Myelodysplastic Syndromes Are Characterized by Gene Expression Changes in Hematopoietic Stem Cells and Alterations in Hematopoietic Stem Cell and Myeloid Progenitor Composition.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1762-1762
Author(s):  
Christopher Y. Park ◽  
Wendy W Pang ◽  
Peter L Greenberg ◽  
Irving L. Weissman
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Bone Marrow ◽  
High Risk ◽  
Low Risk ◽  
Hematopoietic Stem ◽  
Myeloid Progenitor ◽  
Transcriptional Changes ◽  
Equity Ownership ◽  
Myeloid Progenitors

Abstract Abstract 1762 Poster Board I-788 The myelodysplastic syndromes (MDS) represent a heterogeneous group of disorders characterized by peripheral cytopenias due to impaired hematopoietic differentiation. To date, most data characterizing the immature hematopoietic compartment in MDS have relied on evaluation of CD34+ bone marrow cells, which are a heterogeneous population containing a predominance of oligo- and unilineage-potent progenitors and few hematopoietic stem cells (HSC). In this study we show that MDS are disorders of HSC, evidenced by the presence of recurrent cytogenetic alterations, including -5q, -7, and -20q, in highly purified HSC (Lin-CD34+CD38-CD90+CD45RA-) by FISH. Because MDS HSC harbor cytogenetic changes, we sought to better characterize the molecular basis of MDS HSC function by performing whole transcriptome analysis of highly purified HSC and committed myeloid progenitor populations from low-risk (n=8) and high-risk (n=2) MDS patients. When compared to control HSC from healthy patients (n=10), MDS HSC showed broad transcriptional changes. Using the significance analysis of microarrays (SAM) algorithm and Ingenuity Pathways Analysis software, we identified 3,258 differentially expressed genes (FDR < 0.1) with increased expression of genes positively associated with cell growth and proliferation (p < 0.001) and increased expression of inflammatory response genes (p < 0.015). Interestingly, while MDS common myeloid progenitors (CMP, Lin-CD34+CD38+CD123+CD45RA-) showed increased expression of cell death-related genes when compared to normal CMP (p < 0.001), neither MDS HSC nor multipotent progenitors (MPP, Lin-CD34+CD38-CD90-CD45RA-) showed significant differential expression of these genes when compared to their normal counterparts. To assess the cellular and developmental correlates of HSC/committed progenitor transcriptional changes, we evaluated by flow cytometry the frequency of HSC and committed myeloid progenitors in bone marrow aspirates from 35 low-risk MDS, 6 high-risk MDS and 32 healthy patient samples (range 4-84 yo). Low-risk MDS bone marrow samples showed significantly increased numbers of HSC compared to normal bone marrow samples (+3-fold change, p < 0.03). In addition, myeloid progenitor composition was frequently altered in low-risk MDS patients, with decreased percentages of granulocyte-macrophage progenitors (GMP, Lin-CD34+CD38+CD123+CD45RA+) when expressed as a percentage of total myeloid progenitors [including GMP, CMP and megakaryocyte-erythroid progenitors (MEP, Lin-CD34+CD38+CD123loCD45RA-)] (-2.3-fold change, p < 1e-6). This altered myeloid progenitor profile was highly specific to MDS, even when MDS patient samples were compared to a group of control bone marrow samples from non-MDS patients exhibiting at least one cytopenia (n=34, p < 1e-5), allowing for the distinction of MDS samples from non-MDS cytopenias with 0.89 sensitivity and 0.89 specificity. Together, these data indicate that MDS HSC exhibit significantly altered gene expression profiles and suggest that gene expression changes in MDS HSC induce the altered developmental fate decisions and transcriptional changes observed in MDS committed myeloid progenitors. These data also demonstrate that the changes in MDS myeloid progenitor composition may provide a novel, flow cytometric method for distinguishing MDS from other hematologic conditions that mimic MDS. Finally, these studies indicate that molecular characterization of MDS phenotypes may require evaluation of purified hematopoietic progenitors in order to account for the differential effect of MDS-associated changes on specific hematopoietic progenitor populations. Disclosures Weissman: Amgen: Equity Ownership; Cellerant Inc.: Founder; Stem Cells Inc.: Equity Ownership, Founder; U.S. Patent Application 11/528,890 entitled “Methods for Diagnosing and Evaluating Treatment of Blood Disorders.”: Patents & Royalties.

