Effect of the Aldehyde Dehydrogenase Inhibitor, Cyanamide, on the Ex Vivo Sensitivity of Murine Multipotent and Committed Hematopoietic Progenitor Cells to Mafosfamide (Asta Z 7557)

The ex vivo sensitivity of murine multipotent (CFU-GEMM) and committed (CFU-Mk, CFU-GM, BFU-E and CFU-E) hematopoietic progenitor cells to mafosfamide was quantified with and without concurrent exposure to cyanamide, an inhibitor of aldehyde dehydrogenase activity. In the absence of cyanamide, CFU-GEMM, CFU-Mk and CFU-GM were approximately equisensitive to mafosfamide while the erythroid progenitors were more sensitive to the drug. Cyanamide potentiated the cytotoxicity of mafosfamide toward CFU-GEMM and CFU-Mk, but not toward CFU-GM, BFU-E and CFU-E. Cellular aldehyde dehydrogenases are known to catalyze the oxidation of 4-hydroxycyclophos-phamide/aldophosphamide, the major intermediate in cyclophosphamide and mafosfamide activation, to the relatively nontoxic acid, carboxyphosphamide. Thus, our findings indicate that 1) murine CFU-GEMM contain the relevant aldehyde dehydrogenase activity, and 2) the relevant aldehyde dehydrogenase activity is retained upon differentiation to progenitors committed to the megakaryocytoid lineage, but lost upon differentiation to progenitors committed to the granulocytoid/monocytoid and erythroid lineages. The relative insensitivity of CFU-GM to mafosfamide is apparently due to a cellular determinant that influences their sensitivity to all cross-Unking agents since CFU-GM were found to be relatively insensitive to non-oxazaphosphorine cross-linking agents as well.     

Effect of the Aldehyde Dehydrogenase Inhibitor,Cyanamide, on the Ex Vivo Sensitivity of Murine Multipotent and Committed Hematopoietic Progenitor Cells to Mafosfamide (Asta Z 7557)

Abstract

The ex vivo sensitivity of murine multipotent (CFU-GEMM) and committed (CFU-Mk, CFU-GM, BFU-E and CFU-E) hematopoietic progenitor cells to mafosfamide was quantified with and without concurrent exposure to cyanamide, an inhibitor of aldehyde dehydrogenase activity. In the absence of cyanamide, CFU-GEMM, CFU-Mk and CFU-GM were approximately equisensitive to mafosfamide while the erythroid progenitors were more sensitive to the drug. Cyanamide potentiated the cytotoxicity of mafosfamide toward CFU-GEMM and CFU-Mk, but not toward CFU-GM, BFU-E and CFU-E. Cellular aldehyde dehydrogenases are known to catalyze the oxidation of 4-hydroxycyclophos-phamide/aldophosphamide, the major intermediate in cyclophosphamide and mafosfamide activation, to the relatively nontoxic acid, carboxyphosphamide. Thus, our findings indicate that 1) murine CFU-GEMM contain the relevant aldehyde dehydrogenase activity, and 2) the relevant aldehyde dehydrogenase activity is retained upon differentiation to progenitors committed to the megakaryocytoid lineage, but lost upon differentiation to progenitors committed to the granulocytoid/monocytoid and erythroid lineages. The relative insensitivity of CFU-GM to mafosfamide is apparently due to a cellular determinant that influences their sensitivity to all cross-Unking agents since CFU-GM were found to be relatively insensitive to non-oxazaphosphorine cross-linking agents as well.     

Effect of human recombinant erythropoietin on human hemopoietic progenitor cells in vitro

