Nanofiber-Based Expansion and Differentiation Technology for High-Volume Ex Vivo Production of Reticulocytes for P. Vivax Malaria Research

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2357-2357
Author(s):  
Hong Wang ◽  
Adam M Sorkin ◽  
Ramasamy Sakthivel
Keyword(s):  
Cord Blood ◽  
Large Scale ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Rapid Development ◽  
High Volume ◽  
In Vitro Models ◽  
Scale Production ◽  
Hematopoietic Stem

Abstract Abstract 2357 Infection by Plasmodium Vivax (P. Vivax) is the most common cause of Sleeping Malaria. P. Vivax and other plasmodia have grown increasingly resistant to antimalarial drugs. Introduced by mosquito bite, P. vivax sporozoites enter circulation and preferentially penetrate reticulocytes by attaching to the Fya and Fyb Duffy antigen/chemokine receptor (DARC) via PvRBP-1 and PvRBP-2 proteins located at their apical poles. Once in a reticulocyte, the parasite begins to reproduce asexually, releasing of thousands of merozoites into circulation. At this point, merozoites can also enter the liver and triggering relapses months or years later. The emergence of drug-resistant strains of p. vivax has stimulated development of new vaccines and treatments, but progress has been slowed by the dearth of reliable screening platforms. Many vaccine candidates have been developed to act upon vivax merozoites by preventing binding of PvRBP-1 and 2 to DARC, thereby arresting reproduction. However, there is a distinct lack of in vitro models to evaluate candidates that employ this mechanism. We are addressing this issue with a novel ex vivo expansion and differentiation technology for large-scale production of DARC expressing reticulocytes for in vitro P. vivax infection studies. This technology comprises an expansion system that can produce high yields of hematopoietic precursors (CD133+/CD34+ cells) from a variety of sources (marrow, peripheral blood, and cord blood), and a differentiation system to produce a relatively pure population of enucleated erythrocytes. In this study, we have refined the polyethersulfone (PES) nanofiber-based culturing system containing growth factors and cytokines in a serum-free media, to expand hematopoietic stem and progenitor cells (HSPC) ex vivo. This expansion technology allows rapid 200-fold ex vivo proliferation within 7 days of umbilical cord blood derived CD133+/CD34+ HSPCs from a DARC+ donor. Following expansion, over 50% of these cells retained HSPC phenotype (expression of CD34+). We have subsequently demonstrated that feeder layer free three-step differentiation of nanofiber-expanded cells using cytokines results in a population containing predominately enucleated reticulocyte-like cells. At 21 days of differentiation, cells had expanded 50-fold. Around 41% of cells were enucleated reticulocytes. These cells expressed glycophorin-A, a major sialoglycoprotein present on the human erythrocyte membrane. ∼28% of cells were CD36+, and ∼70% were CD71+ indicating an erythroid lineage. These results suggest that this technology can produce a population of DARC+ reticulocytes that is ∼5,000-fold greater than the starting population of HSPCs. We are partnering with leading malaria vaccine researchers to demonstrate that these reticulocytes can be parasitized by p. vivax. We believe that this will provide a unique platform to jumpstart research of malaria parasites and enable rapid development of effective vaccines. Further development of this technology may also have significant implications for large-scale ex vivo production of erythrocytes for general use. Reticulocyte-like cells and expelled nuclei during differentiation of nanofiber-expanded HSPC. Disclosures: No relevant conflicts of interest to declare.

