pluripotency Genes

Induced pluripotent stem cells (iPSCs) can differentiate into all types of cells and can be used in livestock for research on biological development, genetic breeding, and in vitro genetic resource conservation. The Bactrian camel is a large domestic animal that inhabits extreme environments and holds value in the treatment of various diseases and the development of the local economy. Therefore, we transferred four mouse genes (Oct4, Sox2, Klf4, and c-Myc) into Bactrian camel fetal fibroblasts (BCFFs) using retroviruses with a large host range to obtain Bactrian camel induced pluripotent stem cells (bciPSCs). They were comprehensively identified based on cell morphology, pluripotency gene and marker expression, chromosome number, transcriptome sequencing, and differentiation potential. The results showed the pluripotency of bciPSCs. However, unlike stem cells of other species, late formation of stem cell clones was observed; moreover, the immunofluorescence of SSEA1, SSEA3, and SSEA4 were positive, and teratoma formation took four months. These findings may be related to the extremely long gestation period and species specificity of Bactrian camels. By mining RNA sequence data, 85 potential unique pluripotent genes of Bactrian camels were predicted, which could be used as candidate genes for the production of bciPSC in the future. Among them, ASF1B, DTL, CDCA5, PROM1, CYTL1, NUP210, Epha3, and SYT13 are more attractive. In conclusion, we generated bciPSCs for the first time and obtained their transcriptome information, expanding the iPSC genetic information database and exploring the applicability of iPSCs in livestock. Our results can provide an experimental basis for Bactrian camel ESC establishment, developmental research, and genetic resource conservation.

Current advances in primate genomics: novel approaches for understanding evolution and disease

Primate genomics holds the key to understanding fundamental aspects of human evolution and disease. However, genetic diversity and functional genomics data sets are currently available for only a few of the more than 500 extant primate species. Concerted efforts are under way to characterize primate genomes, genetic polymorphism and divergence, and functional landscapes across the primate phylogeny. The resulting data sets will enable the connection of genotypes to phenotypes and provide new insight into aspects of the genetics of primate traits, including human diseases. In this Review, we describe the existing genome assemblies as well as genetic variation and functional genomic data sets. We highlight some of the challenges with sample acquisition. Finally, we explore how technological advances in single-cell functional genomics and induced pluripotent stem cell-derived organoids will facilitate our understanding of the molecular foundations of primate biology.

iPSC Technology: An Innovative Tool for Developing Clean Meat, Livestock, and Frozen Ark

Induced pluripotent stem cell (iPSC) technology is an emerging technique to reprogram somatic cells into iPSCs that have revolutionary benefits in the fields of drug discovery, cellular therapy, and personalized medicine. However, these applications are just the tip of an iceberg. Recently, iPSC technology has been shown to be useful in not only conserving the endangered species, but also the revival of extinct species. With increasing consumer reliance on animal products, combined with an ever-growing population, there is a necessity to develop alternative approaches to conventional farming practices. One such approach involves the development of domestic farm animal iPSCs. This approach provides several benefits in the form of reduced animal death, pasture degradation, water consumption, and greenhouse gas emissions. Hence, it is essentially an environmentally-friendly alternative to conventional farming. Additionally, this approach ensures decreased zoonotic outbreaks and a constant food supply. Here, we discuss the iPSC technology in the form of a "Frozen Ark", along with its potential impact on spreading awareness of factory farming, foodborne disease, and the ecological footprint of the meat industry.

Successful Derivation of Hepatoblasts, Cholangiocytes and Hepatocytes from Simian Induced Pluripotent Stem Cells

The use of primary cells in human liver therapy is limited by a lack of cells. Induced pluripotent stem cells (iPSCs) represent an alternative to primary cells as they are infinitely expandable and can be differentiated into different liver cell types. The aim of our work was to demonstrate that simian iPSCs (siPSCs) could be used as a new source of liver cells to be used as a large animal model for preclinical studies. We first differentiated siPSCs into a homogenous population of hepatoblasts (siHBs). We then separately differentiated them into hepatocytes (siHeps) and cholangiocytes (siChols) expressing respective specific markers and displaying epithelial polarity. Moreover, we showed that polarized siChols can self-organize into 3D structures. These results should facilitate the deciphering of liver development and open the way to exploring co-culture systems that could be assessed during preclinical studies, including in autologous monkey donors, for regenerative medicine purposes.

Research progress and application prospects of stable porcine pluripotent stem cells

Pluripotent stem cells (PSCs) harbor the capacity of unlimited self-renewal and multi-lineage differentiation potential which are crucial for basic research and biomedical science. Establishment of PSCs with defined features were previously reported from mice and humans, while generation of stable large animal PSCs has experienced a relatively long trial stage and only recently has made breakthroughs. Pigs are regarded as ideal animal models for their similarities in physiology and anatomy to humans. Generation of porcine PSCs would provide cell resources for basic research, genetic engineering, animal breeding and cultured meat. In this review, we summarize the progress on the derivation of porcine PSCs and reprogrammed cells and elucidate the mechanisms of pluripotency changes during pig embryo development. This will be beneficial for understanding the divergence and conservation between different species involved in embryo development and the pluripotent regulated signaling pathways. Finally, we also discuss the promising future applications of stable porcine PSCs.

