[Ex-vivo expansion of hematopoietic stem cells: study in the primate model].
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Animals↗
Biomedical subjects
F Norol
Publications and source records attributed to F Norol.
Expression of a foreign protein in human megakaryocytes and platelets by retrovirally mediated gene transfer.
Recent progress in the culture of human megakaryocytes (MKs) has led to the capacity to produce platelets in vitro. This capability enables investigation into the possibility of modifying platelet structure and/or function by genetically altering the MK. To this end, a cDNA for the murine CD9 (mCD9) cell surface protein was introduced into MK progenitors by retrovirally mediated gene transfer and subsequently detected in cultured MKs with a monoclonal antibody (MoAb) that specifically recognizes the murine protein. CD34+ human peripheral blood or marrow progenitors, enriched by immunomagnetic bead selection, were cultured for 5 days in the presence of growth factors, including stem cell factor and thrombopoietin, to induce MK progenitors into the cell cycle. The stimulated cells were then cocultured with the mCD9 retroviral producer cell line for 3 days, followed by culture in serum-depleted medium for 3 to 7 additional days. Flow cytometry analysis using the anti-CD9 MoAb and TAB, a MoAb recognizing human GPIIb, revealed that a large proportion (40-100%) of the MKs expressed mCD9. To ascertain whether these cells were capable of producing mCD9+ platelets, flow cytometry analysis was performed at a time when proplatelets were observed in the culture. mCD9 was detected in up to 59% of the TAB+ platelet-sized particles. Because deteriorating MKs can produce platelet-sized particles in vitro, experiments were performed to determine whether mCD9+ TAB+ particles were functionally active. Addition of phorbol myristate acetate resulted in the redistribution of P-selectin (CD62) from the alpha granule to the platelet surface as detected by MoAbs S12 and G5 in three-color flow cytometry analyses. These studies showed that up to 76% of the mCD9+ TAB+ particles were functionally active. The data show that retrovirally mediated gene transfer is a viable approach for genetically altering MK progenitors, resulting in platelets that express heterologous proteins.
Animals↗
[Thrombopoietin and megakaryocyte differentiation].
Regulation of megakaryocytopoiesis and platelet production is a complex phenomenon. It has been demonstrated that numerous pleiotropic cytokines act in vivo and in vitro on megakaryocytopoiesis. Historically, studies on the regulation of megakaryocytopoiesis were largely dominated by the concept of humoral regulation. Despite 35 years of work, the factor responsible for these effects (thrombopoietin, TPO) could not be purified to homogeneity. The proto-oncogene c-mpl has been demonstrated to encode a protein which is the receptor for a humoral cytokine regulating megakaryocytopoiesis. Its ligand was isolated by three independent groups. The purified protein was termed Mpl-L (Mpl-Ligand), thrombopoietin (TPO), or megakaryocyte growth and development factor (MGDF). Strong evidence that Mpl-L is the homeostatic regulator of platelet production has been provided by c-mpl or Mpl-L knock-out mice which have a severe but not lethal thrombocytopenia. In vitro experiments have indicated that the Mpl-L acts both as a proliferative and differentiative factor as many other CSF. At the unicellular level, Mpl-L acts on MK progenitors inducing their proliferation. Mpl-L induces polyploidisation of the MKs and cytoplasmic maturation leading to an in vitro platelet production. As a single cytokine Mpl-L is the most potent growth factor for the MK lineage in vitro. However, a combination of cytokines can totally replace the effects of Mpl-L both on proliferation of MK progenitors and their maturation. In addition, Mpl-L has a major effect on primitive hematopoietic progenitors.
Animals↗
Reverse seroconversion of hepatitis B after allogeneic bone marrow transplantation: a retrospective study of 37 patients with pretransplant anti-HBs and anti-HBc.
