We analyzed the DNA methylome of ten subpopulations spanning the entire B cell differentiation program by whole-genome bisulfite sequencing and high-density microarrays. We observed that non-CpG methylation disappeared upon B cell commitment, whereas CpG methylation changed extensively during B cell maturation, showing an accumulative pattern and affecting around 30% of all measured CpG sites. Early differentiation stages mainly displayed enhancer demethylation, which was associated with upregulation of key B cell transcription factors and affected multiple genes involved in B cell biology. Late differentiation stages, in contrast, showed extensive demethylation of heterochromatin and methylation gain at Polycomb-repressed areas, and genes with apparent functional impact in B cells were not affected. This signature, which has previously been linked to aging and cancer, was particularly widespread in mature cells with an extended lifespan. Comparing B cell neoplasms with their normal counterparts, we determined that they frequently acquire methylation changes in regions already undergoing dynamic methylation during normal B cell differentiation.

a severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, and real-time reverse transcription-PCR is currently the most reliable diagnostic method for COVID-19 around the world. Korean Society for Laboratory Medicine and the Korea Centers for Disease Prevention and Control propose guidelines for diagnosing COVID-19 in clinical laboratories in Korea. These guidelines are based on other related domestic and international guidelines, as well as expert opinions and include the selection of test subjects, selection of specimens, diagnostic methods, interpretation of test results, and biosafety.

The XN provided reliable results on low cell counts, as well as reduced manual blood film reviews, while maintaining a proper level of diagnostic sensitivity.

Highly sensitive and specific molecular assays such as MEMO sequencing are optimal for detecting the BRAF mutations in thyroid FNAC because these techniques can detect PTC that might be missed by cytology or less sensitive molecular assays.

The epigenetic changes during B-cell development relevant to both normal function and hematologic malignancy are incompletely understood. We examined DNA methylation and RNA expression status during early B-cell development by sorting multiple replicates of four separate stages of pre-B cells derived from normal human fetal bone marrow and applied high-dimension DNA methylation scanning and expression arrays. Features of promoter and gene body DNA methylation were strongly correlated with RNA expression in multipotent progenitors (MPPs) both in a static state and throughout differentiation. As MPPs commit to pre-B cells, a predominantly demethylating phenotype ensues, with 79% of the 2966 differentially methylated regions observed involving demethylation. Demethylation events were more often gene body associated rather than promoter associated; predominantly located outside of CpG islands; and closely associated with EBF1, E2F, PAX5 and other functional transcription factor (TF) sites related to B-cell development. Such demethylation events were accompanied by TF occupancy. After commitment, DNA methylation changes appeared to play a smaller role in B-cell development. We identified a distinct development-dependent demethylation signature which has gene expression regulatory properties for pre-B cells, and provide a catalog reference for the epigenetic changes that occur in pre-B-cell leukemia and other B-cell-related diseases.

Summary.A 20-year-old woman with high-risk acute myelogenous leukaemia was transplanted with granulocyte colony stimulating factor (G-CSF)-mobilized peripheral blood CD34+ haematopoietic stem cells and bone-marrowderived mesenchymal stem cells (MSC) from her human leucocyte antigen haplotype-mismatched father after myeloablative conditioning therapy. The patient engrafted rapidly and had no acute or chronic graft-versus-host disease. Since transplantation, the patient has shown an enduring trilineage haematological complete response without any evidence of leukaemia relapse at 31 months. We suggest that MSC can be used effectively for genetically haploidentical haematopoietic stem cell transplantation for acute leukaemia.

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Objective To suggest an alternative strategy for deriving histocompatible stems cells without undertaking genetic manipulation. Design Prospective approach using an animal model. Setting Stem cell and bioevaluation laboratory, Seoul National University. Animal(s) F1 (C57BL6 × DBA2) and outbred (ICR) mice. Intervention(s) Ovarian stroma cells of less than 40 μm in diameter were subcultured with fibroblast monolayer, and colony-forming cells were characterized. Main Outcome Measure(s) Stemness, genotype, and imprinted gene methylation. Result(s) Two-lines of colony-forming cells were established, which expressed markers specific for embryonic stem cells (ESC) and formed embryoid bodies and teratomas. Complete matching of microsatellite markers with the cell donor strain confirmed their establishment from ovarian tissue, and identification of both homozygotic and heterozygotic chromosomes raised the possibility of their derivation from parthenogenetic oocytes. However, the use of cells smaller than mature oocytes for primary culture, the difference in imprinted gene methylation compared with parthenogenetic ESCs, and failure to establish the ESC-like cells by primary follicle culture collectively suggested the irrelevancy to gametes. Conclusion(s) Coculture of adult ovarian cells with somatic fibroblasts can yield colony-forming cells having ESC-like activity, which may provide an alternative for establishing autologous stem cells from adults that can be obtained without genetic manipulation.