Characterization of gene expression of CD34+ cells from normal and myelodysplastic bone marrow

Blood ◽  
2002 ◽  
Vol 100 (10) ◽  
pp. 3553-3560 ◽  
Author(s):  
Wolf-K. Hofmann ◽  
Sven de Vos ◽  
Martina Komor ◽  
Dieter Hoelzer ◽  
William Wachsman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
High Risk ◽  
Bone Marrow Cells ◽  
Low Risk ◽  
Control Group ◽  
Expression Data ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Marrow Cells

Gene patterns of expression in purified CD34+ bone marrow cells from 7 patients with low-risk myelodysplastic syndrome (MDS) and 4 patients with high-risk MDS were compared with expression data from CD34+ bone marrow cells from 4 healthy control subjects. CD34+ cells were isolated by magnetic cell separation, and high-density oligonucleotide microarray analysis was performed. For confirmation, the expression of selected genes was analyzed by real-time polymerase chain reaction. Class membership prediction analysis selected 11 genes. Using the expression profile of these genes, we were able to discriminate patients with low-risk from patients with high-risk MDS and both patient groups from the control group by hierarchical clustering (Spearman confidence). The power of these 11 genes was verified by applying the algorithm to an unknown test set containing expression data from 8 additional patients with MDS (3 at low risk, 5 at high risk). Patients at low risk could be distinguished from those at high risk by clustering analysis. In low-risk MDS, we found that the retinoic-acid–induced gene (RAI3), the radiation-inducible, immediate-early response gene (IEX1), and the stress-induced phosphoprotein 1 (STIP1) were down-regulated. These data suggest that CD34+cells from patients with low-risk MDS lack defensive proteins, resulting in their susceptibility to cell damage. In summary, we propose that gene expression profiling may have clinical relevance for risk evaluation in MDS at the time of initial diagnosis. Furthermore, this study provides evidence that in MDS, hematopoietic stem cells accumulate defects that prevent normal hematopoiesis.

Haplo-Identical Allogeneic Stem Cell Transplantation Using GCSF-Mobilized Marrow Plus Blood Stem Cells from Parent Donors for Children with High-Risk Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 5084-5084
Author(s):  
Quanyi Lu ◽  
Xiaoqing Niu ◽  
Peng Zhang ◽  
Delong Liu
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
High Risk ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Peripheral Blood ◽  
Peripheral Blood Stem Cells ◽  
Hematopoietic Stem ◽  
Blood Stem Cells

Abstract Increasing number of patients in China have difficulty of finding sibling donors due to limited number of siblings. We therefore explored the feasibility using haploidentical parent donors for allogeneic hematopoietic stem cell transplantation. Eight leukemia patients were studied in our hospital. These included 2 CML-BC, 2 MDS-RAEB, 3 relapsed ALL and 1 relapsed AML. The median age was 12 (7–17). GCSF- mobilized bone marrow and peripheral blood stem cells were collected from parents (1 to 3 locus mismatched). The conditioning regimen consisted of fludarabine (30mg/m2/d x5), bulsulfan (4mg/kg/d x3) and cyclophosphamide (50mg/kg/d x2). Cyclosporin A, mycophenolate mofetil, methotrexate, and ATG were used for GVHD prophylaxis. The total number of CD34+ cell in the grafts ranged between 5–10 x 106/kg. The median follow- up was 13 months (6–24). One patient failed to engraft, the other 7 patients achieved full donor chimerism at day 28. The incidence of acute GVHD (grade II-IV) was 57.1% (4 of 7). The incidence of chronic GVHD of limited stage occurred in the same 4 patients. One patient died of lung complication at 17th month, another patient with CML-BC relapsed 10 months after transplantation. The rest 6 patients are alive without disease. These results suggested that parents could be considered as stem cell donors in the absence of alternative donors for young patients with high-risk diseases. GCSF-primed bone marrow plus peripheral blood stem cells might be beneficial to reduce the risk of GVHD for leukemia children in China. More patients are needed to further study this approach.