Summary Recombinant human erythropoietin (rhEpo), now available, might become increasingly more important for clinical use, e.g., in the treatment of anemia of chronic renal failure. As a prerequisite of clinical trials, we analyzed the stimulatory and suppressive effects of rhEpo on human hemopoiesis by adding rhEpo to in vitro cultures of nonadherent low-density bone marrow cells obtained from normal persons and from patients undergoing hemodialysis for chronic renal failure. rhEpo was shown to be an effective stimulus for erythroid and multilineage colony formation. The dose-response curve was similar for erythroid progenitors BFU-E from normal controls and patients with chronic renal failure. rhEpo had no effect on megakaryocytic colony formation nor on the megakaryocytic differentiation of multilineage stem cells. Because of a good stimulatory activity on erythroid and multilineage stem cells and lack of toxic effects, rhEpo might be useful in the treatment of certain kinds of anemia.Abbreviations BFU-E burst-forming unit-erythroid - CFU-E colony forming unit-erythroid - CFU-GEMM CFU-granulocyte, erythrocyte, macrophage, megakaryocyte - CFU-GM CFU-granulocyte, macrophage - CFU-Mk CFU-megakaryocyte - IMDM Iscove's modified Dulbecco's medium - Mo-CM Mo-cell line conditioned medium - rhEpo recombinant human erythropoietin     

Letter to the EditorActivin A: A Possible Marker for Liver Transplant Outcome

Abstract

The influence of recombinant human IL-17 on granulocyte-macrophage (CFU-GM) and erythroid (BFU-E and CFU-E) progenitors and the release of IL-1α/β, IL-6 and erythropoietin (EPO) was estimated in the bone marrow cells obtained from normal and sub-lethally irradiated mice. In normal mice IL-17 increased CFU-GM and BFU-E and reduced CFU-E derived colonies numbers and augmented release of IL-6 and EPO. In irradiated mice the effects of IL-17 on hematopoietic progenitors were lineage-dependent, as well as dependent on their stage of differentiation and the time after the irradiation. IL-17 had no major effects on CFU-GM on day 1 and 3, but decreased their number on day 2, while enhanced both BFU-E and CFU-E on day 1 and 2 after irradiation, whereas on day 3 its effect on erythroid progenitors was again as observed in normal mice. After irradiation, IL-17 increased the release of IL-1α, IL-6 and EPO. The observed effects suggested the involvement of IL-17 in the regulation of hematopoiesis and indicated that its effects on both hematopoietic progenitors and cytokine release are dependent on the physiological/ pathological status of the organism.     

阵发性睡眠性血红蛋白尿病人骨髓红系和粒－单系祖细胞的特点

本文采用造血祖细胞体外培养技术观察了阵发性睡眠性血红蛋白尿（ＰＮＨ）病人骨髓红系祖细胞（ＢＦＵ一Ｅ和ＣＦＵ一Ｅ）和粒一单系祖细胞（ＣＦＵ一ＧＭ）的增殖能力；骨髓细胞经酸化ＡＢ型血清处理后的ＢＦＵ一Ｅ，ＣＦＵ一Ｅ和ＣＦＵ一ＧＭ的增殖能力；以及ＢＦＵ一Ｅ、ＣＦＵ一Ｅ对红细胞生成素（Ｅｐｏ）和（ＣＦＵ一ＧＭ对粒一单系集落刺激因子（ＧＭ一ＣＳＦ）的反应能力，发现ＰＮＨ病人骨髓ＢＦＵ一Ｅ，ＣＦＵ一Ｅ和ＣＦＵ一ＧＭ集落数明显低于正常；骨髓细胞经新鲜酸化ＡＢ型血清处理后培养的ＢＦＵ一Ｅ、ＣＦＵ一Ｅ和ＣＦＵ一ＧＭ集落数明显低于经热灭活酸化ＡＢ型血清处理后培养的集落数；以及ＢＦＵ一Ｅ，ＣＦＵ一Ｅ对Ｅｐｏ和ＣＦＵ一ＧＭ对ＧＭ一ＣＳＦ的剂量反应曲线低平。因此认为ＰＮＨ病人骨髓红系和粒一单系祖细胞有以下特点：１．增殖能力降低：２．在酸性条件下对补体的敏感性增加；３．对造血因子的敏感性降低。     

Expression of myeloid differentiation antigens on normal and chronic granulocytic leukemia erythroid progenitor cells identified by monoclonal antibodies

