Stem Cells: from Single Cells to the Clinic

Integrative analysis of single-cell RNA-sequencing datasets across mouse gastrulation and organogenesis identifies cell states and trajectories at successive developmental stages, along with transcription factors that could potentially mediate lineage choices.

A protein expression atlas of transcription factors charted onto cell lineage maps of Caenorhabditis elegans development that uncovers mechanisms of spatiotemporal cell fate patterning and regulators of embryogenesis.

Yang et al. report that H3K9me3 is required for DNA methylation maintenance during mouse pre-implantation and identify 22 putative imprinting control-like regions among CpG-rich regions co-marked by H3K9me3 and DNA methylation.

Totipotent cells in mouse embryos and 2-cell-like cells have slow DNA replication fork speed. Perturbations that slow replication fork speed promote 2-cell-like cell emergence and improve somatic cell nuclear transfer reprogramming and formation of induced pluripotent stem cell colonies.

p53 activates Dux in mouse embryos and embryonic stem cells, as well as DUX4 in human facioscapulohumeral muscular dystrophy cell models.

Posfai, Schell, Janiszewski et al. assess candidate totipotent stem cells with in vitro and in vivo assays of increasing stringency to evaluate their developmental potential and lineage contributions.

The development of a transgene-free, rapid and controllable method for producing eight-cell-like cells from human pluripotent stem cells provides a valuable resource to study early human embryogenesis.

An in vitro culture strategy enables the generation of blastocyst-like structures termed human blastoids from naive human pluripotent stem cells, providing a model for studying human embryogenesis.

Human fibroblasts are reprogrammed to generate blastocyst-like structures called iBlastoids, which recapitulate aspects of embryo implantation.

Blastoids derived from naive PXGL-cultured human pluripotent stem cells in which Hippo, TGF-β and ERK pathways are inhibited closely recapitulate aspects of blastocyst development, form cells resembling blastocyst-stage cells and thus provide a model system for implantation and development studies.

Human early development remains largely inaccessible, owing to technical and ethical limitations of working with natural embryos. Here the authors assess the extent to which human expanded pluripotent stem cells can specify distinct cell lineages and capture aspects of early human embryogenesis.

Previous approaches to derive embryoids either lack physiological morphology and signaling interactions, or are unconducive to model post-gastrulation development. Here the authors use a high-throughput approach to induce mouse embryonic stem cells into epiblast-like aggregates, which are then co-cultured with mouse trophoblast stem cell aggregates, to yield embryoids with axial morphogenesis and anterior development.

Somitogenesis has been well characterized in model organisms, resulting in detailed description of the somite segmentation clock. Here they generate somitogenic organoids from human pluripotent stem cells that recapitulate somitogenesis, periodic segmentation, and proper polarity.

A protocol for the production of human spinal-cord-like organoids that recapitulate the tube-forming morphogenesis of the early human spinal cord facilitates screening for antiepileptic drugs that can cause neural-tube defects.

A dual-channel recording system for high-resolution lineage tracing.

Improved glycemic control after transplantation of human pluripotent stem-cell-derived islets for diabetes treatment in non-human primates.

Optimization of vitrification approaches substantially improves pancreatic islet cryopreservation for banking and boosts transplantation outcomes in diabetes.

Millman and colleagues describe a six-stage monolayer culture differentiation protocol for generating insulin-secreting pancreatic β cells from a variety of human pluripotent stem cell lines and outline steps for in vitro functional assessment.

The complexity of hepatocellular carcinoma (HCC) hinders effective treatment. Here, Lee and colleagues summarize cancer stem cell (CSC) origin and plasticity, CSC–immune system interactions and the effects of the microenvironmental niche on cancer stemness in HCC. Potential CSC-based therapies for HCC are also presented.

Berg et al. establish a panel of patient-derived endometrial cancer organoids and xenograft models. They show that their models recapitulate the genetic profile of the donor tumor and can be used for drug testing and development of a prognostic gene signature.

T-cell immunotherapies, such as CAR-T immunotherapy, are being developed against a wide variety of diseases. Here the authors report the feeder-free, scalable differentiation of human induced pluripotent cells (iPSCs) to T-cells with T-cell receptor dependent anti-tumour function in vitro and in vivo.