Hematopoiesis in the Elderly: Age-Associated Effects in Frequency, Function, and Gene Expression of Human Hematopoietic Stem Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1505-1505
Author(s):  
Wendy W. Pang ◽  
Elizabeth A. Price ◽  
Irving L. Weissman ◽  
Stanley L. Schrier
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Stem Cells ◽  
Bone Marrow ◽  
Expression Profiles ◽  
Frequency Function ◽  
Hematopoietic Stem ◽  
Hematopoietic System ◽  
Cell Cycle Status

Abstract Abstract 1505 Poster Board I-528 Aging of the human hematopoietic system is associated with an increase in the development of anemia, myeloid malignancies, and decreased adaptive immune function. While the hematopoietic stem cell (HSC) population in mouse has been shown to change both quantitatively as well as functionally with age, age-associated alterations in the human HSC and progenitor cell populations have not been characterized. In order to elucidate the properties of an aged human hematopoietic system that may predispose to age-associated hematopoietic dysfunction, we evaluated and compared HSC and other hematopoietic progenitor populations prospectively isolated via fluorescence activated cell sorting (FACS) from 10 healthy young (20-35 years of age) and 8 healthy elderly (65+ years of age) human bone marrow samples. Bone marrow was obtained from hematologically normal young and old volunteers, under a protocol approved by the Stanford Institutional Review Board. We determined by flow cytometry the distribution frequencies and cell cycle status of HSC and progenitor populations. We also analyzed the in vitro function and generated gene expression profiles of the sorted HSC and progenitor populations. We found that bone marrow samples obtained from normal elderly adults contain ∼2-3 times the frequency of immunophenotypic HSC (Lin-CD34+CD38-CD90+) compared to bone marrow obtained from normal young adults (p < 0.02). Furthermore, upon evaluation of cell cycle status using RNA (Pyronin-Y) and DNA (Hoechst 33342) dyes, we observed that a greater percentage of HSC from young bone marrow are in the quiescent G0- phase of the cell cycle compared to elderly HSC, of which there is a greater percentage in G1-, S-, G2-, or M-phases of the cell cycle (2.5-fold difference; p < 0.03). In contrast to the increase in HSC frequency, we did not detect any significant differences in the frequency of the earliest immunophenotypic common myeloid progenitors (CMP; Lin-CD34+CD38+CD123+CD45RA-), granulocyte-macrophage progenitors (GMP; Lin-CD34+CD38+CD123+CD45RA+), and megakaryocytic-erythroid progenitors (MEP; Lin-CD34+CD38+CD123-CD45RA-) from young and elderly bone marrow. We next analyzed the ability of young and elderly HSC to differentiate into myeloid and lymphoid lineages in vitro. We found that elderly HSC exhibit diminished capacity to differentiate into lymphoid B-lineage cells in the AC6.21 culture environment. We did not, however, observe significant differences in the ability of young and elderly HSC to form myeloid and erythroid colonies in methylcellulose culture, indicating that myelo-erythroid differentiation capacity is preserved in elderly HSC. Correspondingly, gene expression profiling of young and elderly human HSC indicate that elderly HSC have up-regulation of genes that specify myelo-erythroid fate and function and down-regulation of genes associated with lymphopoiesis. Additionally, elderly HSC exhibit increased levels of transcripts associated with transcription, active cell-cycle, cell growth and proliferation, and cell death. These data suggest that hematopoietic aging is associated with intrinsic changes in the gene expression of human HSC that reflect the quantitative and functional alterations of HSC seen in elderly bone marrow. In aged individuals, HSC are more numerous and, as a population, are more myeloid biased than young HSC, which are more balanced in lymphoid and myeloid potential. We are currently investigating the causes of and mechanisms behind these highly specific age-associated changes in human HSC. Disclosures: Weissman: Amgen: Equity Ownership; Cellerant Inc.: ; Stem Cells Inc.: ; U.S. Patent Application 11/528,890 entitled “Methods for Diagnosing and Evaluating Treatment of Blood Disorders.”: Patents & Royalties.

