Overcoming the UCB HSCs –Derived NK Cells Dysfunctionality through Harnessing RAS/MAPK, IGF-1R and TGF-β Signaling Pathways

Abstract BackgroundNatural killer (NK) cells differentiated from umbilical cord blood (UCB) hematopoietic stem cells (HSCs) may be more suitable for cell-based immunotherapy compared to NK cells from adult donors. This is due to opportunity to choose alloreactive donors and potentially more robust in vivo expansion. However, the cytotoxicity of UCB-HSC derived NK cells against cancer cells might be suboptimal. To overcome this obstacle, we attempted to generate NK cells with potent antitumor activity by targeting RAS/MAPK, IGF-1R and TGF-β signaling pathways.MethodsThe CD34+ cells isolated from human UCB mononuclear cells through MACS with purity of (≥90%) were used to be differentiated into NK cells. After 21 days of induction with SFTG36, IS721 and IL-15/Hsp70 media, NK cells phenotype was studied and their cytotoxicity against K562 human erythroleukemia cell and SKOV3 ovarian carcinoma cells was analyzed.ResultsThe induced NK cells treated with SFTG36/I721 and SFTG36/IS721 growth factor cocktail expressed a phenotype with CD56+16+CD3- and NKG2D+ with mean fluorescence intensity (MFI) of 92.7%±1.45-168.00±19.20 and 93.23%±0.75-168.66±20.00 respectively. These NK cells once activated by IL-15, demonstrated a higher cytotoxicity against K562 (≥90%) (P ≤ 0.001) and SKOV3 tumor cells (≥65%) (P ≤ 0.001) compared to IL-15/Hsp70 activated NK cells.Conclusion The differentiation of ex vivo-expanded CD34+ cells through manipulation of RAS/MAPK, IGF-1R and TGF-β signaling pathways is an efficient approach for generating functional NK cells that can be used for cancer immunotherapy.

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Overcoming the UCB HSCs –Derived NK cells Dysfunction through Harnessing RAS/MAPK, IGF-1R and TGF-β Signaling Pathways

Cancer Cell International ◽

10.1186/s12935-021-01983-z ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Alireza Shokouhifar ◽

Gholamreza Anani Sarab ◽

Mahboubeh Yazdanifar ◽

Mohammad Fereidouni ◽

Masoumeh Nouri ◽

...

Keyword(s):

Nk Cells ◽

Signaling Pathways ◽

Mononuclear Cells ◽

Ex Vivo ◽

Hematopoietic Stem ◽

Generating Functional ◽

Gm Csf ◽

Erythroleukemia Cells ◽

Cd34 Cells

Abstract Background The natural killer (NK) cells differentiated from umbilical cord blood (UCB) hematopoietic stem cells (HSCs) may be more suitable for cell-based immunotherapy compared to the NK cells from adult donors. This is due to the possibility to choose alloreactive donors and potentially more robust in vivo expansion. However, the cytotoxicity of UCB-HSC-derived NK cells against cancer cells might be suboptimal. To overcome this obstacle, we attempted to generate NK cells with potent antitumor activity by targeting RAS/MAPK, IGF-1R and TGF-β signaling pathways using IL-15, IGF-1 and SIS3 respectively. Methods The CD34 + cells were isolated from human UCB mononuclear cells through magnetic activation cell sorting (MACS) with purity of (≥ 90%) and were subjected to differentiate into NK cells. After 21 days of induction with SFTG36 (SCF, FLt-3L, TPO, GM-CSF, IL-3 and IL-6), IS721 (IGF-1, SIS3, IL-7 and IL-21) and IL-15/Hsp70 media, NK cells phenotypes were studied and their cytotoxicity against K562 human erythroleukemia cells and SKOV3 ovarian carcinoma cells was analyzed. Results The NK cells induced in SFTG36/IS721 medium were selected for activation due to their higher expression of CD56 + 16 + CD3 − (93.23% ± 0.75) and mean fluorescence intensity (MFI) of NKG2D + (168.66 ± 20.00) and also a higher fold expansion potential (11.893 ± 1.712) compared to the other groups. These cells once activated with IL-15, demonstrated a higher cytotoxicity against K562 (≥ 90%; P ≤ 0.001) and SKOV3 tumor cells (≥ 65%; P ≤ 0.001) compared to IL-15/Hsp70-activated NK cells. Conclusions The differentiation of ex vivo expanded CD34 + cells through manipulation of RAS/MAPK, IGF-1R and TGF-β signaling pathways is an efficient approach for generating functional NK cells that can be used for cancer immunotherapy.