A real-time pluripotency reporter for the long-term and real-time monitoring of pluripotency changes in induced pluripotent stem cells

To master the technology of reprogramming mouse somatic cells to induced pluripotent stem cells (iPSCs), which will lay a good foundation for setting up a technology platform on reprogramming human cancer cells into iPSCs. Mouse iPSCs (i.e., Oct4-GFP miPSCs) was successfully generated from mouse embryonic fibroblasts (MEFs) harboring Oct4-EGFP transgene by introducing four factors, Oct4, Sox2, c-Myc and Klf4, under mESC (Murine embryonic stem cells) culture conditions. Oct4-GFP miPSCs were similar to mESCs in morphology, proliferation, mESC-specific surface antigens and gene expression. Additionally, Oct4-GFP miPSCs could be cultured in suspension to form embryoid bodies (EBs) and differentiate into cell types of the three germ layers in vitro. Moreover, Oct4-GFP miPSCs could develop to teratoma and chimera in vivo. Unlike cell cycle distribution of MEFs, Oct4-GFP miPSCs are similar to mESCs in the cell cycle structure which consists of higher S phase and lower G1 phase. More importantly, our data demonstrated that MEFs harboring Oct4-EGFP transgene did not express GFP, until they were reprogrammed to the pluripotent stage (iPSCs), while the GFP expression was progressively lost when these pluripotent Oct4-GFP miPSCs exposed to EB-mediated differentiation conditions, suggesting the pluripotency of Oct4-GFP miPSCs can be real-time monitored over long periods of time via GFP assay. Altogether, our findings demonstrate that Oct4-GFP miPSC line is successfully established, which will lay a solid foundation for setting up a technology platform on reprogramming cancer cells into iPSCs. Furthermore, this pluripotency reporter system permits the long-term real-time monitoring of pluripotency changes in a live single-cell, and its progeny.

Stem Cell Transplantation Therapy and Neurological Disorders: Current Status and Future Perspectives

Neurodegenerative diseases are a global health issue with inadequate therapeutic options and an inability to restore the damaged nervous system. With advances in technology, health scientists continue to identify new approaches to the treatment of neurodegenerative diseases. Lost or injured neurons and glial cells can lead to the development of several neurological diseases, including Parkinson's disease, stroke, and multiple sclerosis. In recent years, neurons and glial cells have successfully been generated from stem cells in the laboratory utilizing cell culture technologies, fueling efforts to develop stem cell-based transplantation therapies for human patients. When a stem cell divides, each new cell has the potential to either remain a stem cell or differentiate into a germ cell with specialized characteristics, such as muscle cells, red blood cells, or brain cells. Although several obstacles remain before stem cells can be used for clinical applications, including some potential disadvantages that must be overcome, this cellular development represents a potential pathway through which patients may eventually achieve the ability to live more normal lives. In this review, we summarize the stem cell-based therapies that have been explored for various neurological disorders, discuss the potential advantages and drawbacks of these therapies, and examine future directions for this field.

Non-human primate pluripotent stem cells for the preclinical testing of regenerative therapies

Non-human primates play a key role in the preclinical validation of pluripotent stem cell-based cell replacement therapies. Pluripotent stem cells used as advanced therapy medical products boost the possibility to regenerate tissues and organs affected by degenerative diseases. Therefore, the methods to derive human induced pluripotent stem cell and embryonic stem cell lines following clinical standards have quickly developed in the last 15 years. For the preclinical validation of cell replacement therapies in non-human primates, it is necessary to generate non-human primate pluripotent stem cell with a homologous quality to their human counterparts. However, pluripotent stem cell technologies have developed at a slower pace in non-human primates in comparison with human cell systems. In recent years, however, relevant progress has also been made with non-human primate pluripotent stem cells. This review provides a systematic overview of the progress and remaining challenges for the generation of non-human primate induced pluripotent stem cells/embryonic stem cells for the preclinical testing and validation of cell replacement therapies. We focus on the critical domains of (1) reprogramming and embryonic stem cell line derivation, (2) cell line maintenance and characterization and, (3) application of non-human primate pluripotent stem cells in the context of selected preclinical studies to treat cardiovascular and neurodegenerative disorders performed in non-human primates.

Unraveling Human Brain Development and Evolution Using Organoid Models

Brain organoids are proving to be physiologically relevant models for studying human brain development in terms of temporal transcriptional signature recapitulation, dynamic cytoarchitectural development, and functional electrophysiological maturation. Several studies have employed brain organoid technologies to elucidate human-specific processes of brain development, gene expression, and cellular maturation by comparing human-derived brain organoids to those of non-human primates (NHPs). Brain organoids have been established from a variety of NHP pluripotent stem cell (PSC) lines and many protocols are now available for generating brain organoids capable of reproducibly representing specific brain region identities. Innumerous combinations of brain region specific organoids derived from different human and NHP PSCs, with CRISPR-Cas9 gene editing techniques and strategies to promote advanced stages of maturation, will successfully establish complex brain model systems for the accurate representation and elucidation of human brain development. Identified human-specific processes of brain development are likely vulnerable to dysregulation and could result in the identification of therapeutic targets or disease prevention strategies. Here, we discuss the potential of brain organoids to successfully model human-specific processes of brain development and explore current strategies for pinpointing these differences.

Small Molecules that Promote Self-Renewal of Stem Cells and Somatic Cell Reprogramming

The ground state of embryonic stem cells (ESCs) is closely related to the development of regenerative medicine. Particularly, long-term culture of ESCs in vitro, maintenance of their undifferentiated state, self-renewal and multi-directional differentiation ability is the premise of ESCs mechanism and application research. Induced pluripotent stem cells (iPSC) reprogrammed from mouse embryonic fibroblasts (MEF) cells into cells with most of the ESC characteristics show promise towards solving ethical problems currently facing stem cell research. However, integration into chromosomal DNA through viral-mediated genes may activate proto oncogenes and lead to risk of cancer of iPSC. At the same time, iPS induction efficiency needs to be further improved to reduce the use of transcription factors. In this review, we discuss small molecules that promote self-renewal and reprogramming, including growth factor receptor inhibitors, GSK-3β and histone deacetylase inhibitors, metabolic regulators, pathway modulators as well as EMT/MET regulation inhibitors to enhance maintenance of ESCs and enable reprogramming. Additionally, we summarize the mechanism of action of small molecules on ESC self-renewal and iPSC reprogramming. Finally, we will report on the progress in identification of novel and potentially effective agents as well as selected strategies that show promise in regenerative medicine. On this basis, development of more small molecule combinations and efficient induction of chemically induced pluripotent stem cell (CiPSC) is vital for stem cell therapy. This will significantly improve research in pathogenesis, individualized drug screening, stem cell transplantation, tissue engineering and many other aspects.

