Z C Han

Chinese Academy of Medical Sciences, Peping, Beijing, China

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Publications (46)174.32 Total impact

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    ABSTRACT: Many chemokines have direct suppressive activity in vitro and in vivo on primitive hematopoietic cells. However, few chemokine-derived peptides have shown a significant activity in inhibiting hematopoiesis. Interestingly, a peptide derived from the 34-58 sequence of the CXC chemokine platelet factor 4 (PF4) produced a 30-40% inhibition of proliferation of murine hematopoietic progenitors (CFU-MK, CFU-GM, and BFU-E) in vitro, at concentrations of 30-60-fold lower than PF4. The aim of the present work was to define the structural parameters and motifs involved in conferring biological activity to the peptide PF4(34-58). Both structural predictions and determinations revealed a new helical motif that was further localized between residues 38 and 46. This helix was necessary for binding of the peptide and for permitting the functional DLQ motif at position 54-56 to activate the putative receptor site. Peptides lacking either the helical or the DLQ motif were devoid of inhibitory activity on the hematopoietic progenitors in vitro. However, among inactive peptides, only those having the helical motif counteracted the inhibition induced by the active peptide PF4(34-58). This suggested that the helix might be required for peptide interactions with a putative receptor site, whereas the DLQ motif would be implicated in the activation of this receptor. These results identify for the first time the dual requirements for the design of chemokine-derived peptides with high suppressive activity on hematopoiesis, as well as for the design of molecules with antagonistic action.
    Biochemistry 09/2000; 39(31):9612-22. · 3.38 Impact Factor
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    ABSTRACT: The use of platelet transfusion to ensure the recovery of thrombopoiesis in patients constitutes high-cost support. The identification and cloning of recombinant human thrombopoietin (TPO) and the development of efficient methods of purification of hematopoietic stem cells and progenitor cells have ameliorated the development of strategies of ex vivo expansion of megakaryocyte (MK) progenitor cells and mature MKs. Synergistic combinations of cytokines including TPO, interleukin (IL)-1, IL-3, IL-11, stem cell factor, and FLT-3 ligand induce the ex vivo expansion of colony-forming unit-MK progenitors and MKs from cytokine-mobilized peripheral blood cells, bone marrow, and cord blood CD34+ cells. Depending on the various culture conditions, i.e., combinations of growth factors, initial concentration of CD34+, serum or serum-free cultures, and/or oxygen tensions, the expansion-fold of MKs and their progenitor cells vary greatly. The clinical applications of the reinfusion of ex vivo-generated MK cells have been investigated successfully in cancer patients following high-dose chemotherapy. This review reports the latest information concerning ex vivo expansion of MKs and the current status of clinical trials.
    International Journal of Hematology 05/2000; 71(3):203-10. · 1.68 Impact Factor
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    ABSTRACT: After 35 years of research, a physiological regulator of platelet production has been identified and the recombinant protein is available. With the discovery of thrombopoietin (TPO), its potential use in a wide variety of clinical megakaryocytic and platelet disorders has been expected and clinical trials have been undertaken. To date, the reported encouraging pre-clinical studies indicate that, as with erythropoietin or G-CSF, minimal toxicity can be expected. A potential limiting side-effect of TPO could be the induction of thrombosis. Nevertheless, it is too early to know whether this cytokine will be of major therapeutic importance for patients with life-threatening thrombocytopenia, such as patients undergoing bone marrow transplantation or subjected to a high dose of chemotherapy. Several experimental and clinical studies are still needed to determine the efficacy of TPO in the prevention or the amelioration of bleeding, which is the ultimate goal for the appropriate use of cytokines with haemostatic benefit. Basic and clinical studies on regulators of megakaryocytopoiesis have rapidly progressed. Now, there is no doubt that some of these regulators are effective in correcting haematopoietic disorders of various aetiologies. Studies on negative regulators not only are important to understand the regulation of megakaryocytopoiesis in normal and pathological states but also have a potential clinical application. Some of these regulators have been shown to be effective in the treatment of essential thrombocythaemia and other myeloproliferative disorders. Platelet factor 4 (PF4) and some other chemokines are also capable of protecting progenitor cells from the cytotoxicity of chemotherapeutic drugs. However, detailed investigations are still required to determine the precise mechanism(s) of action of these regulators and to establish the optimal clinical protocols of negative regulators alone or in association with positive regulators for the treatment of various haematological diseases and cancer.