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Screen for Small Molecules Capable of Expanding Human Hematopoietic Stem Cell Ex Vivo

Blood ◽

10.1182/blood.v118.21.1919.1919 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1919-1919

Author(s):

Iman Hatem Fares ◽

Jalila Chagraoui ◽

Jana Krosl ◽

Denis-Claude Roy ◽

Sandra Cohen ◽

...

Keyword(s):

Stem Cell ◽

Hematopoietic Stem Cell ◽

Mononuclear Cells ◽

Conflicts Of Interest ◽

Ex Vivo ◽

Fold Increase ◽

Hematopoietic Stem ◽

Cd34 Cells

Abstract Abstract 1919 Hematopoietic stem cell (HSC) transplantation is a life saving procedure whose applicability is restricted by the lack of suitable donors, by poor responsiveness to mobilization regimens in preparation of autologous transplantations, by insufficient HSC numbers in individual cord blood units, and by the inability to sufficiently amplify HSCs ex vivo. Characterization of Stemregenin (SR1), an aryl hydrocarbon receptor (AHR) antagonist that promotes HSC expansion, provided a proof of principle that low molecular weight (LMW) compounds have the ability to promote HSC expansion. To identify novel putative agonists of HSC self-renewal, we initiated a high throughput screen (HTS) of a library comprising more than 5,000 LMW molecules using the in vitro maintenance of the CD34+CD45RA- phenotype as a model system. Our study was based on the fact that mobilized peripheral blood-derived CD34+CD45RA- cells cultured in media supplemented with: stem cell factor, thrombopoietin, FLT3 ligand and interleukin 6, would promote the expansion of mononuclear cells (MNC) concomitant with a decrease in CD34+CD45RA- population and HSC depletion. LMW compounds preventing this loss could therefore act as agonists of HSC expansion. In a 384-well plate, 2000 CD34+cells were initially cultured/well in 50μl medium comprising 1μM test compounds or 0.1% DMSO (vehicle). The proportions of CD34+CD45RA− cells were determined at the initiation of experiment and after a 7-day incubation. Six of 5,280 LMW compounds (0.11%) promoted CD34+CD45RA− cell expansion, and seventeen (0.32%) enhanced differentiation as determined by the increase in proportions of CD34−CD45RA+ cells compared to control (DMSO). The 6 LMW compounds promoting expansion of the CD34+CD45RA− cell population were re-analyzed in a secondary screen. Four out of these 6 molecules suppressed the transcriptional activity of AHR, suggesting that these compounds share the same molecular pathway as SR1 in stimulating HSC expansion, thus they were not further characterized. The remaining 2 compounds promoted, similar to SR1 or better, a 10-fold and 35-fold expansion of MNC during 7 and 12-day incubations, respectively. The expanded cell populations comprised 65–75% of CD34+ cells compared to 12–30% determined for DMSO controls. During 12-day incubation with these compounds, the numbers of CD34+ cells increased ∼25-fold over their input values, or ∼ 6-fold above the values determined for controls. This expansion of CD34+ cells was associated with a ∼5-fold increase in the numbers of multilineage CFC (granulocyte, erythroid, monocyte, and megakaryocyte, or CFU-GEMM) compared to that found in DMSO control cultures. The ability of the 2 newly identified compounds to expand functional HSCs is currently being evaluated in vivo usingimmunocompromised mice. In conclusion, results of our initial screen suggest that other mechanism, besides inhibition of AhR, are at play for expansion of human HSC. Disclosures: No relevant conflicts of interest to declare.

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A novel lentiviral vector targets gene transfer into human hematopoietic stem cells in marrow from patients with bone marrow failure syndrome and in vivo in humanized mice

Blood ◽

10.1182/blood-2011-04-346619 ◽

2012 ◽

Vol 119 (5) ◽

pp. 1139-1150 ◽

Cited By ~ 31

Author(s):

Cecilia Frecha ◽

Caroline Costa ◽

Didier Nègre ◽

Fouzia Amirache ◽

Didier Trono ◽

...