Poly I:C Stimulates Sca-1 Expression in Murine Bone Marrow and Increases the Number of Phenotypic Hematopoietic Stem Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2504-2504
Author(s):  
Russell Garrett ◽  
Gerd Bungartz ◽  
Alevtina Domashenko ◽  
Stephen G. Emerson
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Conflicts Of Interest ◽  
Hematopoietic Cells ◽  
Poly I:C ◽  
Hematopoietic Stem ◽  
Marrow Cells ◽  
Myeloid Progenitors

Abstract Abstract 2504 Poster Board II-481 Polyinosinic:polycytidlyic acid (poly I:C) is a synthetic double-stranded RNA used to mimic viral infections in order to study immune responses and to activate gene deletion in lox-p systems employing a Cre gene responsive to an Mx-1 promoter. Recent observations made by us and others have suggested hematopoietic stem cells, responding to either poly I:C administration or interferon directly, enter cell cycle. Twenty-two hours following a single 100mg intraperitoneal injection of poly I:C into 10-12 week old male C57Bl/6 mice, the mice were injected with a single pulse of BrdU. Two hours later, bone marrow was harvested from legs and stained for Lineage, Sca-1, ckit, CD48, IL7R, and BrdU. In two independent experiments, each with n = 4, 41 and 33% of Lin- Sca-1+ cKit+ (LSK) IL-7R- CD48- cells from poly I:C-treated mice had incorporated BrdU, compared to 7 and 10% in cells from PBS-treated mice. These data support recently published reports. Total bone marrow cellularity was reduced to 45 and 57% in the two experiments, indicating either a rapid death and/or mobilization of marrow cells. Despite this dramatic loss of hematopoietic cells from the bone marrow of poly I:C treated mice, the number of IL-7R- CD48- LSK cells increased 145 and 308% in the two independent experiments. Importantly, the level of Sca-1 expression increased dramatically in the bone marrow of poly I:C-treated mice. Both the percent of Sca-1+ cells and the expression level of Sca-1 on a per cell basis increased after twenty-four hours of poly I:C, with some cells acquiring levels of Sca-1 that are missing from control bone marrow. These data were duplicated in vitro. When total marrow cells were cultured overnight in media containing either PBS or 25mg/mL poly I:C, percent of Sca-1+ cells increased from 23.6 to 43.7%. Within the Sca-1+ fraction of poly I:C-treated cultures, 16.7% had acquired very high levels of Sca-1, compared to only 1.75% in control cultures. Quantitative RT-PCR was employed to measure a greater than 2-fold increase in the amount of Sca-1 mRNA in poly I:C-treated cultures. Whereas the numbers of LSK cells increased in vivo, CD150+/− CD48- IL-7R- Lin- Sca-1- cKit+ myeloid progenitors almost completely disappeared following poly I:C treatment, dropping to 18.59% of control marrow, a reduction that is disproportionately large compared to the overall loss of hematopoietic cells in the marrow. These cells are normally proliferative, with 77.1 and 70.53% accumulating BrdU during the 2-hour pulse in PBS and poly I:C-treated mice, respectively. Interestingly, when Sca-1 is excluded from the analysis, the percent of Lin- IL7R- CD48- cKit+ cells incorporating BrdU decreases following poly I:C treatment, in keeping with interferon's published role as a cell cycle repressor. One possible interpretation of these data is that the increased proliferation of LSK cells noted by us and others is actually the result of Sca-1 acquisition by normally proliferating Sca-1- myeloid progenitors. This new hypothesis is currently being investigated. Disclosures: No relevant conflicts of interest to declare.

Hematopoietic Stem Cells Are the Disease-Initiating Cells in the Myelodysplastic Syndromes

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 789-789 ◽  
Author(s):  
Christopher Y. Park ◽  
Wendy W Pang ◽  
Elizabeth Price ◽  
John A. Pluvinage ◽  
Stanley L. Schrier ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Low Risk ◽  
In Vitro Assays ◽  
Preclinical Model ◽  
Functional Evaluation ◽  
Hematopoietic Stem ◽  
Cytogenetic Abnormalities

