Single-cell analyses and machine learning define hematopoietic progenitor and HSC-like cells derived from human PSCs.

Hematopoietic stem and progenitor cells (HSPCs) develop in distinct waves at various anatomical sites during embryonic development. The in vitro differentiation of human pluripotent stem cells (hPSCs) recapitulates some of these processes; however, it has proven difficult to generate functional hematopoietic stem cells (HSCs). To define the dynamics and heterogeneity of HSPCs that can be generated in vitro from hPSCs, we explored single-cell RNA sequencing (scRNAseq) in combination with single-cell protein expression analysis.

A human iPSC line capable of differentiating into functional macrophages expressing ZsGreen: a tool for the study and tracking of therapeutic cells.

We describe the production of a human induced pluripotent stem cell (iPSC) line, SFCi55-ZsGr, that has been engineered to express the fluorescent reporter gene, ZsGreen, in a constitutive manner. The CAG-driven ZsGreen expression cassette was inserted into the locus and a high level of expression was observed in undifferentiated iPSCs and in cell lineages derived from all three germ layers including haematopoietic cells, hepatocytes and neurons. We demonstrate efficient production of terminally differentiated macrophages from the SFCi55-ZsGreen iPSC line and show that they are indistinguishable from those generated from their parental SFCi55 iPSC line in terms of gene expression, cell surface marker expression and phagocytic activity.

SplitAx: A novel method to assess the function of engineered nucleases.

Engineered nucleases have been used to generate knockout or reporter cell lines and a range of animal models for human disease. These new technologies also hold great promise for therapeutic genome editing. Current methods to evaluate the activity of these nucleases are time consuming, require extensive optimization and are hampered by readouts with low signals and high background.

Activation of KLF1 Enhances the Differentiation and Maturation of Red Blood Cells from Human Pluripotent Stem Cells.

Blood transfusion is widely used in the clinic but the source of red blood cells (RBCs) is dependent on donors, procedures are susceptible to transfusion-transmitted infections and complications can arise from immunological incompatibility. Clinically-compatible and scalable protocols that allow the production of RBCs from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been described but progress to translation has been hampered by poor maturation and fragility of the resultant cells. Genetic programming using transcription factors has been used to drive lineage determination and differentiation so we used this approach to assess whether exogenous expression of the Erythroid Krüppel-like factor 1 (EKLF/KLF1) could augment the differentiation and stability of iPSC-derived RBCs.

Enforced Expression of HOXB4 in Human Embryonic Stem Cells Enhances the Production of Hematopoietic Progenitors but Has No Effect on the Maturation of Red Blood Cells.

Unlabelled: : We have developed a robust, Good Manufacturing Practice-compatible differentiation protocol capable of producing scalable quantities of red blood cells (RBCs) from human pluripotent stem cells (hPSCs). However, translation of this protocol to the clinic has been compromised because the RBCs produced are not fully mature; thus, they express embryonic and fetal, rather than adult globins, and they do not enucleate efficiently. Based on previous studies, we predicted that activation of exogenous HOXB4 would increase the production of hematopoietic progenitor cells (HPCs) from hPSCs and hypothesized that it might also promote the production of more mature, definitive RBCs.

A Role for MOSPD1 in Mesenchymal Stem Cell Proliferation and Differentiation.

Mesenchymal stem cells (MSCs) isolated from many tissues including bone marrow and fat can be expanded in vitro and can differentiate into a range of different cell types such as bone, cartilage, and adipocytes. MSCs can also exhibit immunoregulatory properties when transplanted but, although a number of clinical trials using MSCs are in progress, the molecular mechanisms that control their production, proliferation, and differentiation are poorly understood. We identify MOSPD1 as a new player in this process.

Transcribed enhancers lead waves of coordinated transcription in transitioning mammalian cells.

Although it is generally accepted that cellular differentiation requires changes to transcriptional networks, dynamic regulation of promoters and enhancers at specific sets of genes has not been previously studied en masse. Exploiting the fact that active promoters and enhancers are transcribed, we simultaneously measured their activity in 19 human and 14 mouse time courses covering a wide range of cell types and biological stimuli. Enhancer RNAs, then messenger RNAs encoding transcription factors, dominated the earliest responses.