Dekkers et al. provide a toolbox for the long-term culture, genetic manipulation and xenotransplantation of human normal and breast cancer organoids.

Long-term monitoring of patients with Wiskott–Aldrich syndrome following lentiviral gene therapy shows a safe profile and a reduction in the frequency of autoimmune manifestations and bleeding events, despite incomplete platelet reconstitution.

Short term systemic expression of the reprogramming factors Oct-3/4, Sox2, Klf4, c-Myc (OSKM) rejuvenates aging cells and promotes tissue regeneration. Here the authors show that myofiber-specific expression of OSKM accelerates muscle regeneration by reducing secretion of muscle stem cell quiescence promoting Wnt4.

Jeong et al. report a series of COVID-19 patients with hearing- and balance-related symptoms. The authors show that human and mouse inner ear tissues, as well as human inner ear cells and organoids derived from induced pluripotent stem cells, express SARS-CoV-2 entry factors, and that these in vitro models of the human inner ear are susceptible to SARS-CoV-2 infection

The CEPT cocktail comprising four small molecules enhances pluripotent stem cell survival, biobanking, organoid formation, and single-cell cloning efficiency by reducing cellular stress.

Intestinal tissue engineering offers a potential therapeutic option for short bowel syndrome. This Review examines the progress in intestinal tissue engineering, discusses the components required for engineered intestinal grafts, preclinical progress and efforts towards clinical translation, including challenges to overcome.

Patterned organoids and bioprinted tissues can be generated by simultaneously co-differentiating pluripotent stem cells into distinct cell types via the forced overexpression of transcription factors, independently of culture-media composition.

Investigations of human cardiac disease involving human pluripotent stem cell-derived cardiomyocytes are limited by the disorganized presentation of biomechanical cues resulting in cell immaturity. Here the authors develop a platform of micron-scale 2D cardiac muscle bundles to precisely deliver physiologic cues, improving reproducibility and throughput.

The metabolically driven maturation of geometrically aligned human cardiac microtissues on a microfabricated chip reduces cell-phenotype-dependent variabilities in the action-potential morphology and calcium handling of the cardiomyocytes.

Organs consist of parenchyma and stroma. Nishinakamura and colleagues induce renal stromal progenitors from mouse pluripotent stem cells (PSCs), and generate completely PSC-derived organoids that reproduce complex kidney structure.

A protocol is described for generating human brain assembloids and performing viral labeling and retrograde tracing, 3D live imaging of axon projection and optogenetics with calcium imaging and electrophysiological recordings to model neural circuits.

In this study, the authors report that pluripotent stem cell-derived ventricular progenitors target loss of myocardium and fibrotic scarring to promote heart regeneration, thus offering new potential therapeutic strategies for heart injury.

The HSC signature RUNX1⁺HOXA9⁺MLLT3⁺MECOM⁺HLF⁺SPINK2⁺ distinguishes haematopoietic stem cells from their endothelial precursors and differentiated progenitors throughout ontogeny

Meacham et al. report that adiponectin receptors suppress chronic inflammatory signalling by immune effector cells to prevent haematopoietic stem cell exit from quiescence and, thus, protect them from exhaustion.

Polarity cues regulate intestinal stem cell fate. Böttcher et al. demonstrate that mouse intestinal stem cells, which express the Wnt/planar cell polarity reporter Flattop, are primed either towards the enteroendocrine or Paneth cell lineage.

Organoid models of intestinal stem cell differentiation into Paneth cells allow for the identification, via high-throughput phenotypic screening, of biological targets and small molecules regulating the composition of intestinal epithelium.

The polarity of gastrointestinal organoids is reversed to study epithelial biology and host–microbe interactions. Access to the apical surface of the epithelium is increased while preserving epithelial integrity and secretory and absorptive functions.

In the male germline, DNMT3C methylates retrotransposons whereas DNMT3A globally methylates the genome and regulates spermatogonial stem cell (SSC) plasticity. Single-cell RNA-sequencing analysis shows that Dnmt3A mutant SSCs self-renew but do not differentiate.