BACKGROUND: Reverse seroconversion to hepatitis B virus (HBV), i.e., HBV reactivation in patients with pretransplant antibodies to hepatitis B surface antigen (anti-HBs) and to hepatitis B core antigen (anti-HBc), is rarely re-ported after allogeneic bone marrow transplantation. METHODS: To determine this risk, we studied clinical outcome and serological changes in 37 patients with pretransplant anti-HBs and anti-HBc. RESULTS: In 33 cases, no change in HBV markers was observed in the posttransplant period. In four cases, anti-HBs and anti-HBc were lost, and hepatitis B surface antigen, hepatitis B e antigen, and HBV DNA emerged together with acute hepatitis, after cessation of immunosuppression. The actuarial risk of reactivation in the 37 patients was 20.5% (median follow-up 20 months). No reactivation occurred in patients with anti-HBs-positive donors. CONCLUSION: Although few cases of postallogeneic bone marrow transplantation reverse seroconversion to HBV have been reported, this study demonstrates that the actuarial risk is relatively high and suggests that donor vaccination might be proposed prophylactically or that HBs-specific immunoglobulin infusions might be warranted.
Adolescent↗
Platelet transfusion: a dose-response study.
Early recommendations on prophylactic transfusion of thrombocytopenic patients involved a standard platelet dose of about 0.5 x 10(11)/10 kg body weight. Given the lack of data supporting this dose, we prospectively studied the dose response to platelet transfusions in adults and children with hematologic malignancies. Each patient received, in similar clinical conditions, a medium, high, and very high dose of fresh (< 24 hours old) ABO-compatible platelets, in the form of apheresis platelet concentrates (APC). For the adults, the medium dose was defined as APC containing between 4 and 6 x 10(11) platelets, the high dose between 6 and 8 x 10(11), and the very high dose > 8 x 10(11); for the children, the three doses corresponded to 2 to 4, 4 to 6, and > 6 x 10(11) platelets. The end points were the platelet increment, platelet recovery, and the transfusion interval, and the results were compared with a paired t-test. Sixty-nine adults and 13 children could be assessed. Recoveries in the adults were similar with the three doses (from 28% to 30%), but the high and very high doses led to a significantly better platelet increment (52 and 61 x 10(9)/L, respectively) than the medium dose (33 x 10(9)/L, P < .01). The main difference was in the transfusion interval, which increased with the dose of platelets transfused, from 2.6 days with the medium dose to 3.3 and 4.1 days with the high and very high doses, respectively (P < .01). The positive effect of the high dose was observed regardless of pretransfusional clinical status, but was more marked in patients with no clinical factors known to impair platelet recovery. In these patients, a platelet dose of 0.07 x 10(11) per kg of body weight led to a transfusion interval of more than 2 days in 95% of cases. In patients with clinical factors favoring platelet consumption, the proportion of transfusions yielding an optimal platelet increment and transfusion interval increased with the dose of platelets. The platelet dose-effect was also significant in the children, in whom the high and very high doses led to 1.5-fold to twofold higher posttransfusion platelet counts and transfusion intervals. We conclude that transfusion of high platelet doses can reduce the number of platelet concentrates required by thrombocytopenic patients and significantly reduce donor exposure.
Acute Disease↗
Endomitosis of human megakaryocytes are due to abortive mitosis.
During megakaryocyte differentiation, the promegakaryoblast (immature megakaryocyte) increases its ploidy to a 2(x) DNA content by a poorly understood process called endomitosis. This leads to the formation of a giant cell, the megakaryocyte (MK), which subsequently gives rise to platelets. In this report, we show that endomitosis of human MKs is due to abortive mitosis. Human MKs were obtained by a two-step purification of CD34(+) blood or marrow precursors followed by in vitro culture in the presence of MK growth factors. Microscopic examination shows that a large number of centrosomes (up to 32) and centrioles are present in polyploid MKs. After nocodazole treatment, more than 20% of the MK are blocked in a typical pseudo-metaphase. Both spontaneous and nocodazole-induced endomitosis are associated with a breakdown of the nuclear envelope and possess a complex mitotic spindle composed of several asters. Spindle microtubules radiate from each aster, creating a spherical structure. At metaphase, expression of the kinetochore phosphoepitope recognized by the 3F3/2 antibody is lost, and the sister chromatids segregate moving toward the spindle poles. After limited segregation, the chromosomes decondense and the nuclear envelope reforms in the absence of cytokinesis, isolating all chromosomes in a single nucleus. It has been proposed that endomitosis could be due to an abnormal CDK1 activity or an absence of cyclin B1. Our results show that cyclin B1 can be detected in all MKs, including those with a ploidy of 8N or more. The cyclin B1 staining colocalizes with the mitotic spindle. Using flow cytometry, the level of cyclin B1 increased until 8N, but remained identical in 16N and 32N MKs. Cell sorting was used to separate the MKs into a 2N/4N and >4N population. Both cyclin B1 and CDK1 could be detected in the endomitotic polyploid MKs using Western blot analysis, and a histone H1 kinase activity was associated with immunoprecipitated cyclin B1. We conclude that endomitosis of human MKs is due to abortive mitosis, possibly due to alterations in the regulation of mitotic exit.