    Haemostasis 10/1999; 29(1):27-40.
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    ABSTRACT: Arsenic trioxide (As2O3) has been demonstrated to be effective for the treatment of acute promyelocytic leukemia (APL) and to inhibit proliferation and produce apoptosis in the APL cell line NB4. To determine if As2O3 might be useful for the treatment of other lineages, we investigated the effects of As2O3 on viability, proliferation, and induction of apoptosis in the megakaryocytic leukemia cell lines HEL, Meg-01, UT7, and M07e. Our results showed that As2O3, at concentrations of 0.1-2.0 microM, causes a dose- and time-dependent inhibition of survival and growth in all four megakaryocytic leukemia cell lines studied. In contrast, As2O3 at similar concentrations had no effects on either viability or growth of the nonmegakaryocytic leukemia cell line HL60 and two human breast cancer cell lines, ZR75 and MCF7. In situ end-labeling of DNA fragments (TUNEL assay) indicated that As2O3, at concentrations of 0.5-2 microM, could significantly induce apoptosis in the aforementioned four megakaryocytic leukemia cell lines, but not in the nonmegakaryocytic HL60, ZR75, and MCF7 cell lines. These results were confirmed using conventional morphologic assessment and the DNA ladder assay. Induction of apoptosis in arsenic-treated Meg-01 and UT7 cells was accompanied by a dose-response decrease of Bcl-2 protein, whereas As2O3 had no effect on this measurement in HL60, ZR75, and MCF7 cell lines. Pertinently, these concentrations of As2O3 produced identical changes in the characteristics of the APL cell line NB4. Collectively, these data demonstrate that As2O3 can selectively inhibit growth and induce apoptosis in megakaryocytic leukemia cell lines. The use of As2O3 for the treatment of malignant megakaryocytic disorders should be considered.
    Experimental Hematology 06/1999; 27(5):845-52. · 2.91 Impact Factor
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    ABSTRACT: The tetrapeptide Acetyl-Ser-Asp-Lys-Pro (AcSDKP) has been described as an inhibitor of CFU-S entry into DNA synthesis; as a result, its administration can protect mice against lethal doses of cytosine arabinoside (Ara-C). In the present study, we tested the protective effect of AcSDKP on CFU-MK and CFU-GM progenitor cells in mice treated at lower doses of Ara-C more relevant to human clinical situations. Firstly, we report for the first time that in vitro pre-incubation of murine BM MNC with AcSDKP at concentrations of 10(-10) and 10(-9) M for 48 h decreased CFU-MK, in parallel to CFU-GM, progenitor growth. This resulted in an increase of recovery of these progenitors after exposure to Ara-C. Secondly, we tested the effect of AcSDKP on progenitor cells in vivo in different conditions in Ara-C treated mice. We show that the administration of AcSDKP before starting Ara-C treatment resulted in a significant increase in progenitor CFU-GM, CFU-MK and mature MK numbers, 6 and 8 days after the first Ara-C injection. Interestingly, no difference was observed whether AcSDKP was started 24 or 48 h before Ara-C. In a protocol in which AcSDKP was administered for 8 days starting 48 h before Ara-C treatment, the dose did not appear to be critical at least within the range tested (4 vs. 40 micrograms/injection). In addition, the administration of AcSDKP at 64 micrograms/kg per injection for 5 days and stopping it 3 days before the end of Ara-C treatment, i.e. five instead of eight applications, further increased its protective effect. Thus our results demonstrate protective effect of AcSDKP for progenitors during a fractionated protocol of Ara-C treatment and indicates an importance of the dose and the schedule of administration of AcSDKP in designing future clinical trials.