Effects of feeder cells on proliferation of inducible pluripotent stem cells in chicken

Although inducible pluripotent stem cells (iPSC) have been identified in poultry, the induction efficiency is low, because different culture media, feeder cells and feeder layer treatments affect the efficiency of somatic cell reprogramming. We investigated improvement of the feeder culture system for induction of chicken iPSC by comparing the effects of different types and treatments of feeder cells on the growth and proliferation of chicken iPSC. Mouse embryo fibroblasts (MEF), but not Sandoz inbred mouse-derived thioguanine-resistant and ouabain-buffalo rat cells, were suitable feeder cells that supported proliferation of chicken iPSC. Institute of Cancer Research (ICR) mice, but not Kunming mice, were suitable for preparing MEF that support cell proliferation. Also, MEF feeder cells that had been inactivated by mitomycin C were effective. Leukemia inhibitory factor was not required for chicken iPSC culture when MEF feeder cells were used. The optimal feeder culture system for growth and proliferation of chicken iPSC consisted of MEF feeder cells derived from ICR mice that were inactivated by mitomycin C combined with embryonic germ cell culture medium.

Alternative Animal Models of Aging Research

Most research on mechanisms of aging is being conducted in a very limited number of classical model species, i.e., laboratory mouse (Mus musculus), rat (Rattus norvegicus domestica), the common fruit fly (Drosophila melanogaster) and roundworm (Caenorhabditis elegans). The obvious advantages of using these models are access to resources such as strains with known genetic properties, high-quality genomic and transcriptomic sequencing data, versatile experimental manipulation capabilities including well-established genome editing tools, as well as extensive experience in husbandry. However, this approach may introduce interpretation biases due to the specific characteristics of the investigated species, which may lead to inappropriate, or even false, generalization. For example, it is still unclear to what extent knowledge of aging mechanisms gained in short-lived model organisms is transferable to long-lived species such as humans. In addition, other specific adaptations favoring a long and healthy life from the immense evolutionary toolbox may be entirely missed. In this review, we summarize the specific characteristics of emerging animal models that have attracted the attention of gerontologists, we provide an overview of the available data and resources related to these models, and we summarize important insights gained from them in recent years. The models presented include short-lived ones such as killifish (Nothobranchius furzeri), long-lived ones such as primates (Callithrix jacchus, Cebus imitator, Macaca mulatta), bathyergid mole-rats (Heterocephalus glaber, Fukomys spp.), bats (Myotis spp.), birds, olms (Proteus anguinus), turtles, greenland sharks, bivalves (Arctica islandica), and potentially non-aging ones such as Hydra and Planaria.

Genome-wide R-loop Landscapes during Cell Differentiation and Reprogramming

DNA:RNA hybrids play key roles in both physiological and disease states by regulating chromatin and genome organization. Their homeostasis during cell differentiation and cell plasticity remains elusive. Using an isogenic human stem cell platform, we systematically characterize R-loops, DNA methylation, histone modifications, and chromatin accessibility in pluripotent cells and their lineage-differentiated derivatives. We confirm that a portion of R-loops formed co-transcriptionally at pluripotency genes in pluripotent stem cells and at lineage-controlling genes in differentiated lineages. Notably, a subset of R-loops maintained after differentiation are associated with repressive chromatin marks on silent pluripotency genes and undesired lineage genes. Moreover, in reprogrammed pluripotent cells, cell-of-origin-specific R-loops are initially present but are resolved with serial passaging. Our analysis suggests a multifaceted role of R-loops in cell fate determination that may serve as an additional layer of modulation on cell fate memory and cell plasticity.

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.

Valproic Acid Enhance Reprogramming of Bactrian Camel Cells through Promoting the Expression of Endogenous Gene c-Myc and the Process of Angiogenesis

Background and Objectives

Induced pluripotent stem cells (iPSCs) are usually generated by reprogramming differentiated cells through the introduction of specific transcription factors, but this is a difficult and inefficient process. Valproic acid (VPA) is a histone deacetylase inhibitor that significantly improves the efficiency of iPSC generation. But its role and mechanism are still unclear.

Methods and Results

We transduced Bactrian camel fetal fibroblasts (BCFFs) with retroviruses carrying defined factors (OCT4, SOX2, KLF4, c-MYC and EGFP; OSKMG) in the presence of VPA. Cells were collected (Day 7) and analyzed using RNA-seq technology. Afterwards, different groups of cells and transcriptomics results were detected by PCR and qRT-PCR technology. The results showed that VPA promoted the expression of the endogenous gene c-Myc and inhibited cell proliferation; at the same time, it promoted the expression of VEGF and other genes related to angiogenesis.

Conclusions

When VPA is added to the culture medium, only the cells that have begun to reprogram can break the G2/M repression through the expression of the endogenous gene c-Myc, and use the nutrients and space in the culture dish to proliferate normally, which can achieve the purpose of directly improving the efficiency of reprogramming. Another new discovery for Bactrian camels, VPA significantly increased the expression of VEGFC and other genes, promoting the transformation of fibroblasts to endothelial cells (different from the mesenchymal-to-epithelial transition process of other species) to accelerate the early induction of Bactrian camels iPSc process. Overall, this study proved the new mechanism of VPA in enhancing the induction of pluripotency from the transcriptome level.

