RNAi Screen Identifies MTA1 as an Epigenetic Modifier of Differentiation Commitment in Human HSPCs.

The molecular mechanisms regulating key fate decisions of hematopoietic stem cells (HSCs) remain incompletely understood. Here, we targeted global shRNA libraries to primary human hematopoietic stem and progenitor cells (HSPCs) to screen for modifiers of self-renewal and differentiation, and identified metastasis-associated 1 (MTA1) as a negative regulator of human HSPC propagation in vitro. Knockdown of MTA1 by independent shRNAs in primary human cord blood (CB) HSPCs led to a cell expansion during culture and a relative accumulation of immature CD34CD90 cells with perturbed in vitro differentiation potential.

Sister chromatid cohesion defects are associated with chromosomal copy number heterogeneity in high hyperdiploid childhood acute lymphoblastic leukemia.

High hyperdiploid acute lymphoblastic leukemia (ALL) is one of the most common malignancies in children. The main driver event of this disease is a nonrandom aneuploidy consisting of gains of whole chromosomes but without overt evidence of chromosomal instability (CIN). Here, we investigated the frequency and severity of defective sister chromatid cohesion-a phenomenon related to CIN-in primary pediatric ALL.

Efficient and nontoxic biomolecule delivery to primary human hematopoietic stem cells using nanostraws.

Introduction of exogenous genetic material into primary stem cells is essential for studying biological function and for clinical applications. Traditional delivery methods for nucleic acids, such as electroporation, have advanced the field, but have negative effects on stem cell function and viability. We introduce nanostraw-assisted transfection as an alternative method for RNA delivery to human hematopoietic stem and progenitor cells (HSPCs).

Lysine-specific demethylase 1A restricts ex vivo propagation of human HSCs and is a target of UM171.

Culture conditions in which hematopoietic stem cells (HSCs) can be expanded for clinical benefit are highly sought after. Here, we report that inhibition of the epigenetic regulator lysine-specific histone demethylase 1A (LSD1) induces a rapid expansion of human cord blood-derived CD34+ cells and promotes in vitro propagation of long-term repopulating HSCs by preventing differentiation. The phenotype and molecular characteristics of cells treated with LSD1 inhibitors were highly similar to cells treated with UM171, an agent promoting expansion of HSCs through undefined mechanisms and currently being tested in clinical trials.

Peak window correlation method for drug screening using Raman spectroscopy.

Modern portable and hand-held Raman spectrometers that recently have become widespread in drug quality screening have good reproducibility and are able to detect small concentrations of substances in mixtures of several components or distinguish compounds similar in structure and having minimal differences in spectrum with appropriate mathematical processing methods. Among other spectrum comparison approaches, the peak search at their location is the most important task of spectral imaging of the studied samples. In this work, the Raman spectra of liquid drugs involved in the governmental non-destructive quality screening program performed by 8 mobile laboratories equipped with Raman spectrometers with uncooled detector and a 532 nm laser were compared with reference sample spectra using the peak windows correlation (PWC) algorithm developed in this work by authors.

Cohesin in haematopoiesis and leukaemia.

Purpose Of Review: Disturbance of the delicate balance between self-renewal and differentiation in haematopoietic stem cells (HSCs) can lead to both leukaemia and bone marrow failure. The regulation of this balance in HSC biology has been intensely investigated in several model systems, and lately the importance of epigenetic modifications as well as the organization and architecture of chromatin has become increasingly recognized. In this review, we will focus on the role of the chromatin organizing protein complex cohesin in regulation of normal and malignant haematopoiesis.

Forward RNAi Screens in Human Hematopoietic Stem Cells.

Identifying the genes and pathways that regulate self-renewal and differentiation in somatic stem cells is a central goal in stem cell and cancer biology. Here, we describe a method for RNA interference (RNAi)-based screens combined with next-generation sequencing (NGS) in primary human hematopoietic stem and progenitor cells (HSPCs). These cells are suitable targets for complex, selection-based screens using pooled lentiviral short hairpin RNA (shRNA) libraries.

SUITABILITY OF PORTABLE RADIONUCLIDE IDENTIFIERS FOR EMERGENCY INCORPORATION MONITORING.

The suitability of portable nuclide inspectors for incorporation measurements were tested with three probes (LaBr3(Ce), NaI(Tl) and HPGe) differing in sensitive volume and energy resolution. The efficiencies for the measurement of whole-body and lung radionuclide burden were calibrated using a whole-body block phantom with traceable radionuclide sources of 60Co, 133Ba, 137Cs, 152Eu and 40K. A standing geometry was chosen as it allows rapid positioning of persons for the measurements.

Genome-wide RNAi Screen Identifies Cohesin Genes as Modifiers of Renewal and Differentiation in Human HSCs.

To gain insights into the regulatory mechanisms of hematopoietic stem cells (HSCs), we employed a genome-wide RNAi screen in human cord-blood derived cells and identified candidate genes whose knockdown maintained the HSC phenotype during culture. A striking finding was the identification of members of the cohesin complex (STAG2, RAD21, STAG1, and SMC3) among the top 20 genes from the screen. Upon individual validation of these cohesin genes, we found that their knockdown led to an immediate expansion of cells with an HSC phenotype in vitro.

Bile Acids Protect Expanding Hematopoietic Stem Cells from Unfolded Protein Stress in Fetal Liver.

During development, hematopoietic stem cells (HSCs) undergo a rapid expansion in the fetal liver (FL) before settling in the adult bone marrow. We recently reported that proliferating adult HSCs are vulnerable to ER stress caused by accumulation of mis-folded proteins. Here, we find that FL-HSCs, despite an increased protein synthesis rate and a requirement for protein folding, do not upregulate ER chaperones.

Jarid2 regulates hematopoietic stem cell function by acting with polycomb repressive complex 2.

Polycomb repressive complex 2 (PRC2) plays a key role in hematopoietic stem and progenitor cell (HSPC) function. Analyses of mouse mutants harboring deletions of core components have implicated PRC2 in fine-tuning multiple pathways that instruct HSPC behavior, yet how PRC2 is targeted to specific genomic loci within HSPCs remains unknown. Here we use short hairpin RNA-mediated knockdown to survey the function of PRC2 accessory factors that were defined in embryonic stem cells (ESCs) by testing the competitive reconstitution capacity of transduced murine HSPCs.

RNAi screen identifies MAPK14 as a druggable suppressor of human hematopoietic stem cell expansion.

We report on a forward RNAi screen in primary human hematopoietic stem and progenitor cells, using pooled lentiviral shRNA libraries deconvoluted by next generation sequencing. We identify MAPK14/p38α as a modulator of ex vivo stem cell proliferation and show that pharmacologic inhibition of p38 dramatically enhances the stem cell activity of cultured umbilical cord blood derived hematopoietic cells. p38 inhibitors should thus be considered in strategies aiming at expanding stem cells for clinical benefit.