    International Journal of Hematology 09/1998; 68(2):145-55. · 1.68 Impact Factor
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    ABSTRACT: Platelet factor 4 (PF-4) inhibits angiogenesis in vitro and in vivo. The mechanism of inhibition is poorly understood. We have investigated the mechanism of inhibition by examining the interaction of PF-4 and the fibroblast growth factor-2 (FGF-2)/fibroblast growth factor receptor (FGFR) system. PF-4 inhibited the binding of FGF-2 to high-affinity and low-affinity binding sites in murine microvascular endothelial cells (LEII cells) and proliferation. Maximum inhibition of binding to endothelial FGF receptors was observed at PF-4 concentrations between 5 and 10 microg/mL (half maximum inhibition at 0.6 micro/mL), and proliferation was completely inhibited at 2 microg/mL. At this concentration, PF-4 reduced internalization of 125I-FGF-2 by threefold and delayed degradation. To gain insight into the mechanism of inhibition, we have analyzed the interaction of PF-4 with FGF-2/FGFR by using mutant heparan sulfate-deficient Chinese hamster ovary (CHO) cells transfected with the FGFR-1 cDNA (CHOm-FGFR-1) and by examining the direct interaction with FGF-2. In the absence of heparin, PF-4 inhibited binding of 125I-FGF-2 to CHOm-FGFR-1 cells in a concentration-dependent manner, although not completely. In the presence of heparin, PF-4 abolished totally the stimulatory effect of heparin. Furthermore, PF-4 complexed to FGF-2 and inhibited endogenous or heparin-induced FGF-2 dimerization. These results indicate that PF-4 interacts with FGF-2 by complex formation, inhibiting FGF-2 dimerization, binding to FGF receptors, and internalization. This mechanism most likely contributes to the antiangiogenic properties of PF-4.
    Blood 06/1998; 91(9):3289-99. · 9.78 Impact Factor
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    ABSTRACT: Platelet factor 4 (PF4) has been recognized as an inhibitor of myeloid progenitors. However, the mechanism of action of this chemokine remains poorly understood. The present study was designed to determine its structure/function relationship. A series of peptides overlapping the C-terminal and central regions of PF4 were analyzed in vitro for their action on murine hematopoietic progenitor growth to assess the minimal sequence length required for activity. The peptides p17-58 and p34-58 possessed an increased hematopoietic inhibitory activity when compared with PF4, whereas the shorter peptides p47-58 and p47-70 were equivalent to the native molecule and the peptide p58-70 was inactive. The PF4 functional motif DLQ located in 54-56 was required for the activity of these peptides. The peptide p34-58 impaired to a similar extent the growth of colony-forming unit-megakaryocyte (CFU-MK) as well as burst-forming unit-erythroid (BFU-E) and colony-forming unit-granulocyte-macrophage (CFU-GM), whereas PF4 was more active on CFU-MK. In the experiments using purified murine CD34(+) marrow cells, statistically significant inhibition induced by p34-58 was shown at concentrations of 2.2 nmol/L or greater for progenitors of the three lineages, whereas that induced by PF4 was seen at 130 nmol/L for CFU-MK and 650 nmol/L for CFU-GM and BFU-E, indicating that the p34-58 acts directly on hematopoietic progenitors and its activity is approximately 60- to 300-fold higher than PF4. The p34-58, unlike PF4, lacked affinity for heparin and its inhibitory activity could not be abrogated by the addition of heparin. In addition, an antibody recognizing p34-58 neutralized the activity of p34-58 but not whole PF4 molecule. These results demonstrate that PF4 contains a functional domain in its central region, which is independent of the heparin binding properties, and provide evidence for a model of heparin-dependent and independent pathways of PF4 in inhibiting hematopoiesis.