Induced pluripotent stem cells from farm animals

The development of the induced pluripotent stem cells (iPSCs) technology has revolutionized the world on the establishment of pluripotent stem cells (PSCs) across a great variety of animal species. Generation of iPSCs from domesticated animals would provide unrestricted cell resources for the study of embryonic development and cell differentiation of these species, for screening and establishing desired traits for sustainable agricultural production, and as veterinary and preclinical therapeutic tools for animal and human diseases. Induced PSCs from domesticated animals thus harbor enormous scientific, economical, and societal values. Although much progress has been made toward the generation of PSCs from these species, major obstacles remain precluding the exclamation of the establishment of bona fide iPSCs. The most prominent of them remain the inability of these cells to silence exogenous reprogramming factors, the obvious reliance on exogenous factors for their self-renewal, and the restricted development potential in vivo. In this review, we summarize the history and current progress in domestic farm animal iPSC generation, with a focus on swine, ruminants (cattle, ovine, and caprine), horses, and avian species (quails and chickens). We also discuss the problems associated with the farm animal iPSCs and potential future directions toward the complete reprogramming of somatic cells from farm animals.

Generation and Cultivation of Transgene-Free Macaque and Baboon iPSCs Under Chemically Defined Conditions

Non-human primates (NHP), and in particular Old World monkeys including macaques and baboons, are key animal models for the late preclinical testing of novel stem cell-based therapies and other advanced therapy medical products (ATMP) for the treatment of degenerative diseases. These pathologies are characterized by the loss of functional cells in an organ, as in Parkinson's disease, age-related macular degeneration, or after myocardial infarction. For preclinically relevant testing of induced pluripotent stem cell (iPSC)-based therapies, robust, and standardized protocols for the generation, characterization, and differentiation of NHP-iPSCs are required. Since the discovery of iPSCs by Takahashi and Yamanaka in 2006, human reprogramming protocols have been continuously refined. However, the generation of integration-free NHP-iPSC lines and a stable feeder- and serum-free long-term culture turned out to be difficult or even impossible with the current protocols established for human iPSCs. Here, we provide a robust protocol for the generation of transgene-free Old World monkey (and human) iPSCs and long-term cultivation under chemically defined conditions. This protocol was successfully applied to generate human, baboon (Papio anubis), rhesus (Macaca mulatta), and cynomolgus macaque (Macaca fascicularis) iPSCs from skin fibroblasts. The resulting NHP-iPSCs provide a valuable resource for the preclinical testing of regenerative therapies in NHP.

Genome-wide CRISPR-Cas9 screen identified KLF11 as a druggable suppressor for sarcoma cancer stem cells

Cancer stem cells (CSCs) are involved in tumorigenesis, recurrence, and therapy resistance. To identify critical regulators of sarcoma CSCs, we performed a reporter-based genome-wide CRISPR-Cas9 screen and uncovered Kruppel-like factor 11 (KLF11) as top candidate. In vitro and in vivo functional annotation defined a negative role of KLF11 in CSCs. Mechanistically, KLF11 and YAP/TEAD bound to adjacent DNA sites along with direct interaction. KLF11 recruited SIN3A/HDAC to suppress the transcriptional output of YAP/TEAD, which, in turn, promoted KLF11 transcription, forming a negative feedback loop. However, in CSCs, this negative feedback was lost because of epigenetic silence of KLF11, causing sustained YAP activation. Low KLF11 was associated with poor prognosis and chemotherapy response in patients with sarcoma. Pharmacological activation of KLF11 by thiazolidinedione effectively restored chemotherapy response. Collectively, our study identifies KLF11 as a negative regulator in sarcoma CSCs and potential therapeutic target.

Effect of bFGF on fibroblasts derived from the golden snub-nosed monkey

Golden snub-nosed monkeys are endangered animals in China, and their cells have been demonstrated to be important as genetic resources and in applications for advancing biological research. Moreover, in primary research, basic fibroblast growth factor (bFGF) is used to promote the proliferation of fibroblasts to create abundant cells for cryopreservation. To further investigate the effect of bFGF on the efficiency of preservation of fibroblasts obtained from an endangered species, a fibroblast cell line was isolated from a dead golden snub-nosed monkey. Cell viability and mitochondrial membrane potential were assessed using CCK8 and JC-1 assay kits. The karyotype was analyzed by chromosomal microarray analysis, while RNA sequencing and gene expression analyses were performed to assess molecular changes in response to bFGF. Flow cytometry was used to characterize changes in cell surface markers in response to bFGF treatment. The results showed that cells maintained typical fibroblast morphology, while cell viability and mitochondrial membrane potential were not significantly affected between three and eight passages (p > 0.05). We also observed that the addition of bFGF promoted fibroblast proliferation and increased mitochondrial membrane potential. In addition, the bFGF treatment did not alter the normal karyotype of cells, downregulating fibroblast-associated genes and upregulating those associated with cell regulation, including those of the WNT, PI3K and MAPK pathways. The addition of bFGF also increased CD29, CD90, CD105, CD34 and CD44 expression while decreasing that of CD14 and HLA-DR at the protein level. Taken together, these results demonstrate that bFGF may upregulate the WNT, PI3K and MAPK pathways to promote cell proliferation while also increasing the expression of genes and surface markers associated with mesenchymal and hematopoietic cell linages.