The antigenic phenotype of erythroid progenitor cells (BFU-E and CFU-E) in bone marrow and peripheral blood from normal individuals and patients with chronic granulocytic leukaemia (CGL) was studied using 14 myeloid monoclonal antibodies (Mc Abs) in a complement dependent cytotoxicity assay followed by culture in methylcellulose. Mc Abs which reacted with normal CFU-GEMM and CFU-GM antigens usually reacted strongly with normal and CGL-BFU-E. In contrast, the majority of myeloid Mc Abs used in the study reacted poorly or did not recognize the antigens on normal and CGL CFU-E. HLA-DR antigens recognized by L243 Mc Ab were expressed on the majority of BFU-E from blood and bone marrow of normal individuals and CGL patients. On the other hand, those antigens were not expressed on normal and leukaemic CFU-E. Two Mc Abs, R1.B19 and WGHS29.1, which recognised the antigens on "late" CFU-GM and not on "early" CFU-GM reacted with a higher proportion of BFU-E from the marrow and blood of CGL patients than of normal subjects. These results indicate that BFU-E in CGL are more differentiated than their normal counterparts. The Mc Ab 54/39, frequently expressed on platelets, recognized a higher percentage of BFU-E and CFU-E from CGL patients than from normal individuals. This may suggest that in CGL there exists a tendency for the expression of megakaryocytic markers on erythroid progenitor cells.     

Superoxide dismutase specifically inhibits erythroid cell DNA synthesis and proliferation.

The antioxidant enzyme superoxide dismutase (SOD) was previously shown to inhibit both the proliferation of murine erythroid DA-1 cells growing in the presence of Interleukin-3 (IL-3) and the DNA synthesis of marrow erythroid progenitor cells (BFU-E) in vitro. We show here that the inhibition of marrow cell DNA synthesis by SOD is specific for BFU-E and erythroid precursors (CFU-E), with other myeloid progenitors (CFU-GM) and stem cells (CFU-S) being unaffected, and IL-3 blocks the inhibitory effects of SOD on BFU-E in a dose-dependent manner. Extending earlier observations on the effects of SOD on cell proliferation, it was found that SOD was capable of inhibiting DA-1 cell proliferation supported by either IL-3 or erythropoietin (epo), but had no effect on IL-3 dependent FDCP-1 cells, nor on epo-dependent HCD-57 cells. Of several murine erythroleukemia cell lines tested, only those transformed with Friend SFFVa virus were inhibited by SOD, while those transformed with Friend SFFVp or MuLV virus were not affected. These results show that the effects of SOD are not antagonistic to particular growth factors but rather the inhibition is specific for erythroid cells, and cells of the proper stage can be inhibited even if they have been transformed to factor independence.     

Kinetics of haemopoietic progenitor cells during a Trypanosoma congolense rechallenge infection in Boran cattle

In a preliminary study, using clonogenic assays, the in vitro kinetics of committed haemopoietic progenitors were monitored during a Trypanosoma congolense rechallenge infection in five trypanosusceptible Boran cattle. Early in the infection (week 2), in the absence of any detectable parasitaemia, a drop in the number of nucleated marrow cells was recorded. This was accompanied by a marked but transient decrease in the levels of the colony-forming units-erythroid (CFU-E) followed by a partial recovery by weeks 3–4 after infection. The burst-forming units-erythroid (BFU-E) and the colony-forming units-granulocyte macrophage (CFU-GM) also significantly decreased between weeks 2 and 4. After a transient rise at weeks 3–5 postinfection, the CFU-GM steadily declined and remained below preinfection levels throughout the infection. The BFU-E remained below preinfection levels until the end of the experiment. The drop in nucleated marrow cells associated with the decreased numbers of CFU-E, BFU-E and CFU-GM was suggestive of a defect at the pluripotential stem cell level early in the infection (week 2). The erythrocyte indices, i.e. mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC), were unchanged until week 10 postinfection. Two animals became severely anaemic; one was euthanised at week 8 and one treated at week 9. The three remaining animals developed chronic anaemia with mean packed cell volume (PCV) fluctuating around 18%–19% between weeks 11 and 14. Low parasitaemia levels were recorded during that period. A CFU-E peak above preinfection levels was noted at week 12 and BFU-E appeared in the peripheral blood culture of two animals between weeks 11 and 14. A progressive rise in MCV associated with a gradual decrease in MCHC also characterised that period. A return to near preinfection levels was recorded for the numbers of all three progenitors three weeks after trypanocidal treatment followed by a full recovery five months after treatment. Although ineffective haemopoiesis has been suggested to contribute to the anaemia of bovine trypanosomiasis, this is the first demonstration of a negative effect on erythroid development in cultures of bone marrow of trypanosome-infected cattle.     

