Secondary loss of miR-3607 reduced cortical progenitor amplification during rodent evolution

Expression of miR-3607 in embryonic mammalian cerebral cortex was lost in rodents, limiting progenitor cell proliferation.

Audit of donor centre: guidelines by the World Marrow Donor Association Quality and Regulation Working Group

According to the Standards of the World Marrow Donor Association (WMDA) 2020 [1] unrelated stem cell donor registries are responsible for compliance of their donor centres with these Standards. To ensure high stem cell product quality and high standards for safety and satisfaction of voluntary unrelated stem cell donors, we present here guidelines for audits of donor centres (DC) that can be used by new and established donor registries. They have been developed for registries relying on independent national or international DCs for the recruitment and management of Unrelated Donors (UD) for verification typing (VT)/extended tying (ET), work up processes and Hemopoietic Progenitor Cell (HPC) donation. The main goal of these guidelines is to support registries in verifying and auditing their affiliated DCs to ensure they are compliant with the WMDA Standards, as well as WMDA recommendations. We define the general requirements and recommendations for collaboration with the DC and guidelines to manage the UD, step by step from recruitment to follow-up. We also provide a checklist, intended to serve as a resource for auditors performing an audit at a DC.

Cardiovascular Disease (CVD) Risk Assessment of HIV Medication Regimens using hematopoietic CD34+ progenitor cells

Background To determine the effects of integrase inhibitor (INSTI) in comparison to non INSTI based regimens such as non-nucleoside reverse transcriptase inhibitors (NNRTIs) based regimens on cardiovascular disease (CVD) risk in HIV+ patients without overt history of CVD or diabetes, with normal CD4:CD8 count. For CVD risk assessment we primarily used hematopoietic CD34+ progenitor cells, as a biomarker.Methods19 male subjects ages 32-61 years with BMI 21.0- 36.0, were enrolled. This was a single time point, cross-sectional, observational study. Subjects were enrolled under 2 groups (either on INSTI based regimen with 13 subjects or NNRTI (non-INSTI) based regimens with 6 subjects) who were taking stable doses of HAART. The medication regimens were a combination of one NRTI (typically tenofovir-emtricitabine) plus one INSTI or NNRTI. Our outcome measures were focused on cardiovascular and endothelial cell function and systemic inflammation. Our primary outcome measures were peripheral blood derived hematopoietic progenitor cell number (CD34 and CD133 positive), CD34+ cell function and gene expression studies. Our secondary outcomes were arterial stiffness measures and serum-based markers of inflammation. ResultsA significant increase in percentage number of progenitor cells, CD133+ cells (P=0.004) was noted along with an increase of double progenitor mark positive CD133+/CD34+ progenitor cell population was observed in INSTI group as compared to NNRTI group, by flow-cytometry. mRNA gene expression for antioxidant gene catalase was noted along with a trend towards a decrease in gene expression of inflammatory marker IL6 (p=0.06) was observed in CD34+ from INSTI group vs NNRTI group. The plasma IL-6 and CRP levels did not change significantly between the groups. Neutrophil-Lymphocyte ratio (NLR), an important marker of inflammation, was noted to be lower in INSTI group. A mean fasting glucose level was also lower in the INSTI group compared to NNRTI group (p=0.03). Interestingly, Urine- Microalbumin levels were higher in the INSTI group compared to NNRTI group (p=0.08), while eGFR levels were lower in the INSTI group (p=0.002). The arterial stiffness measures did not show statistically significant differences between the two groups. ConclusionWe conclude that the INSTI regimen may provide a better CVD risk profile compared to NNRTI based HAART regimen; however the increased albuminuria along with lower eGFR, noted in INSTI group is of concern. Because of the small size, these results would need replication in additional studies before changing clinical practice.Clinical Trial Registration https://clinicaltrials.gov/ct2/show/NCT03782142?cond=Hiv&spons=Sabyasachi+sen&cntry=US&state=US%3ADC&city=Washington&draw=2&rank=1ClinicalTrials.gov Identifier: NCT03782142

Identification of a modular super-enhancer in murine retinal development

Super-enhancers are expansive regions of genomic DNA comprised of multiple putative enhancers that contribute to the dynamic gene expression patterns during development. This is particularly important in neurogenesis because many essential transcription factors have complex developmental stage– and cell–type specific expression patterns across the central nervous system. In the developing retina, Vsx2 is expressed in retinal progenitor cells and is maintained in differentiated bipolar neurons and Müller glia. A single super-enhancer controls this complex and dynamic pattern of expression. Here we show that deletion of one region disrupts retinal progenitor cell proliferation but does not affect cell fate specification. The deletion of another region has no effect on retinal progenitor cell proliferation but instead leads to a complete loss of bipolar neurons. This prototypical super-enhancer may serve as a model for dissecting the complex gene expression patterns for neurogenic transcription factors during development. Moreover, it provides a unique opportunity to alter expression of individual transcription factors in particular cell types at specific stages of development. This provides a deeper understanding of function that cannot be achieved with traditional knockout mouse approaches.

