Number Of Granulocyte-macrophage Colony-forming Units Research Articles

Frizzled-6 promotes hematopoietic stem/progenitor cell mobilization and survival during LPS-induced emergency myelopoiesis

SummaryEmergency hematopoiesis involves the activation of bone marrow hematopoietic stem/progenitor cells (HSPCs) in response to systemic inflammation by a combination of cell-autonomous and stroma-dependent signals and leads to their release from bone marrow and migration to periphery. We have previously shown that FZD6 plays a pivotal role in regulating HSPC expansion and long-term maintenance. Now we sought to better understand the underlying mechanisms. Using lipopolysaccharide (LPS)-induced emergency granulopoiesis as a model, we show that failed expansion was intrinsic to FZD6-deficient HSPCs but also required a FZD6-deficient environment. FZD6-deficient HSPCs became more strongly activated, but their mobilization to peripheral blood was impaired and they were more susceptible to inflammatory cell death, leading to enhanced release of pro-inflammatory cytokines in the marrow. These studies indicate that FZD6 has a protective effect in the bone marrow to prevent an overactive inflammatory response and further suggest that mobilization improves HSPC survival during bone marrow inflammation.

CLL Cell-Derived Exosomes Promote Bone Marrow Fibrosis and Inhibit Normal Hematopoietic Colony Proliferation

CLL Cell-Derived Exosomes Promote Bone Marrow Fibrosis and Inhibit Normal Hematopoietic Colony Proliferation

Breakthroughs in Preclinical Development of Ataluren (PTC124) As Therapeutic Option for Patients Affected By Shwachman-Diamond Syndrome: Towards the First Clinical Trial

Shwachman-Diamond syndrome (SDS) is one of the more common inherited bone marrow failure syndromes (IBMFS). Almost 90% of patients with SDS present mutations in the Shwachman-Bodian-Diamond syndrome gene (SBDS) which encodes for the homonymous small protein involved in ribogenesis. SDS is a multiple-organ disease mostly characterized by exocrine pancreas insufficiency, bone malformations, and more importantly bone marrow failure. Most patients with SDS present severe neutropenia, whereas thrombocytopenia and anemia are less frequent. Furthermore, 15-20% of patients develop myelodysplastic syndrome with high risk of acute myeloid leukemia (AML). STAT3 pathway is upregulated both in primary SDS leukocytes and immortalized B cells. Being STAT3 a key regulator of interleukin-6 (IL-6), we postulated that STAT3 hyper-activation could lead to a dysregulation of the IL-6 signaling cascade. Increased levels of IL-6 have been found in pediatric patients with AML and it has been associated with poorer outcomes in these patients, highlighting IL-6 as a cytokine potentially involved in the development of AML. Thus, our hypothesis is that STAT3-IL6 axis may contribute to leukemogenesis in SDS. Almost 55% of patients with SDS carry a specific nonsense mutations, namely the c.183-184TA>CT, which cause a premature termination codon (PTC). Ataluren (PTC124, PTC Therapeutics Inc, NJ) is a small PTC suppressor molecule already approved by the European Medicines Agency as a therapeutic option for Duchenne muscular dystrophy. Interestingly, we recently reported that ataluren can restore SBDS expression in bone marrow progenitors and in peripheral blood mononuclear cells isolated from patients with SDS. Moreover, we have shown that ataluren can reduce mTOR hyper-phosphorylation and excessive apoptotic rate observed in SDS leukocytes. More importantly, we reported that ataluren can improve myeloid differentiation in a small cohort of patients (Bezzerri et al, Am J Hematol 2018). In this further analysis considering an enlarged cohort of 20 SDS patients carrying nonsense mutations we found the following: Ataluren can significantly improve both myeloid colony-forming unit-granulocyte/macrophage (CFU-GM) and colony-forming unit granulocyte, erythrocyte, monocyte, megakaryocyte (CFU-GEMM) generation from bone marrow mononuclear stem cells obtained from an enlarged cohort of 20 patients with SDS carrying nonsense mutations. Ataluren indeed almost doubled the number of CFU-GM and CFU-GEMM after 7 and 14 days of treatment.Colony-forming unit erythroid (CFU-E) generation was not affected by the treatment.Ataluren induces neutrophil maturation in SDS bone marrow mononuclear stem cells (mean increase of 61% CD16+ CD11b+ cells over untreated controls) after 24-48 hours of treatment.Consistently with STAT3 hyper-activation observed in SDS cells, here we show that patients with SDS present a significantly increased level of IL-6 in plasma (4.3-fold higher expression than the healthy control group). Also lymphoblastoid cell lines (LCL) and primary bone marrow mesenchymal stromal cells (MSC) obtained from patients with SDS show increased IL-6 release in culture supernatants compared to healthy controls (2.5-fold and 6.8-fold higher levels, respectively).Of note, ataluren can reduce IL-6 expression in SDS cells restoring normal levels both in LCL and MSC. In conclusion, these new data support the enrollment of patients for the first clinical trial for this drug in SDS. Furthermore, this study could pave the way for the use of ataluren for other nonsense mutation-mediated IBMFS where STAT3-IL6 axis and similar pro-leukemic pathways are involved. Disclosures Bezzerri: Marco Cipolli, Valentino Bezzerri, Baroukh Maurice Assael: Patents & Royalties: WO2018/050706 A1 "Method of treatment of Shwachman-Diamond syndrome". Cipolli:Marco Cipolli, Valentino Bezzerri, Baroukh Maurice Assael: Patents & Royalties: WO2018/050706 A1 "Method of treatment of Shwachman-Diamond syndrome".

