Colony-forming Unit Granulocyte-macrophage Growth Research Articles

CLL Cell-Derived Exosomes Promote Bone Marrow Fibrosis and Inhibit Normal Hematopoietic Colony Proliferation

CLL Cell-Derived Exosomes Promote Bone Marrow Fibrosis and Inhibit Normal Hematopoietic Colony Proliferation

Molecular Basis and Clinical Application of Growth-Factor-Independent In Vitro Myeloid Colony Formation in Chronic Myelomonocytic Leukemia.

We have originally reported that colony-forming units granulocyte/macrophage (CFU-GM) formation is an in vitro feature of chronic myelomonocytic leukemia (CMML) and a strong predictor for short survival. Elucidation of the molecular basis underlying this in vitro phenomenon could be helpful to define molecular features that predict inferior outcome in patients. We studied the correlation between the mutational landscape and spontaneous colony formation in 164 samples from 125 CMML patients. As compared to wildtype samples, spontaneous in vitro CFU-GM formation was significantly increased in samples containing mutations in NRAS, CBL and EZH2 that were confirmed as independent stimulatory factors by multiple regression analysis. Inducible expression of mutated RAS but not JAK2 was able to induce growth factor independence of Ba/F3 cells. Whereas high colony CFU-GM growth was a strong unfavorable parameter for survival (p < 0.00001) and time to transformation (p = 0.01390), no single mutated gene had the power to significantly predict for both outcome parameters. A composite molecular parameter including NRAS/CBL/EZH2, however, was predictive for inferior survival (p = 0.00059) as well as for increased risk of transformation (p = 0.01429). In conclusion, we show that the composite molecular profile NRAS/CBL/EZH2 derived from its impact on spontaneous in vitro myeloid colony formation improves the predictive power over single molecular parameters in patients with CMML.

In vitro and in vivo effects of JAK2 inhibition in chronic myelomonocytic leukemia.

In chronic myelomonocytic leukemia (CMML), colony-forming units granulocyte/macrophage (CFU-GM), which grow in vitro in the absence of exogenous growth factors, arise from the abnormal clone that is responsible for the overproduction of granulomonocytic cells. Previous in vitro findings including ours suggest that divergent molecular aberrations in CMML seem to converge within the GM-CSF signaling pathway. As JAK2 is a sentinel kinase in this pathway, JAK2 inhibition may be an attractive treatment approach in CMML. We investigated the in vitro effects of the specific JAK2 inhibitor TG101209 on the autonomous CFU-GM formation from peripheral blood mononuclear cells of patients with CMML. TG101209 was found to either block or strongly inhibit spontaneous CFU-GM growth in all 10 patients tested. This inhibitory effect was dose dependent and significantly more pronounced as compared to the inhibitory effect on stimulated CFU-GM growth from normal individuals. In a CMML patient with splenomegaly, who was treated with the JAK1/2 inhibitor ruxolitinib off label, we can demonstrate a spleen response and the disappearance of constitutional symptoms which was associated with a decrease in autonomous CFU-GM formation ex vivo. Pharmacological JAK2 inhibition may be an interesting approach to be systematically studied in patients with CMML.

Interleukin-10 inhibits autonomous myelopoiesis in patients with myelofibrosis.

The spontaneous formation of colony-forming units granulocyte/macrophage (CFU-GM) in semisolid cultures has been shown to be due to the endogenous release of cytokines and/or to the hypersensitivity of cells against growth factors. We have reported that increased autonomous CFU-GM growth is an in vitro characteristic of myelofibrosis (MF) which may reflect aberrant hematopoiesis in vivo. Because of its cytokine synthesis-inhibiting action, we speculated that interleukin-10 (IL-10) may inhibit pathological overproduction of myeloid cells in MF by suppression of autonomous myelopoiesis. In this study, IL-10 significantly inhibited autonomous CFU-GM formation in vitro from peripheral blood mononuclear cells (PB MNC) in 10 of 11 patients with MF tested. In all patients, there was a mean inhibition of 69% ranging from 35% to 100%. Suppression of autonomous CFU-GM formation by IL-10 was dose dependent and reversible by the addition of anti-IL-10 antibodies. Our results indicate that IL-10 is a potentially useful molecule to affect aberrant myelopoiesis in patients with MF.