    Blood 04/1998; 91(8):2772-80. · 9.78 Impact Factor
  • A M Maurer, J P Caen, Z C Han
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    ABSTRACT: Chemokines are a large family of cytokines that act not only as immune and inflammatory regulators but also as regulators of hematopoiesis. Two major subfamilies of chemokines are distinguished on the basis of whether the first two cysteines are separated by a single residue (CXC) or three residues (CX3C) or they are adjacent (CC) or there is a single C. The Macrophage Inflammatory Protein 1 alpha (MIP-1 alpha), which belongs to CC family is a powerful inhibitor of hematopoisis in vitro and in vivo. The sub-family CXC comprises two main groups. The first sub-group includes the ELR chemokines, in which interleukin-8 (IL-8) is the most prototypic and possesses suppressive activities on hematopoiesis. Platelet Factor 4 (PF4) belongs to the sub-group of non-ELR CXC chemokines. PF4 acts as an inhibitor of hematopoiesis, particularly of the megakaryocytopoiesis. Recently, it has been shown that a peptide of PF4, 34-58 which does not contain the site of heparin binding, is able to inhibit the growth of hematopoietic progenitors in vitro, providing evidence for a model of heparin dependent and independent pathways of PF4 action on hematopoiesis. PF4 can reduce the chimiosensitivity of hematopoietic cells in mice treated by the cytotoxic drug 5-Fluorouracyl, suggesting a potential clinical application of PF4 in cancer therapy.
    Comptes rendus des séances de la Société de biologie et de ses filiales 02/1998; 192(5):917-23.
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    ABSTRACT: A computer-assisted automatic image procedure was karyocytopoiesis in culture. This analysis system was based on acetylcholinesterase staining, a specific staining for murine bone marrow megakaryocytes, and an image capturing instrument with a computer program. Two kinds of routine megakaryocyte culture methods were used, the plasma clot and the serum-free agar systems. A comparison between manual counting and the instrument was made. The image analysis software was able to distinguish between megakaryocytes (MK) at different stages of maturation. The results show that this analysis system can simultaneously detect not only the number of megakaryocytes and their colonies in each dish, but also the surface area of individual megakaryocytes. In addition, this analysis system functions automatically 24 hours a day and the results obtained are reproducible. Using this system, we have confirmed previous observations that thrombopoietin (TPO) and heparin stimulate both proliferation and maturation of megakaryocytes. In addition, we found that platelet factor 4 (PF-4) significantly reduced the number of megakaryocytes but not their cell surface area, whereas TGFbeta1 decreased both number and surface area of megakaryocytes, suggesting that PF4 and TGFbeta1 negatively regulate megakaryocytopoiesis by different mechanisms. We noticed that megakaryocytes grown under agar culture conditions regularly had an increased size in comparison with those grown in a plasma clot system, which may be an indication that the plasma clot culture media contains an inhibitor(s) of megakaryocyte maturation. Our data indicate that this image analysis system, in addition to its automatic and reproducible features, is more efficient and allows detection of more parameters than routine manual microscopic detection.
    Platelets 02/1998; 9(2):121-7. · 2.24 Impact Factor
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    ABSTRACT: Mouse embryonic stem (ES) cells transfected with a 1.7 kb cDNA of porcine transforming growth factor type beta1 (TGFbeta1), known as ES-T cells, were found to be able to differentiate in vitro into cystic embryonic bodies (EBs) with outspread tubular structures. Morphological analysis using light, phase-contrast and electron microscopes revealed that in culture, the EBs of ES-T cells initially developed some flat endothelial-like cells which further proliferated and migrated to form thread structures. At 8-10 days after EB formation, these thread structures further developed into net-like and tubular structures connecting directly to EBs. Immunofluorescent assays using antibodies against Flk-1 and von Willebrand factor (vWF) indicated that these net-like and tubular structures of ES-T cells consisted of vascular endothelial cells. Further analysis by RT-PCR revealed that the EBs with tubular structures expressed the mRNA of other markers of vascular endothelial cells, including VE-cadherin and platelet-endothelial cell adhesion molecule (PECAM). Cells of hematopoietic origin were not detected on the outside of EBs by immunostaining using several antibodies specific for granulocytes, macrophages and lymphocytes as well as by benzidine staining for erythroid cells on the outside of EBs. Our data demonstrates that the transfer of TGFbeta1 into ES cells results in a significant vasculogenesis without concomitant hematopoiesis. ES-T cells could therefore provide an excellent model for studying blood vessel formation and vasculogenic and hematopoietic interactions.