In Vitro Production of Erythrocytes

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. SCI-39-SCI-39
Author(s):  
Luc Douay
Keyword(s):  
Stem Cells ◽  
Cord Blood ◽  
Blood Group ◽  
Pluripotent Stem Cells ◽  
Large Scale ◽  
Conflicts Of Interest ◽  
Embryonic Stem ◽  
In Vitro Production ◽  
Hematopoietic Stem

Abstract Abstract SCI-39 The generation of red blood cells (RBCs) in vitro using biotechnologies could represent an interesting alternative to classical transfusion products, in that it would combine adequate supplies with the specific production of blood products of a particular phenotype and the reduction of infection risks. This presentation will review how it is now possible to obtain in vitro complete maturation of the erythroid line to the stage of enucleation, starting from hematopoietic stem cells (HSCs) from peripheral blood, bone marrow or umbilical cord blood, or embryonic stem cells or adult pluripotent stem cells (induced pluripotent stem cells, iPSCs). This presentation will discuss how the functionality of cultured human RBCs (cRBCs) is settled in terms of deformability, hemoglobin maturation, oxygen carrying capacity, enzyme content, and terminal maturation from the reticulocyte stage to mature RBC after infusion into the NOD/SCID mouse model. The clinical feasibility of this concept has recently been demonstrated by reporting that cRBCs generated in vitro from peripheral HSCs under GMP conditions encounter in vivo the conditions required for their maturation and that they persist in the circulation for several weeks in humans. These data have established the proof of principle for transfusion of in vitro-generated RBCs and the pathway toward new developments in transfusion medicine. The most proliferative source of stem cells for generating cRBCs is cord blood, but it is limited in terms of HSCs and is dependent on donations. Pluripotent stem cell technology represents a potentially unlimited source of RBCs and opens the door to the development of a new generation of allogeneic transfusion products. Because iPSCs can be selected for a phenotype of interest, they are obviously the best candidate for organizing complementary sources of RBCs for transfusion. It is established that only three human iPSC clones would have been sufficient to match more than 99 percent of the patients in need of RBC transfusions. As a whole, a very limited number of RBC clones would provide for the needs of most alloimmunized patients and those with a rare blood group. Generating cRBCs from iPSCs has been done but needs to be optimized to lead to a clinical application in blood transfusion. Several crucial points remain to be resolved, notably, the choice of the initial cell type, the method of reprogramming (i.e., to ensure the safety of the iPSCs and to ensure their clinical grade), the optimization of the erythrocyte differentiation, and the definition of GMP conditions for industrial production. Assuming that in vitro large-scale cultured RBC production efficiently operates in the near future, this presentation will highlight the potential applications for alloimmunized patients and those with a rare blood group. Disclosures: No relevant conflicts of interest to declare.

Ex vivo treatment of proliferating human cord blood stem cells with stroma-derived factor–1 enhances their ability to engraft NOD/SCID mice

Blood ◽  
2002 ◽  
Vol 99 (9) ◽  
pp. 3454-3457 ◽  
Author(s):  
Hanno Glimm ◽  
Patrick Tang ◽  
Ian Clark-Lewis ◽  
Christof von Kalle ◽  
Connie Eaves
Keyword(s):  
Stem Cells ◽  
Cord Blood ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Severe Combined Immunodeficiency ◽  
Human Cord Blood ◽  
Hematopoietic Stem ◽  
Steel Factor ◽  
Tgf Β1

Abstract Ex vivo proliferation of hematopoietic stem cells (HSCs) is important for cellular and gene therapy but is limited by the observation that HSCs do not engraft as they transit S/G2/M. Recently identified candidate inhibitors of human HSC cycling are transforming growth factor-β1(TGF-β1) and stroma-derived factor–1 (SDF-1). To determine the ability of these factors to alter the transplantability of human HSCs proliferating in vitro, lin− cord blood cells were first cultured for 96 hours in serum-free medium containing Flt3 ligand, Steel factor, interleukin-3, interleukin-6, and granulocyte colony-stimulating factor. These cells were then transferred to medium containing Steel factor and thrombopoietin with or without SDF-1 and/or TGF-β1 for 48 hours. Exposure to SDF-1 but not TGF-β1 significantly increased (> 2-fold) the recovery of HSCs able to repopulate nonobese diabetic/severe combined immunodeficiency mice. These results suggest new strategies for improving the engraftment activity of HSCs stimulated to proliferate ex vivo.