Clinical, Hematological, and Biologic Characteristics in Chronic Myelomonocytic Leukemia Patients with a JAK2 V617F Mutation

▪Background:Chronic myelomonocytic leukemia (CMML) is a hematopoietic malignancy of the elderly with a heterogenous molecular pathophysiology. Whereas mutations in components of the RAS pathways are among the most common somatic mutations in CMML the JAK2 V617F mutation which is a typical finding in polycythemia vera and around 50% of patients with essential thrombocythemia and primary myelofibrosis, respectively, is by far less frequently detected in CMML but can be consistently found in a subgroup of patients in larger series. Due to the fact that JAK2 V617F-positive CMML is a rare disease the clinical, hematological and in vitro growth characteristics of this entity are poorly investigated. In the "Austrian Biodatabase for Chronic Myelomonocytic Leukemia (ABCMML)" we retrospectively and prospectively collect clinical, biologic, and molecular information of patients with CMML from different centers in a real life setting.Aims:Our aim was to characterize the clinical, hematological, molecular and biologic features of CMML patients harboring a JAK2 V617F mutation.Methods:The diagnosis of CMML was established according to diagnostic criteria of the World Health Organization (WHO) classification of 2008 (Vardiman et al, Blood 2009). Clinical and hematological data were obtained from patients records. For molecular characterization we used next-generation sequencing with amplicon-based target enrichment of 39 CMML associated genes. Only mutations with an allele burden of >10% were considered positive in this analysis. Autonomous colony-forming units granulocyte/macrophage (CFU-GM) growth in the absence of exogenous cytokines was assessed using semisolid cultures as previously described (Geissler et al, J Exp Med 1996).Results:Up to now targeted NGS data are available in 116 patients and in vitro culture data in 75 patients respectively. We identified 13 CMML patients who had a JAK2 V617F mutation with an allele frequency >10%. Clinical, hematological, and biologic characteristics in these patients were compared with 103 patients who had NGS sequencing and were negative for the JAK2 V617F mutation. As shown in Table 1 JAK2 V617F-positive CMML patients had significantly higher WBC counts, higher hemoglobin values, higher platelet counts and more pronounced splenomegaly as compared to JAK2 V617F-negative patients. On the other hand the percentage on monocytes in peripheral blood and the numbers of CFU-GM growing in vitro without addition of exogenous growth factors were lower in CMML patients with the JAK2 V617F mutation as compared to patients without this mutation. The majority of JAK2 V617F-positive patients had additional mutations that can be also found in JAK2 V617F-negative patients, in particular mutations in genes of epigenetic regulation and RNA-splicing, respectively. As shown in Figure 1 there was a trend towards a better survival of patients with the JAK2 V617F mutation as compared to JAK2 V617F-negative patients (p=0.05). In a JAK2 V617F-positive CMML patient with splenomegaly, who was treated with the JAK1/2 inhibitor ruxolitinib off label, we were able to demonstrate the disappearance of constitutional symptoms and a durable spleen response lasting for over 56 months (Fig. 2).Conclusion:Out data show that CMML patients with the JAK2 V617F mutation have hematological, biologic and clinical characteristics different from JAK2 V617F-negative CMML patients. These findings suggest that JAK2 V617F-positive CMML patients should be regarded as a distinct subgroup which may benefit from specific targeted treatments. [Display omitted] [Display omitted] [Display omitted] DisclosuresGeissler:Novartis: Honoraria. Pfeilstöcker:Novartis: Consultancy, Speakers Bureau. Burgstaller:Novartis: Consultancy, Honoraria. Zach:Novartis: Other: Honoraria for Advisory Board. Hörmann:Novartis: Other: Honoraria for Advisory Board. Jäger:Roche: Other: Personal fees, Research Funding. Sperr:Amgen: Honoraria, Research Funding; Novartis: Honoraria. Kusec:Novartis: Other: Honoraria for lectures. Valent:Novartis: Honoraria, Research Funding; Amgen: Honoraria; Celegene: Honoraria, Research Funding.

The JAK2-Selective Inhibitor NS-018 Preferentially Suppresses CFU-GM Colony Formation By Bone-Marrow Cells From High-Risk Myelodysplastic Syndrome Patients

