Induction of mouse totipotent stem cells by a defined chemical cocktail

Multiscale engineering of brain organoids for disease modeling

Brain organoids hold great potential for modeling human brain development and pathogenesis. They recapitulate certain aspects of the transcriptional trajectory, cellular diversity, tissue architecture and functions of the developing brain. In this review, we explore the engineering strategies to control the molecular-, cellular- and tissue-level inputs to achieve high-fidelity brain organoids. We review the application of brain organoids in neural disorder modeling and emerging bioengineering methods to improve data collection and feature extraction at multiscale. The integration of multiscale engineering strategies and analytical methods has significant potential to advance insight into neurological disorders and accelerate drug development.

Obox4 promotes zygotic genome activation upon loss of Dux

Once fertilized, mouse zygotes rapidly proceed to zygotic genome activation (ZGA), during which long terminal repeats (LTRs) of murine endogenous retroviruses with leucine tRNA primer (MERVL) are activated by a conserved homeodomain-containing transcription factor, DUX. However, Dux-knockout embryos produce fertile mice, suggesting that ZGA is redundantly driven by an unknown factor(s). Here, we present multiple lines of evidence that the multicopy homeobox gene, Obox4, encodes a transcription factor that is highly expressed in mouse two-cell embryos and redundantly drives ZGA. Genome-wide profiling revealed that OBOX4 specifically binds and activates MERVL LTRs as well as a subset of murine endogenous retroviruses with lysine tRNA primer (MERVK) LTRs. Depletion of Obox4 is tolerated by embryogenesis, whereas concomitant Obox4/Dux depletion markedly compromises embryonic development. Our study identified OBOX4 as a transcription factor that provides genetic redundancy to preimplantation development.

Toward developing human organs via embryo models and chimeras

Developing functional organs from stem cells remains a challenging goal in regenerative medicine. Existing methodologies, such as tissue engineering, bioprinting, and organoids, only offer partial solutions. This perspective focuses on two promising approaches emerging for engineering human organs from stem cells: stem cell-based embryo models and interspecies organogenesis. Both approaches exploit the premise of guiding stem cells to mimic natural development. We begin by summarizing what is known about early human development as a blueprint for recapitulating organogenesis in both embryo models and interspecies chimeras. The latest advances in both fields are discussed before highlighting the technological and knowledge gaps to be addressed before the goal of developing human organs could be achieved using the two approaches. We conclude by discussing challenges facing embryo modeling and interspecies organogenesis and outlining future prospects for advancing both fields toward the generation of human tissues and organs for basic research and translational applications.

Dual-role transcription factors stabilize intermediate expression levels

Precise control of gene expression levels is essential for normal cell functions, yet how they are defined and tightly maintained, particularly at intermediate levels, remains elusive. Here, using a series of newly developed sequencing, imaging, and functional assays, we uncover a class of transcription factors with dual roles as activators and repressors, referred to as condensate-forming level-regulating dual-action transcription factors (TFs). They reduce high expression but increase low expression to achieve stable intermediate levels. Dual-action TFs directly exert activating and repressing functions via condensate-forming domains that compartmentalize core transcriptional unit selectively. Clinically relevant mutations in these domains, which are linked to a range of developmental disorders, impair condensate selectivity and dual-action TF activity. These results collectively address a fundamental question in expression regulation and demonstrate the potential of level-regulating dual-action TFs as powerful effectors for engineering controlled expression levels.

Epigenetic reprogramming in the transition from pluripotency to totipotency

Mammalian development commences with the zygote, which can differentiate into both embryonic and extraembryonic tissues, a capability known as totipotency. Only the zygote and embryos around zygotic genome activation (ZGA) (two-cell embryo stage in mice and eight-cell embryo in humans) are totipotent cells. Epigenetic modifications undergo extremely extensive changes during the acquisition of totipotency and subsequent development of differentiation. However, the underlying molecular mechanisms remain elusive. Recently, the discovery of mouse two-cell embryo-like cells, human eight-cell embryo-like cells, extended pluripotent stem cells and totipotent-like stem cells with extra-embryonic developmental potential has greatly expanded our understanding of totipotency. Experiments with these in vitro models have led to insights into epigenetic changes in the reprogramming of pluri-to-totipotency, which have informed the exploration of preimplantation development. In this review, we highlight the recent findings in understanding the mechanisms of epigenetic remodeling during totipotency capture, including RNA splicing, DNA methylation, chromatin configuration, histone modifications, and nuclear organization.