Attenuation of Surface CXCR4 Down-Regulation in Human Cord Blood HSC during Ex Vivo Expansion Using the HUBEC Co-Culture System.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1068-1068
Author(s):  
Naoko Takebe ◽  
Thomas MacVittie ◽  
Xiangfei Cheng ◽  
Ann M. Farese ◽  
Emily Welty ◽  
...  
Keyword(s):  
Cord Blood ◽  
Culture System ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Receptor Internalization ◽  
Down Regulation ◽  
Human Cord Blood ◽  
Hematopoietic Stem ◽  
Gm Csf

Abstract Down-modulation of surface CXCR4, a G-protein-coupled receptor, in hematopoietic stem cells (HSCs) undergoing ex vivo expansion culturing is considered to be one of the major causes of marrow reconstitution failure, possibly due to an HSC homing defect. Recently, it has been reported that severe combined immunodeficiency (SCID)-repopulating cells (SRC) were expanded from the CD34-enriched human adult bone marrow (ABM) or cord blood (CB) hematopoietic stem cells (HSC) using a human brain endothelial cell (HUBEC) co-culture system. We found that primitive cord blood cells expressing surface CXCR4 (82+5%) lost this capability significantly during 7 days of ex vivo expansion in the HUBEC co-culture containing the cytokines stem cell factor (SCF), flt-3, interleukin (IL)-6, IL-3, and granulocyte macrophage colony stimulating factor (GM-CSF). Expression levels of other surface proteins relevant to HSC homing, such as CD49d, CD95, CD26, or CD11a, were not down-modulated. We hypothesized that CXCR4 down-regulation was caused by a receptor internalization and tested several methods to reverse CXCR4 internalization back to the surface, such as elimination of GM-CSF in the culture media, performing a non-contact culture using the transwell, or adding either 0.3Mor 0.4M sucrose, or 25μg/ml chlorpromazine (CPZ), 24 hours prior to the analysis. CPZ and sucrose are known inhibitors of the cytokine-induced endocytosis of CXCR4 in neutrophils (Bruhl H. et al. Eur J Immunol 2003). Interestingly, 0.4M sucrose showed approximately a 2-fold increase of surface CXCR4 expression on CB CD34+ cells by flow cytometry analysis. CPZ and 0.3M sucrose showed a moderate increase expression of CXCR4. Using a transwell HUBEC co-culture system, CXCR4 surface expression on CD34+ cells was down-regulated during the ex vivo culture. In vitro HSC migration test showed 3.1-fold increase in migration compared to the control after incubation of HSC with 0.1M sucrose for 16 hours prior to the in vitro migration study. Eliminating GM-CSF from the cytokine cocktail or adding MG132 increased migration 1.36- and 1.2-fold compared to the control. We are currently performing an in vivo homing assay using nonobese diabetic (NOD)-SCID mice. In conclusion, the HUBEC ex vivo culture system down-regulates surface CXCR4 in human cord blood HSC. The mechanism of CXCR4 surface down regulation may be receptor internalization by cytokines. Sucrose may be useful in attenuation of CXCR4 surface expression in CD34+ HSC by inhibition of receptor internalization via clathrin-coated pits.

Study of In Vitro Proliferation Potential of CD133 Positive Cells Derived from Umbilical Cord Blood.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4039-4039
Author(s):  
Ri Zhang ◽  
Wenjin Gao ◽  
Yuanyuan Sun ◽  
Jingcheng Miao ◽  
Xueguang Zhang
Keyword(s):  
Cord Blood ◽  
Progenitor Cells ◽  
Umbilical Cord ◽  
Umbilical Cord Blood ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Hematopoietic Stem ◽  
Low Concentration ◽  
Tgf Β1