Antigens, CD34↗
Effects of cytokines on platelet production from blood and marrow CD34+ cells.
The late stages of megakaryocytopoiesis, consisting of the terminal processes of cytoplasmic maturation and platelet shedding, remain poorly understood. A simple liquid culture system using CD34+ cells in serum-free medium has been developed to study the regulation of platelet production in vitro. Platelets produced in vitro were enumerated by flow cytometry. A truncated form of human Mpl-Ligand conjugated to polyethylene glycol (PEG-rHuMGDF) played a crucial role in both proplatelet formation and platelet production. A combination of stem cell factor (SCF), interleukin-3 (IL-3), and IL-6 was as potent as PEG-rHuMGDF for the growth of megakaryocytes (MKs). However, the number of proplatelet-displaying MKs and platelets was increased 10-fold when PEG-rHuMGDF was used. Peripheral blood mobilized CD34+ cells gave rise to a threefold augmentation of platelets compared with marrow CD34+ cells. This finding was related to the higher proliferative capacity of the former population because the proportion of proplatelet-displaying MKs was similar for both types of CD34+ cells. The production of platelets per MK from CD34+ cells was low, perhaps because of the low ploidy of the cultured MKs. This defect in polyploidization correlated with the degree of proliferation of MK progenitors induced by cytokines. In contrast, ploidy development closer to that observed in marrow MKs was observed in MKs derived from the low proliferative CD34+ CD41+ progenitors and was associated with a twofold to threefold increment in platelet production per MK. As shown using this CD34+ CD41+ cell population, PEG-rHuMGDF was required throughout the culture period to potently promote platelet production, but was not involved directly in the process of platelet shedding. IL-3, SCF, and IL-6 alone had a very weak effect on proplatelet formation and platelet shedding. Surprisingly, when used in combination, these cytokines elicited a degree of platelet production which was decreased only 2.4-fold in comparison with PEG-rHuMGDF. This suggests that proplatelet formation may be inhibited by non-MK cells which contaminate the cultures when the entire CD34+ cell population is used. Cultured platelets derived from PEG-rHuMGDF- or cytokine combination-stimulated cultures had similar ultrastructural features and a nearly similar response to activation by thrombin. The data show that this culture system may be useful to study the effects of cytokines and the role of polyploidization on platelet production and function.
Antigens, CD34↗
Apparent reactivation of a red cell alloantibody in a healthy individual after G-CSF administration.
Granulocyte-colony stimulating factor (G-CSF) has been successfully administered to healthy subjects to mobilize peripheral blood stem cells (PBSC) for allogeneic transplantation. Adverse events are moderate. We report the first case of apparent reactivation of an alloantibody to a blood cell antigen (Jk(a)) after G-CSF administration to a healthy subject and its transmission to the PBSC transplant recipient; no concomitant reactivation of other alloantibodies was detected. This case raises questions on the effect of G-CSF on the immune system and its safety in healthy individuals.
Adjuvants, Immunologic↗
Peripheral blood stem cell and bone marrow transplantation for solid tumors and lymphomas: hematologic recovery and costs. A randomized, controlled trial.