Increased sensitivity to complement or erythroid and myeloid progenitors in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria is an acquired hemolytic anemia characterized by a membrane defect leading to increased sensitivity of erythrocytes, granulocytes, platelets, and bone-marrow erythroid and myeloid cells to complement-mediated lysis. To determine whether the phenotype of paroxysmal nocturnal hemoglobinuria is also expressed on erythroid and myeloid progenitors, marrow cells from five patients with the disease were exposed to a sucrose hemolytic system and then assayed for colony-forming units-erythroid (CFU-E), burst-forming units-erythroid (BFU-E), and colony-forming units-granulocyte/macrophage (CFU-GM). A 50 percent or greater decrease in the numbers of erythroid and myeloid colonies was noted when marrow cells from the patients with paroxysmal nocturnal hemoglobinuria were exposed to a sucrose solution of low ionic strength in the presence of complement but not in its absence. Such a decrease was not noted in similarly treated normal marrow cells or in marrow cells from a patient with the disease in remission. These results suggest that in paroxysmal nocturnal hemoglobinuria, CFU-E, BFU-E, and CFU-GM express a membrane abnormality similar to that on erythrocytes, and that the disease is the result of a change occurring at the level of the pluripotent hematopoietic stem cell.     

Superoxide Dismutase Specifically Inhibits Erythroid Cell DNA Synthesis and Proliferation

Abstract

The antioxidant enzyme superoxide dismutase (SOD) was previously shown to inhibit both the proliferation of murine erythroid DA-1 cells growing in the presence of Interleukin-3 (IL-3) and the DNA synthesis of marrow erythroid progenitor cells (BFU-E) in vitro. We show here that the inhibition of marrow cell DNA synthesis by SOD is specific for BFU-E and erythroid precursors (CFU-E), with other myeloid progenitors (CFU-GM) and stem cells (CFU-S) being unaffected, and IL-3 blocks the inhibitory effects of SOD on BFU-E in a dose-dependent manner. Extending earlier observations on the effects of SOD on cell proliferation, it was found that SOD was capable of inhibiting DA-1 cell proliferation supported by either IL-3 or erythropoietin (epo), but had no effect on IL-3 dependent FDCP-1 cells, nor on epo-dependent HCD-57 cells. Of several murine erythroleukemia cell lines tested, only those transformed with Friend SFFVa virus were inhibited by SOD, while those transformed with Friend SFFVp or MuLV virus were not affected. These results show that the effects of SOD are not antagonistic to particular growth factors but rather the inhibition is specific for eryrthroid cells, and cells of the proper stage can be inhibited even if they have been transformed to factor independence.     

Kinetics of haemopoietic progenitor cells during a Trypanosoma congolense rechallenge infection in Boran cattle