Keyword(s):

Gene Therapy ◽

Cord Blood ◽

Mononuclear Cells ◽

Lentiviral Vector ◽

Ex Vivo ◽

Bone Marrow Failure ◽

Humanized Mice ◽

Hematopoietic Stem ◽

Cd34 Cells

AbstractIn vivo lentiviral vector (LV)–mediated gene delivery would represent a great step forward in the field of gene therapy. Therefore, we have engineered a novel LV displaying SCF and a mutant cat endogenous retroviral glycoprotein, RDTR. These RDTR/SCF-LVs outperformed RDTR-LVs for transduction of human CD34+ cells (hCD34+). For in vivo gene therapy, these novel RDTR/SCF-displaying LVs can distinguish between the target hCD34+ cells of interest and nontarget cells. Indeed, they selectively targeted transduction to 30%-40% of the hCD34+ cells in cord blood mononuclear cells and in the unfractionated BM of healthy and Fanconi anemia donors, resulting in the correction of CD34+ cells in the patients. Moreover, RDTR/SCF-LVs targeted transduction to CD34+ cells with 95-fold selectivity compared with T cells in total cord blood. Remarkably, in vivo injection of the RDTR/SCF-LVs into the BM cavity of humanized mice resulted in the highly selective transduction of candidate hCD34+Lin− HSCs. In conclusion, this new LV will facilitate HSC-based gene therapy by directly targeting these primitive cells in BM aspirates or total cord blood. Most importantly, in the future, RDTR/SCF-LVs might completely obviate ex vivo handling and simplify gene therapy for many hematopoietic defects because of their applicability to direct in vivo inoculation.

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Combining Immunocytokine and Ex Vivo Activated NK Cells as a Platform for Enhancing Graft-Versus-Tumor Effects Against GD2+ Murine Neuroblastoma

Frontiers in Immunology ◽

10.3389/fimmu.2021.668307 ◽

2021 ◽

Vol 12 ◽

Author(s):

Paul D. Bates ◽

Alexander L. Rakhmilevich ◽

Monica M. Cho ◽

Myriam N. Bouchlaka ◽

Seema L. Rao ◽

...

Keyword(s):

Tumor Growth ◽

Nk Cells ◽

Nk Cell ◽

Ex Vivo ◽

Cell Transplant ◽

Hematopoietic Stem ◽

Allogeneic Hsct ◽

Tnf Α

Management for high-risk neuroblastoma (NBL) has included autologous hematopoietic stem cell transplant (HSCT) and anti-GD2 immunotherapy, but survival remains around 50%. The aim of this study was to determine if allogeneic HSCT could serve as a platform for inducing a graft-versus-tumor (GVT) effect against NBL with combination immunocytokine and NK cells in a murine model. Lethally irradiated C57BL/6 (B6) x A/J recipients were transplanted with B6 bone marrow on Day +0. On day +10, allogeneic HSCT recipients were challenged with NXS2, a GD2+ NBL. On days +14-16, mice were treated with the anti-GD2 immunocytokine hu14.18-IL2. In select groups, hu14.18-IL2 was combined with infusions of B6 NK cells activated with IL-15/IL-15Rα and CD137L ex vivo. Allogeneic HSCT alone was insufficient to control NXS2 tumor growth, but the addition of hu14.18-IL2 controlled tumor growth and improved survival. Adoptive transfer of ex vivo CD137L/IL-15/IL-15Rα activated NK cells with or without hu14.18-IL2 exacerbated lethality. CD137L/IL-15/IL-15Rα activated NK cells showed enhanced cytotoxicity and produced high levels of TNF-α in vitro, but induced cytokine release syndrome (CRS) in vivo. Infusing Perforin-/- CD137L/IL-15/IL-15Rα activated NK cells had no impact on GVT, whereas TNF-α-/- CD137L/IL-15/IL-15Rα activated NK cells improved GVT by decreasing peripheral effector cell subsets while preserving tumor-infiltrating lymphocytes. Depletion of Ly49H+ NK cells also improved GVT. Using allogeneic HSCT for NBL is a viable platform for immunocytokines and ex vivo activated NK cell infusions, but must be balanced with induction of CRS. Regulation of TNFα or activating NK subsets may be needed to improve GVT effects.