Abstract Abstract 789 Myelodysplastic syndrome (MDS) is a disorder of ineffective hematopoiesis presumed to originate from self-renewing clonal hematopoietic stem cells (HSC). Previous work has shown that immunophenotypic HSC from MDS patients harbor characteristic clonal cytogenetic abnormalities such as del(5q) at high levels, strongly suggesting that the HSC is the MDS-initiating cell (Tehranchi R., et al., NEJM, 363:11;1025-37, 2010); however, these studies did not examine other cytogenetic subtypes of MDS, nor did they functionally evaluate the HSC from these patients for their ability to initiate disease. We began a molecular and functional evaluation of FACS-purified HSC (Lin-CD34+CD38−CD90+CD45RA-) from MDS patients. These studies showed that the frequency of HSC in MDS bone marrow is not expanded when compared to normal, age-matched control samples. Annexin V staining also demonstrated no difference in apoptosis levels in MDS HSC compared to normal HSC; however, MDS committed myeloid progenitors (Lin-CD34+CD38+) exhibited increased apoptosis compared with normal progenitors (18% vs 39%, respectively, p <0.05). Transciptome analysis of FACS-purified MDS HSC from 10 low-risk MDS patients compared with HSC from an equal number of normal adults showed dysregulation of 3,258 mRNAs (FDR <0.1) including increased expression of genes positively associated with cell growth and proliferation (p < 0.001) and increased expression of inflammatory response genes (p < 0.015). In addition, there was widespread downregulation of numerous ribosomal protein transcripts in non-5q MDS including RPS6 and RPS19, but not RPS14 (p < 0.05). When FACS-purified HSC from a group of low-risk MDS patients were evaluated for the presence of known FISH abnormalities, the vast majority of HSC in MDS patients with defined cytogenetic abnormalities harbored clonal abnormalities (n=5, range 84–92% of total HSC) but they were not completely replaced, suggesting that non-MDS clones co-exist with MDS clones in MDS patient bone marrows. Finally, we show that FACS-purified MDS HSC can engraft irradiated, immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) pup recipients transplanted with as few as 1000 purified HSC. Long-term engraftment (assessed >12 weeks) was achieved with 50% of MDS samples tested (4/8), and resulted predominantly in myeloid engraftment with 0.8–5% total hCD45+ chimerism in the bone marrow. For each MDS HSC engrafted mouse, engraftment of the MDS clone was verified by FISH by detecting previously characterized cytogenetic abnormalities in FACS-sorted hCD45+ cells. The frequency of FISH positive cells was similar to that seen in the primary samples, suggesting no competitive disadvantage of MDS HSC in the xenotransplantation assay. Interestingly, methylcellulose colony and clonal liquid culture assays initiated from FACS-purified MDS HSC consistently grew poorly, suggesting that in vitro assays of hematopoietic potential may not accurately reflect MDS HSC biology. Together, these studies indicate that while MDS HSC are molecularly and functionally different from normal HSC, they are capable of engrafting immunodeficient NSG pups. Moreover, these data formally demonstrate that the HSC is the disease-initiating cell in MDS. This finding has significant implications for MDS research, as it provides a potential in vivo preclinical model for testing MDS therapeutics – an experimental model previously not available to investigators. Disclosures: Schrier: Locus: Consultancy.

Let-7a, Mir-17 and Mir-20a Expression Levels in CD34+ Bone Marrow Cells of Patients with Myelodysplastic Syndromes (MDS) Are Associated with Established Prognostic Factors, Supporting Their Implication in the Pathogenesis of the Disease,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3792-3792 ◽  
Author(s):  
Christos K Kontos ◽  
Vassiliki Pappa ◽  
Diamantina Vasilatou ◽  
Maria-Angeliki S Pavlou ◽  
Frida Kontsioti ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Prognostic Factors ◽  
High Risk ◽  
Mirna Expression ◽  
Who Classification ◽  
Low Risk ◽  
Expression Levels ◽  
Cd34 Cells ◽  
Bone Marrow Blasts