In a preliminary study, using clonogenic assays, the in vitro kinetics of committed haemopoietic progenitors were monitored during a Trypanosoma congolense rechallenge infection in five trypanosusceptible Boran cattle. Early in the infection (week 2), in the absence of any detectable parasitaemia, a drop in the number of nucleated marrow cells was recorded. This was accompanied by a marked but transient decrease in the levels of the colony-forming units-erythroid (CFU-E) followed by a partial recovery by weeks 3–4 after infection. The burst-forming units-erythroid (BFU-E) and the colony-forming units-granulocyte macrophage (CFU-GM) also significantly decreased between weeks 2 and 4. After a transient rise at weeks 3–5 postinfection, the CFU-GM steadily declined and remained below preinfection levels throughout the infection. The BFU-E remained below preinfection levels until the end of the experiment. The drop in nucleated marrow cells associated with the decreased numbers of CFU-E, BFU-E and CFU-GM was suggestive of a defect at the pluripotential stem cell level early in the infection (week 2). The erythrocyte indices, i.e. mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC), were unchanged until week 10 postinfection. Two animals became severely anaemic; one was euthanised at week 8 and one treated at week 9. The three remaining animals developed chronic anaemia with mean packed cell volume (PCV) fluctuating around 18%–19% between weeks 11 and 14. Low parasitaemia levels were recorded during that period. A CFU-E peak above preinfection levels was noted at week 12 and BFU-E appeared in the peripheral blood culture of two animals between weeks 11 and 14. A progressive rise in MCV associated with a gradual decrease in MCHC also characterised that period. A return to near preinfection levels was recorded for the numbers of all three progenitors three weeks after trypanocidal treatment followed by a full recovery five months after treatment. Although ineffective haemopoiesis has been suggested to contribute to the anaemia of bovine trypanosomiasis, this is the first demonstration of a negative effect on erythroid development in cultures of bone marrow of trypanosome-infected cattle.     

Suppression of erythroid progenitors in ponies infected with equine infectious anaemia virus

Six clinically normal ponies were infected intravenously with equine infectious anaemia virus (EIAV) to determine the effect of EIAV on numbers of erythroid, granulocyte/monocyte and fibroblastic progenitors in the bone marrow. Bone marrow progenitor assays were performed at weeks 1, 2, 3, 4 and 8 postinfection. The late erythroid progenitors, colony-forming units-erythroid (CFU-E), were suppressed at each time point postinfection with the maximal suppression occurring at week 2 postinfection. The maximal suppression corresponded to the peak of plasma virus concentration. The maximal suppression of the early erythroid progenitors, burst-forming units-erythroid (BFU-E), also occurred at week 2 postinfection. Removal of adherent cells from the bone marrow mononuclear cells (BMMC) abrogated the suppression. Neither granulocyte/monocyte progenitors (CFU-GM) nor fibroblastic progenitors (CFU-F) were affected by EIAV infection.     

Antithymocyte globulin treatment of retrovirus-induced feline erythroid aplasia: in vivo and in vitro studies

The Kawakami-Theilen strain of feline leukemia virus (FeLV-KT) was used experimentally to produce erythroid aplasia in cats. The in vivo effects of goat anti-feline-thymocyte globulin (ATG) on hematopoiesis were investigated in FeLV-negative normal and FeLV-positive anemic cats. Treatment was initiated in anemic cats between 4 and 6 weeks postinoculation (PI) when erythroid progenitors were reduced to 10% of normal levels. During the first 2 weeks of treatment, ATG significantly increased the numbers of erythroid precursors in bone marrow from 15 to 35% in anemic cats and from 28 to 43% in normal cats. ATG stimulated a twofold increase of CFU-E and a threefold increase of CFU-GM in normal cats between 2 and 4 weeks after initiation of treatment but had no effect on CFU-E or CFU-GM in anemic cats. The in vivo effects of ATG were transient despite weekly treatment. Cats treated with normal globulin were not significantly different from untreated anemic control cats. In vitro treatment of low density bone marrow mononuclear cells with ATG plus complement increased CFU-E and BFU-E of bone marrow from cats prior to inoculation but not from viremic cats. These results indicate that, although ATG stimulates erythropoiesis and granulopoiesis in normal cats, it does not reverse retrovirus-induced erythroid aplasia.     