BackgroundCell signaling mediated by the JAK2-STAT (Janus kinase 2-signal transducer and activator of transcription) pathway plays a critical role in hematopoiesis, and its aberrant activation is associated with the progression of hematological malignancies. For instance, somatic mutations in the JAK2 gene that lead to constitutive activation of STATs are involved in the pathogenesis of myeloproliferative neoplasms (MPN) and refractory anemia with ringed sideroblasts with thrombocytosis, one of the myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN, U). In addition, insufficient inactivation of the JAK-STAT pathway due to repression of SOCS-1 (suppressor of cytokine signaling 1) through hypermethylation of the SOCS-1 gene is involved in the disease progression of high-risk myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) (Brakensiek et al.; Br. J. Haematol. 2005;130:209). These observations prompted us to investigate the effect of the JAK2-selective inhibitor NS-018, which is in an early-phase clinical trial for MPN, on the colony formation by bone marrow hematopoietic progenitor cells from high-risk de novo MDS patients and the phosphorylation status of STAT3 in these cells. MethodsBone marrow mononuclear cells (BMMNCs) from six MDS patients and three healthy volunteers were collected with informed consent in accordance with the Declaration of Helsinki and with the approval of the Institutional Review Board. The MDS subtypes of the six patients included two RCMD, three RAEB-1 and one RAEB-2 according to the WHO classification. All MDS patients had complex cytogenetic abnormalities and their prognostic risks were defined to be high (N=1) or very high (N=5) in the IPSS-R. Commercially available normal human CD34+ BM cells were also examined for comparison. Cells were incubated in methylcellulose medium containing cytokines with or without NS-018. Burst forming unit-erythroid (BFU-E) and colony forming unit-granulocyte/macrophage (CFU-GM) were scored on day 14 of culture. Colony-forming cells were then collected and subjected to western blotting analysis. ResultsWe first examined the colony-formation capacity of MDS-derived BMMNCs. CFU-GM colony formation was observed in four of six MDS samples, although the absolute CFU-GM numbers from MDS BMMNCs were less than those from normal BMMNCs and normal CD34+BM cells. MDS-derived BMMNCs produced larger numbers of CFU-GM colonies (78–99% of total colonies) than BFU-E, similar to the findings usually observed in AML, whereas normal BMMNCs and normal CD34+BM cells formed virtually the same numbers of CFU-GM colonies and BFU-E colonies. These results suggest that BMMNCs from four of the MDS patients enrolled in this study had characteristics similar to AML BMMNCs, although they showed less proliferation than AML BMMNCs. We next examined the effect of NS-018 on CFU-GM colony formation. NS-018 treatment decreased the numbers of CFU-GM colonies from MDS-derived BMMNCs in a dose-dependent manner, and this effect was significantly more potent against MDS-derived than against normal cells (57.2% inhibition in MDS cells vs. 12.8% inhibition in normal cells at 0.5 mM NS-018; see Figure). These results indicate that NS-018 is preferentially efficacious in inhibiting CFU-GM formation from BMMNCs from high risk MDS. In addition, the level of phospho-STAT3 in MDS-derived colony-forming cells was twice as high as in colony-forming cells from normal BMMNCs, and 1.0 mM NS-018 completely suppressed the phosphorylation of STAT3 in CFU-GM colony-forming cells from MDS. ConclusionOur results show for the first time that a JAK2 inhibitor, NS-018, potently suppresses the formation of MDS colonies. NS-018 could be a new therapeutic option for high-risk MDS patients. [Display omitted] Disclosures:Kodama:Nippon Shinyaku: Employment. Naito:Nippon Shinyaku: Employment. Nakaya:Nippon Shinyaku: Employment. Taniwaki:Novartis: Honoraria.

Definition of the Variables Affecting Efficacy of Immunodepletion Ex Vivo of Peripheral Blood Progenitor Cell Grafts by Alemtuzumab (Campath in the Bag)

The immunodepleting effects of alemtuzumab on peripheral blood progenitor cell (PBPC) grafts for stem cell transplantation need to be better defined. The optimal graft cell concentration, antibody dose, need for complement, and whether alemtuzumab is infused with the graft during transplantation remain unclear. PBPC from 6 normal allogeneic stem cell donors harvested by apheresis were first quantitated and the cellular content defined by flow cytometry. Mononuclear cells were then incubated with incremental concentrations of alemtuzumab (.00001, .0001, .001, and .01 mg/mL) for 30 minutes at 20°C or in cell dose responses with 1, 5, and 10 × 106 mononuclear cells/mL added to a fixed dose of .001 mg/mL of alemtuzumab with or without a source of complement. Cells were enumerated and analyzed by flow cytometry before and after exposure to alemtuzumab. To determine the presence of unbound anti-CD52, the supernatant of the cell dose responses were tested using the ELISA assay. Selected CD34+ lineage-negative cells were incubated with antibody at the same working concentrations and conditions and cultured in granulocyte-macrophage colony-forming unit assay. The colony numbers were compared with control cultures devoid of the antibody. Incremental concentrations of alemtuzumab led to a significant (2 log) reduction in CD3, CD4, and CD8 populations, which plateaued at .001 mg/mL. Addition of complement led to a further significant reduction in the CD4 and CD8 cells. The maximum CD4 (3 log) and CD8 (2 log) cell death was obtained at 10 × 106 cells/mL. Analysis of supernatants for soluble alemtuzumab by ELISA showed a significant reduction in the free antibody concentration when the cell number was increased from 1 to 10 × 106 cells/mL implying utilization/binding of the antibody by target cells. Incremental concentrations of alemtuzumab did not affect the number of granulocyte-macrophage colony-forming units. Alemtuzumab depletes all cells expressing the CD52 antigen and has higher activity on CD3, CD8, and particularly on CD4 cells, which are depleted in excess of 2 logs. From this study, we were able to derive that the optimal cell kill in the graft without detectable free alemtuzumab in the supernatant can be achieved with 1 mg of antibody per 100 mL containing 10 × 109 cells and active complement (AB serum).

