A heterozygous CEBPA mutation disrupting the bZIP domain in a RUNX1 and SRSF2 mutational background causes MDS disease progression.

Myelodysplastic syndrome disease (MDS) is caused by the successive acquisition of mutations and thus displays a variable risk for progression to AML. Mutations in CEBPA are commonly associated with a high risk of disease progression, but whether they are causative for AML development is unclear. To analyse the molecular basis of disease progression we generated MDS patient-derived induced pluripotent stem cells from a low risk male patient harbouring RUNX1/SRSF2 mutations.

Engraftment of Human Hematopoietic Cells in Biomaterials Implanted in Immunodeficient Mouse Models.

Over the last 20 years, significant progress has been made in the development of immunodeficient mouse models that now represents the gold standard tool in stem cell biology research. The latest major improvement has been the use of biomaterials in these xenogeneic mouse models to generate human "bone marrow like" tissues, which not only provides a more relevant xenograft model but can also potentially enable us to delineate the interactions that are specific between human bone marrow cells. There are a number of biomaterials and strategies to create humanized niches in immunodeficient mouse models, and the methods can also differ significantly among various research institutes.

Ectopic humanized mesenchymal niche in mice enables robust engraftment of myelodysplastic stem cells.

Myelodysplastic syndrome (MDS) are clonal stem cell diseases characterized mainly by ineffective hematopoiesis. Here, we present an approach that enables robust long-term engraftment of primary MDS stem cells (MDS-SCs) in mice by implantation of human mesenchymal cell-seeded scaffolds. Critically for modelling MDS, where patient sample material is limiting, mononuclear bone marrow cells containing as few as 10 CD34 cells can be engrafted and expanded by this approach with the maintenance of the genetic make-up seen in the patients.

Advances in Human Immune System Mouse Models for Studying Human Hematopoiesis and Cancer Immunotherapy.

Immunotherapy has established itself as a promising tool for cancer treatment. There are many challenges that remain including lack of targets and some patients across various cancers who have not shown robust clinical response. One of the major problems that have hindered the progress in the field is the dearth of appropriate mouse models that can reliably recapitulate the complexity of human immune-microenvironment as well as the malignancy itself.

Treg sensitivity to FasL and relative IL-2 deprivation drive idiopathic aplastic anemia immune dysfunction.

Idiopathic aplastic anemia (AA) has 2 key characteristics: an autoimmune response against hematopoietic stem/progenitor cells and regulatory T-cells (Tregs) deficiency. We have previously demonstrated reduction in a specific subpopulation of Treg in AA, which predicts response to immunosuppression. The aims of the present study were to define mechanisms of Treg subpopulation imbalance and identify potential for therapeutic intervention.

Impact of somatic mutations in myelodysplastic patients with isolated partial or total loss of chromosome 7.

Monosomy 7 [-7] and/or partial loss of chromosome 7 [del(7q)] are associated with poor and intermediate prognosis, respectively, in myelodysplastic syndromes (MDS), but somatic mutations may also play a key complementary role. We analyzed the impact on the outcomes of deep targeted mutational screening in 280 MDS patients with -7/del(7q) as isolated cytogenetic abnormality (86 with del(7q) and 194 with -7). Patients with del(7q) or -7 had similar demographic and disease-related characteristics.

Modeling the human bone marrow niche in mice: From host bone marrow engraftment to bioengineering approaches.

Xenotransplantation of patient-derived samples in mouse models has been instrumental in depicting the role of hematopoietic stem and progenitor cells in the establishment as well as progression of hematological malignancies. The foundations for this field of research have been based on the development of immunodeficient mouse models, which provide normal and malignant human hematopoietic cells with a supportive microenvironment. Immunosuppressed and genetically modified mice expressing human growth factors were key milestones in patient-derived xenograft (PDX) models, highlighting the importance of developing humanized microenvironments.

Versatile humanized niche model enables study of normal and malignant human hematopoiesis.