Positioning canine induced pluripotent stem cells (iPSCs) in the reprogramming landscape of naïve or primed state in comparison to mouse and human iPSCs

AIMS

Deriving canine-induced pluripotent stem cells (ciPSCs) have paved the way for developing novel cell-based disease models and transplantation therapies in the dog. Though ciPSCs have been derived in the presence of Leukemia inhibitory factor (LIF) as well in the presence of basic fibroblast growth factor (bFGF), the positioning of ciPSCs in the naïve or the primed state of pluripotency remains elusive. This study aims to understand whether canine iPSCs belong to naïve or prime state in comparison to mouse (m) iPSCs and human (h) iPSCs.

MAIN METHODS

In the present study, we derived ciPSCs in presence of LIF and compared their state of pluripotency with that of miPSCs and hiPSCs by culturing them in the presence of LIF, bFGF, and LIF + bFGF. Gene expression level at transcript level was performed by RT-PCR and qRT-PCR and at the protein level was analysed by immunofluorescence. We also attempted to understand the pluripotency state using lipid body analysis by bodipy staining and blue fluorescence emission.

KEY FINDINGS

In contrast to miPSCs, the naïve pluripotent stem cells, ciPSCs showed the expression of FGF5 similar to that of primed pluripotent stem cell, hiPSCs. Compared to miPSCs, ciPSCs cultured in presence of LIF showed enhanced expression of primed pluripotent marker FGF5, similar to hiPSCs cultured in presence of bFGF. Upon culturing in hiPSC culture condition, ciPSCs showed enhanced expression of core pluripotency genes compared to miPSCs cultured in similar condition. However, ciPSCs expressed naïve pluripotent marker SSEA1 similar to miPSCs and lacked the expression of primed state marker SSEA4 unlike hiPSCs. Interestingly, for the first time, we demonstrate the ciPSC pluripotency using lipid body analysis wherein ciPSCs showed enhanced bodipy staining and blue fluorescence emission, reflecting the primed state of pluripotency. ciPSCs expressed higher levels of fatty acid synthase (FASN), the enzyme involved in the synthesis of palmitate, similar to that of hiPSCs and higher than that of miPSCs. As ciPSCs exhibit characteristic properties of both naïve and primed pluripotent state, it probably represents a unique intermediary state of pluripotency that is distinct from that of mice and human pluripotent stem cells.

SIGNIFICANCE

Elucidating the pluripotent state of ciPSCs assists in better understanding of the reprogramming events and development in different species. The study would provide a footprint of species-specific differences involved in reprogramming and the potential implication of iPSCs as a tool to analyse evolution.

A novel xeno-organoid approach: exploring the crosstalk between human iPSC-derived PGC-like and rat testicular cells

Specification of germ cell-like cells from induced pluripotent stem cells has become a clinically relevant tool for research. Research on initial embryonic processes is often limited by the access to foetal tissue, and in humans, the molecular events resulting in primordial germ cell (PGC) specification and sex determination remain to be elucidated. A deeper understanding of the underlying processes is crucial to describe pathomechanisms leading to impaired reproductive function. Several protocols have been established for the specification of human pluripotent stem cell towards early PGC-like cells (PGCLC), currently representing the best model to mimic early human germline developmental processes in vitro. Further sex determination towards the male lineage depends on somatic gonadal cells providing the necessary molecular cues. By establishing a culture system characterized by the re-organization of somatic cells from postnatal rat testes into cord-like structures and optimizing efficient PGCLC specification protocols, we facilitated the co-culture of human germ cell-like cells within a surrogate testicular microenvironment. Specified conditions allowed the survival of rat somatic testicular and human PGCLCs for 14 days. Human cells maintained the characteristic expression of octamer-binding transcription factor 4, SRY-box transcription factor 17, and transcription factor AP-2 gamma and were recovered from the xeno-organoids by cell sorting. This novel xeno-organoid approach will allow the in vitro exploration of early sex determination of human PGCLCs.

Double sperm cloning (DSC) is a promising strategy in mammalian genetic engineering and stem cell research

Embryonic stem cells (ESCs) derived from somatic cell nuclear transfer (SCNT) and induced pluripotent stem cells (iPSCs) are promising tools for meeting the personalized requirements of regenerative medicine. However, some obstacles need to be overcome before clinical trials can be undertaken. First, donor cells vary, and the reprogramming procedures are diverse, so standardization is a great obstacle regarding SCNT and iPSCs. Second, somatic cells derived from a patient may carry mitochondrial DNA mutations and exhibit telomere instability with aging or disease, and SCNT-ESCs and iPSCs retain the epigenetic memory or epigenetic modification errors. Third, reprogramming efficiency has remained low. Therefore, in addition to improving their success rate, other alternatives for producing ESCs should be explored. Producing androgenetic diploid embryos could be an outstanding strategy; androgenic diploid embryos are produced through double sperm cloning (DSC), in which two capacitated sperms (XY or XX, sorted by flow cytometer) are injected into a denucleated oocyte by intracytoplasmic sperm injection (ICSI) to reconstruct embryo and derive DSC-ESCs. This process could avoid some potential issues, such as mitochondrial interference, telomere shortening, and somatic epigenetic memory, all of which accompany somatic donor cells. Oocytes are naturally activated by sperm, which is unlike the artificial activation that occurs in SCNT. The procedure is simple and practical and can be easily standardized. In addition, DSC-ESCs can overcome ethical concerns and resolve immunological response matching with sperm providers. Certainly, some challenges must be faced regarding imprinted genes, epigenetics, X chromosome inactivation, and dosage compensation. In mice, DSC-ESCs have been produced and have shown excellent differentiation ability. Therefore, the many advantages of DSC make the study of this process worthwhile for regenerative medicine and animal breeding.

