Volume 02 · Issue 01 · 2020

GATA2, a principal member of the GATA family, plays important roles in the generation and maintenance of hematopoietic stem/progenitor cells. Among the three mRNA transcripts, the distal first exon of GATA2 (IS exon) is specific for hematopoietic and neuronal cells. GATA2 mutants with abnormal expression are often present in acute myeloid leukemia-related familial diseases and myelodysplastic syndrome, indicating the crucial significance of GATA2 in the proper maintenance of blood system functions. This article offers an overview of the regulation dynamics and function of GATA2 in the generation, proliferation, and function of hematopoietic stem cells in both mouse and human models. We acknowledge the current progress in the cell fate determination mechanism by dynamic GATA2 expression. The gene modification approaches for inspecting the role of GATA2 in definitive hematopoiesis demonstrate the potential for acquiring hPSC-derived hematopoietic stem cells via manipulated GATA2 regulation.

Oligonucleotide aptamers are a class of small-molecule ligands. Functionally similar to protein antibodies, aptamers can specifically bind to their targets with high affinity. Biomedical studies have revealed the potential clinical value of aptamer technology for disease diagnosis and targeted therapy. Lymphoma is a group of cancers originating from the lymphatic system. Currently, chemotherapy is the primary treatment for lymphoma, although it may cause serious side effects in patients due to lack of target specificity. Here, we selectively discuss the recent development of potential applications of aptamer technology for precision lymphoma therapy, which are able to not only achieve high therapeutic efficacy but also do not cause off-target side effects.

Graft-versus-host disease (GVHD) is a major source of morbidity and mortality following allogeneic hematopoietic stem cell transplant (allo-HSCT), one of the most effective approaches to treat hematopoietic malignancies.¹ However, current prophylaxis regimens and treatments that reduce the detrimental effect of acute GVHD can be offset by increased incidence in opportunistic infections and relapse of the primary malignancy.² In addition, the majority of the approaches that inhibit T cell responses are non-specific, resulting in the inhibition of both alloreactive T cells and protective T cells from the donor. Therefore, there is an increase in the demand to develop novel approaches that selectively target alloreactive T cells. One potential means to address this issue is to take advantage of the unique metabolic profile of activated T cells.

T cells play essential roles in antitumor therapy. Via gene engineering technique to enhance tumor-antigen specificity, patient peripheral blood-derived T cells (PBT) show encouraging clinical outcomes in treating certain blood malignancies. However, the high costs, functionality exhaustion, and disease-condition-dependent availability of PBT prompt the attempts of exploring alternative T cell sources. Theoretically, induced T cells from pluripotent stem cells (PSC) are ideal candidates that integrate plenty of advantages that primary T cells lack, including unlimited off-the-shelf cell source and precision gene editing feasibility. However, researchers are still struggling with developing a straightforward protocol to induce functional and immunocompetent human T cells from PSC. Based on stromal cell-expressing or biomaterial-presenting Notch ligands DLL1 or DLL4, natural and induced blood progenitors can differentiate further toward T lineage commitment. However, none of the reported T induction protocols has yet translated into any clinical application, signaling the existence of numerous technical barriers for regenerating T cells functionally matching their natural PBT counterparts. Alternatively, new approaches have been developed to repopulate induced T lymphopoiesis via in vivo reprogramming or transplanting induced T cell precursors. Here, we review the most recent progress in the T cell regeneration field, and the remaining challenges dragging their clinical applications.

PML nuclear bodies (NBs), which are increasingly recognized as the central hub of many cellular signaling events, are superassembled spherical complexes with diameters of 0.1-2 μm. Recent studies reveal that RING tetramerization and B1-box polymerization are key factors to the overall PML NBs assembly. The productive RBCC oligomerization allows subsequent PML biogenesis steps, including the PML auto-sumoylation and partners recruitment via SUMO-SIM interactions. In promyelocytic leukemia, the oncoprotein PML/RARα (P/R) inhibits PML NBs assembly and leads to a full-fledged leukemogenesis. In this review, we review the recent progress in PML and acute promyelocytic leukemia fields, highlighting the protein oligomerization as an important direction of future targeted therapy.

The RNA editing enzyme ADAR1 has been shown to be an essential molecule for hematopoietic cell differentiation, embryonic development, and regulation of immune responses. Here, we present evidence in a T-cell-specific gene knockout mouse model that ADAR1 is required for early T cell development. Loss of ADAR1 led to cell death of the progenitors at the double negative stage and prevented T cell maturation in the thymus. Furthermore, ADAR1 deletion in pre-T cells preferentially affected TCRβ-expressing cells causing TCRβ positive cell depletion. Interruption of IFN signaling occurred in the premature T cells, indicating a role of IFN signaling in the survival of TCRβ-expressing cells regulated by ADAR1. This study demonstrated an essential role for the RNA editing enzyme ADAR1 as a potential regulator for T-cell fate determination during clonal selection, which, in turn, contributes to immunologic homeostasis.

Hematological malignancies are usually life-limiting conditions. Limitations of care need to be decided early, based on acceptability to the patient, family, physician, and community. Inappropriate intensive care unit (ICU) admission is likely to result in significant physical, psychological, and economic burden. There is little published on the impact of non-acute preadmission disease factors on ICU outcomes in hematological malignancies.