The role of lipids in genome integrity and pluripotency

Pluripotent stem cells (PSCs), comprising embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), offer immense potential for regenerative medicine due to their ability to differentiate into all cell types of the adult body. A critical aspect of harnessing this potential is understanding their metabolic requirements during derivation, maintenance, and differentiation in vitro. Traditional culture methods using fetal bovine serum often lead to issues such as heterogeneous cell populations and diminished pluripotency. Although the chemically-defined 2i/LIF medium has provided solutions to some of these challenges, prolonged culturing of these cells, especially female ESCs, raises concerns related to genome integrity. This review discusses the pivotal role of lipids in genome stability and pluripotency of stem cells. Notably, the introduction of lipid-rich albumin, AlbuMAX, into the 2i/LIF culture medium offers a promising avenue for enhancing the genomic stability and pluripotency of cultured ESCs. We further explore the unique characteristics of lipid-induced pluripotent stem cells (LIP-ESCs), emphasizing their potential in regenerative medicine and pluripotency research.

Unlocking trophectoderm mysteries: In vivo and in vitro perspectives on human and mouse trophoblast fate induction

In recent years, the pursuit of inducing the trophoblast stem cell (TSC) state has gained prominence as a compelling research objective, illuminating the establishment of the trophoblast lineage and unlocking insights into early embryogenesis. In this review, we examine how advancements in diverse technologies, including in vivo time course transcriptomics, cellular reprogramming to TSC state, chemical induction of totipotent stem-cell-like state, and stem-cell-based embryo-like structures, have enriched our insights into the intricate molecular mechanisms and signaling pathways that define the mouse and human trophectoderm/TSC states. We delve into disparities between mouse and human trophectoderm/TSC fate establishment, with a special emphasis on the intriguing role of pluripotency in this context. Additionally, we re-evaluate recent findings concerning the potential of totipotent-stem-like cells and embryo-like structures to fully manifest the trophectoderm/trophoblast lineage's capabilities. Lastly, we briefly discuss the potential applications of induced TSCs in pregnancy-related disease modeling.

Reprogramming fibroblast into human iBlastoids

The study of early human embryogenesis has relied on the use of blastocysts donated to research or simple stem cell culture systems such as pluripotent and trophoblast stem cells, which have been seminal in shedding light on many key developmental processes. However, simple culture systems lack the necessary complexity to adequately model the spatiotemporal, cellular and molecular dynamics occurring during the early phases of embryonic development. As such, an in vitro model of the human blastocyst is advantageous in many aspects to decipher human embryogenesis. Here we describe a step-by-step protocol for the generation of induced blastoids (iBlastoids), an in vitro integrated model of the human blastocyst derived via somatic reprogramming. This protocol details the workflow for reprogramming of human dermal fibroblasts and subsequent generation of iBlastoids using the reprogramming intermediates, which together takes ~27 days (21 days for reprogramming and 6 days for iBlastoid generation). We also discuss several characterization/functional assays that can be used on the iBlastoids. We believe that a person trained in cell culture with ~1 year of experience with human somatic cell and reprogramming/cell differentiation assays would be able to perform this protocol. In short, the iBlastoids present an alternative tool as a model to the blastocyst to facilitate the scientific community in the exploration of early human development.

