Lineage tracing of human development through somatic mutations.

The ontogeny of the human haematopoietic system during fetal development has previously been characterized mainly through careful microscopic observations. Here we reconstruct a phylogenetic tree of blood development using whole-genome sequencing of 511 single-cell-derived haematopoietic colonies from healthy human fetuses at 8 and 18 weeks after conception, coupled with deep targeted sequencing of tissues of known embryonic origin. We found that, in healthy fetuses, individual haematopoietic progenitors acquire tens of somatic mutations by 18 weeks after conception.

Integrative Single-Cell RNA-Seq and ATAC-Seq Analysis of Human Developmental Hematopoiesis.

Regulation of hematopoiesis during human development remains poorly defined. Here we applied single-cell RNA sequencing (scRNA-seq) and single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq) to over 8,000 human immunophenotypic blood cells from fetal liver and bone marrow. We inferred their differentiation trajectory and identified three highly proliferative oligopotent progenitor populations downstream of hematopoietic stem cells (HSCs)/multipotent progenitors (MPPs).

Single-Cell Transcriptomic Analysis of Hematopoietic Cells.

Single-cell RNA sequencing (scRNA-Seq) allows the complete and unbiased analysis of the transcriptional state of an individual cell. In the past 5 years, scRNA-Seq contributed to the progress of the hematology field, advancing our knowledge of both normal and malignant hematopoiesis. Different scRNA-Seq methods are available, all relying on the conversion of RNA to cDNA, followed by amplification of cDNA in order to obtain a sufficient amount of genetic material for sequencing.

Publisher Correction: Human mid-trimester amniotic fluid (stem) cells lack expression of the pluripotency marker OCT4A.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Application of single-cell RNA sequencing methodologies in understanding haematopoiesis and immunology.

The blood and immune system are characterised by utmost diversity in its cellular components. This heterogeneity can solely be resolved with the application of single-cell technologies that enable precise examination of cell-to-cell variation. Single-cell transcriptomics is continuously pushing forward our understanding of processes driving haematopoiesis and immune responses in physiological settings as well as in disease.

Human mid-trimester amniotic fluid (stem) cells lack expression of the pluripotency marker OCT4A.

Expression of OCT4A is one of the hallmarks of pluripotency, defined as a stem cell's ability to differentiate into all the lineages of the three germ layers. Despite being defined as non-tumorigenic cells with high translational potential, human mid-trimester amniotic fluid stem cells (hAFSCs) are often described as sharing features with embryonic stem cells, including the expression of OCT4A, which could hinder their clinical potential. To clarify the OCT4A status of hAFSCs, we first undertook a systematic review of the literature.

Dissecting human disease with single-cell omics: application in model systems and in the clinic.

Probing cellular population diversity at single-cell resolution became possible only in recent years. The popularity of single-cell 'omic' approaches, which allow researchers to dissect sample heterogeneity and cell-to-cell variation, continues to grow. With continuous technological improvements, single-cell omics are becoming increasingly prevalent and contribute to the discovery of new and rare cell types, and to the deciphering of disease pathogenesis and outcome.

Single-cell biology: resolving biological complexity, one cell at a time.

In March 2018, over 250 researchers came together at the Wellcome Genome Campus in Hinxton, Cambridge, UK, to present their latest research in the area of single-cell biology. A highly interdisciplinary meeting, the Single Cell Biology conference covered a variety of topics, ranging from cutting-edge technological innovation, developmental biology and stem cell research to evolution and cancer. This meeting report summarises the key findings presented and the major research themes that emerged during the conference.

Micro-computed tomography reconstructions of tibiae of stem cell transplanted osteogenesis imperfecta mice.

Micro-computed tomography (micro-CT) is commonly used to assess bone quality and to evaluate the outcome of experimental therapies in animal models of bone diseases. Generating large datasets is however challenging and data are rarely made publicly available through shared repositories. Here we describe a dataset of micro-CT reconstructed scans of the proximal part of 21 tibiae from wild-type mice, osteogenesis imperfecta mice (homozygous oim/oim) and oim/oim mice transplanted with human amniotic fluid stem cells.

Embryonic Stem Cell-Derived Mesenchymal Stem Cells (MSCs) Have a Superior Neuroprotective Capacity Over Fetal MSCs in the Hypoxic-Ischemic Mouse Brain.

Human mesenchymal stem cells (MSCs) have huge potential for regenerative medicine. In particular, the use of pluripotent stem cell-derived mesenchymal stem cells (PSC-MSCs) overcomes the hurdle of replicative senescence associated with the in vitro expansion of primary cells and has increased therapeutic benefits in comparison to the use of various adult sources of MSCs in a wide range of animal disease models. On the other hand, fetal MSCs exhibit faster growth kinetics and possess longer telomeres and a wider differentiation potential than adult MSCs.

TGFβ-induced osteogenic potential of human amniotic fluid stem cells via CD73-generated adenosine production.

The human amniotic fluid stem cell (hAFSC) population consists of two morphologically distinct subtypes, spindle-shaped and round-shaped cells (SS-hAFSCs and RS-hAFSCs). Whilst SS-hAFSCs are routinely expanded in mesenchymal-type (MT) conditions, we previously showed that they acquire broader differentiation potential when cultured under embryonic-type (ET) conditions. However, the effects of culture conditions on RS-hAFSCs have not been determined.

Human Amniocytes Are Receptive to Chemically Induced Reprogramming to Pluripotency.

Restoring pluripotency using chemical compounds alone would be a major step forward in developing clinical-grade pluripotent stem cells, but this has not yet been reported in human cells. We previously demonstrated that VPA_AFS cells, human amniocytes cultivated with valproic acid (VPA) acquired functional pluripotency while remaining distinct from human embryonic stem cells (hESCs), questioning the relationship between the modulation of cell fate and molecular regulation of the pluripotency network. Here, we used single-cell analysis and functional assays to reveal that VPA treatment resulted in a homogeneous population of self-renewing non-transformed cells that fulfill the hallmarks of pluripotency, i.

Counteracting bone fragility with human amniotic mesenchymal stem cells.

The impaired maturation of bone-forming osteoblasts results in reduced bone formation and subsequent bone weakening, which leads to a number of conditions such as osteogenesis imperfecta (OI). Transplantation of human fetal mesenchymal stem cells has been proposed as skeletal anabolic therapy to enhance bone formation, but the mechanisms underlying the contribution of the donor cells to bone health are poorly understood and require further elucidation. Here, we show that intraperitoneal injection of human amniotic mesenchymal stem cells (AFSCs) into a mouse model of OI (oim mice) reduced fracture susceptibility, increased bone strength, improved bone quality and micro-architecture, normalised bone remodelling and reduced TNFα and TGFβ sigalling.