Abstract Transforming growth factor-beta 1 (TGF-β1) is known to maintain primitive human hematopoietic stem/progenitor cells with polyfunctional role in a quiescent state and CD133 is a new stem cell antigen that may provide an alternative to CD34 for the selection and expansion of hematopoietic cells for transplantation. To investigate the specific effect of TGF-β1 on proliferation and differentiation of CD133 positive cells derived from umbilical cord blood (UCB) during short-term culture in vitro, CD133 positive cells from 20 fresh UCB samples were selected using Miltenyi Biotec’s CliniMACS separation device and were cultured in IMDM medium with 20% FCS in the presence of a cytokine combination of SCF, IL-6, thrombopoietin, IL-3 and Flt3-ligand for up to 2 weeks and TGF-β1 with low concentration was also added to the mediumon day 4. The proliferative response was assessed at day 7, day 10 and day 14 by evaluating the following parameters: nucleated cells (NC), clonogenic progenitors (CFU-GEMM,CFU-GM and BFU-E), and immunophenotypes (CD133 and CD34). The results showed that efficacious expansion of various hematopoietic stem/progenitor cells was constantly observed during the culture. The fold expansion of NC on day7, day10 and day14 expansion were 33.59,224.26 and 613.48, respectively. The fold expansion of CFU-GEMM, CFU-GM and BFU-E on day 10 were 24.89, 41.62 and 49.28, respectively, obviously higher than that without ex vivo expansion (P<0.05). The expansions of CD133+, CD133+CD34+ and CD34+ subpopulation on day 14 were up to 25.83-fold, 16.16-fold and 60.54-fold, respectively. Furthermore the expansion systems with TGF-β1 showed more CD133+ cells than control at every time points. Our datas suggested that the CD133+ cells from human UCB have great expansion potential for ex-vivo expansion. The low concentration of TGF-β1 may delay over-differentiation of hematopoietic stem/progenitor cells.

Cytokine Treatment of CD34+ Cord Blood Cells with G-CSF, GM-CSF, or SCF During 48 Hours of Ex Vivo Culture Alters CD26/DPPIV Peptidase Activity and Subsequent Engraftment Into NSG Immunodeficient Mice.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1460-1460
Author(s):  
Laura A Paganessi ◽  
Lydia Luy Tan ◽  
Sucheta Jagan ◽  
Robin Frank ◽  
Antonio M. Jimenez ◽  
...  
Keyword(s):  
Cord Blood ◽  
Ex Vivo ◽  
Hematopoietic Stem ◽  
Immunodeficient Mice ◽  
Gm Csf ◽  
Cytokine Treatment ◽  
Ex Vivo Culture ◽  
Inhibitor Treatment