The impact of induced pluripotent stem cells in animal conservation

It is widely acknowledged that we are currently facing a critical tipping point with regards to global extinction, with human activities driving us perilously close to the brink of a devastating sixth mass extinction. As a promising option for safeguarding endangered species, induced pluripotent stem cells (iPSCs) hold great potential to aid in the preservation of threatened animal populations. For endangered species, such as the northern white rhinoceros (Ceratotherium simum cottoni), supply of embryos is often limited. After the death of the last male in 2019, only two females remained in the world. IPSC technology offers novel approaches and techniques for obtaining pluripotent stem cells (PSCs) from rare and endangered animal species. Successful generation of iPSCs circumvents several bottlenecks that impede the development of PSCs, including the challenges associated with establishing embryonic stem cells, limited embryo sources and immune rejection following embryo transfer. To provide more opportunities and room for growth in our work on animal welfare, in this paper we will focus on the progress made with iPSC lines derived from endangered and extinct species, exploring their potential applications and limitations in animal welfare research.

Nr5a2 ensures inner cell mass formation in mouse blastocyst

Recent studies have elucidated Nr5a2's role in activating zygotic genes during early mouse embryonic development. Subsequent research, however, reveals that Nr5a2 is not critical for zygotic genome activation but is vital for the gene program between the 4- and 8-cell stages. A significant gap exists in experimental evidence regarding its function during the first lineage differentiation's pivotal period. In this study, we observed that approximately 20% of embryos developed to the blastocyst stage following Nr5a2 ablation. However, these blastocysts lacked inner cell mass (ICM), highlighting Nr5a2's importance in first lineage differentiation. Mechanistically, using RNA sequencing and CUT&Tag, we found that Nr5a2 transcriptionally regulates ICM-specific genes, such as Oct4, to establish the pluripotent network. Interference with or overexpression of Nr5a2 in single blastomeres of 2-cell embryos can alter the fate of daughter cells. Our results indicate that Nr5a2 works as a doorkeeper to ensure ICM formation in mouse blastocyst.

Applications, advancements, and challenges of 3D bioprinting in organ transplantation

To date, organ transplantation remains an effective method for treating end-stage diseases of various organs. In recent years, despite the continuous development of organ transplantation technology, a variety of problems restricting its progress have emerged one after another, and the shortage of donors is at the top of the list. Bioprinting is a very useful tool that has huge application potential in many fields of life science and biotechnology, among which its use in medicine occupies a large area. With the development of bioprinting, advances in medicine have focused on printing cells and tissues for tissue regeneration and reconstruction of viable human organs, such as the heart, kidneys, and bones. In recent years, with the development of organ transplantation, three-dimensional (3D) bioprinting has played an increasingly important role in this field, giving rise to many unsolved problems, including a shortage of organ donors. This review respectively introduces the development of 3D bioprinting as well as its working principles and main applications in the medical field, especially in the applications, and advancements and challenges of 3D bioprinting in organ transplantation. With the continuous update and progress of printing technology and its deeper integration with the medical field, many obstacles will have new solutions, including tissue repair and regeneration, organ reconstruction, etc., especially in the field of organ transplantation. 3D printing technology will provide a better solution to the problem of donor shortage.

Hallmarks of totipotent and pluripotent stem cell states

Though totipotency and pluripotency are transient during early embryogenesis, they establish the foundation for the development of all mammals. Studying these in vivo has been challenging due to limited access and ethical constraints, particularly in humans. Recent progress has led to diverse culture adaptations of epiblast cells in vitro in the form of totipotent and pluripotent stem cells, which not only deepen our understanding of embryonic development but also serve as invaluable resources for animal reproduction and regenerative medicine. This review delves into the hallmarks of totipotent and pluripotent stem cells, shedding light on their key molecular and functional features.

Transition from totipotency to pluripotency in mice: insights into molecular mechanisms

Totipotency is the ability of a single cell to develop into a full organism and, in mammals, is strictly associated with the early stages of development following fertilization. This unlimited developmental potential becomes quickly restricted as embryonic cells transition into a pluripotent state. The loss of totipotency seems a consequence of the zygotic genome activation (ZGA), a process that determines the switch from maternal to embryonic transcription, which in mice takes place following the first cleavage. ZGA confers to the totipotent cell a transient transcriptional profile characterized by the expression of stage-specific genes and a set of transposable elements that prepares the embryo for subsequent development. The timely silencing of this transcriptional program during the exit from totipotency is required to ensure proper development. Importantly, the molecular mechanisms regulating the transition from totipotency to pluripotency have remained elusive due to the scarcity of embryonic material. However, the development of new in vitro totipotent-like models together with advances in low-input genome-wide technologies, are providing a better mechanistic understanding of how this important transition is achieved. This review summarizes the current knowledge on the molecular determinants that regulate the exit from totipotency.