Abstract Abstract 3792 Introduction: MicroRNAs are single, small non-coding RNA molecules of approximately 21–26 nucleotides, which regulate the expression of numerous genes. miRNAs may act either at the post-transcriptional or the post-translational level to repress gene expression; still, upregulation of gene expression has been noticed in some cases as a direct effect of miRNA function. The importance of miRNAs in carcinogenesis is emphasized by the association of cancers with alterations in miRNA expression. Many miRNAs, including let-7a and those of the miR-17-92 cluster (miR-17, miR-20a, etc.), have been shown or are predicted to affect the activities of targeted mRNAs encoding proteins that have oncogenic or anti-oncogenic functions. let-7a downregulates KRAS, while miR-17 and miR-20a downregulate E2F1. Both these proteins are overexpressed in myelodysplastic syndromes (MDS) and have been shown to be involved in the pathobiology of the disease. Purpose: In the current study, we examined the prognostic value of let-7a, miR-17 and miR-20a levels in MDS and their potential as novel molecular biomarkers. Furthermore, we investigated the protein expression levels of validated targets of these three miRNAs in bone marrow CD34+ cells of MDS patients. Material and Methods: We evaluated 43 patients with MDS (34 men, 9 women) with a median age of 73 years (range 45–87). According to WHO classification, 12 patients (27.9%) were diagnosed with RA, 6 (13.9%) RCMD, 8 (18.6%) with RAEB-I, 7 (16.3%) with RAEB-II, 8 (18.6%) with AML, and 2 (4.7%) with CMML. According to IPSS, 13 patients (32.5%) had low risk, 14 (35.0%) intermediate I risk, 6 (15.0%) intermediate II, and 7 (17.5%) high risk disease. WPSS classification was: 8 (23.5%) very low risk, 5 (14.7%) low risk, 8 (23.5%) intermediate, 9 (26.5%) high risk, and 4 (11.8%) very high risk. We isolated CD34+ cells from bone marrow mononuclear cells from MDS patients, as well as from peripheral blood of donors of CD34+ cells for stem cell transplantation, using magnetic beads. Extraction of small RNA-containing total RNA from CD34+ cells was performed and cDNA of let-7a, miR-17 and miR-20a was synthesized using specific primers. miRNA expression levels were determined using quantitative real-time PCR, the TaqMan® chemistry and the relative quantification (2−ΔΔCT) method. The snoRNA RNU48 was used as reference gene. Furthermore, total protein was extracted from CD34+ cells using a lysis buffer and subsequently quantified using the Bradford assay. Western blot analysis was carried out for MYC, E2F1, Cyclin D1 (CCND1), BCL2 and KRAS, while Actin was used as reference protein. Results: In MDS patients, let-7a expression levels were 0.053–506.1 copies/RNU48 copies, while miR-17 and miR-20a expression levels were 0.005–2694.5 and 0.003–3116.7 copies/103RNU48 copies, respectively. No significant differences were found between patients and controls regarding let-7a, miR-17 and miR-20a expression. let-7a underexpression was associated with high (>10%) bone marrow blasts percentage (P =0.036), presence of WHO classification subtypes with poor prognosis (RAEB-I, RAEB-II and AML) (P =0.020), and high IPSS (P =0.037). Furthermore, miR-17 underexpression was related to high (>10%) bone marrow blasts percentage (P =0.008), intermediate and/or high risk karyotype (P =0.018) and high IPSS (P =0.016). Moreover, miR-20a underexpression was associated with high IPSS (P =0.037) and WPSS (P =0.013). Interestingly, protein expression levels of all targets analyzed in the current study were shown to be lower in samples overexpressing let-7a, miR-17 and/or miR-20a, in comparison with the corresponding protein levels noticed in specimens showing lower expression of these three miRNAs. Conclusion: To the best of our knowledge, this is the first study showing that expression levels of let-7a, miR-17 and miR-20a are associated with established prognostic factors in MDS, including IPSS and WPSS. Furthermore, these three miRNAs seem to be implicated in the pathogenesis of the disease, most probably by finely tuning the expression of target proteins that are involved in highly important molecular pathways, therefore affecting key cellular functions, such as cell cycle control, apoptosis, cell proliferation, and regulation of gene expression. Undoubtedly, further studies are needed to confirm the present findings and clarify their association with the pathogenesis of different MDS subgroups. Disclosures: No relevant conflicts of interest to declare.