Requirement for PLCγ2 in IL-3 and GM-CSF-stimulated MEK/ERK phosphorylation in murine and human hematopoietic stem/progenitor cells

Even though the involvement of intracellular Ca(2+) Ca(i)(2+) in hematopoiesis has been previously demonstrated, the relationship between Ca(i)(2+) signaling and cytokine-induced intracellular pathways remains poorly understood. Herein, the molecular mechanisms integrating Ca(2+) signaling with the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in primary murine and human hematopoietic stem/progenitor cells stimulated by IL-3 and GM-CSF were studied. Our results demonstrated that IL-3 and GM-CSF stimulation induced increased inositol 1,4,5-trisphosphate (IP(3) ) levels and Ca(i)(2+) release in murine and human hematopoietic stem/progenitor cells. In addition, Ca(i)(2+) signaling inhibitors, such as inositol 1,4,5-trisphosphate receptor antagonist (2-APB), PKC inhibitor (GF109203), and CaMKII inhibitor (KN-62), blocked phosphorylation of MEK activated by IL-3 and GM-CSF, suggesting the participation of Ca(2+) -dependent kinases in MEK activation. In addition, we identify phospholipase Cγ2 (PLCγ2) as a PLCγ responsible for the induction of Ca(2+) release by IL-3 and GM-CSF in hematopoietic stem/progenitor cells. Furthermore, the PLCγ inhibitor U73122 significantly reduced the numbers of granulocyte-macrophage colony-forming units after cytokine stimulation. Similar results were obtained in both murine and human hematopoietic stem/progenitor cells. Taken together, these data indicate a role for PLCγ2 and Ca(2+) signaling through the modulation of MEK in both murine and human hematopoietic stem/progenitor cells.

Preferential Inhibition of An Activated Form of Janus Kinase 2 (JAK2) by a Novel JAK2 Inhibitor, NS-018

AbstractAbstract 4107A somatic point mutation of Janus Kinase 2 (JAK2) tyrosine kinase (JAK2 V617F) has been shown to occur at a high frequency in myeloproliferative neoplasm (MPN) patients. JAK2 V617F is a constitutively activated kinase that activates the JAK/STAT signaling pathway and dysregulates cell growth and function. These findings suggest that the inhibition of aberrant JAK2 activation has a therapeutic benefit.Our novel JAK2 inhibitor, NS-018, is highly active against JAK2 with an IC50 value of less than 1 nM, and it has 30–50-fold selectivities for JAK2 over other JAK-family kinases such as JAK1, JAK3 and Tyk2. We determined the X-ray structure of JAK2 in complex with NS-018. An Asp-Phe-Gly (DFG) motif is located at the N-terminus of the activation loop and regulates ATP binding. The resolved X-ray structure showed that NS-018 bound to JAK2 in the “DFG-in” active conformation. A molecular modeling study indicated that NS-018 would hardly bind to JAK2 in the “DFG-out” inactive conformation. In accordance with the structural analysis, NS-018 preferentially suppressed the growth of bone-marrow cells expressing activated JAK2. Thus, NS-018 reduced in a dose-dependent manner the number of erythroid colony-forming units (CFU-E) derived from bone-marrow cells taken from JAK2 V617F transgenic mice, but had only a limited effect on the number of colonies from wild-type mice (Figure A). NS-018 had no effect on the number of granulocyte-macrophage colony-forming units (CFU-GM) from either mouse strain. Furthermore, NS-018 showed potent antiproliferative activity against Ba/F3 cells expressing JAK2 V617F with an IC50 value of <100 nM but showed only minimal cytotoxicity against most other hematopoietic and non-hematopoietic cell lines (IC50 >3 μ M). In a mouse Ba/F3-JAK2 V617F leukemia model, NS-018 significantly prolonged survival during repeated oral administrations at 6.25 mg/kg bid and reduced splenomegaly at doses as low as 1.5 mg/kg bid. NS-018 was well tolerated at dosages of more than 100 mg/kg bid. [Display omitted] In conclusion, NS-018 is a potent JAK2 inhibitor which preferentially inhibits an activated form of JAK2 and has potent in vitro and in vivo efficiency in preclinical studies. NS-018 is expected to be suitable for the treatment of MPN caused by aberrant JAK2 activation and its effectiveness will be verified by early-phase clinical investigations in the near future.JAK2 V617F preferential inhibition of erythrocyte colony growthBone-marrow cells were collected from femurs of JAK2 V617F transgenic mice and same-strain BDF1 wild-type mice. (a) To detect CFU-E colonies, cells were treated with NS-018 in semisolid methylcellulose containing erythropoietin (EPO) and cell clusters were counted after incubation for two days. (b) To detect CFU-GM colonies, cells were treated with NS-018 in semisolid methylcellulose containing EPO, interleukin-3 (IL-3), IL-6 and stem cell factor and colonies were counted on day 7. Disclosures:Nakaya:Nippon Shinyaku Co., Ltd: Employment. Naito:Nippon Shinyaku Co., Ltd: Employment. Homan:Nippon Shinyaku Co., Ltd: Employment. Sugahara:Nippon Shinyaku Co., Ltd: Employment. Horio:Nippon Shinyaku Co., Ltd: Employment. Niwa:Nippon Shinyaku Co., Ltd: Employment. Shimoda:Nippon Shinyaku Co., Ltd: Research Funding.