Enhancing regenerative medicine: the crucial role of stem cell therapy

Stem cells offer new therapeutic avenues for the repair and replacement of damaged tissues and organs owing to their self-renewal and multipotent differentiation capabilities. In this paper, we conduct a systematic review of the characteristics of various types of stem cells and offer insights into their potential applications in both cellular and cell-free therapies. In addition, we provide a comprehensive summary of the technical routes of stem cell therapy and discuss in detail current challenges, including safety issues and differentiation control. Although some issues remain, stem cell therapy demonstrates excellent potential in the field of regenerative medicine and provides novel tactics and methodologies for managing a wider spectrum of illnesses and traumas.

Induction of Transient Morula-Like Cells in Mice Through STAT3 Activation

Developing in vitro cell models that faithfully replicate the molecular and functional traits of cells from the earliest stages of mammalian development presents a significant challenge. The strategic induction of signal transducer and activator of transcription 3 (STAT3) phosphorylation, coupled with carefully defined culture conditions, facilitates the efficient reprogramming of mouse pluripotent cells into a transient morula-like cell (MLC) state. The resulting MLCs closely mirror their in vivo counterparts, exhibiting not only molecular resemblance but also the ability to differentiate into both embryonic and extraembryonic lineages. This reprogramming approach provides valuable insights into controlled cellular fate choice and opens new opportunities for studying early developmental processes in a dish.

Topical section: embryonic models (2023) for Current Opinion in Genetics & Development

Stem cell-based mammalian embryo models facilitate the discovery of developmental mechanisms because they are more amenable to genetic and epigenetic perturbations than natural embryos. Here, we highlight exciting recent advances that have yielded a plethora of models of embryonic development. Imperfections in these models highlight gaps in our current understanding and outline future research directions, ushering in an exciting new era for embryology.

Engineered stem cells by emerging biomedical stratagems

Stem cell therapy holds immense potential as a viable treatment for a widespread range of intractable disorders. As the safety of stem cell transplantation having been demonstrated in numerous clinical trials, various kinds of stem cells are currently utilized in medical applications. Despite the achievements, the therapeutic benefits of stem cells for diseases are limited, and the data of clinical researches are unstable. To optimize tthe effectiveness of stem cells, engineering approaches have been developed to enhance their inherent abilities and impart them with new functionalities, paving the way for the next generation of stem cell therapies. This review offers a detailed analysis of engineered stem cells, including their clinical applications and potential for future development. We begin by briefly introducing the recent advances in the production of stem cells (induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs)). Furthermore, we present the latest developments of engineered strategies in stem cells, including engineered methods in molecular biology and biomaterial fields, and their application in biomedical research. Finally, we summarize the current obstacles and suggest future prospects for engineered stem cells in clinical translations and biomedical applications.

Haploid-genetic screening of trophectoderm specification identifies Dyrk1a as a repressor of totipotent-like status

Trophectoderm (TE) and the inner cell mass are the first two lineages in murine embryogenesis and cannot naturally transit to each other. The barriers between them are unclear and fascinating. Embryonic stem cells (ESCs) and trophoblast stem cells (TSCs) retain the identities of inner cell mass and TE, respectively, and, thus, are ideal platforms to investigate these lineages in vitro. Here, we develop a loss-of-function genetic screening in haploid ESCs and reveal many mutations involved in the conversion of TSCs. The disruption of either Catip or Dyrk1a (candidates) in ESCs facilitates the conversion of TSCs. According to transcriptome analysis, we find that the repression of Dyrk1a activates totipotency, which is a possible reason for TE specification. Dyrk1a-null ESCs can contribute to embryonic and extraembryonic tissues in chimeras and can efficiently form blastocyst-like structures, indicating their totipotent developmental abilities. These findings provide insights into the mechanisms underlying cell fate alternation in embryogenesis.