HOXB4 can enhance the differentiation of embryonic stem cells by modulating the hematopoietic niche.

Hematopoietic differentiation of embryonic stem cells (ESCs) in vitro has been used as a model to study early hematopoietic development, and it is well documented that hematopoietic differentiation can be enhanced by overexpression of HOXB4. HOXB4 is expressed in hematopoietic progenitor cells (HPCs) where it promotes self-renewal, but it is also expressed in the primitive streak of the gastrulating embryo. This led us to hypothesize that HOXB4 might modulate gene expression in prehematopoietic mesoderm and that this property might contribute to its prohematopoietic effect in differentiating ESCs.

Induction of hematopoietic differentiation of mouse embryonic stem cells by an AGM-derived stromal cell line is not further enhanced by overexpression of HOXB4.

Hematopoietic differentiation of embryonic stem (ES) cells can be enhanced by co-culture with stromal cells derived from hematopoietic tissues and by overexpression of the transcription factor HOXB4. In this study, we compare the hematopoietic inductive effects of stromal cell lines derived from different subregions of the embryonic aorta-gonad-mesonephros tissue with the commonly used OP9 stromal cell line and with HOXB4 activation. We show that stromal cell lines derived from the aorta and surrounding mesenchyme (AM) act at an earlier stage of the differentiation process compared with the commonly used OP9 stromal cells.

Expression-independent gene trap vectors for random and targeted mutagenesis in embryonic stem cells.

Promoterless gene trap vectors have been widely used for high-efficiency gene targeting and random mutagenesis in embryonic stem (ES) cells. Unfortunately, such vectors are only effective for genes expressed in ES cells and this has prompted the development of expression-independent vectors. These polyadenylation (poly A) trap vectors employ a splice donor to capture an endogenous gene's polyadenylation sequence and provide transcript stability.

Aminopeptidase O contains a functional nucleolar localization signal and is implicated in vascular biology.

We have identified a gene trap integration into Aminopeptidase O, the gene encoding a member of the M1 family of metalloproteases. Using the betagal reporter of the gene trap vector, we have revealed that at least some ApO isoforms are expressed predominantly in embryonic and adult blood vessels leading us to propose that ApO plays a role in vascular cell biology. The protein produced from an engineered Gfp-ApO fusion cDNA localises to the nucleolus in transfected COS7 cells.

A novel transmembrane MSP-containing protein that plays a role in right ventricle development.

We have identified and characterized a gene, Mospd3 on mouse chromosome 5 using gene trapping in ES cells. MOSPD3 is part of a family of proteins, including MOSPD1, which is defined by the presence of a major sperm protein (MSP) domain and two transmembrane domains. Interestingly Mospd3 is mammalian specific and highly conserved between mouse and man.

Hemolytic uremic syndrome associated with Denys-Drash syndrome.

The Denys-Drash syndrome is defined by the occurrence of combinations of pseudohermaphroditism, nephrotic syndrome with diffuse mesangial sclerosis, Wilms' tumor, and constitutional mutations in the WT1 suppressor gene. Most patients develop end-stage renal failure. Atypical hemolytic uremic syndrome (HUS) is defined by onset of acute hemolytic anemia with fragmented erythrocytes, thrombocytopenia, and renal failure in the absence of a gastrointestinal prodromal illness of bloody diarrhea.

Mutational hot spot within a new RPGR exon in X-linked retinitis pigmentosa.

The gene RPGR was previously identified in the RP3 region of Xp21.1 and shown to be mutated in 10-20% of patients with the progressive retinal degeneration X-linked retinitis pigmentosa (XLRP). The mutations predominantly affected a domain homologous to RCC1, a guanine nucleotide exchange factor for the small GTPase Ran, although they were present in fewer than the 70-75% of XLRP patients predicted from linkage studies.

Missense mutations in the most ancient residues of the PAX6 paired domain underlie a spectrum of human congenital eye malformations.