Slow platelet recovery after PBPC transplantation from unrelated donors

The effects of the composition of PBPC grafts from matched related donors (MRDs) and matched unrelated donors (MUDs) have not been compared. In a single-center study, the compositions of 55 MRD PBPC grafts and 33 MUD grafts were studied for their effect on the rate of engraftment in patients who had evidence of donor cell engraftment on day +28. The MUD grafts came more frequently from young male donors and contained more CD34(+) cells but similar numbers of colony-forming units granulocyte-macrophage (CFU-GM) and burst forming units-erythroid. The recovery of neutrophils to >500/mm(3) was equally fast in both groups, but recovery of platelets to >20,000/mm(3) was significantly delayed in the MUD group (P<0.001). The MUD group also required more transfusions of platelets and red cells. Patients receiving grafts containing low numbers of CFU-GM had markedly delayed platelet recovery. The patients with the slowest engraftment tended to have prolonged transportation times. Storage experiments suggested a major loss of viable CD34(+) cells and CFU-GM when undiluted PBPC products are stored at room temperature. The data suggest that a fraction of the MUD grafts suffer during transportation. In vitro proliferation assays should be part of the validation and auditing of transportation of MUD grafts.

A Novel Role of Complement in Mobilization: Immunodeficient Mice Are Poor Granulocyte-Colony Stimulating Factor Mobilizers Because They Lack Complement-Activating Immunoglobulins

Complement (C) and innate immunity emerge as important and underappreciated modulators of mobilization of hematopoietic stem/progenitor cells (HSPC). We reported that (a) C becomes activated in bone marrow (BM) during granulocyte-colony-stimulating factor (G-CSF)-induced mobilization by the classic immunoglobulin (Ig)-dependent pathway and that (b) C3 cleavage fragments increase the responsiveness of HSPC to a stromal derived factor-1 gradient. Since patients suffering from severe combined immunodeficiency (SCID) mobilize poorly, we hypothesized that this could be directly linked to the lack of C activating Ig in these patients. In the current study to better elucidate the role of C activation in HSPC mobilization, we mobilized mice that lack Ig (RAG2, SCID, and Jh) by G-CSF or zymosan, compounds that activate C by the classic Ig-dependent and the alternative Ig-independent pathways, respectively. In addition, we evaluated mobilization in C5-deficient animals. Mobilization was evaluated by measuring the number of colony-forming unit-granulocyte macrophage and leukocytes circulating in peripheral blood. We found that (a) G-CSF- but not zymosan-induced mobilization was severely reduced in RAG2, SCID, and Jh mice; (b) impaired G-CSF-induced mobilization was restored after infusion of purified wild-type Ig; and (c) mobilization was severely reduced in C5-deficient mice. These data provide strong evidence that the C system plays a pivotal role in mobilization of HSPC and that egress of HSPC from BM occurs as part of an immune response. Disclosure of potential conflicts of interest is found at the end of this article.

The impact of post-thaw colony-forming units-granulocyte/macrophage on engraftment following unrelated cord blood transplantation in pediatric recipients

We retrospectively reviewed the engraftment kinetics following unrelated cord blood transplantation (CBT) in association with the post-thaw colony-forming units-granulocyte/macrophage (CFU-GM) number along with the numbers of total nucleated cells (TNC), CD34(+) cells and CD3(+) cells. A total of 71 cord blood units prepared for 53 patients (double-unit CBT in 18 patients) were evaluated. Either the number of infused CFU-GM or CD34(+) cells was significantly lower in patients who failed to achieve engraftment (P=0.028 and 0.005, respectively). Post-thaw CFU-GM, TNC and CD34(+) cells correlated with the speed of neutrophil engraftment (P=0.004, 0.037 and 0.004, respectively), whereas only CFU-GM showed a significant correlation with platelet engraftment (r=-0.385, P=0.024). In double-unit transplants, the number of CFU-GM was the only significant factor predicting engraftment of the predominating unit (P=0.006). We conclude that the post-thaw CFU-GM number is a reliable predictor of rapid engraftment after CBT as well as of the predominating unit in double-unit transplants. Thus, it would be important to perform post-thaw CFU-GM assay on cryopreserved aliquots from several candidate cord blood units in advance before CBT to avoid selecting the unit that might possess a low clonogenic potential.

Large‐scale expansion and transplantation of CD34+ hematopoietic cells: in vitro and in vivo confirmation of neutropenia abrogation related to the expansion process without impairment of the long‐term engraftment capacity

Herein are reported the results obtained in all multiple myeloma patients transplanted with peripheral blood hematopoietic progenitor cells submitted to ex vivo expansion. Patients had blood progenitor cell mobilization with cyclophosphamide and filgrastim. CD34+ cells were expanded for 10 days in a medium containing granulocyte-colony-stimulating factor (G-CSF), stem cell factor, and megakaryocyte growth and development factor (MGDF). Twenty-seven patients underwent transplantation with expanded and nonexpanded cells and 7 patients underwent transplantation with expanded cells only. The median fold cell expansion was 29.1. The number of colony-forming unit-granulocyte-macrophage (CFU-GM) and CD34+ cells, and the long-term culture-initiating cell (LTC-IC) activity increased with median fold values of 14.7, 2.75, and 2.25, respectively. Postmyeloablative neutropenia was abrogated in 24 of 27 patients transplanted with expanded cells plus nonexpanded cells. The median duration of severe neutropenia was 0 days and correlated with the number of cells and CFU-GM infused. Survival was similar to that of a historical control group. Our LTC-IC and NOD-SCID mice studies showed that the expanded cells are able of sustaining long-term hematopoiesis. Seven other patients received transplantation with expanded cells alone. Absolute neutropenia was abrogated in 6 patients. The median duration of neutropenia was 0 days. Two patients who received the lower number of total cells or CFU-GM had brief secondary neutropenia, which resolved after G-CSF injections. CD34+ cells expanded ex vivo can abrogate absolute and severe neutropenia after high-dose therapy. The results of the amplification process are strongly related to the delay of hematopoietic recovery.