    Endothelium 02/1998; 6(2):95-106. · 1.65 Impact Factor
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    ABSTRACT: We have recently reported that platelet factor 4 (PF4), a megakaryocyte-platelet protein, is a potent inhibitor of human and murine megakaryocytopoiesis. In addition, PF4 accelerated the recovery of the marrow precursor cells in 5-fluorouracil (5-FU) treated mice. We show in this study that a slight modification of the C-terminal peptide related to PF4 (C13-24DE), which was previously reported as the carboxy terminal region of PF4 implicated in PF4 inhibitory activity, is also able to significantly increase murine high proliferating-potential-colony forming cells (HPP-CFC), colony-forming-unit megakaryocyte (CFU-MK) and colony-forming unit granulocyte-macrophage (CFU-GM) progenitor number, eight days after 5-FU administration, when it was given intraperitoneally twice a day (200 micrograms/kg/inj) prior to 5-FU administration (150 mg/kg). Furthermore, the C13-24DE pretreatment enhanced both the number and the diameter of single megakaryocyte (MK) by day 8. These data indicate that the C13-24DE peptide related to PF4 accelerated the in vivo recovery of stem cells, progenitors (CFU-GM, CFU-MK) and single MK after 5-FU treatment and may have a hemoprotective effect against chemotherapeutic agents.
    International Journal of Hematology 01/1998; 66(4):435-44. · 1.68 Impact Factor
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    ABSTRACT: The effects of platelet factor 4 (PF4) on the viability and chemosensitivity of normal hematopoietic cells and cancer cell lines were studied to determine the mechanisms whereby PF4 functions as either an inhibitor or a protector and to evaluate its clinical significance. Two other chemokines, interleukin-8 (IL-8) and neutrophil-activating peptide-2 (NAP-2), were also studied in comparison to PF4. Using a tetrazolium salt assay for cell viability, we observed that PF4 at 1 to 50 microg/mL supported the viability of normal human bone marrow cells. Approximately 45% of cells cultured for 48 hours survived, whereas 80% or more survived in the presence of PF4 5 microg/mL. PF4 also supported the viability of CD34+ cord blood (CB) cells and protected them from apoptosis induced by transforming growth factor beta1 (TGFbeta1) and cytotoxic drugs. Pretreatment of CD34+ cells by PF4, but not by TGFbeta1, caused an increase in the number of megakaryocyte colonies after these cells were replated in secondary cultures. Flow cytometry analysis showed that when CD34+ cells were preincubated with PF4 or TGFbeta1 for 12 days in hematopoietic growth factor-rich medium, an increased number of remaining CD34+ cells was observed only for PF4-treated cells. Furthermore, PF4 significantly reduced the chemosensitivity of bone marrow cells, as shown by its ability to increase the 50% inhibition concentration (IC50) of several cytotoxic agents. Like PF4, IL-8 and NAP-2 at 0.1, 0.6, and 1 microg/mL supported the survival of myeloid progenitors, including colony-forming units granulocyte, erythroblast, monocyte, megakaryocyte (CFU-GEMM), CFU-megakaryocyte (CFU-MK), CFU-granulocyte/macrophage (CFU-GM), and burst-forming units-erythroblast (BFU-E), and reduced their sensitivity to the toxicity of etoposide (ETP). Protamine sulfate at 1 to 100 microg/mL showed no such activity of PF4. Interestingly, the three chemokines failed to affect significantly the viability and chemosensitivity of three leukemic and two other tumor cell lines. Based on these results, we conclude for the first time that PF4 and IL-8 and NAP-2 support the survival of normal hematopoietic precursors and protect them from the toxicity of chemotherapeutic agents. Because such activities are unique to normal hematopoietic cells but not to the cancer cell lines evaluated, a potential clinical application of these molecules in the treatment of cancer is suggested.