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In Vitro and In Vivo Evidence That Ex Vivo Cytokine Priming of Donor Marrow Cells May Ameliorate Posttransplant Thrombocytopenia

Blood ◽

10.1182/blood.v91.1.353 ◽

1998 ◽

Vol 91 (1) ◽

pp. 353-359 ◽

Cited By ~ 34

Author(s):

Mariusz Z. Ratajczak ◽

Janina Ratajczak ◽

Boguslaw Machalinski ◽

Rosemarie Mick ◽

Alan M. Gewirtz

Keyword(s):

Mononuclear Cells ◽

Recovery Period ◽

Hematopoietic Stem ◽

Platelet Recovery ◽

Serum Free ◽

Cd34 Cells ◽

In Vivo Animal Model ◽

Marrow Cells

AbstractThrombocytopenia is typically observed in patients undergoing hematopoietic stem cell transplantation. We hypothesized that delayed platelet count recovery might be ameliorated by increasing the number of megakaryocyte colony- forming units (CFU-Meg) in the hematopoietic cell graft. To test this hypothesis, we evaluated cytokine combinations and culture medium potentially useful for expanding CFU-Meg in vitro. We then examined the ability of expanded cells to accelerate platelet recovery in an animal transplant model. Depending on the cytokine combination used, we found that culturing marrow CD34+cells for 7 to 10 days in serum-free cultures was able to expand CFU-Meg ∼40 to 80 times over input number. Shorter incubation periods were also found to be effective and when CD34+ cells were exposed to thrombopoietin (TPO), kit ligand (KL), interleukin-1α (IL-1α), and IL-3 in serum-free cultures for as few as 48 hours, the number of assayable CFU-Meg was still increased ∼threefold over input number. Of interest, cytokine primed marrow cells were also found to form colonies in vitro more quickly than unprimed cells. The potential clinical utility of this short-term expansion strategy was subsequently tested in an in vivo animal model. Lethally irradiated Balb-C mice were transplanted with previously frozen syngeneic marrow mononuclear cells (106/mouse), one tenth of which (105) had been primed with [TPO, KL, IL-1a, and IL-3] under serum-free conditions for 36 hours before cryopreservation. Mice receiving the primed frozen marrow cells recovered their platelet and neutrophil counts 3 to 5 days earlier than mice transplanted with unprimed cells. Mice which received marrow cells that had been primed after thawing but before transplantation had similar recovery kinetics. We conclude that pretransplant priming of hematopoietic cells leads to faster recovery of all hematopoietic lineages. Equally important, donor cell priming before transplant may represent a highly cost-effective alternative to constant administration of cytokines during the posttransplant recovery period.

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Directed Differentiation of Mobilized Hematopoietic Stem and Progenitor Cells into Functional NK Cells with Enhanced Antitumor Activity

Cells ◽

10.3390/cells9040811 ◽

2020 ◽

Vol 9 (4) ◽

pp. 811

Author(s):

Pranav Oberoi ◽

Kathrina Kamenjarin ◽

Jose Francisco Villena Ossa ◽

Barbara Uherek ◽

Halvard Bönig ◽

...

Keyword(s):

Nk Cells ◽

Progenitor Cells ◽

Peripheral Blood ◽

Cell Expansion ◽

Nk Cell ◽

Ex Vivo ◽

Feeder Cells ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Stem And Progenitor Cells