Effects of Delta1 and Jagged1 on Early Human Hematopoiesis: Correlation with Expression of Notch Signaling‐Related Genes in CD34 + Cells

It has been shown that Notch signaling mediated by ligands of both Jagged and Delta families expands the hematopoietic stem cell compartment while blocking or delaying terminal myeloid differentiation. Here we show that Delta1- and Jagged1-expressing stromal cells have distinct effects on the clonogenic and differentiation capacities of human CD34(+) CD38(+) cells. Jagged1 increases the number of bipotent colony-forming unit-granulocyte macrophage (CFU-GM) and unipotent progenitors (CFU-granulocytes and CFU-macrophages), without quantitatively affecting terminal cell differentiation, whereas Delta1 reduces the number of CFU-GM and differentiated monocytic cells. Expression analysis of genes coding for Notch receptors, Notch targets, and Notch signaling modulators in supernatant CD34(+) cells arising upon contact with Jagged1 and Delta1 shows dynamic and differential gene expression profiles over time. At early time points, modest upregulation of Notch1, Notch3, and Hes1 was observed in Jagged1-CD34(+) cells, whereas those in contact with Delta1 strikingly upregulated Notch3 and Hes1. Later, myeloid progenitors with strong clonogenic potential emerging upon contact with Jagged1 upregulated Notch1 and Deltex and downregulated Notch signaling modulators, whereas T/NK progenitors originated by Delta1 strikingly upregulated Notch3 and Deltex and, to a lesser extent, Hes1, Lunatic Fringe, and Numb. Together, the data unravel previously unrecognized expression patterns of Notch signaling-related genes in CD34(+) CD38(+) cells as they develop in Jagged1- or Delta1-stromal cell environments, which appear to reflect sequential maturational stages of CD34(+) cells into distinct cell lineages.

Antitumour activity of [1,2-di(cyclopentadienyl)-1,2-di( p- N, N-dimethylaminophenyl)-ethanediyl] titanium dichloride in xenografted Ehrlich's ascites tumour

The effects of a new titanocene compound with an ansa ligand in the cyclopentadienyl rings, the 1,2-di(cyclopentadienyl)-1,2-di( p- N, N-dimethylaminophenyl)-ethanediyl] titanium dichloride (TITANOCENE X), on the growth and differentiation of granulocyte–macrophage progenitor cells [colony-forming unit-granulocyte–macrophage (CFU-GM)] and Natural killer (NK) cell activity in Ehrlich's ascites tumour (EAT)-bearing mice were studied. Myelosuppression concomitant with increased numbers of spleen CFU-GM was observed in tumour-bearing mice. Treatment of these animals with TITANOCENE X (2.5–50 mg/kg/day) produced an increase in myelopoiesis, in a dose-dependent manner, and reduced spleen colony formation. In addition, the treatment of EAT-bearing mice with 3 doses of 20 or 50 mg/kg TITANOCENE X restored to normal values the reduced Natural killer cell function observed during tumour growth. In parallel, TITANOCENE X prolonged, in a dose-dependent manner, the survival of mice inoculated with Ehrlich's ascites tumour. The highest dose of 50 mg/kg prolonged in 50% the survival time of EAT-bearing mice, compared to non-treated tumour-bearing controls. In comparison with previous results from our laboratory addressing the effects of titanocenes on haematopoiesis, we observed with TITANOCENE X a similar effective profile as for bis(cyclopentadienyl) dithiocyanate titanium(IV), being both less effective than di(cyclopentadienyl) dichloro titanium(IV), since the latter not only prolonged, but also increased the rate of survival. These differences in efficacy may be due to the nature of the ansa-cyclopentadienyl ligand used in TITANOCENE X, since the C 2 bridge between the two cyclopentadienyl groups will increase the hydrolytic stability by an organometallic chelate effect. Also, the introduction of two dimethylamino substituents increases the water solubility of TITANOCENE X when compared to titanocene dichloride itself.

Effects of Amifostine and Fengling Polysaccharide on Proliferation and Chemoprotection of Human Granulocyte-Macrophage Progenitor Cells.