Proteomic identification of proliferation and progression markers in human polycythemia vera stem and progenitor cells

Polycythemia vera (PV) is a stem cell disorder characterized by hyperproliferation of the myeloid lineages and the presence of an activating JAK2 mutation. To elucidate mechanisms controlling PV stem and progenitor cell biology, we applied a recently developed highly sensitive data-independent acquisition mass spectrometry workflow to purified hematopoietic stem and progenitor cell (HSPC) subpopulations of patients with chronic and progressed PV. We integrated proteomic data with genomic, transcriptomic, flow cytometry and in vitro colony formation data. Comparative analyses revealed added information gained by proteomic compared with transcriptomic data in 30% of proteins with changed expression in PV patients. Upregulated biological pathways in hematopoietic stem and multipotent progenitor cells (HSC/MPPs) of PV included MTOR, STAT and interferon signaling. We further identified a prominent reduction of clusterin (CLU) protein expression and a corresponding activation of NFĸB signaling in HSC/MPPs of untreated PV patients compared with controls. Reversing the reduction of CLU and inhibiting NFĸB signaling decreased proliferation and differentiation of PV HSC/MPPs in vitro. Upon progression of PV, we identified upregulation of LGALS9 and SOCS2 protein expression in HSC/MPPs. Treatment of patients with hydroxyurea normalized the expression of CLU and NFĸB2, but not of LGALS9 and SOCS2. These findings expand the current understanding of the molecular pathophysiology underlying PV and provide new potential targets (CLU and NFĸB) for antiproliferative therapy in PV patients.

GATA2 deficiency elevates Interferon Regulatory Factor-8 to subvert a progenitor cell differentiation program

Cell type-specific transcription factors control stem and progenitor cell transitions by establishing networks containing hundreds of genes and proteins. Network complexity renders it challenging to discover essential versus modulatory or redundant components. This scenario is exemplified by GATA2 regulation of hematopoiesis during embryogenesis. Loss of a far upstream Gata2 enhancer (-77) disrupts the GATA2-dependent transcriptome governing hematopoietic progenitor cell differentiation. The aberrant transcriptome includes the transcription factor Interferon Regulatory Factor-8 and a host of innate immune regulators. Mutant progenitors lose the capacity to balance production of diverse hematopoietic progeny. To elucidate mechanisms, we asked if IRF8 is essential, contributory or not required. Reducing Irf8, in the context of the -77 mutant allele, reversed granulocytic deficiencies and the excessive accumulation of dendritic cell committed progenitors. Despite many dysregulated components that control vital transcriptional, signaling and immune processes, the aberrant elevation of a single transcription factor deconstructed the differentiation program.

Developmental maturation of the hematopoietic system controlled by a Lin28b-let-7-PRC1 axis

Hematopoiesis changes over life to meet the demands of maturation and aging. Here, we find that the definitive hematopoietic stem and progenitor cell (HSPC) compartment is remodeled from gestation into adulthood, a process regulated by the heterochronic Lin28b/let-7 axis. Native fetal and neonatal HSPCs distribute with a pro-lymphoid/erythroid bias with a shift toward myeloid output in adulthood. By mining transcriptomic data comparing juvenile and adult HSPCs and reconstructing coordinately activated gene regulatory networks, we uncover the Polycomb repressor complex 1 (PRC1) component Cbx2 as an effector of Lin28b/let-7 control of hematopoietic maturation. We find that juvenile Cbx2-/- hematopoietic tissues show impairment of B-lymphopoiesis and a precocious adult-like myeloid bias and that Cbx2/PRC1 regulates developmental timing of expression of key hematopoietic transcription factors. These findings define a novel mechanism of epigenetic regulation of HSPC output as a function of age with potential impact on age-biased pediatric and adult blood disorders.

Recent Advances in Single-Cell View of Mesenchymal Stem Cell in Osteogenesis

Osteoblasts continuously replenished by osteoblast progenitor cells form the basis of bone development, maintenance, and regeneration. Mesenchymal stem cells (MSCs) from various tissues can differentiate into the progenitor cell of osteogenic lineage and serve as the main source of osteoblasts. They also respond flexibly to regenerative and anabolic signals emitted by the surrounding microenvironment, thereby maintaining bone homeostasis and participating in bone remodeling. However, MSCs exhibit heterogeneity at multiple levels including different tissue sources and subpopulations which exhibit diversified gene expression and differentiation capacity, and surface markers used to predict cell differentiation potential remain to be further elucidated. The rapid advancement of lineage tracing methods and single-cell technology has made substantial progress in the characterization of osteogenic stem/progenitor cell populations in MSCs. Here, we reviewed the research progress of scRNA-seq technology in the identification of osteogenic markers and differentiation pathways, MSC-related new insights drawn from single-cell technology combined with experimental technology, and recent findings regarding the interaction between stem cell fate and niche in homeostasis and pathological process.