    Blood 05/1997; 89(7):2328-35. · 9.78 Impact Factor
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    ABSTRACT: The effects of native thrombospondin (TSP), an 18 kd recombinant protein comprising residues 1-174 of TSP (TSP1-174) with heparin-binding domain and a fusion protein comprising residues 559-669 of TSP (TSP559-669) on murine hematopoiesis, were studied by using different in vitro culture systems. TSP by itself did not show an inhibitory effect on colony-forming unit-megakaryocyte (CFU-MK) growth in a serum-free agar system and on the growth of colony-forming unit-granulocyte and macrophage (CFU-GM) in a plasma clot system. It was, however, found that in the plasma clot culture system when using aplastic anemia serum as the source of thrombopoietin or C-Mpl ligand (TPO), TSP and TSP1-174, but not TSP559-669, were able to inhibit the growth of CFU-MK from unfractionated and lineage negative (Lin-) bone marrow cells in a dose-dependent manner. A statistically significant suppression was seen at 1 microg/ml of TSP and 5 microg/ml of TSP1-174. This inhibitory effect of TSP was further found in both the serum-free agar system and the plasma clot system without aplastic anemia serum, where megakaryocyte colony growth was stimulated by recombinant TPO, basic fibroblast growth factor (bFGF), or interleukin-3 (IL-3). In a methylcellulose system, where a combination of stem cell factor (SCF), IL-3, and granulocyte/macrophage colony-stimulating factor (GM-CSF) were used, TSP inhibited the growth of colony-forming unit-granulocyte-erythroblast, megakaryocyte, and macrophage (CFU-GEMM) but not CFU-GM and burst-forming unit-erythroblast (BFU-E). Interestingly, this inhibitory effect of TSP on megakaryocyte colony growth could be counteracted by Fraxiparin, a low-molecular-weight heparin. These results demonstrate that TSP is a negative modulator of megakaryocytopoiesis and suggest that its inhibitory effect is at least partially mediated by N-terminal heparin-binding domain.
    Journal of Laboratory and Clinical Medicine 03/1997; 129(2):231-8. · 2.62 Impact Factor
  • S Bellucci, Z C Han, J Caen
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    ABSTRACT: Heparin, a glycosaminoglycan (GAG) derivative has been widely used as an anticoagulation agent for more than 50 years. This study was conducted to demonstrate that, due to their modulatory effect on cytokines, heparin and other GAGs can favor megakaryocytopoiesis both in vitro and in vivo in mice. In vitro addition of heparin and other GAGs (excepting keratane sulfate) into plasma clot cultures induces a significant increase in the number of megakaryocyte colonies. Optimal heparin and GAG concentrations for maximal effect are approximately 50-100 micrograms/ml. In agar culture without serum, all GAGs do not have this stimulating effect on megakaryocyte colonies. This would suggest that the GAG action depends on the presence of one or more plasma factors. Interactions between GAGs and cytokines such as IL3, IL6, G-SCF, GM-CSF, aFGF, TPO and EPO as well as PF4 and TGFB1 were also conducted. The results demonstrate that heparin and chondroitin sulfate significantly increases the action of TPO, IL6 and aFGF but not the action of IL3, G-SCF and EPO. Heparin and other GAGs can also neutralize PF4 and TGFB1 inhibitory action. In vivo, the effect of low-molecular-weight heparin (Fraxiparine) injected in normal mice treated with 5-fluorouracil increases megakaryocytopoiesis. The findings demonstrate that heparin and its derivatives have a potentializing effect on megakaryocytopoiesis and could be used as therapeutic agents in the treatment of thrombocytopenia.