Abstract Abstract 1460 Many patients with hematologic malignancies choose hematopoietic stem cell transplantation (HSCT) as a treatment option. The most common source of Hematopoietic Stem and Progenitor Cells (HSC/HPC) for adult recipients is mobilized Peripheral Blood (mobPB). Limited quantities of HSC/HPC obtainable from an umbilical cord restricts its use for adult recipients. Ex vivo treatment of umbilical cord blood (CB) with cytokines and growth factors is being used to expand the population of cord blood HSC/HPCs in hopes of obtaining higher numbers of transplantable CB cells. In addition, cytokines and growth factors are often utilized post-transplant in an attempt to improve the rate of immune reconstitution. It has been previously reported that granulocyte-colony-stimulating factor (G-CSF), and granulocyte-macrophage-colony-stimulating factor (GM-CSF) up-regulate CD26 (dipeptidyl peptidase IV/DPPIV) activity on freshly isolated CD34+ CB cells within 18 hours of culture [Christopherson, et al. Exp Hematol 2006]. Separate studies have demonstrated that treatment of uncultured CD34+ CB cells with the CD26 inhibitor Diprotin A increases transplant efficiency into immunodeficient mice [Christopherson, et al. Stem Cells Dev. 2007]. We evaluated here the in vitro and in vivo effects of CD26 inhibitor treatment on previously frozen CB CD34+ cells cultured ex vivo with G-CSF, GM-CSF or SCF for 48 hours. We examined CD26 expression by multivariate flow cytometry, CD26 activity using the established chromogenic CD26 substrate, Gly-Pro-p-nitroanilide (Gly-Pro-pNA), and SDF-1α induced migration and adhesion. In vivo, we examined long-term engraftment in NSG (NOD/SCID/IL2Rγnull) immunodeficient mice. After 48 hours of culture with cytokine treatment we observed altered CD26 expression on CD34+ CB cells. There was both an increase in the percentage of CD26+ cells and the mean fluorescence intensity (MFI) of CD26. Additionally, CD26 activity was 1.20, 1.59, 1.58, and 1.65 fold greater after ex vivo culture in untreated, G-CSF, GM-CSF and SCF treated CB CD34+ cells respectively compared to the CD26 activity prior to culture. The increase in CD26 activity as a result of treatment with G-CSF (p≤ 0.01), GM-CSF (p≤ 0.05) or SCF (p≤ 0.01) was significantly higher than the CD26 activity measured in the untreated cells following 48 hours of culture. Post-culture treatment with the CD26 inhibitor, Diprotin A, significantly improved SDF-1α induced migration and adhesion of cultured CD34+ CB cells in vitro, particularly in G-CSF treated cells (p≤ 0.05). Diprotin A treatment of CD34+ CB cells previously treated with G-CSF also significantly increased the long-term in vivo engraftment of stem and progenitor (CD34+CD38-, p=0.032), monocyte (CD14+, p=0.015), and megakaryocyte/platelet (CD61+, p=0.020) cells in the bone marrow of NSG mice. CD26 has been previously shown to cleave SDF-1 (stromal cell-derived factor 1/CXCL12). After cleavage, SDF-1 retains its ability to bind to its receptor (CXCR4) but no longer signals. SDF-1 is a powerful chemoattractant and has been shown to be important in mobilization, homing, and engraftment of HSCs and HPCs. This study demonstrates the influence of ex vivo culture and the effect of cytokine treatment on CD26 activity and subsequent biologic function related to HSCT. All three cytokines studied caused a significant increase in enzymatic activity at 48 hours compared to untreated cells. The up-regulation of CD26 protein expression caused by cytokine treatment for 48 hours, in particular G-CSF, had a significant impact on SDF-1 stimulated migration and adhesion. This was demonstrated in vitro by the improvement in cell function after CD26 inhibitor treatment and in vivo by the improved engraftment seen in the G-CSF treated cells with CD26 inhibitor treatment. These experiments suggest that combining CD26 inhibitor treatment following culture with G-CSF treatment during culture has the greatest overall benefit in engraftment outcome. By increasing our understanding of the effects of exogenous cytokines during culture on trafficking, ex vivo expanded CB has the potential to become a more effective means of not only increasing numbers of CB HSC/HPCs but also engraftment outcomes. This would ultimately allow expanded cord blood to become a more viable option for HSCT. Disclosures: No relevant conflicts of interest to declare.

Kinetics of Engraftment and Graft Versus Host Disease After Cotransplantation of Ex Vivo Expanded and Unexpanded Cord Blood Units In Immunodeficient Mice.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3722-3722
Author(s):  
Li Ming Ong ◽  
Xiubo Fan ◽  
Pak Yan Chu ◽  
Florence Gay ◽  
Justina Ang ◽  
...  
Keyword(s):  
Cord Blood ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Hematopoietic Stem ◽  
Immunodeficient Mice ◽  
Insulin Growth Factor ◽  
Nsg Mice ◽  
Nonobese Diabetic ◽  
Cd34 Cells