BACKGROUND: Previous studies have suggested that peripheral blood stem cell (PBSC) transplantation has an advantage over autologous bone marrow transplantation. OBJECTIVE: To compare the hematologic recovery and costs associated with PBSC transplantation with those associated with autologous bone marrow transplantation in patients receiving high-dose chemotherapy for solid tumors or lymphomas. DESIGN: Multicenter, randomized, controlled clinical trial. SETTING: French Federation of Cancer Centers, located in cancer facilities or public hospitals with transplantation units. PATIENTS: Children and adults with solid tumors or lymphomas who were candidates for high-dose chemotherapy. INTERVENTIONS: Bone marrow or filgrastim-mobilized PBSCs. MEASUREMENT: The major and point was the duration of thrombocytopenia (platelet count < 50 x 10(9)/L). An economic evaluation of both types of transplantation was done prospectively to measure costs and cost-effectiveness. RESULTS: 129 patients entered the trial; 64 had PBSC transplantation, and 65 had bone marrow transplantation. The median duration of thrombocytopenia was 16 days in the PBSC group and 35 days in the bone marrow group (P < 0.001). All of the other clinical end points studied (time to last platelet transfusion, duration of granulocytopenia, number of transfusion episodes, and duration of hospitalization) favored PBSC transplantation. A cost analysis showed that total cost was decreased by 17% in adults and 29% in children with PBSC transplantation; thus, PBSC transplantation was clearly more cost-effective than bone marrow transplantation for both platelet and granulocyte recovery. CONCLUSION: Transplantation of PBSCs is associated with more rapid hematologic recovery than is bone marrow transplantation after high-dose chemotherapy for solid tumors or lymphomas. Furthermore, global costs are lower and cost-effectiveness ratios are better with PBSC transplantation.
Adolescent↗
Ultrastructure of platelet formation by human megakaryocytes cultured with the Mpl ligand.
The site and mechanism of platelet production by bone marrow megakaryocytes (MKs) has been the subject of extensive studies, but is still a matter of controversy. However, the recent discovery of the Mpl ligand (Mpl-l), also called megakaryocyte growth and development factor (MGDF) or thrombopoietin, has resulted in considerable progress in the understanding of the maturation of the MK lineage. To better understand the mechanism of platelet production, we examined the late stage of MK maturation by electron microscopy in cells cultured in the presence of Mpl-l. Human bone marrow CD34+ CD38+ cells, which contain late MK progenitors, were purified by flow cytometry and cultured in a serum-free liquid medium containing recombinant human Mpl-l (MGDF 10 ng/mL) for 7 days. In this system, the majority of cultured cells were large MKs with lobulated polyploid nuclei. The MKs displayed a smooth surface with harmonious cytoplasmic maturation and abundant, regularly distributed demarcation membranes and alpha-granules, and even some dense granules. Interestingly, approximately 30% of the MKs observed displayed morphologic evidence of platelet production: at optical microscopy, MKs formed long filamentous cytoplasmic extensions (proplatelets) that fragmented into platelet-sized particles. Moreover, flow cytometric analysis of this cultured cell population showed GPIIb-positive particles of the size of platelets. Electron microscopic observation showed that MKs producing platelets displayed thin pseudopods on the surface, and that the channels of the demarcation membrane system were dilated, allowing long strands of cytoplasm to extend from the cell periphery. These cytoplasmic strands displayed beading with constrictions separating platelet-sized segments; the more distal to the cell core, the smaller the fragments were. They eventually detached from the cell core into the culture medium either occasionally still elongated or, more often, separated into individual platelets. Parallel longitudinal and perpendicular microtubules were visualized in the constricted regions of these cytoplasmic strips; immunogold study of tubulin localization confirmed this subcellular distribution. On both sides of the constricted areas, vacuoles were noted, the fusion of which might have led to the detachment of individual platelets. Finally, in close proximity to the platelet-forming MKs, numerous microparticles were shed. Although some of these particles might correspond to transverse sections of pseudopods, this did not seem to be the case, since they were rarely seen around thrombin-stimulated MKs with surfaces bristled by numerous pseudopods. Flow cytometry showed that apart from shed cytoplasmic fragments of platelet size, numerous smaller particles strongly labeled for CD41 were also released by mature MKs. In conclusion, this study describes the ultrastructure of human platelet production in cultured MKs, involving the formation of proplatelets and the shedding of microparticles.