Obtaining sufficient numbers of functional natural killer (NK) cells is crucial for the success of NK-cell-based adoptive immunotherapies. While expansion from peripheral blood (PB) is the current method of choice, ex vivo generation of NK cells from hematopoietic stem and progenitor cells (HSCs) may constitute an attractive alternative. Thereby, HSCs mobilized into peripheral blood (PB-CD34+) represent a valuable starting material, but the rather poor and donor-dependent differentiation of isolated PB-CD34+ cells into NK cells observed in earlier studies still represents a major hurdle. Here, we report a refined approach based on ex vivo culture of PB-CD34+ cells with optimized cytokine cocktails that reliably generates functionally mature NK cells, as assessed by analyzing NK-cell-associated surface markers and cytotoxicity. To further enhance NK cell expansion, we generated K562 feeder cells co-expressing 4-1BB ligand and membrane-anchored IL-15 and IL-21. Co-culture of PB-derived NK cells and NK cells that were ex-vivo-differentiated from HSCs with these feeder cells dramatically improved NK cell expansion, and fully compensated for donor-to-donor variability observed during only cytokine-based propagation. Our findings suggest mobilized PB-CD34+ cells expanded and differentiated according to this two-step protocol as a promising source for the generation of allogeneic NK cells for adoptive cancer immunotherapy.

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Ex Vivo Expansion of Frozen Cord Blood Products without Selection.

Blood ◽

10.1182/blood.v104.11.2844.2844 ◽

2004 ◽

Vol 104 (11) ◽

pp. 2844-2844

Author(s):

Ian K. McNiece ◽

Jenny Harrington ◽

Joshua Kellner ◽

Jennifer Turney ◽

Elizabeth J. Shpall

Keyword(s):

Cord Blood ◽

Mononuclear Cells ◽

Ex Vivo ◽

Ex Vivo Expansion ◽

In Vivo Studies ◽

Adherent Cells ◽

Blood Products ◽

Cd34 Cells ◽

Duke University

Abstract Ex vivo expansion of cord blood products (CB) has been proposed as an approach to increase the number of cells available from a single CB unit. We and others have reported the requirement of CD34 selection for optimal expansion of CB products, however, the selection of frozen CB products results in significant losses of CD34+ cells with a median recovery of 43% (range 6 to 203%, N=40) and low purities resulting in decreased expansion. Therefore we explored approaches to expand CB without prior selection and have described the use of co-culture of CB mononuclear cells (MNC) on mesenchymal stem cells (MSC). In the present study we have evaluated the expansion of clinical CB products (provided by Duke University CB Bank CB). MNC were obtained after ficol separation of RBCs and 10% of the CB product was cultured on preformed layers of MSC in T150 flasks containing 50ml of defined media (Sigma Aldrich) plus 100 ng/ml each of rhSCF, rhG-CSF and rhTpo. After 6 days of culture, the non adherent cells were transferred to a Teflon bag and a further 50 ml of media and GFs added to the flask. Again at day 10, non adherent cells were transferred to the Teflon bag and media and growth factors replaced. At day 12 to 13 of incubation the cells were harvested, washed and total nucleated cell (TNC) counts and progenitor assays performed. In three separate experiments we have achieved greater than 20 fold expansion of TNC with a median of 22, and a median expansion of GM-CFC of 37 fold. Morphologic analysis demonstrated the expanded cells contained high levels of mature neutrophils and neutrophil precursors. In vivo studies in NOD/SCID mice also demonstrated that the expanded cells maintained in vivo engraftment potential. Clinical studies are being designed to evaluate the in vivo potential of CB MNC products expanded on MSC.

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Ex Vivo Expansion and Long-Term Hematopoietic Reconstitution Ability of Sorted CD34+CD59+ Cells from Patients with Paroxysmal Nocturnal Hemoglobinuria.

Blood ◽

10.1182/blood.v112.11.2324.2324 ◽

2008 ◽

Vol 112 (11) ◽

pp. 2324-2324

Author(s):

Juan Xiao ◽

Bing Han ◽

Wanling Sun ◽

Yuping Zhong ◽

Yongji Wu

Keyword(s):