Chemical reprogramming for cell fate manipulation: Methods, applications, and perspectives

Chemical reprogramming offers an unprecedented opportunity to control somatic cell fate and generate desired cell types including pluripotent stem cells for applications in biomedicine in a precise, flexible, and controllable manner. Recent success in the chemical reprogramming of human somatic cells by activating a regeneration-like program provides an alternative way of producing stem cells for clinical translation. Likewise, chemical manipulation enables the capture of multiple (stem) cell states, ranging from totipotency to the stabilization of somatic fates in vitro. Here, we review progress in using chemical approaches for cell fate manipulation in addition to future opportunities in this promising field.

Unlocking the Potential of Mesenchymal Stem Cells in Gynecology: Where Are We Now?

Stem cells, with their remarkable capacity for differentiation into diverse cell types, are vital for the development as well as maintenance of health and homeostasis. Two unique abilities set them apart from other cells: self-renewal and the capacity for differentiation. They play important roles in embryogenesis, development, regeneration, and various other processes. Over the last decade, there has been increased interest in their potential use in the treatment of numerous diseases and disorders across multiple fields of medicine in acute, chronic, innate, and acquired diseases. Stem cells are key to maintaining the body's homeostasis and regulating growth and tissue functions. There are several types of stem cells-embryonic, adult, and human-induced pluripotent cells. Currently, mesenchymal stem cells are of great interest due to their regenerative, immunomodulatory, analgesic, and antimicrobial (anti-inflammatory) effects. Recent studies have shown the potent regenerative effect of stem cell therapy in gynecologic diseases such as infertility, Asherman syndrome, lichen sclerosus, polycystic ovary syndrome, premature ovarian insufficiency, genitourinary syndrome of menopause, and rectovaginal fistulas. Moreover, the successful isolation of oogonial stem cells could lead to a revolution in the field of gynecology and the potential treatment of the conditions discussed. This review aims to provide a better understanding of the latest therapeutic options involving stem cells and raise awareness of this promising yet not widely known topic in gynecology and medicine in general.

Analysis of meristems and plant regeneration at single-cell resolution

Rapid development of high-throughput single-cell RNA sequencing (scRNA-seq) technologies offers exciting opportunities to reveal new and rare cell types, previously hidden cell states, and continuous developmental trajectories. In this review, we first illustrate the ways in which scRNA-seq enables researchers to distinguish between distinct plant cell populations, delineate cell cycle continuums, and infer continuous differentiation trajectories of diverse cell types in shoots, roots, and floral and vascular meristems with unprecedented resolution. We then highlight the emerging power of scRNA-seq to dissect cell heterogeneity in regenerating tissues and uncover the cellular basis of cell reprogramming and stem cell commitment during plant regeneration. We conclude by discussing related outstanding questions in the field.

Human 8-cell embryo-like cells from pluripotent stem cells

The totipotent embryo initiates transcription during zygotic or embryonic genome activation (EGA, ZGA). ZGA occurs at the 8-cell stage in humans and its failure leads to developmental arrest. Understanding the molecular pathways underlying ZGA and totipotency is essential to comprehend human development. Recently, human 8-cell-like cells (8CLCs) have been discovered in vitro that resemble the 8-cell embryo. 8CLCs exist among naive pluripotent stem cells and can be induced genetically or chemically. Their ZGA-like transcriptome, transposable element activation, 8-cell embryo-specific protein expression, and developmental properties make them an exceptional model system to study early embryonic cell-state transitions and human totipotency programs in vitro.

Recent advances in stem cell-based blastocyst models

Early embryo development is a highly dynamic process that plays a crucial role in determining the health and characteristics of an organism. For many years, embryonic and extraembryonic stem cell lines representing various developmental stages have served as valuable models for studying early embryogenesis. As our understanding of stem cell culture and embryo development has advanced, researchers have been able to create more sophisticated 3D structures mimicking early embryos, such as blastocyst-like structures (blastoids). These innovative models represent a significant leap forward in the field. In this mini-review, we will discuss the latest progress in stem cell-based embryo models, explore potential future directions, and examine how these models contribute to a deeper understanding of early mammalian development.