Mutations of the human PAX6 gene underlie aniridia (congenital absence of the iris), a rare dominant malformation of the eye. The spectrum of PAX6 mutations in aniridia patients is highly biased, with 92% of all reported mutations leading to premature truncation of the protein (nonsense, splicing, insertions and deletions) and just 2% leading to substitution of one amino acid by another (missense). The extraordinary conservation of the PAX6 protein at the amino acid level amongst vertebrates predicts that pathological missense mutations should in fact be common even though they are hardly ever seen in aniridia patients.

EYA4, a novel vertebrate gene related to Drosophila eyes absent.

We have isolated a family of four vertebrate genes homologous to eyes absent (eya), a key regulator of ocular development in Drosophila. Here we present the detailed characterization of the EYA4 gene in human and mouse. EYA4 encodes a 640 amino acid protein containing a highly conserved C-terminal domain of 271 amino acids which in Drosophila eya is known to mediate developmentally important protein-protein interactions.

A new set of primers for mutation analysis of the human PAX6 gene.

Mutations in the human PAX6 gene are an important cause of dominantly inherited congenital malformations of the eye, including aniridia, Peters' anomaly, keratitis, and isolated foveal hypoplasia. To satisfy the need for efficient detection of PAX6 mutations, we have developed a new set of oligonucleotides for genomic SSCP based on the recently completed genomic sequence of the entire human PAX6 gene. We also describe PAX6 mutations in eight aniridia patients, five of which are novel.

Combined SSCP/heteroduplex analysis in the screening for PAX6 mutations.

We demonstrate the use of combined SSCP and heteroduplex analysis in the detection of PAX6 mutations using non-radioactive silver staining. A panel of aniridia patients was screened by this approach and we show that a greater number of mutations was detected than would have been found by running each technique alone. Six previously unreported aniridia mutations in PAX6 are also described.

The incidence of PAX6 mutation in patients with simple aniridia: an evaluation of mutation detection in 12 cases.

Twelve aniridia patients, five with a family history and seven presumed to be sporadic, were exhaustively screened in order to test what proportion of people with aniridia, uncomplicated by associated anomalies, carry mutations in the human PAX6 gene. Mutations were detected in 90% of the cases. Three mutation detection techniques were used to determine if one method was superior for this gene.

A single-tube multiplex system for the simultaneous detection of 10 common cystic fibrosis mutations.

We describe a nonisotopic single-tube polymerase chain reaction (PCR) multiplex system that detects 10 of the more common cystic fibrosis (CF) mutations (delta F508, delta I507, V520F, G551D, G542X, R553X, R117H, 621 + 1G-->T, N1303K, A455E). The use of this method detects approximately 90% of the CF alleles in the British population. Five exons of the CF gene are amplified simultaneously by PCR, followed by an overnight triple enzyme restriction digest, and then resolved by high-resolution gel acrylamide electrophoresis.

Antenatal screening for cystic fibrosis: a trial of the couple model.

Objective: To assess the delivery and acceptability of antenatal couple screening for cystic fibrosis. Carrier status was notified only when both members of a partnership had cystic fibrosis alleles and therefore a one in four risk of having an affected child.

Design: Mouthwash samples were tested when both partners participated.

Use of stable dye-DNA intercalating complexes to detect cystic fibrosis mutations.

Several dyes are now known which intercalate into double-stranded DNA with fluorescence enhancement. One such is TOTO (1,1'-(4,4,7,7-tetramethyl-4,7-diazaundecamethylene)-bis-4-[3-meth yl-2,3- dihydro-(benzo-1,3-thiazole)-2-methlyidene]-quinolinium tetraiodide), a homodimer of thiazole orange, whose complexes with DNA are stable to electrophoresis and show a 1000-fold enhancement after binding. We demonstrate that this reagent can be successfully used in combination with a laser-excited fluorescence gel scanner to detect the three most common cystic fibrosis mutant alleles, delta F508, G551D and G542X.

Mass screening for cystic fibrosis heterozygotes: two assay systems compared.

Two different assay systems were used to detect mutant cystic fibrosis alleles in mouthwash samples from pregnant women attending antenatal clinics. In the first phase of the study, comprising 3110 consecutive samples, we compared the performance of an in-house system and a commercial amplification refractory mutation system (ARMS). Successful analyses were completed at first attempt in approximately 90% of samples, and the patient resampling rate was 1.