Objective: This paper is to study the proliferation and chemoprotection effects of amifostine (WR-2721) and fengling polysaccharide (FLPS) on the human granulocyte-macrophage progenitor cells.Method: (1) Mononuclear cells (MNC) were deparated by Ficoll (1.077g/ml). The MNC of WR-2721 and FLPS treatment were cultured in methylcellulose senisolid medium, the colony forming unit-granulocyte macrophage(CFU-GM) was measured. The effects of WR-2721 and FLPS on CFU-GM were studied. (2) MNC of WR-2721 treatment or containing FLPS were cultured 14h at 37°C with VP16. The cytoprotective activity against VP16 toxic effects of WR-2721 and FLPS on CFU-GM were observed. (3)To study the effects of WR-2721 on proliferation inhibition and apoptosis of HL-60 human leukemia cell line, the cell apoptosis rate of HL-60 was determined by annexinV/PI double staining method, cell proliferation and chemotherapy sensitivity were analyzed with XTT assay, and the changes of cell cycle were observed through flow cytometry.(4) HL-60 cells of containing FLPS were cultured 14h at 37°C with VP16. The cytoprotective activity against VP16 toxic effects of FLPS on HL-60 cells were observed.Results: (1) The number of CFU-GM was significantly increased in 10 groups by addition of 0.5–25μg/ml FLPS and 12 groups treated with 0.01–5mmol/L WR-2721( 30 min, 37°C), p<0.05. The mean value of CFU-GM in groups of negative control, WR-2721 (1mmol/L), FLPS(5μg/ml) and WR-2721+FLPS were 91.4±50.4,119.8±62.9,143.2±76.4 and 179.2±97.6 per 1×105, respectively, Compared with control, singnificant differences were seen between each group, p<0.05. WR-2721+FLPS group compared with WR-2721 and FLPS group, p<0.01 and p<0.05. (2) The number of CFU-GM was significantly increased in MNC of adding FLPS or WR-2721 treatment. The mean value of CFU-GM in groups of VP-16 control, negative control, WR-2721 + VP16, FLPS + VP-16 and WR-2721 + FLPS + VP16 were 30.9±22.5, 83.2±43.8, 64.6±41.2, 55.3±33.5 and 78.3±48.2 per 1×105, respectively. Compared with VP16 control group, singnificant differences were seen between each group, p < 0.01. (3) After treatment (30min,37°C)with WR-2721, the sensitivity of HL-60 cells to VP-16 was enhanced, and the IC50 descended from 52.5μg/ml to 40.5μg/ml. After 72hours trentment of HL-60 cells with WR-2721, the early apoptotic cells (annexinV-FITC positive/PI negative) were increased from(5.5±1.9)% to (48.5±8.4)%(p<0.001), late apoptotic cells(annexinV-FITC positive/PI positive)were increased from(1.2±0.5)% to (39.0±4.0)% (p<0.001), and HL-60cells were arrested in G2-M phase. (4) HL60 cells were cultured 14h at 37°C with 20μg/ml VP16 and 50μg/ml FLPS, the cell survival rate was 88.0%±2.3%, negetive control was 90.5%±2.9%, no singnificant difference was seen between two group, n =21, p >0.05.Conclusion :(1) WR-2721 and FLPS can increase the prolification of CFU-GM. Combination of WR-2721 and FLPS show stronger effect than the WR-2721 or FLPS alone. (2) WR-2721 and FLPS selectiveiy protect human peripheral blood CFU-GM from the cytotoxicity of VP16 without decreasing its cytotoxic effect on HL60 cells. (3) WR-2721 treatment can enhance HL-60 cells chemotherapy sensitivity to VP-16, inhibit proliferation, induce HL-60 cells apoptosis and accumulation of cells in G2-M phase.

HOXB4-Induced Self-Renewal of Hematopoietic Stem Cells Is Significantly Enhanced by p21 Deficiency

Enforced expression of the HOXB4 transcription factor and downregulation of p21(Cip1/Waf) (p21) can each independently increase proliferation of murine hematopoietic stem cells (HSCs). We asked whether the increase in HSC self-renewal generated by overexpression of HOXB4 is enhanced in p21-deficient HSCs. HOXB4 was overexpressed in hematopoietic cells from wild-type (wt) and p21-/- mice. Bone marrow (BM) cells were transduced with a retroviral vector expressing HOXB4 together with GFP (MIGB4), or a control vector containing GFP alone (MIG) and maintained in liquid culture for up to 11 days. At day 11 of the expansion culture, the number of primary CFU-GM (colony-forming unit granulocyte-macrophage) colonies and the repopulating ability were significantly increased in MIGB4 p21-/- BM (p21B4) cells compared with MIGB4-transduced wt BM (wtB4) cells. To test proliferation of HSCs in vivo, we performed competitive repopulation experiments and obtained significantly higher long-term engraftment of expanded p21B4 cells compared with wtB4 cells. The 5-day expansion of p21B4 HSCs generated 100-fold higher numbers of competitive repopulating units compared with wtMIG and threefold higher numbers compared with wtB4. The findings demonstrate that increased expression of HOXB4, in combination with suppression of p21 expression, could be a useful strategy for effective and robust expansion of HSCs.

Effect of peripheral blood progenitor cell dose on hematopoietic recovery: identification of minimal progenitor cell requirements for rapid engraftment.