    Annales de medecine interne 02/1997; 148(2):150-3.
  • S Bellucci, Z C Han, J P Caen
    British Journal of Haematology 02/1997; 96(1):212-3. · 4.94 Impact Factor
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    ABSTRACT: In vivo effects of platelet factor 4 (PF4) and tetrapeptide N-acetyl-Ser-Asp-Lys-Pro (AcSDKP) on haemopoietic progenitors were studied in mice treated with 5-fluorouracil (5-FU). The mice were injected with PF4 (40 micrograms/kg) or AcSDKP (4 micrograms/kg) twice at 6 h intervals, and 20 h after the second injection they were given one injection of 5-FU (150 mg/kg). 6, 8 and 13 d later the high proliferative potential-colony forming cell (HPP-CFC), burst-forming unit erythroid (BFU-E), colony forming unit granulocyte-macrophage (CFU-GM) colony forming unit megakaryocyte (CFU-MK), and megakaryocytes (MK) were examined. The results showed that the administration of PF4 or AcSKDP resulted in a significant increase in the number of HPP-CFC on days 6-8 and BFU-E and CFU-GM on day 8 when compared to 5-FU alone. Furthermore, PF4 was found to increase significantly the number of CFU-MK and MK on day 8, which was not observed with AcSDKP. However, both molecules had no obvious effect on peripheral blood cells. These data indicate that PF4 or AcSDKP accelerate the recovery in vivo of HPP-CFC, CFU-GM and BFU-E after 5-FU treatment but their effect may be different on megakaryocytic progenitors and suggests that both molecules may have a haemoprotective effect against chemotherapeutic agents.
    British Journal of Haematology 10/1996; 94(3):443-8. · 4.94 Impact Factor
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    ABSTRACT: We have previously reported that heparin is capable of stimulating in vitro and in vivo megakaryocytopoiesis in mice and has a thrombopoietic effect when given in chronic immune thrombocytopenic purpura and that heparin and several other glycosaminoglycans (GAGs) promote the growth of human megakaryoblastic cell lines in the presence of serum. We show here that GAGs, including heparan sulfate (HS), chondroitin sulfate (CS), dermatan sulfate (DS), and hyaluronic acid (HA), also stimulate in vitro growth of murine megakaryocyte progenitors and augment the diameter of individual megakaryocytes in the presence of serum. However, in a serum-free agar system, the GAGs alone had no effect on megakaryocyte colony formation, suggesting that GAGs cooperate with some serum factor(s) to exert their activity. We also show that heparin significantly potentiates the megakaryocytopoietic activity of C-Mpl ligand and interleukin (IL)-6 but not IL3, GM-CSF, SCF, and Epo. In addition, the GAGs significantly neutralize the inhibitory action of platelet factor 4 (PF4) and transforming growth factor beta 1 (TGF beta 1) on megakaryocyte colony growth. These results demonstrate a stimulating activity of GAGs on megakaryocytopoiesis by modifying the activity of several growth-regulating factors.
    Journal of Cellular Physiology 08/1996; 168(1):97-104. · 4.22 Impact Factor
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    ABSTRACT: Mechanisms of the action of platelet factor 4 (PF4) on the growth of megakaryocyte (MK) progenitor cells in CD34+ cord blood (CB) cells were studied in comparison with transforming growth factor beta1 (TGFbeta1). Development of MK from CD34+ CB cells in both plasma clot culture and liquid culture was significantly inhibited by either purified human PF4 and by recombinant human TGFbeta1. Inhibition of MK colony formation by PF4 was reversible because CD34+ cells preincubated with PF4 could regenerate colonies after washing and replating into secondary cultures. In contrast, TGFbeta1-preincubated CD34+ cells gave rise to few colonies following replating. Moreover, incubation of CD34+ cells with PF4 in liquid culture caused the increased number of both stem cell factor (SCF)-binding cells and CD34 antigen-bearing cells. In addition, PF4-preincubated CD34+ cells exhibited a higher potential in MK colony formation in the presence of 5-fluorouracil (5FU). These results demonstrate that both PF4 and TGFbeta1 inhibit MK development from CD34+ CB cells by different mechanisms, and suggest that PF4, unlike TGFbeta1, exerts its inhibitory effect on the growth of the target cells in a reversible manner which results in a preservation of a more immature and 5FU-resistant cell population.