Anatomical templates for tissue (re)generation and beyond

Induced pluripotent stem cells (iPSCs) represent a valuable alternative to stem cells in regenerative medicine overcoming their ethical limitations, like embryo disruption. Takahashi and Yamanaka in 2006 reprogrammed, for the first time, mouse fibroblasts into iPSCs through the retroviral delivery of four reprogramming factors: Oct3/4, Sox2, c-Myc, and Klf4. Since then, several studies started reporting the derivation of iPSC lines from animals other than rodents for translational and veterinary medicine. Here, we review the potential of using these cells for further intriguing applications, such as "cellular agriculture." iPSCs, indeed, can be a source of in vitro, skeletal muscle tissue, namely "cultured meat," a product that improves animal welfare and encourages the consumption of healthier meat along with environmental preservation. Also, we report the potential of using iPSCs, obtained from endangered species, for therapeutic treatments for captive animals and for assisted reproductive technologies as well. This review offers a unique opportunity to explore the whole spectrum of iPSC applications from regenerative translational and veterinary medicine to the production of artificial meat and the preservation of currently endangered species.

Generation of Pluripotent Stem Cells Using Somatic Cell Nuclear Transfer and Induced Pluripotent Somatic Cells from African Green Monkeys

Patient-specific stem cells derived from somatic cell nuclear transfer (SCNT) embryos or from induced pluripotent stem cells (iPSCs) could be used to treat various diseases with minimal immune rejection. Many studies using these cells have been conducted in rats and mice; however, there exist numerous dissimilarities between the rodents and humans limiting the clinical predictive power and experimental utility of rodent experiments alone. Nonhuman primates (NHPs) share greater homology to human than rodents in all respects, including genomics, physiology, biochemistry, and the immune system. Thus, experimental data obtained from monkey studies would be more predictive for designing an effective cell replacement therapy in humans. Unfortunately, there are few iPSC lines and even fewer SCNT lines that have been derived in NHPs, hampering broader studies in regenerative medicine. One promising potential therapy would be the replacement of dopamine neurons that are lost in Parkinson's disease. After dopamine depletion by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), the African green monkey (Chlorocebus sabaeus) shows the most complete model of Parkinsonism compared with other species and brain pathology and behavioral changes are almost identical to those in humans after accidental exposure to MPTP. Therefore, we have developed a SCNT procedure to generate multiple pluripotent stem cell lines in this species for studies of possible treatment of Parkinsonism and for comparing with cells derived from iPSCs. Using 24 female monkeys as egg donors and 7 somatic cell donor monkeys, we have derived 11 SCNT embryonic stem cell lines that expressed typical stemness genes and formed all three germ layer derivatives. We also derived two iPSC lines using an episome-mediated reprogramming factor delivery system. This report describes the process for deriving these cell lines and proving their pluripotency for differentiation into various potentially therapeutic cells.

Potential of transposon-mediated cellular reprogramming towards cell-based therapies

Induced pluripotent stem (iPS) cells present a seminal discovery in cell biology and promise to support innovative treatments of so far incurable diseases. To translate iPS technology into clinical trials, the safety and stability of these reprogrammed cells needs to be shown. In recent years, different non-viral transposon systems have been developed for the induction of cellular pluripotency, and for the directed differentiation into desired cell types. In this review, we summarize the current state of the art of different transposon systems in iPS-based cell therapies.

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.

Non-Human Primate iPSC Generation, Cultivation, and Cardiac Differentiation under Chemically Defined Conditions

Non-human primates (NHP) are important surrogate models for late preclinical development of advanced therapy medicinal products (ATMPs), including induced pluripotent stem cell (iPSC)-based therapies, which are also under development for heart failure repair. For effective heart repair by remuscularization, large numbers of cardiomyocytes are required, which can be obtained by efficient differentiation of iPSCs. However, NHP-iPSC generation and long-term culture in an undifferentiated state under feeder cell-free conditions turned out to be problematic. Here we describe the reproducible development of rhesus macaque (Macaca mulatta) iPSC lines. Postnatal rhesus skin fibroblasts were reprogrammed under chemically defined conditions using non-integrating vectors. The robustness of the protocol was confirmed using another NHP species, the olive baboon (Papio anubis). Feeder-free maintenance of NHP-iPSCs was essentially dependent on concurrent Wnt-activation by GSK-inhibition (Gi) and Wnt-inhibition (Wi). Generated NHP-iPSCs were successfully differentiated into cardiomyocytes using a combined growth factor/GiWi protocol. The capacity of the iPSC-derived cardiomyocytes to self-organize into contractile engineered heart muscle (EHM) was demonstrated. Collectively, this study establishes a reproducible protocol for the robust generation and culture of NHP-iPSCs, which are useful for preclinical testing of strategies for cell replacement therapies in NHP.

Tissue Engineering and Regenerative Medicine: Achievements, Future, and Sustainability in Asia

Exploring innovative solutions to improve the healthcare of the aging and diseased population continues to be a global challenge. Among a number of strategies toward this goal, tissue engineering and regenerative medicine (TERM) has gradually evolved into a promising approach to meet future needs of patients. TERM has recently received increasing attention in Asia, as evidenced by the markedly increased number of researchers, publications, clinical trials, and translational products. This review aims to give a brief overview of TERM development in Asia over the last decade by highlighting some of the important advances in this field and featuring major achievements of representative research groups. The development of novel biomaterials and enabling technologies, identification of new cell sources, and applications of TERM in various tissues are briefly introduced. Finally, the achievement of TERM in Asia, including important publications, representative discoveries, clinical trials, and examples of commercial products will be introduced. Discussion on current limitations and future directions in this hot topic will also be provided.