The BM niche comprises a tightly controlled microenvironment formed by specific tissue and cells that regulates the behavior of hematopoietic stem cells (HSCs). Here, we have provided a 3D model that is tunable in different BM niche components and useful, both in vitro and in vivo, for studying the maintenance of normal and malignant hematopoiesis. Using scaffolds, we tested the capacity of different stromal cell types to support human HSCs.

Deep phenotyping of Tregs identifies an immune signature for idiopathic aplastic anemia and predicts response to treatment.

Idiopathic aplastic anemia (AA) is an immune-mediated and serious form of bone marrow failure. Akin to other autoimmune diseases, we have previously shown that in AA regulatory T cells (Tregs) are reduced in number and function. The aim of this study was to further characterize Treg subpopulations in AA and investigate the potential correlation between specific Treg subsets and response to immunosuppressive therapy (IST) as well as their in vitro expandability for potential clinical use.

SF3B1 mutant MDS-initiating cells may arise from the haematopoietic stem cell compartment.

Despite the recent evidence of the existence of myelodysplastic syndrome (MDS) stem cells in 5q-MDS patients, it is unclear whether haematopoietic stem cells (HSCs) could also be the initiating cells in other MDS subgroups. Here we demonstrate that SF3B1 mutation(s) in our cohort of MDS patients with ring sideroblasts can arise from CD34(+)CD38(-)CD45RA(-)CD90(+)CD49f(+) HSCs and is an initiating event in disease pathogenesis. Xenotransplantation of SF3B1 mutant HSCs leads to persistent long-term engraftment restricted to myeloid lineage.

Spliceosome mutations exhibit specific associations with epigenetic modifiers and proto-oncogenes mutated in myelodysplastic syndrome.

The recent identification of acquired mutations in key components of the spliceosome machinery strongly implicates abnormalities of mRNA splicing in the pathogenesis of myelodysplastic syndromes. However, questions remain as to how these aberrations functionally combine with the growing list of mutations in genes involved in epigenetic modification and cell signaling/transcription regulation identified in these diseases. In this study, amplicon sequencing was used to perform a mutation screen in 154 myelodysplastic syndrome patients using a 22-gene panel, including commonly mutated spliceosome components (SF3B1, SRSF2, U2AF1, ZRSR2), and a further 18 genes known to be mutated in myeloid cancers.

TP53 mutations in myelodysplastic syndrome are strongly correlated with aberrations of chromosome 5, and correlate with adverse prognosis.

This study aimed to determine the incidence/prognostic impact of TP53 mutation in 318 myelodysplastic syndrome (MDS) patients, and to correlate the changes to cytogenetics, single nucleotide polymorphism array karyotyping and clinical outcome. The median age was 65 years (17-89 years) and median follow-up was 45 months [95% confidence interval (CI) 27-62 months]. TP53 mutations occurred in 30 (9.

Functional characterization of CD4+ T cells in aplastic anemia.

The role of CD4(+) T cells in the pathogenesis of aplastic anemia (AA) is not well characterized. We investigate CD4(+) T-cell subsets in AA. Sixty-three patients with acquired AA were studied.

Next-generation sequencing of the TET2 gene in 355 MDS and CMML patients reveals low-abundance mutant clones with early origins, but indicates no definite prognostic value.

Mutations in the TET2 gene are frequent in myeloid disease, although their biologic and prognostic significance remains unclear. We analyzed 355 patients with myelodysplastic syndromes using "next-generation" sequencing for TET2 aberrations, 91 of whom were also subjected to single-nucleotide polymorphism 6.0 array karyotyping.

Novel TET2 mutations associated with UPD4q24 in myelodysplastic syndrome.

Purpose: Cryptic chromosomal aberrations, such as regions of uniparental disomy (UPD), have been shown to harbor homozygous mutations and are a common feature in myelodysplastic syndrome (MDS). We investigated the sequence integrity of 4q24 candidate tumor suppressor gene TET2 in MDS patients with UPD on chromosome 4.

Patients And Methods: The coding exons of TET2 were analyzed by 454 deep sequencing and Sanger sequencing in nine patients with UPD on 4q.