Human trophoblast stem cell-state acquisition from pluripotent stem cells and somatic cells

For an extended period of time, research on human embryo implantation and early placentation was hindered by ethical limitation and lack of appropriate in vitro models. Recently, an explosion of new research has significantly expanded our knowledge of early human trophoblast development and facilitated the derivation and culture of self-renewing human trophoblast stem cells (hTSCs). Multiple approaches have been undertaken in efforts to derive and understand hTSCs, including from blastocysts, early trophoblast tissue, and, more recently, from human pluripotent stem cells (hPSCs) and somatic cells. In this concise review, we summarize recent advances in derivation of hTSCs, with a focus on derivation from naive and primed hPSCs, as well as via reprogramming of somatic cells into induced hTSCs. Each of these methods harbors distinct advantages and setbacks, which are discussed. Finally, we briefly explore the possibility of the existence of trophectoderm-like hTSCs corresponding to earlier, preimplantation trophoblast cells.

Current state of stem cell research in non-human primates: an overview

The remarkable similarity between non-human primates (NHPs) and humans establishes them as essential models for understanding human biology and diseases, as well as for developing novel therapeutic strategies, thereby providing more comprehensive reference data for clinical treatment. Pluripotent stem cells such as embryonic stem cells and induced pluripotent stem cells provide unprecedented opportunities for cell therapies against intractable diseases and injuries. As continue to harness the potential of these biotechnological therapies, NHPs are increasingly being employed in preclinical trials, serving as a pivotal tool to evaluate the safety and efficacy of these interventions. Here, we review the recent advancements in the fundamental research of stem cells and the progress made in studies involving NHPs.

Chemically induced reprogramming to reverse cellular aging

A hallmark of eukaryotic aging is a loss of epigenetic information, a process that can be reversed. We have previously shown that the ectopic induction of the Yamanaka factors OCT4, SOX2, and KLF4 (OSK) in mammals can restore youthful DNA methylation patterns, transcript profiles, and tissue function, without erasing cellular identity, a process that requires active DNA demethylation. To screen for molecules that reverse cellular aging and rejuvenate human cells without altering the genome, we developed high-throughput cell-based assays that distinguish young from old and senescent cells, including transcription-based aging clocks and a real-time nucleocytoplasmic compartmentalization (NCC) assay. We identify six chemical cocktails, which, in less than a week and without compromising cellular identity, restore a youthful genome-wide transcript profile and reverse transcriptomic age. Thus, rejuvenation by age reversal can be achieved, not only by genetic, but also chemical means.

PHDs-seq: a large-scale phenotypic screening method for drug discovery through parallel multi-readout quantification

High-throughput phenotypic screening is a cornerstone of drug development and the main technical approach for stem cell research. However, simultaneous detection of activated core factors responsible for cell fate determination and accurate assessment of directional cell transition are difficult using conventional screening methods that focus on changes in only a few biomarkers. The PHDs-seq (Probe Hybridization based Drug screening by sequencing) platform was developed to evaluate compound function based on their transcriptional effects in a wide range of signature biomarkers. In this proof-of-concept demonstration, several sets of markers related to cell fate determination were profiled in adipocyte reprogramming from dermal fibroblasts. After validating the accuracy, sensitivity and reproducibility of PHDs-seq data in molecular and cellular assays, a panel of 128 signalling-related compounds was screened for the ability to induce reprogramming of keloid fibroblasts (KF) into adipocytes. Notably, the potent ATP-competitive VEGFR/PDGFR inhibitor compound, ABT869, was found to promote the transition from fibroblasts to adipocytes. This study highlights the power and accuracy of the PHDs-seq platform for high-throughput drug screening in stem cell research, and supports its use in basic explorations of the molecular mechanisms underlying disease development.