Bone Marrow ◽

Ex Vivo ◽

Peripheral Blood Cell ◽

Intravascular Hemolysis ◽

Blood Cell Count ◽

Normal Cells ◽

Hematopoietic Stem ◽

Cd34 Cells

Abstract Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder characterized by intravascular hemolysis, venous thrombosis, and bone marrow (BM) failure. Until now, allogeneic hematopoietic stem cell transplantation is still the only way to cure PNH. Eculizumab, although very promising, is not the eradication of the disease because of raising the possibility of severe intravascular hemolysis if therapy is interrupted. Here we enriched the residual bone marrow normal progenitor cells (marked by CD34+CD59+) from PNH patients, tried to find an effective way of expanding the progenitors cells used for autologous bone marrow transplantation (ABMT). Objective To expand CD34+CD59+ cells isolated from patients with PNH and observe the long-term hemaotopoietic reconstruction ability of the expanded cells both ex vivo and in vivo. Methods CD34+CD59+ cells from 13 patients with PNH and CD34+ cells from 11 normal controls were separated from the bone marrow monouclear cells first by immunomagnetic microbead and then by flow cytometry autoclone sorting. The selected cells were then cultivated under different conditions for two weeks to find out the optimal expansion factors. The long-term hematopoietic supporting ability of expanded CD34+CD59+ cells was evaluated by long-term culture in semi-solid medium in vitro and long-term engraftment in irradiated severe combined immunodeficiency(SCID) mice in vivo. Results The best combination of hematopoietic growth factors for ex vivo expansion was SCF+IL-3+IL-6+FL+Tpo+Epo, and the most suitable time for harvest was on day 7. Although the CD34+CD59+ PNH cells had impaired ex vivo increase compared with normal CD34+ cells (the biggest expansion was 23.49±3.52 fold in CD34+CD59+ PNH cells and 38.82±4.32 fold in CD34+ normal cells, P<0.01 ), they remained strong colony-forming capacity even after expansion ( no difference was noticed in CFCs or LTC-IC of PNH CD34+CD59+ cells before and after expansion, P>0.05). According to the above data, 11/13(84.3%) patients with PNH can get enough CD34+CD59+cells for ABMT after expansion. The survival rate and human CD45 expression in different organs was similar between the irradiated SCID mice transplanted with expanded CD34+CD59+ PNH cells and those with normal CD34+ cells (P>0.05). The peripheral blood cell count recovered on day 90 in mice transplanted with PNH cells, which was compatible with those transplanted with normal cells (P>0.05). On secondary transplantation, the peripheral blood cell count returned to almost normal on day 30 in mice transplanted with either PNH cells or normal cells. Lower CD45 percentage was found in secondary transplantation compared with primary transplantation but no difference between mice transplanted with different cells. Conclusion Isolated CD34+CD59+ cells from patients with PNH can be effectively expanded ex vivo and can support lasting hematopoiesis both ex vivo and in vivo. These data provide a new potential way of managing PNH with ABMT.

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Single Cell Mass Cytometry of Dysregulated Signaling Networks in Myeloproliferative Neoplasms and Secondary Acute Myeloid Leukemia

Blood ◽

10.1182/blood.v120.21.703.703 ◽

2012 ◽

Vol 120 (21) ◽

pp. 703-703 ◽

Cited By ~ 1

Author(s):

Daniel A.C. Fisher ◽

Erin F. Simonds ◽

Gregory K. Behbehani ◽

Garry P. Nolan ◽

Sean C. Bendall ◽

...

Keyword(s):