Blood Platelets↗
Characteristics of peripheral blood progenitor cells frozen after 24 hours of liquid storage.
Peripheral blood progenitor cells (PBPC) harvested for autologous transplantation are usually cryopreserved within 2-4 h of collection. However, there are conditions in which it would be useful to freeze PBPC after a liquid storage period. This study was performed to evaluate whether prior storage for just 24 h damages frozen PBPC. First, leukapheresis products were obtained from 9 patients and divided into three fractions. The first fraction was frozen within 2 h and used as a control. The second and the third fractions were stored either at 4 degrees C or at 22 degrees C for 24 h before freezing. Cell counts, CFU-GM values, and pH were studied after collection, after storage, and after cryopreservation. Similar results were obtained at 4 degrees C and 22 degrees C. However, pH decreased most markedly at 22 degrees C. Mean postcryopreservation CFU-GM recoveries were not significantly different and were, respectively, 74.03% (control), 96.39% (4 degrees C), and 80.33% (22 degrees C). These observations were confirmed in an additional study of frozen PBPC collected from 12 patients and previously stored for 24 h at 4 degrees C. These data indicate that blood progenitors may be stored for 24 h and subsequently frozen without quantitative and qualitative impairment.
Cryopreservation↗
Photochemotherapy in kidney transplantation: preliminary results.
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Adult↗
[Ineffectiveness of platelet transfusions in the course of thrombocytopenia of central origin. Work Group coordinated by ANDEM].
This study, conducted under the auspices of ANDEM, was aimed at determining the reasons for the inefficacy of platelet transfusions for thrombocytopenia of central origin, and to establish recommendations for therapy and prevention. It was based on a critical review of the literature. Three main causes of inefficacy were identified: an immunological conflict (mainly anti-HLA alloimmunization), clinical status, and the quality of platelet preparations (especially storage time). Our recommendations depend on several factors, such as the degree of urgency, the cause of platelet refractoriness, clinical status and the availability of platelet preparations. The mainstay of the recommendations is prevention, based on the quality of platelet preparations (as fresh as possible, in adequate number preferably obtained by apheresis and ABO compatible) and on the prevention of anti-HLA alloimmunization.
Brain Diseases↗
Cutaneous chronic graft-vs-host disease and hepatitis C virus.
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Adult↗
[Transfusion and alloimmunization in sickle cell anemia patients].
Transfusion therapy for sickle cell anemia is limited by the development of antibodies to red cell antigens. The aim of this study was to evaluate whether transfusion of blood matched for antigens Rh and Kell would reduce the incidence of alloimmunization. We determined the transfusion history, red cell phenotype and development of alloantibodies in 173 patients with sickle all anemia who received transfusions. Forty nine patients were transfused exclusively with frozen red blood cells (RBL) matched for antigens Rh and Kell; the rate of alloimmunization was 8.2%; antibodies to the Jkb, Jka, Fya and S were developed; 1 patient developed 2 antibodies. In a control group of 124 patients who received standard red blood cells, the rate of alloimmunization was significantly increased to 30.6% (p < 0.05); antibodies against C, E, K, Fya were the most frequently developed and 19 patients (16%) developed antibodies reacting with different antigens. In the 2 groups, alloimmunization occurred after receiving a significantly different number of transfusions: mean 9 in the patients transfused with matched RBC and 32 in the control group. The influence of the kinetics of transfusion was not demonstrated. To assess the effect that racial differences might have on alloimmunization, comparison of the red cell phenotype of patients with that of a panel of unselected blood bank donors was performed: the patients had a significant decrease in the frequency of red cell antigens corresponding to most of the detected alloantibodies JkB, C, S. Fyb, Fya and Kell.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Hepatitis C virus infection and allogeneic bone marrow transplantation.