Sustained zidovudine treatment on hematopoiesis in immunodeficient mice

Zidovudine (AZT) has been the drug of choice in the treatment of human AIDS; however, associated with the use of zidovudine has been the development of hematopoietic toxicity, the mechanism of which is not clearly defined. We report here studies designed to evaluate dose-escalation of zidovudine, i.e. 0.1 and 1.0 mg/ml placed in the drinking water on hematopoiesis in C57BL/6 normal and LP-BM5 immunodeficiency virus-infected mice. Over a 6-week evaluation period, compared to normal, non-virus-infected controls, murine immunodeficiency (MAIDS) infection was associated with reduced hematopoietic progenitors, i.e. CFU-E, BFU-E, CFU-GM, and CFU-Meg from bone marrow and spleen. Following zidovudine treatment, further suppression of marrow-derived progenitors was observed, while increased numbers of progenitors were obtained from the spleen. Spleen-derived erythroid progenitors, i.e. CFU-E, were increased by 950% (P<0.001) from MAIDS-infected animals receiving 1.0 mg/ml of drug following 4-weeks exposure compared to non-drug-treated MAIDS control animals. Splenic BFU-E were increased 654% following 6-weeks exposure compared to non-drug-treated MAIDS-infected mice. This study suggests that the bone marrow is particularly sensitive to zidovudine toxicity which, at least early in exposure, appears to be compensated by splenic-derived hematopoiesis, in particular, erythropoiesis. Overt toxicity develops when, at least in this immunodeficiency model, the spleen is unable to provide progenitors is response to continued zidovudine exposure in vivo.     

Comparison of erythropoietic response to androgen in young and old senescence accelerated mice.

In this study, to clarify whether the functional capacity of hemopoietic progenitor cells and the micro-environment of aged mice are identical with those of the young, we investigated the changes in the number of hemopoietic progenitor cells and the production of regulatory cytokines from splenic cells as well as changes in the serum levels of cytokine in senescence-accelerated mice (SAM) after administration of 19-nandrolone decanoate (19-ND), a synthetic androgenic anabolic steroid. 19-ND induced an increase in erythroid colony-forming units (CFU-E), erythroid burst-forming units (BFU-E), and granulocytic-macrophage committed progenitor cells (CFU-GM) in bone marrow and spleen; especially remarkable increases were observed in the splenic CFU-E in both young and old mice. Antigen expression analysis of hemopoietic organs revealed that total TER-119+ cells per spleen of young and old mice with androgen treatment rose 2.6- and 3.2-fold over their respective control values. The responsiveness of hemopoietic progenitor cells to androgen did not change with age. Injection of 19-ND into young and old mice markedly enhanced the erythropoietin levels but not IL3 and GM-CSF levels in the serum of both groups. Cytokine production assessed by pokeweed mitogen-stimulated spleen condition medium showed an age-related decline. Androgen treatment could not influence IL-3 and GM-CSF production of spleen. These findings suggest that the spleen of both old and young mice served as the major site of regenerative repopulation of hemopoietic progenitors, especially the late erythroid progenitors in 19-ND-treated mice. The proliferative reserve of erythropoiesis with androgen treatment in aged mice was not reduced more than that in treated-young mice.     

Pluripotent and committed haemopoietic progenitor cells in rat peripheral blood

The assay system for determination of haemopoietic progenitors in peripheral blood of rats is essen tial for potential studies on mobilisation and transplantation of circulating progenitor cells in a rat experimental model. This paper demonstrates the possibility of detection and quantification of pluripotent progenitors (Colony Forming Units-Spleen day 8-CFU-Sd8) and committed progenitors (Colony Forming Units Granulocyte Macrophage-CFU-GM and Burst Forming Units-Erythroid-BFU-E) in peripheral blood of rats in a steady state. For determination of CFU-Sd8 the rat to mouse in vivo assay was used, and for committed progenitors in vitro assays on methylcellulose were employed. The CFU-Sd8 incidence ranged from 7.3 to 11.6/ml of rat blood, similar to that reported in literature for mice. The incidence of CFU-GM was found to be 59.7 ± 9.4/ml which is in the range of the literature data for mice, rabbits, dogs and humans. The incidence of BFU-E in rat peripheral blood was 4.3 ± 1/ml, which was relatively low, but could be also considered as comparable with some literature data for dogs and humans. The CFU-E were not detected by the technique used. These results confirmed the existence of circulatory blood pluripotent progenitors (CFU-Sd8) and committed (CFU-GM and BFU-E) progenitors in rat, as has been established for some other mammalian species.     