    British Journal of Haematology 06/1996; 93(2):265-72. · 4.94 Impact Factor
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    ABSTRACT: We have previously reported that platelet factor 4 (PF4) inhibits human erythroleukemic (HEL) cell growth in a dose-dependent fashion in vitro and that PF4 binds to HEL cells in a specific, saturable, and concentration-dependent manner. In this article we demonstrate that the binding of PF4 on HEL cells and its inhibitory effect on HEL cell growth were mediated by heparan sulfate. We found that binding of iodine 125-labeled PF4 to HEL cells was inhibited by heparin, heparan sulfate, and dermatan sulfate and to a smaller extent by chondroitin sulfate. Ninety percent of 125I-labeled PF4 bound to HEL cells was released by cells after exposure to heparin and heparan sulfate. Treatment of cells with heparitinase and heparinase induced a decrease in the binding of 125I-labeled PF4 to cells. Binding of 125I-labeled PF4 was partially inhibited by the presence of increasing concentrations of protamine sulfate and basic fibroblast growth factor. To test whether PF4 bound to cell surface proteoglycans, proteoglycan synthesis was inhibited by using 4-methylumbelliferyl-beta-D-xyloside. The binding of 125I-labeled PF4 on treated cells was decreased, and xyloside treatment of cells abrogated the biologic activity of PF4 in a plasma clot culture system. The inhibitory effect of PF4 was retained in a serum-free agar culture system, which indicates that the binding of PF4 to HEL cells induces cell growth inhibition in a direct fashion. Taken together, these findings suggest that PF4 directly acts on HEL cell growth by fixation on heparan sulfate proteoglycans on the HEL cell surface.
    Journal of Laboratory and Clinical Medicine 05/1996; 127(4):382-90. · 2.62 Impact Factor
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    ABSTRACT: We have previously shown that platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) inhibit the growth of the human erythroleukemia cell line (HEL). We further studied the effect of PF4, beta-TG, and various related peptides on human leukemic lineages to determine the specificity and the relationship between the inhibitory activity and the molecular structure of PF4. The results showed that PF4 and beta-TG had an inhibitory activity on the megakaryocytic growth. Furthermore, peptides corresponding to the 1-24 and 13-24 residues but not to the 16-24 residue of the PF4 C-terminal region, the 21-29 and 20-28 C-terminal region of beta-TG and IL-8, inhibited only the megakaryocytic cell growth. Interestingly, when Gln and Asn located at positions 15 and 24, respectively, of the PF4 C-terminal region were replaced by Glu and Asp (C13-24DE), an increase in the inhibitory activity was observed. Moreover, the 13-24 monomeric form (13-24M) and modified form (13-24A), where a cysteine in C-terminal position 19 was substituted by arginine, were no longer active. These results suggest that the inhibitory activity of PF4 and its related peptides might be localized in their 13-24 C-terminal region and that a dimeric structure seems to be necessary to exert inhibitory activity.
    Journal of Laboratory and Clinical Medicine 03/1996; 127(2):179-85. · 2.62 Impact Factor

Publication Stats

604 Citations
174.32 Total Impact Points

Institutions

  • 1999–2000
    • Chinese Academy of Medical Sciences
      Peping, Beijing, China
  • 1998
    • Northeast Institute of Geography and Agroecology
      • Institute of Biochemistry and Cell Biology
      Beijing, Beijing Shi, China
  • 1990
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France