Research progress in clinical trials of stem cell therapy for stroke and neurodegenerative diseases

The incidence of stroke and neurodegenerative diseases is gradually increasing in modern society, but there is still no treatment that is effective enough. Stem cells are cells that can reproduce (self-renew) and differentiate into the body, which have shown significance in basic research, while doctors have also taken them into clinical trials to determine their efficacy and safety. Existing clinical trials mainly include middle-aged and elderly patients with stroke or Parkinson's disease (mostly 40-80 years old), mainly involving injection of mesenchymal stem cells and bone marrow mesenchymal stem cells through the veins and the putamen, with a dosage of mostly 106-108 cells. The neural and motor functions of the patients were restored after stem cell therapy, and the safety was found to be good during the follow-up period of 3 months to 5 years. Here, we review all clinical trials and the latest advances in stroke, Alzheimer's disease, and Parkinson's disease, with the hope that stem cell therapy will be used in the clinic in the future to achieve effective treatment rates and benefit patients.

Stem Cell Therapies in Movement Disorders: Lessons from Clinical Trials

Stem cell-based therapies (SCT) to treat neurodegenerative disorders have promise but clinical trials have only recently begun, and results are not expected for several years. While most SCTs largely lead to a symptomatic therapeutic effect by replacing lost cell types, there may also be disease-modifying therapeutic effects. In fact, SCT may complement a multi-drug, subtype-specific therapeutic approach, consistent with the idea of precision medicine, which matches molecular therapies to biological subtypes of disease. In this narrative review, we examine published and ongoing trials in SCT in Parkinson's Disease, atypical parkinsonian disorders, Huntington's disease, amyotrophic lateral sclerosis, and spinocerebellar ataxia in humans. We discuss the benefits and pitfalls of using this treatment approach within the spectrum of disease-modification efforts in neurodegenerative diseases. SCT may hold greater promise in the treatment of neurodegenerative disorders, but much research is required to determine the feasibility, safety, and efficacy of these complementary aims of therapeutic efforts.

Interplay of phytohormones and epigenetic regulation: A recipe for plant development and plasticity

Both phytohormone signaling and epigenetic mechanisms have long been known to play crucial roles in plant development and plasticity in response to ambient stimuli. Indeed, diverse signaling pathways mediated by phytohormones and epigenetic processes integrate multiple upstream signals to regulate various plant traits. Emerging evidence indicates that phytohormones and epigenetic processes interact at multiple levels. In this review, we summarize the current knowledge of the interplay between phytohormones and epigenetic processes from the perspective of phytohormone biology. We also review chemical regulators used in epigenetic studies and propose strategies for developing novel regulators using multidisciplinary approaches.

Attempts for deriving extended pluripotent stem cells from common marmoset embryonic stem cells

Extended pluripotent stem cells (EPSCs) derived from mice and humans showed an enhanced potential for chimeric formation. By exploiting transcriptomic approaches, we assessed the differences in gene expression profile between extended EPSCs derived from mice and humans, and those newly derived from the common marmoset (marmoset; Callithrix jacchus). Although the marmoset EPSC-like cells displayed a unique colony morphology distinct from murine and human EPSCs, they displayed a pluripotent state akin to embryonic stem cells (ESCs), as confirmed by gene expression and immunocytochemical analyses of pluripotency markers and three-germ-layer differentiation assay. Importantly, the marmoset EPSC-like cells showed interspecies chimeric contribution to mouse embryos, such as E6.5 blastocysts in vitro and E6.5 epiblasts in vivo in mouse development. Also, we discovered that the perturbation of gene expression of the marmoset EPSC-like cells from the original ESCs resembled that of human EPSCs. Taken together, our multiple analyses evaluated the efficacy of the method for the derivation of marmoset EPSCs.