New addiction to the NRF2-related factor NRF3 in cancer cells: Ubiquitin-independent proteolysis through the 20S proteasome

Accumulating evidence has revealed that human cancers develop by sequentially mutating pivotal genes, including driver genes, and acquiring cancer hallmarks. For instance, cancer cells are addicted to the transcription factor NRF2 (NFE2L2), which is a driver gene that utilizes the cellular cytoprotection system against oxidative stress and metabolic pathway reprogramming for sustaining high growth. Our group has recently discovered a new addiction to the NRF2-related factor NRF3 (NFE2L3) in cancer. For many years, the physiological function of NRF3 remained obscure, in part because Nrf3-deficient mice do not show apparent abnormalities. Nevertheless, human cancer genome databases suggest critical roles of NRF3 in cancer because of high NRF3 mRNA induction in several cancer types, such as colorectal cancer and pancreatic adenocarcinoma, with a poor prognosis. We found that NRF3 promotes tumor growth and malignancy by activating ubiquitin-independent 20S proteasome assembly through inducing the expression of the proteasome maturation protein (POMP) chaperone and thereby degrading the tumor suppressors p53 and Rb. The NRF3-POMP-20S proteasome axis has an entirely different effect on cancer than NRF2. In this review, we describe recent research advances regarding the new cancer effector NRF3, including unclarified ubiquitin-independent proteolysis by the NRF3-POMP-20S proteasome axis. The expected development of cancer therapeutic interventions for this axis is also discussed.

Improving Cell Survival in Injected Embryos Allows Primed Pluripotent Stem Cells to Generate Chimeric Cynomolgus Monkeys

Monkeys are an optimal model species for developing stem cell therapies. We previously reported generating chimeric cynomolgus monkey fetuses using dome-shaped embryonic stem cells (dESCs). However, conventional primed pluripotent stem cells (pPSCs) lack chimera competency. Here, by altering the media in which injected morulae are cultured, we observed increased survival of cynomolgus monkey primed ESCs, induced PSCs, and somatic cell nuclear transfer-derived ESCs, thereby enabling chimeric contributions with 0.1%-4.5% chimerism into the embryonic and placental tissues, including germ cell progenitors in chimeric monkeys. Mechanically, dESCs and pPSCs belong to different cell types and similarly express epiblast ontogenic genes. The host embryonic microenvironment could reprogram injected PSCs to embryonic-like cells. However, the reprogramming level and chimerism were associated with the cell state of injected PSCs. Our findings provide a method to understand pluripotency and broaden the use of embryonic chimeras for basic developmental biology research and regenerative medicine.

TGFβ Family Signaling Pathways in Pluripotent and Teratocarcinoma Stem Cells' Fate Decisions: Balancing Between Self-Renewal, Differentiation, and Cancer

The transforming growth factor-β (TGFβ) family factors induce pleiotropic effects and are involved in the regulation of most normal and pathological cellular processes. The activity of different branches of the TGFβ family signaling pathways and their interplay with other signaling pathways govern the fine regulation of the self-renewal, differentiation onset and specialization of pluripotent stem cells in various cell derivatives. TGFβ family signaling pathways play a pivotal role in balancing basic cellular processes in pluripotent stem cells and their derivatives, although disturbances in their genome integrity induce the rearrangements of signaling pathways and lead to functional impairments and malignant transformation into cancer stem cells. Therefore, the identification of critical nodes and targets in the regulatory cascades of TGFβ family factors and other signaling pathways, and analysis of the rearrangements of the signal regulatory network during stem cell state transitions and interconversions, are key issues for understanding the fundamental mechanisms of both stem cell biology and cancer initiation and progression, as well as for clinical applications. This review summarizes recent advances in our understanding of TGFβ family functions in naїve and primed pluripotent stem cells and discusses how these pathways are involved in perturbations in the signaling network of malignant teratocarcinoma stem cells with impaired differentiation potential.

Research and therapy with induced pluripotent stem cells (iPSCs): social, legal, and ethical considerations

Induced pluripotent stem cells (iPSCs) can self-renew indefinitely in culture and differentiate into all specialized cell types including gametes. iPSCs do not exist naturally and are instead generated (“induced” or “reprogrammed”) in culture from somatic cells through ectopic co-expression of defined pluripotency factors. Since they can be generated from any healthy person or patient, iPSCs are considered as a valuable resource for regenerative medicine to replace diseased or damaged tissues. In addition, reprogramming technology has provided a powerful tool to study mechanisms of cell fate decisions and to model human diseases, thereby substantially potentiating the possibility to (i) discover new drugs in screening formats and (ii) treat life-threatening diseases through cell therapy-based strategies. However, various legal and ethical barriers arise when aiming to exploit the full potential of iPSCs to minimize abuse or unauthorized utilization. In this review, we discuss bioethical, legal, and societal concerns associated with research and therapy using iPSCs. Furthermore, we present key questions and suggestions for stem cell scientists, legal authorities, and social activists investigating and working in this field.

Haematopoietic stem cell reprogramming and the hope for a universal blood product

Haematopoietic stem cells (HSCs) are the only adult stem cells with a demonstrated clinical use, even though a tractable method to maintain and expand human HSCs in vitro has not yet been found. Owing to the introduction of transplantation strategies for the treatment of haematological malignancies and, more recently, the promise of gene therapy, the need to improve the generation, manipulation and scalability of autologous or allogeneic HSCs has risen steeply over the past decade. In that context, reprogramming strategies based on the expression of exogenous transcription factors have emerged as a means to produce functional HSCs in vitro. These approaches largely stem from the assumption that key master transcription factors direct the expression of downstream target genes thereby triggering haematopoiesis. Both somatic and pluripotent cells have been used to this end, yielding variable results in terms of haematopoietic phenotype and functionality. Here, we present an overview of the haematopoietic reprogramming methods reported to date, provide the appropriate historical context and offer some critical insight about where the field stands at present.