Serum antibodies to hepatitis C virus (HCV) were tested for inpatients undergoing allogeneic BMT to determine the risk of acquiring HCV infection and the role of HCV in posttransplant liver complications. The HCV seroconversion rate was evaluated according to the date of BMT and blood donor screening at the time. Anti-HCV antibodies (anti-HCV) were detected with a second-generation ELISA and confirmed with a second-generation radioimmunoblot assay. All patients received leukocyte-depleted blood products and most received apheresis platelet concentrates. One hundred twenty of 181 consecutive patients transplanted from January 1987 to December 1991 were anti-HCV-negative before BMT, had at least 6 months of follow-up, and were thus evaluated for the seroconversion rate. Before screening for non-A, non-B hepatitis, 14% of the patients seroconverted to HCV (0.44% per unit transfused). After introduction of screening for alanine aminotransferase and antibodies to hepatitis B core antigen the risk of seroconversion was 4% per patient (0.26% per unit). When, in addition, blood was screened for anti-HCV the risk fell to 1.6% (0.03% per unit). Positive anti-HCV status before and after BMT was not predictive of veno-occlusive disease, liver graft-versus-host disease (GVHD), or death due to liver dysfunction. In contrast, the risk of chronic hepatitis was significantly increased.
Adolescent↗
Influence of clinical status on the efficiency of stored platelet transfusion.
The efficiency of stored platelet transfusion was evaluated in terms of clinical status in 141 thrombocytopenic patients. In a paired prospective study in which fresh platelets were used as controls, clinical efficiency was assessed on the basis of the ability to increase platelet count (recovery) and the time to the next transfusion (D). In 48 clinically stable patients, recovery of fresh and stored platelets was similar (47% and 41%, respectively) and the interval to the next transfusion was D4 and D3. In contrast, 27 patients who had bacterial infections showed significantly different recoveries (24%/5%) and the interval to the next transfusion was D3/D1 for fresh and stored platelets respectively. Similarly, in 16 patients who were treated concurrently with amphotericin B, 18 other patients with graft-versus-host disease, nine with splenomegaly and four with veno-occlusive disease (VOD), fresh platelets performed better than stored platelets, showing recoveries of 27%/18%, 29%/15%, 16%/3% and 15%/2%. Furthermore, the need for retransfusion within 24 h was significantly increased with stored platelets. In 19 patients with anti-HLA alloimmunization who were transfused with HLA-matched fresh and stored apheresis platelet concentrate (APC), efficiency was similar (38%/36% and D4/D3). This study indicates that the storage induces an impressive decrease in the in-vivo platelet recovery and survival in patients with certain clinical conditions.
Adult↗
Comparison of autografting using mobilized peripheral blood stem cells with and without granulocyte colony-stimulating factor in malignant lymphomas.
Peripheral blood is becoming widely used as the only source of hematopoietic stem cells to support marrow ablative therapy in advanced lymphoma. We report data from 23 patients with high risk non-Hodgkin's (n = 19) and Hodgkin's lymphoma (n = 4) who underwent high-dose therapy with mobilized peripheral blood stem cell (PBSC) autografting. Peripheral blood progenitors were recruited using cytotoxic chemotherapy followed by administration of recombinant human G-CSF (filgrastim 5 micrograms/kg/day). Myeloablative treatment with autologous PBSC support was administrated to the 23 patients and followed by G-CSF at the same dose after cell reinjection. Hematopoietic reconstitution was compared with a control group of lymphoma patients who received chemotherapy mobilized PBSC transplantation but without G-CSF prior to leukaphereses or after high-dose therapy. The median time to neutrophil recovery > 0.5 x 10(9)/l was significantly shorter in study patients compared with the control patients (10 days and 17 days respectively) (p < 0.05). Self sustaining platelet counts of > 50 x 10(9)/l occurred at a median time of 17 days in both groups. Stable hemopoietic reconstitution was seen with a follow-up of 6 months after PBSC transplantation. In addition, a significant relationship was observed between the number of CFU-GM infused and the time to platelet recovery. We confirm the effectiveness of G-CSF given prior to PBSC harvesting in generating high numbers of progenitor cells. Hematologic recovery following high-dose therapy was improved after PBSC rescue and G-CSF.
Adolescent↗