Single Cell ◽

Signaling Pathways ◽

Myeloid Leukemia ◽

Feedback Inhibition ◽

Ex Vivo ◽

Myeloproliferative Neoplasms ◽

Cytokine Signaling ◽

Secondary Acute Myeloid Leukemia ◽

Cd34 Cells

Abstract Abstract 703 The classic myeloproliferative neoplasms (MPNs) polycythemia vera (PV), essential thrombocythemia, and primary myelofibrosis (PMF) are frequently associated with the JAK2 V617F mutation or other genetic alterations in members of the JAK-STAT axis. These mutations have been shown to cause hyperactivated JAK-STAT signaling in cell lines and mouse models. How accurately these models recapitulate human MPN pathogenesis remains uncertain, as in vivo signaling in MPNs is likely modulated by other genetic changes and regulatory dynamics. In addition, the phenotypic changes that accompany transformation of chronic MPNs to secondary acute myeloid leukemia (sAML) have not been well characterized. While targeted inhibitors of JAK2 have shown activity in MPNs, the incomplete responses observed clinically have called into question the utility of JAK2 as a therapeutic target, suggesting that dysregulation of other signaling pathways may be important in MPN pathogenesis. Therefore, a more complete assessment of JAK-STAT and related signaling pathways in MPNs is needed. Mass cytometry is a novel technology that merges aspects of flow cytometry with mass spectrometry – cells are labeled with antibodies conjugated to elemental isotope reporters and then analyzed on the CyTOF mass cytometer. Each mass channel is distinct, such that no compensation is required, thus circumventing the spectral limitations of fluorescence-based flow cytometry and enabling the simultaneous measurement of 30+ parameters at the single cell level. We have utilized this approach to examine multiple signaling effectors in cell populations throughout hematopoietic differentiation. Our initial experiment included samples from three MPN patients (PV, PMF, post-PV sAML), and one normal donor. Cells were exposed to nine different perturbation conditions ex vivo, including cytokines and the JAK1/2 inhibitor ruxolitinib. Cells were stained with a panel of 17 surface markers and 13 dynamic intracellular signaling effectors and analyzed on the CyTOF. Single cell data was uploaded into SPADE (spanning-tree analysis of density-normalized events), which distills multidimensional data down to interconnected cell subsets and creates 2D tree plots based on shared surface marker expression. These plots identified recognizable cell subsets, including hematopoietic stem/progenitors (HSPCs) and myeloid and lymphoid lineage subsets. Heat maps were constructed to depict the relative induction of each intracellular marker in response to each condition. In the HSPC compartment, several expected responses were observed, particularly in PV. Erythropoietin-mediated activation of STAT3 and thrombopoietin (Tpo)-mediated activation of STAT3/5 were enhanced in PV committed progenitors. On a broader level, PV HSPCs exhibited heightened signaling sensitivities involving several cytokines and downstream effectors. Notably, CREB and S6 phosphorylation were strongly induced by Tpo, G-CSF, and IL-3. Ruxolitinib pre-treatment markedly inhibited signaling mediated by Tpo in PV CD34+ cells, indicating that the HSPC compartment can be effectively targeted by ex vivo JAK1/2 inhibition. In contrast to PV, PMF HSPCs exhibited lesser sensitivity to cytokine stimulation. In several instances, such as IL-3 induction of pSTAT5, the responses were in fact suppressed compared to normal. CD34+ HSPC from the sAML patient generally exhibited subnormal signaling responses. However, widespread hyperactivation following exposure to the phosphatase inhibitor pervanadate (PVO4) was observed in sAML CD34+ cells, suggesting that these signaling pathways were activated in vivo, but that feedback inhibition in response to persistent activity led to downregulation of their ex vivo inducibility. Based on these preliminary findings, we hypothesize that the fundamental chronic phase MPN state is one of heightened cytokine signaling sensitivity, while the advanced phase (especially sAML) state is one of tonic or constitutive downstream signaling activity with persistent feedback inhibition on cytokine signaling pathways. To test this hypothesis, experiments with a larger cohort of MPN samples are currently underway. These studies will provide a comprehensive framework of altered signaling in MPNs and provide deeper insights into the role of targeted therapy for MPNs. Disclosures: No relevant conflicts of interest to declare.

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Small Molecule Combination Enhances CD34+/CD38- Cell Proliferation Via Inhibition of Differentiation

Blood ◽

10.1182/blood.v128.22.658.658 ◽

2016 ◽

Vol 128 (22) ◽

pp. 658-658

Author(s):

Lan Wang ◽

Xin Guan ◽

Huihui Wang ◽

Bin Shen ◽

Yu Zhang ◽

...

Keyword(s):