Recombinant scAAV2 Vector-Mediated Ex Vivo Transduction of Primary Human Hematopoietic Stem Cells from a β-Thalassemia Patient and Human β-Globin Gene Expression in a Murine Xenograft Model in Vivo

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5951-5951
Author(s):  
Liu-Jiang Song ◽  
Xin-Hua Zhang ◽  
Jun Zhu ◽  
Jue-Lian Wu ◽  
Xiao-Ling Yin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Globin Gene ◽  
Rt Pcr ◽  
Post Transplantation ◽  
Hematopoietic Stem ◽  
Human Hscs ◽  
Globin Gene Expression

Abstract Background: The most severe form of β-thalassemia, β°-thalassemia major, is characterized by the complete absence of normal β-globin chain, and is often lethal. Autologous transplantation of genetically-modified hematopoietic stem cells (HSCs) using lentiviral vectors have been used successfully to achieve clinical efficacy in one patient, although clonal expansion of a myeloid cell population also occurred in this patient which was associated with the activation of a cellular proto-oncogene, HMGA2. We reasoned that recombinant vectors based on a non-pathogenic human parvovirus, the adeno-associated virus (AAV), might offer a safer alternative. We have previously documented that although the conventional single-stranded (ss) AAV2 vectors mediated β-globin gene transfer and expression in primary human fetal liver cells and in human HSCs from patients with β-thalassemia patients in vitro, the level of transgene expression was sub-optimal. In the present study, we investigated whether double-stranded self-complementary (sc) AAV2 vectors could overcome this limitation. Methods: Human HSCs, obtained from a β-thalassemia homozygous patient, were mock-transduced or transduced with recombinant scAAV2-β-globin vectors at 5×104 vgs/cell, followed by i.v. injection into sub-lethally irradiated NOD/SCID mice (2.65 cGy total body irradiation), which were also pre-treated with 200 µg purified anti-IL2RB/CD122 monoclonal antibody. Recipient mice were sacrificed 12 weeks post-transplantation. Bone marrow cells from recipient mice were analyzed by BFU-E assays. Human β-globin gene expression in human erythroid progenitor cells from transplanted mice was evaluated by RT-PCR. Results: Pre-treatment of NOD/SCID mice with anti-CD122 antibody improves engraftment of human HSCs in bone marrow of receipt mice. Human β-actin (538-bp) and β-globin (272-bp) transcripts were detected by RT-PCR in bone marrow cells from all recipient mice, indicating that recombinant scAAV2-β-globin–transduced HSCs from a patient with β-thalassemia were successfully transduced and transplanted in these mice and that human β-globin gene was transcriptionally active 12 weeks post-transplantation. Conclusion: Our results indicate that human HSCs from β-thalassemia patients can be efficiently transduced by recombinant scAAV2-β-globin vectors followed by expression of normal human β-globin gene. These studies provide the proof-of-concept that scAAV2 vector-mediated gene transfer into human HSCs might be a potentially safer alternative approach for gene therapy of β-thalassemia. Disclosures No relevant conflicts of interest to declare.

Hematopoietic stem cells with controllable tEpoR transgenes have a competitive advantage in bone marrow transplantation

Blood ◽  
2000 ◽  
Vol 95 (12) ◽  
pp. 3710-3715 ◽  
Author(s):  
Suzanne Kirby ◽  
William Walton ◽  
Oliver Smithies
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Erythropoietin Receptor ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Myeloid Progenitor ◽  
Colony Forming Units

Abstract In a previous study, it was found that a truncated erythropoietin receptor transgene (tEpoR tg) enables multilineage hematopoietic progenitor amplification after treatment with erythropoietin (epo) in vitro and in vivo. This study used competitive bone marrow (BM) repopulation to show that tEpoR tg facilitates transplantation by hematopoietic stem cells (HSC). Individual multilineage colonies, committed myeloid progenitor colonies, and lymphoid colonies (pre-B colony-forming units) were grown from the marrow of animals 6 months after they received a 50/50 mixture of transgene and wild-type BM cells. In epo-treated recipients, the transgene-bearing cells significantly outcompeted the wild-type cells (84%-100% versus 16%-0%, respectively). In recipients treated with phosphate-buffered saline, the repopulation was minimally different from the donor mixture (49%-64% transgene versus 51%-36% wild-type). The epo-induced repopulation advantage is maintained in secondary transplants. In addition, neither accelerated HSC depletion nor uncontrollable proliferation occurred during epo-stimulated serial transplants of transgene-containing BM. Thus, the tEpoR tg functions in a benign fashion in HSC and allows for a significant and controllable repopulation advantage in vivo without excessive HSC depletion relative to wild-type BM.

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