Clonogenic haematopoietic progenitor assays from clinically normal horses

Clonal assays for haematopoietic progenitors were performed on mononuclear cells isolated from bone marrow samples collected from the sternebrae of normal horses. Colony-forming units-erythroid (CFUE), burst-forming units-erythroid (BFU-E), colony-forming units-granulocyte/monocyte (CFU-GM) and colony-forming units-fibroblastic (CFU-F) were assayed, and reference values for clinically normal horses were established. The mean numbers of CFU-E, BFU-E and CFU-GM per 5 × 10⁴ cells were 329 ± 48, 30 ± 5 and 131 ± 13, respective. The mean number of CFU-F was 49 ± 6 per 2 ± 10 cells. The numbers of CFU-E and BFU-E were linearly related to the concentrations of fetal bovine serum (FBS), bovine serum albumin (BSA) and the cell number plated. The number of CFU-E were increased in the presence of erythropoietin (EPO) but its presence was not required for colony growth. BFU-E had an absolute requirement for EPO but the number of BFU-E was not linearly related to dose of EPO. Methods for clonal assays of equine hematopoietic progenitors are described.     

Comparison of dideoxynucleoside drugs (DDI and zidovudine) and induction of hematopoietic toxicity using normal human bone marrow cells in vitro

The drug zidovudine (AZT), a synthetic thymidine analog, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has induced hematopoietic toxicity manifested by anemia, neutropenia and on occasion thrombocytopenia. Such toxicity has stimulated the development of alternative dideoxynucleoside drugs capable of exerting anti-viral potency while minimizing the risk for inducing organ toxicities. One such alternative dideoxynucleoside drug is 2′,3′-dideoxyinosine (ddI). Recent therapeutic anti-viral strategy, now undergoing clinical trial, is the evaluation of combined zidovudine ddI treatment. Unfortunately a complete assessment of their potential toxicity using this drug regimen has not been thoroughly examined. We report here the results of studies comparing the toxicity profile of zidovudine versus ddI on their ability to influence several classes of hematopoietic progenitor stem cells, e.g. granulocyte-macrophage (CFU-GM), megakaryocyte (CFU-Meg) and erythroid (CFU-E/BFU-E) following in vitro co-culture with normal human bone marrow. Since the main clinical toxicity associated with zidovudine in vitro is the development of anemia, additional in vitro studies compared the dose-escalation effect of erythropoietin in the presence of combined zidovudine and ddI. CFU-GM, CFU-Meg, CFU-E and BFU-E were all reduced (P<0.05) following incubation with either zidovudine or ddI thus determining their ID₅₀ concentrations for these classes of hematopoietic progenitors; however, the extent of toxicity associated with ddI was lower than what was observed with zidovudine. More importantly, dose-escalation escalation of erythropoietin was effective in reversing the inhibition observed for ddI on erythroid progenitors CFU-E and BFU-E (P<0.05), an effect not reported with zidovudine in vitro. Furthermore, in combination, ddI plus zidovudine significantly reduced erythroid colony formation which was not influenced by dose-escalation of erythropoietin. These results indicate ddI plus zidovudine may produce synergistic hematopoietic toxicity; however, with ddI, amelioration of the potential to develop anemia may respond to erythropoietin treatment.     

转IL—3基因的骨髓基质细胞体外以造血功能的促进作用

目的 探讨用逆转录病毒载体转入mIL-3基因的基质细胞系QXMSC1对骨央造血细胞前体的影响。方法 用含鼠IL－3基因的逆转录病毒载体感染骨央基质细胞系QXMSC1，获得IL－3高表达细胞系QXMSC1 IL－3用于实验，观察QXMSC1 IL－3细胞上清对骨央前体细胞CFU－GM、CFU－E、CFU－GEMM的影响，QXMSC1 IL－3基质细胞对长期培养起始细包的影响。结果 QXMSC1 IL－3培养上清对骨髓前体细胞、CFU－GM、CFU－E、CFU－GEMM有明显促进作用。QXMSC1 IL－3能明显增加有核细胞数和长期培养起始细胞数，诱导分化形成CFU－GM增多，阻断基质细胞与造血细胞相互接触，QXMSC1 IL－3促造血细胞增殖作用有所减弱。结论 基质QXMSC1 IL－3可能作为有效的基因载体进一步促进骨髓移植后或辐射损伤后的造血和免疫功能重建。