Cell Proliferation ◽

Small Molecules ◽

Cell Expansion ◽

Target Genes ◽

Ex Vivo ◽

Hematopoietic Stem ◽

Qpcr Analysis ◽

Cd34 Cells ◽

Cells Cultured

Abstract Hematopoietic stem cells (HSCs) have become increasingly attractive for the therapy of various hematological system disorders. The aim of this study is to identify approaches that promote the expansion of HSCs. We present here the identification of a combination of small molecules and cytokines that is effective in retaining high stemness of hematopoietic stem/progenitor cells while promoting cell proliferation by inhibiting differentiation. Firstly, five small-molecule candidates were screened for their individual effects on ex vivo expansion of human peripheral blood CD34+ cells in the presence of selected cytokines. The best compounds at their optimal concentrations were further analyzed in combination, to achieve maximum capacity for stimulating the CD34+CD38- cell expansion ex vivo. The extent of cell expansion and the immunophenotype of expanded cells were assessed through flow cytometry. Additional cell and molecular assays were performed to confirm that the expanded CD34± cells are functionally normal in vitro. Subsequently, the expanded cells were transplanted into sublethally irradiated NOD/SCID mice for the assessment ofhuman cell viability and engraftment potential in vivo. Furthermore, the expression of several genes in the cell proliferation and differentiation pathways was analyzed through qPCR during the process of CD34±cell expansion. Following multiple rounds of screening, an optimal formula (named as "SVC cocktail") was obtained, which consisted of four cytokines (stem cell factor, flt-3 ligand, thrombopoietin and interleukin-6) and three small molecules (Stem Regenin 1, valproic acid and CAY10433). CD34+ cells cultured with SVC cocktail had a purity of 76.2%±7.5% and reached expansion folds of 27.9±4.3 for CD34+/CD38- HSCs on day 7. In contrast, CD34+ cells cultured with the cytokines alone displayed a purity of 27.4%±6.3% and expansion folds of 15.5±2.2 for CD34+/CD38- cells. The groups with small molecules only (plus DMSO, the vehicle), or with basal medium only, showed no surviving cells on day 4. Furthermore, cell cycle analysis indicated that the SVC cocktail-induced CD34+/CD38- cells stayed in a more quiescent state (G0/G1: 75.2%±3.6%; S: 9.2%±2.4%). On the other hand, the cells cultured without the three small molecules had active DNA synthesis (G0/G1: 56.0%±2.0%; S: 31.8%±3.2%), implicating a trend of enhanced cell differentiation in the cytokine alone group. RT-qPCR analysis further demonstrated that the expression of HSC stemness markers CD90, CD133, CD117, ALDH1, Bmi1, HoxB4, GATA-2, Runx1, and CXCR4 were elevated in the SVC cocktail-induced CD34+ cells, but dramatically reduced or barely detectable in the cytokine alone group. In addition, CFU assays for the SVC cocktail group vs the cytokine alone group demonstrated BFU-E of 54.0±4.6 vs 11.7±1.5, CFU-GM of 71.0±2.7 vs 8.3±2.5, CFU-GEMM of 40.7±3.8 vs 5.0±2.0 and CFU-Mk of 6.7±1.5 vs 0.7±0.6, respectively. For the in vivo engraftment in mouse bone marrow, human CD45 rate in the SVC cocktail group was much higher than in the cytokine alone group (21.1%±2.7% vs 0.5%±0.1%); similar group differences were also found in the CD34+ and CD34+CD38- rate (7.7%±1.4% vs 1.6%±1.2% and 6.8%±2.2% vs 1.6%±0.1% respectively), all at 8 weeks post transplantation. Moreover, qPCR analysis of Notch and Wnt signaling pathways for cultured cells on day 7 showed that the expression of Notch target genes (related to high activation of HSC property) was enhanced in the SVC cocktail group compare to the cytokine group (HES5: 9.2±2.3 vs 3.6±1.4 in arbitrary units; HEY1: 6.3±1.9 vs 2.6±1.2; HES1: 3.2±1.3 vs 1.3±0.4; Notch1: 1.4±0.3 vs 1.2±0.3), whereas the expression of Wnt target genes (related to activation of HSC differentiation) was greater in the cytokine alone group than in the SVC cocktail group (CCND1: 10.1±4.3 vs 1.2±0.8; LEF1: 4.3±0.6 vs 2.9±0.2; PPAR D: 3.4±0.3 vs 1.5±0.1; FZD2: 1.8±0.2 vs 1.0±0.1). Taken together, our results show that the new SVC cocktail is able to retain the characteristics of HSCs remarkably well, by enhancing their expansion while inhibiting their differentiation. Mechanistically, it appears that the three small molecules can effectively inhibit the cytokines' pro-differentiation effects on CD34+CD38- cells without affecting the cytokines' ability to stimulate cell proliferation. Disclosures Wang: Biopharmagen Corp.: Employment. Ren:Biopharmagen Corp: Employment. Jiang:Biopharmagen Corp: Consultancy.

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