Abstract Abstract 3722 Ex vivo expansion of cord blood (CB) hematopoietic stem cells (HSCs) and cotransplantation of two CB units can enhance applicability of CB transplants to adult patients. This is the first study on cotransplantation of ex vivo expanded and unexpanded human CB units in immunodeficient mice, simulating conditions for ex vivo CB expansion clinical trials. CB units were cultured in serum-free medium supplemented with Stem Cell Factor, Flt-3 ligand, Thrombopoietin and Insulin Growth Factor Binding Protein-2 with mesenchymal stromal co-culture. Cotransplantation of unexpanded and expanded CB cells was achieved by tail vein injection into forty-five sublethally irradiated nonobese diabetic SCID-IL2γ−/− (NSG) mice. Submandibular bleeding was performed monthly and mice were sacrificed 4 months following transplantation to analyze for human hematopoietic engraftment. CB expansion yielded 40-fold expansion of CD34+ cells and 18-fold expansion of HSCs based on limiting dilution analysis of NSG engraftment. Mice receiving expanded grafts had 4.30% human cell repopulation, compared to 0.92% in mice receiving only unexpanded grafts at equivalent starting cell doses (p = 0.07). Ex vivo expanded grafts with lower initiating cell doses also had equivalent engraftment to unexpanded grafts with higher cell dose (8.0% vs 7.9%, p= 0.93). However, the unexpanded graft, richer in T-cells, predominated in final donor chimerism. Ex vivo expansion resulted in enhanced CB engraftment at equivalent starting cell doses, even though the unexpanded graft predominated in long-term hematopoiesis. The expanded graft with increased stem/progenitor cells enhanced initial engraftment despite eventual rejection by the unexpanded graft. Disclosures: No relevant conflicts of interest to declare.

Innate Lymphoid Cell-Derived IL-22 Mediates Endogenous Thymic Repair Under the Control of IL-23

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 143-143
Author(s):  
Jarrod A Dudakov ◽  
Alan M Hanash ◽  
Lauren F. Young ◽  
Natalie V Singer ◽  
Mallory L West ◽  
...  
Keyword(s):  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Critical Role ◽  
Lymphoid Cells ◽  
Thymic Epithelial Cells ◽  
Immune Competence ◽  
Strong Negative Correlation ◽  
Hematopoietic Stem ◽  
Stimulation Of

Abstract Abstract 143 Despite being exquisitely sensitive to insult, the thymus is remarkably resilient in young healthy animals. Endogenous regeneration of the thymus is a crucial function that allows for renewal of immune competence following infection or immunodepletion caused by cytoreductive chemotherapy or radiation. However, the mechanisms governing this regeneration remain poorly understood. Thymopoiesis is a highly complex process involving cross-talk between developing thymocytes and their supporting non-hematopoietic stromal microenvironment, which includes highly specialized thymic epithelial cells (TECs) that are crucial for T cell development. IL-22 is a recently identified cytokine predominantly associated with maintenance of barrier function at mucosal surfaces. Here we demonstrate for the first time a critical role for IL-22 in endogenous thymic repair. Comparing IL-22 KO and WT mice we observed that while IL-22 deficiency was redundant for steady-state thymopoiesis, it led to a pronounced and prolonged loss of thymus cellularity following sublethal total body irradiation (SL-TBI), which included depletion of both thymocytes (p=0.0001) and TECs (p=0.003). Strikingly, absolute levels of IL-22 were markedly increased following thymic insult (p<0.0001) despite the significant depletion of thymus cellularity. This resulted in a profound increase in the production of IL-22 on a per cell basis (p<0.0001). These enhanced levels of IL-22 peaked at days 5 to 7 after SL-TBI, immediately following the nadir of thymic cellularity. This was demonstrated by a strong negative correlation between thymic cellularity and absolute levels of IL-22 (Fig 1a). In mucosal tissues the regulation of IL-22 production has been closely associated with IL-23 produced by dendritic cells (DCs) and ex vivo incubation of cells with IL-23 stimulates the production of IL-22. Following thymic insult there was a significant increase in the amount of IL-23 produced by DCs (Fig 1b) resulting in similar kinetics of intrathymic levels of IL-22 and IL-23. We identified a population of radio-resistant CD3−CD4+IL7Ra+RORg(t)+ thymic innate lymphoid cells (tILCs) that upregulate both their production of IL-22 (Fig 1c) and expression of the IL-23R (p=0.0006) upon exposure to TBI. This suggests that they are responsive to IL-23 produced by DCs in vivo following TBI and, in fact, in vitro stimulation of tILCs by IL-23 led to upregulation of Il-22 production by these cells (Fig 1d). We found expression of the IL-22Ra on cortical and medullary TECs (cTECs and mTECs, respectively), and uniform expression across both mature MHCIIhi mTEC (mTEChi) and immature MHCIIlo mTECs (mTEClo). However, in vitro stimulation of TECs with recombinant IL-22 led to enhanced TEC proliferation primarily in cTEC and mTEClo subsets (p=0.002 and 0.004 respectively). It is currently unclear if IL-22 acts as a maturation signal for mTECs, however, the uniform expression of IL-22Ra between immature mTEClo and mature Aire-expressing mTEChi, together with the preferential promotion of proliferation amongst mTEClo and cTEC seem to argue against IL-22 as a maturational signal but rather as promoter of proliferation, which ultimately leads to terminal differentiation of TECs. Of major clinical importance, administration of exogenous IL-22 led to enhanced thymic recovery (Fig. 1e) following TBI, primarily by promoting the proliferation of TECs. Consistent with this, the administration of IL-22 also led to significantly enhanced thymopoiesis following syngeneic BMT. Taken together these findings suggest that following thymic insult, and specifically the depletion of developing thymocytes, upregulation of IL-23 by DCs induces the production of IL-22 by tILCs and regeneration of the supporting microenvironment. This cascade of events ultimately leads to rejuvenation of the thymocyte pool (Fig. 1f). These studies not only reveal a novel pathway underlying endogenous thymic regeneration, but also identify a novel regenerative strategy for improving immune competence in patients whose thymus has been damaged from infection, age or cytoreductive conditioning required for successful hematopoietic stem cell transplantation. Finally, these findings may also provide an avenue of study to further understand the repair and regeneration of other epithelial tissues such as skin, lung and breast. Disclosures: No relevant conflicts of interest to declare.