Current status of producing autologous hematopoietic stem cells

Hematopoietic stem cells (HSCs) transplantation is an established therapy for many diseases of the hematopoietic system, for example aplastic anemia, acute myeloid leukemia and acute lymphoblastic leukemia. With the development of the HSCs research, HSCs provide an attractive method for treating hereditary blood disorders and immunotherapy of cancer by introducing gene modification. Compared with allogenic HSCs transplantation, using autologous HSCs or HSCs from induced pluripotent stem cells (iPSCs) would eliminate the probability of alloimmunization and transfusion-transmitted infectious diseases. The methods for obtaining autologous HSCs include amplifying patients' HSCs or inducing patients' somatic cells to HSCs (graph abstract). However, the biggest problem is inducing HSCs to proliferate in vitro and maintaining their stemness at the same time. Although many tests have been made to transform iPSCs to HSCs, the artificially generated HSCs still have substantial disparity compared with physiological HSCs. This review summarized the application status and obstacles to implantation of autologous HSCs and iPSC-derived HSCs. Meanwhile, we summarized the latest research progress in HSCs amplification and iPSCs reprogramming methods, which will help to solve the problems mentioned above.

Chemical journey of somatic cells to pluripotency

Reprogramming somatic cells to pluripotent stem cells has revolutionized the biomedical field by providing enormous hopes and opportunities for the regeneration of tissues and organs for transplantation. Using a small molecule cocktail of epigenetic modifiers and cell signalling inhibitors, a chemical-based easy and controllable technique for converting human somatic cells into chemically induced pluripotent stem cells was recently reported (Guan, Nature 605:325–31, 2022). This novel approach offers well-defined, safe, simple, easy, and clinical-grade manufacturing strategies for modifying the fate of human cells required for regenerative therapeutics.

Comparative functional genomics identifies unique molecular features of EPSCs

The authors provide a comprehensive resource on proteomics, transcriptomic, and epigenetic level details of EPSCs to shed light on possible molecular pathways regulating their expanded pluripotency potential.

Extended pluripotent or expanded potential stem cells (EPSCs) possess superior developmental potential to embryonic stem cells (ESCs). However, the molecular underpinning of EPSC maintenance in vitro is not well defined. We comparatively studied transcriptome, chromatin accessibility, active histone modification marks, and relative proteomes of ESCs and the two well-established EPSC lines to probe the molecular foundation underlying EPSC developmental potential. Despite some overlapping transcriptomic and chromatin accessibility features, we defined sets of molecular signatures that distinguish EPSCs from ESCs in transcriptional and translational regulation as well as metabolic control. Interestingly, EPSCs show similar reliance on pluripotency factors Oct4, Sox2, and Nanog for self-renewal as ESCs. Our study provides a rich resource for dissecting the regulatory network that governs the developmental potency of EPSCs and exploring alternative strategies to capture totipotent stem cells in culture.

The regulation of totipotency transcription: Perspective from in vitro and in vivo totipotency

Totipotency represents the highest developmental potency. By definition, totipotent stem cells are capable of giving rise to all embryonic and extraembryonic cell types. In mammalian embryos, totipotency occurs around the zygotic genome activation period, which is around the 2-cell stage in mouse embryo or the 4-to 8-cell stage in human embryo. Currently, with the development of in vitro totipotent-like models and the advances in small-scale genomic methods, an in-depth mechanistic understanding of the totipotency state and regulation was enabled. In this review, we explored and summarized the current views about totipotency from various angles, including genetic and epigenetic aspects. This will hopefully formulate a panoramic view of totipotency from the available research works until now. It can also help delineate the scaffold and formulate new hypotheses on totipotency for future research works.

Stem cell-based models of early mammalian development

The complex process by which a single-celled zygote develops into a viable embryo is nothing short of a miraculous wonder of the natural world. Elucidating how this process is orchestrated in humans has long eluded the grasp of scientists due to ethical and practical limitations. Thankfully, pluripotent stem cells that resemble early developmental cell types possess the ability to mimic specific embryonic events. As such, murine and human stem cells have been leveraged by scientists to create in vitro models that aim to recapitulate different stages of early mammalian development. Here, we examine the wide variety of stem cell-based embryo models that have been developed to recapitulate and study embryonic events, from pre-implantation development through to early organogenesis. We discuss the applications of these models, key considerations regarding their importance within the field, and how such models are expected to grow and evolve to achieve exciting new milestones in the future.