Repeated high-dose chemotherapy (HDC) with stem cell support is advocated for curative treatment of epithelial ovarian cancer patients, requiring large quantities of progenitor cell harvest. Although the switchover to peripheral blood stem cell transplantation has generally made possible the harvest of large quantities of progenitor cells, the minimum threshold is still pertinent for planning the safe conduct of HDC. However, as the minimum threshold for safe peripheral blood stem cell transplantation (PBSCT) is not yet established, this study was designed to clarify the minimum amount of progenitor cells required for prompt recovery of hematopoietic. Retrospective analysis was performed on 52 HDCs administered in 37 ovarian cancer patients. After autologous bone marrow aspiration (10 patients) or peripheral blood stem cell harvest (27 patients), colony-forming unit granulocyte macrophage (CFU-GM) were enumerated prior to cryopreservation. Numbers of CFU-GM were again calculated before reinfusion and the patients were divided into eight groups: 0.13-<0.4, 0.4-<0.7, 0.7-<1.0, 1.0-<3.5, 3.5-<5.0, 5.0-<10.0, 10.0-<20.0 and >20.0 (x 10(5)/kg). The minimum CFU-GM threshold (x 10(5)/kg) was found to be 1.0-<3.5 for platelets and 3.5-<5.0 for white blood cells. Higher infusion doses did not lead to significant benefits in hematopoietic reconstruction. These results indicate that preservation of a minimum of 7-10 x 10(5)/kg CFU-GM is recommended for the safe conduct of tandem HDCs.

Comprehensive comparison of the cytotoxic activities of onconase and bovine seminal ribonuclease

Onconase (ONC) and bovine seminal ribonuclease (BS-RNase) are homologs of bovine pancreatic ribonuclease (RNase A). Unlike RNase A, ONC and BS-RNase can evade the cytosolic ribonuclease inhibitor protein and are potent cytotoxins. Here, the endogenous cytotoxic activities of ONC and BS-RNase are compared in a wide variety of assays. Injections of ONC into one or both testes of mice and rats evokes a stronger aspermatogenic activity than does the injection of BS-RNase. Epididymides exposed to ONC lose mass and all sperm. Testicular tissue is gradually colonized by immunite and fibrocytic cells. Yet, Leydig cells are always present and functional in the ligamented parts of testicles injected with ONC or BS-RNase. ONC is likewise more toxic to mouse embryos than is BS-RNase, both in vitro and in vivo. The antiproliferative effect of ONC on human tumor cell line ML-2 and lymphocytes in a mixed lymphocyte culture is also more pronounced than is that of BS-RNase. The number of granulocyte-macrophage colony-forming units is repressed almost completely by ONC, whereas a five-fold higher dose of BS-RNase does not cause substantial inhibition. In mice, ONC is less immunogenic than BS-RNase but more immunogenic than RNase A. Together, these data indicate that ONC is a pluripotent cytotoxin, and serves as the benchmark with which to gauge the cytotoxicity of other ribonucleases.

Intracellular signal transduction of interferon on the suppression of haematopoietic progenitor cell growth.

Interferon (IFN)-alpha and IFN-gamma suppress the growth of haematopoietic progenitor cells. IFN-alpha activates Janus kinase-1 (Jak1) and Tyrosine kinase-2 (Tyk2), followed by the phosphorylation of the signal transducers and activators of transcription, Stat1 and Stat2. IFN-gamma activates Jak1 and Jak2, followed by the activation of Stat1. Activated Stats bind the promoter regions of IFN-inducible genes. We evaluated the role of Tyk2 and Stat1 in the IFN-mediated inhibition of haematopoietic progenitor cell growth. While IFN-alpha (1000 U/ml) suppressed the number of granulocyte-macrophage colony-forming units (CFU-GM) or erythroid burst-forming units (BFU-E) from wild-type mouse bone marrow cells, this suppression was partially inhibited by a deficiency in Tyk2 and completely inhibited by a deficiency in Stat1. High levels of IFN-alpha (10,000 U/ml) suppressed the CFU-GM or BFU-E obtained from Stat1-deficient mice, but did not suppress this growth in cells from Tyk2-deficient mice. Stat1 was phosphorylated by IFN-alpha in Tyk2-deficient cells, although the level of phosphorylation was weaker than that observed in wild type mice. Thus, the inhibitory signal on haematopoietic progenitor cells mediated by IFN-alpha may be transduced by two signalling pathways, one regulated by Tyk2 and the other dependent on Stat1. IFN-gamma also suppressed the number of CFU-GM or BFU-E, and this pathway was mediated by IFN-gamma in a Stat1-dependent manner, independently of Tyk2.

The effect of a Titanocene Dichloride derivative, Ti IV (C 5H 5) 2 NCS 2, on the haematopoietic response of Ehrlich tumour-bearing mice

The effects of the [Ti IV (C 5H 5) 2 NCS 2] metallocene (BCDT), a Titanocene Dichloride derivative, on the growth and differentiation of granulocyte-macrophage progenitor cells [colony-forming unit-granulocyte-macrophage (CFU-GM)] and bone marrow cellularity in normal and Ehrlich ascites tumour-bearing mice were studied. As expected for the Ehrlich ascites tumour-model, concomitant myelosuppression, increased number of spleen CFU-GM and changes in bone marrow cellularity were observed. The treatment of Ehrlich ascites tumour-bearing mice with BCDT (10–30 mg/kg/day) produced a dose-dependent increase in myelopoiesis, a reduction in splenic colonies and a restoration in the total and differential marrow cell counts. We also observed an increase in CFU-GM number when bone marrow cells obtained from normal mice were incubated in vitro with serum from normal mice treated with BCDT. In addition, BCDT prolonged, in a dose-dependent manner, the survival of mice inoculated with Ehrlich ascites tumour. Although it has been previously reported that substitutions in the two halides of the titanocene do not interfere with antitumoural effect, our results with BCDT demonstrated a reduction in antitumour efficacy when compared to previous results with the original titanocene produced in our laboratory.