Role of PDGF/PDGFR in Regulation of Thrombopoiesis: A Possible Explanation for Imatinib Mesylate-Induced Thrombocytopenia in the Treatment of CML

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3348-3348
Author(s):  
Mo Yang ◽  
Fanyi Meng ◽  
Jie yu Ye ◽  
Yue Xu ◽  
Bin Xiao ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Imatinib Mesylate ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Potential Effect ◽  
Mice Model ◽  
Hematopoietic Stem ◽  
Platelet Recovery ◽  
Bone Marrow Histology

Abstract Abstract 3348 Platelet-derived growth factor (PDGF), a platelet alpha-granule molecule, imply their potential effect in the regulation of megakaryocytopoiesis and thrombopoiesis, which also intimates the existence of an autocrine and/or paracrine loop constructed by megakaryocytes/platelets and their granular constituents. Our previous studies demonstrated the presence of functional PDGF receptors (PDGFR) on human megakaryocytes and platelets (Yang et al, Thromb Haemastasis, 1997) and CD34+ cells, and their ability to mediate a mitogenic response. PDGF promoted the ex vivo expansion of human hematopoietic stem (CD34+) and progenitor (CD41+ CD61+) cells. More significantly, PDGF enhanced the engraftment of human CD45+ cells and their myeloid subsets (CD33+, CD14+ cells) in NOD/SCID mice. PDGF stimulated in vitro megakaryocytopoiesis via PDGFR and/or the indirect effect on bone marrow microenvironment to produce TPO and other cytokines. It also showed a direct stimulatory effect of PDGF on c-Fos, GATA-1 and NF-E2 expressions in megakaryocytes. We speculate that these transcription factors might be involved in the signal transduction of PDGF on the regulation of megakaryocytopoiesis. PDGF also enhanced platelet recovery in mice model with radiation-induced thrombocytopenia. Studies showed that PDGF, like thrombopoietin (TPO), significantly promoted platelet recovery and the formation of bone marrow colony-forming unit-megakaryocyte (CFU-MK) in this irradiated-mouse. An increased number of hematopoietic stem/progenitor cells and a reduction of apoptosis were found in the bone marrow histology sections. In the M-07e apoptotic model, PDGF had a similar anti-apoptotic effect as TPO on megakaryocytes. We also demonstrated that PDGF activated the PI3k/Akt signaling pathway, while addition of imatinib mesylate reduced p-Akt expression. Our findings suggested that the PDGF-initiated radioprotective effect is likely to be mediated via PDGF receptors with subsequent activation of the PI3k/Akt pathway. The study provides a possible explanation that blockage of PDGFR may reduce thrombopoiesis and play a role in imatinib mesylate-induced thrombocytopenia in the treatment of CML. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Human Fetal Liver: AnIn VitroModel of Erythropoiesis