Differentiation of Baboon (Papio anubis) Induced-Pluripotent Stem Cells into Enucleated Red Blood Cells

As cell culture methods and stem cell biology have progressed, the in vitro production of cultured RBCs (cRBCs) has emerged as a viable option to produce cells for transfusion or to carry therapeutic cargoes. RBCs produced in culture can be quality-tested either by xeno-transfusion of human cells into immuno-deficient animals, or by transfusion of autologous cells in immuno-competent models. Although murine xeno-transfusion methods have improved, they must be complemented by studies in immuno-competent models. Non-human primates (NHPs) are important pre-clinical, large animal models due to their high biological and developmental similarities with humans, including their comparable hematopoietic and immune systems. Among NHPs, baboons are particularly attractive to validate cRBCs because of the wealth of data available on the characteristics of RBCs in this species that have been generated by past blood transfusion studies. We report here that we have developed a method to produce enucleated cRBCs by differentiation of baboon induced pluripotent stem cells (iPSCs). This method will enable the use of baboons to evaluate therapeutic cRBCs and generate essential pre-clinical data in an immuno-competent, large animal model. Production of the enucleated baboon cRBCs was achieved by adapting the PSC-RED protocol that we previously developed for human cells. Baboon-PSC-RED is an efficient chemically-defined method to differentiate iPSCs into cRBCs that are about 40% to 50% enucleated. PSC-RED is relatively low cost because it requires no albumin and only small amounts of recombinant transferrin.

Induced pluripotent stem cells throughout the animal kingdom: Availability and applications

Up until the mid 2000s, the capacity to generate every cell of an organism was exclusive to embryonic stem cells. In 2006, researchers Takahashi and Yamanaka developed an alternative method of generating embryonic-like stem cells from adult cells, which they coined induced pluripotent stem cells (iPSCs). Such iPSCs possess most of the advantages of embryonic stem cells without the ethical stigma associated with derivation of the latter. The possibility of generating “custom-made” pluripotent cells, ideal for patient-specific disease models, alongside their possible applications in regenerative medicine and reproduction, has drawn a lot of attention to the field with numbers of iPSC studies published growing exponentially. IPSCs have now been generated for a wide variety of species, including but not limited to, mouse, human, primate, wild felines, bovines, equines, birds and rodents, some of which still lack well-established embryonic stem cell lines. The paucity of robust characterization of some of these iPSC lines as well as the residual expression of transgenes involved in the reprogramming process still hampers the use of such cells in species preservation or medical research, underscoring the requirement for further investigations. Here, we provide an extensive overview of iPSC generated from a broad range of animal species including their potential applications and limitations.

A new combination of transcription factors increases the harvesting efficiency of pacemaker‑like cells

Biological pacemakers that combine cell-based and gene-based therapies are a promising treatment for sick sinus syndrome or severe atrioventricular block. The current study aimed to induce differentiation of adipose tissue-derived stem cells (ADSCs) into cardiac pacemaker cells through co-expression of the transcription factors insulin gene enhancer binding protein 1 (ISL-1) and T-box18 (Tbx18). ADSCs were transfected with green fluorescent protein, ISL-1, Tbx18 or ISL-1+Tbx18 fluorescent protein lentiviral vectors, and subsequently co-cultured with neonatal rat ventricular cardiomyocytes in vitro for 7 days. The potential for regulating the differentiation of ADSCs into pacemaker-like cells was evaluated by cell morphology, beating rate, reverse transcription-quantitative polymerase chain reaction, western blotting, immunofluorescence and electrophysiological activity. ADSCs were successfully transformed into spontaneously beating cells that exhibited a behavior similar to that of co-cultured pacemaker cells. This effect was significantly increased in the combined ISL-1 and Tbx18 group. These results provide a potential strategy for enriching the cardiac pacemaker cell population from ADSCs.

Stem-Cell Therapy Advances in China

Stem-cell therapy is a promising method for treating patients with a wide range of diseases and injuries. Increasing government funding of scientific research has promoted rapid developments in stem-cell research in China, as evidenced by the substantial increase in the number and quality of publications in the past 5 years. Multiple high-quality studies have been performed in China that concern cell reprogramming, stem-cell homeostasis, gene modifications, and immunomodulation. The number of translation studies, including basic and preclinical investigations, has also increased. Around 100 stem-cell banks have been established in China, 10 stem-cell drugs are currently in the approval process, and >400 stem cell-based clinical trials are currently registered in China. With continued state funding, advanced biotechnical support, and the development of regulatory standards for the clinical application of stem cells, further innovations are expected that will lead to a boom in stem-cell therapies. This review highlights recent achievements in stem-cell research in China and discusses future prospects.

Induced Pluripotent Stem Cells and Their Use in Human Models of Disease and Development

The discovery of somatic cell nuclear transfer proved that somatic cells can carry the same genetic code as the zygote, and that activating parts of this code are sufficient to reprogram the cell to an early developmental state. The discovery of induced pluripotent stem cells (iPSCs) nearly half a century later provided a molecular mechanism for the reprogramming. The initial creation of iPSCs was accomplished by the ectopic expression of four specific genes (OCT4, KLF4, SOX2, and c-Myc; OSKM). iPSCs have since been acquired from a wide range of cell types and a wide range of species, suggesting a universal molecular mechanism. Furthermore, cells have been reprogrammed to iPSCs using a myriad of methods, although OSKM remains the gold standard. The sources for iPSCs are abundant compared with those for other pluripotent stem cells; thus the use of iPSCs to model the development of tissues, organs, and other systems of the body is increasing. iPSCs also, through the reprogramming of patient samples, are being used to model diseases. Moreover, in the 10 years since the first report, human iPSCs are already the basis for new cell therapies and drug discovery that have reached clinical application. In this review, we examine the generation of iPSCs and their application to disease and development.