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Guillaume Pourcher ◽  
Christelle Mazurier ◽  
Yé Yong King ◽  
Marie-Catherine Giarratana ◽  
Ladan Kobari ◽  
...  
Keyword(s):  
Stem Cells ◽  
Large Scale ◽  
Adult Stem Cells ◽  
Fetal Liver ◽  
Es Cells ◽  
Embryonic Stem ◽  
Scale Production ◽  
Cloning Efficiency ◽  
Hematopoietic Stem

We previously described the large-scale production of RBCs from hematopoietic stem cells (HSCs) of diverse sources. Our present efforts are focused to produce RBCs thanks to an unlimited source of stem cells. Human embryonic stem (ES) cells or induced pluripotent stem cell (iPS) are the natural candidates. Even if the proof of RBCs production from these sources has been done, their amplification ability is to date not sufficient for a transfusion application. In this work, our protocol of RBC production was applied to HSC isolated from fetal liver (FL) as an intermediate source between embryonic and adult stem cells. We studied the erythroid potential of FL-derived CD34+cells. In thisin vitromodel, maturation that is enucleation reaches a lower level compared to adult sources as observed for embryonic or iP, but, interestingly, they (i) displayed a dramaticin vitroexpansion (100-fold more when compared to CB CD34+) and (ii) 100% cloning efficiency in hematopoietic progenitor assays after 3 days of erythroid induction, as compared to 10–15% cloning efficiency for adult CD34+cells. This work supports the idea that FL remains a model of study and is not a candidate forex vivoRBCS production for blood transfusion as a direct source of stem cells but could be helpful to understand and enhance proliferation abilities for primitive cells such as ES cells or iPS.

Ex Vivo Large Scale Generation of Human Platelets from Cord Blood CD34+ Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1892-1892
Author(s):  
Takuya Matsunaga ◽  
Ikuta Tanaka ◽  
Masayoshi Kobune ◽  
Yutaka Kawano ◽  
Maki Tanaka ◽  
...  
Keyword(s):  
Cord Blood ◽  
Culture System ◽  
Large Scale ◽  
Culture Medium ◽  
Ex Vivo ◽  
Aggregation Assay ◽  
Three Phase ◽  
Cd34 Cells ◽  
Phase Culture

Abstract To obtain a large quantity of platelets (PLTs) from cord blood stem cells (CBSC) in vitro, we employed three-phase culture system. We first expanded CBSC on a monolayer of human telomerase catalytic subunit gene-transduced human stromal cells (hTERT stroma) in serum-free medium supplemented with stem cell factor (SCF), Flt-3/Flk-2 ligand (FL) and thrombopoietin (TPO) for 14 days (1st phase), and then cultured them to differentiate into megakaryocytes for another 14 days with refreshing medium which contain interleukin-11 (IL-11) in addition to original cytokine cocktail (2nd phase). Subsequently, we transferred the cells to a liquid culture medium containing SCF, FL, TPO and IL-11, and cultured them for 5 days (3rd phase) to recover PLTs in the culture medium. The quantity of PLTs recovered from one CB unit (5 x 106 CD34+ cells) was calculated to be 10.5 units (2 x 1011 PLTs). These CB-derived PLTs exhibited quite similar feature as those from peripheral blood in morphology as revealed by electron micrograph and in functions as revealed by aggregation assay and by FACS detecting expression of P-selectin and activated glycoprotein IIb-IIIa antigens upon fibrinogen/ADP stimulation. Thus our three-phase culture system was considered to be useful for large scale generation of PLTs from CB for clinical usage.

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