Effect of the Cdk-inhibitor roscovitine on mouse hematopoietic progenitors in vivo and in vitro

Myelosuppression is one the most frequent side effects of chemotherapy. New agents that more selectively target cancer cells have been developed in attempt to improve the effects and to decrease the side effects of cancer treatment. Roscovitine is a purine analogue and cyclin-dependent kinase inhibitor. Several studies have shown its cytotoxic effect in cancer cell lines in vitro and in xenograft models in vivo. In this study, we investigated the effect of roscovitine on hematopoietic progenitors in vitro and in vivo in mice. The clonogenic capacity of hematopoietic progenitors was studied using burst-forming unit-erythroid (BFU-E), colony-forming unit granulocyte, macrophage (CFU-GM) and colony-forming unit granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM). In vitro, bone marrow cells were exposed to roscovitine (25-250 microM) in Iscove's modified Dulbecco's media for 4 h or to roscovitine (1-100 microM) in MethoCult media for 12 days. No effect on colony formation was observed after exposure to roscovitine for 4 h; however, concentration- and cell type-dependent effects were observed after 12 days. Roscovitine in concentration of 100 microM inhibited the growth of all types of colonies, while lower concentrations have shown differential effect on hematopoietic progenitors. The most sensitive were CFU-GEMM, followed by BFU-E and then CFU-GM. In vivo, mice were treated with single dose of roscovitine (50, 100 or 250 mg/kg) and the effect on bone marrow was studied on day 1, 3, 6, 9 or 12 after the treatment. In the second part of experiment, the mice were treated with roscovitine 350 mg/kg/day divided into two daily doses for 4 days. The bone marrow was examined on day 1 and 5 after the last dose of roscovitine. On day 1, BFU-E decreased to less than 50% of the controls (P = 0.019). No decrease in BFU-E formation was observed on day 5. No significant effect was observed on CFU-GM and CFU-GEMM growth after the treatment with multiple doses of roscovitine. Single doses of roscovitine or dimethylsulfoxide did not affect the colony formation. We also studied the distribution of roscovitine to the bone marrow after a dose of 50 mg/kg was administered intraperitoneally. Only 1.5% of the drug was detected in the bone marrow. Thus, the roscovitine effect on hematopoietic progenitors in bone marrow in vivo is only transient. One reason may be that only a small fraction of roscovitine reaches the bone marrow. Another explanation may be the short half-life observed for roscovitine that might not allow enough cell exposure to the drug. However, the toxicity of roscovitine to hematopoietic progenitors in vitro is within the same exposure range as cytotoxicity to cancer cells. Thus, precaution should be taken in clinical trials, especially when combinations with myelosuppressive cytostatics are used.

Platelet-Derived Microparticels Stimulate Proliferation of Colony-Forming Unit Granulocyte-Macrophage of Umbilical Cord Blood Hematopoietic Stem Cells.

Umbilical Cord blood has become an important source of hematopoietic stem-progenitor cells for transplantation, however hematopoietic recovery after transplantation with umbilical cord blood is slower than with bone marrow or mobilized peripheral blood. Adhesion molecules on hematopoietic cells are involved in hematopoietic cells' homing, which is considered the most important step of hematological recovery. Some articles indicated that expressions of adhesion molecules on CD34+ cells could predict the time to hematopoietic recovery after transplantation with bone marrow and peripheral blood of many adhesion molecules (such as CD62, CXCR4) are significantly lower on umbilical cord blood than on bone marrow. It is a possible reason for the difficulty in hematopoietic recovery after umbilical cord blood transplant. Platelet -derived microparticles (PMPs) are submicroscopic (<1 μm) membrane vesicles released from platelet if they are stimulated with agonists such as thrombin, collagen, or calcium ionophore A23187 or if exposed to high-stress shear forces. PMPs express several platelet-endothelium attachment receptors on their surface, for example, glycoprotein IIb/IIIa (CD41), Ib and IaIIa, and P-selectin (CD62P) and several other platelet relevant receptors such as CXCR4 and PAR-1. Some articles indicate that PMPs can affect the function of hematopoietic stem cells by increasing the adhesion of hematopoietic cells to fibrinogen, which suggests that PMP-transferred CD41 antigen plays an important role in this process. PMPs can also increase the survival of human hematopoietic cells including human CD34+ clonogenic progenitors. In our research, we observe the function of PMP to affect the cloning efficiency of colony-forming unit granulocyte-macrophage (CFU-GM).We adopt different concentrations of Thrombin (2U/ml, 1.5U/ml, 1.0U/ml and 0.5U/ml) to activate the platelet and acquire PMPs. Then PMPs were evaluated by using flow cytometry. Based on the result that stimulation of platelets by Thrombin (1U/ml) can acquire the best efficiency of PMPs, we used this concentration in all subsequent experiments. Umbilical cord mononuclear cells (MNCs) were obtained from healthy donors and isolate the MNCs by Ficoll-Hypaque density gradient centrifugation. Briefly, MNCs incubated with or without PMPs cultured in 2.7% methylcellulose. CFU-GM growth was stimulated with 30% umbilical cord serum, rhIL-3 and rh GM-CSF. Cultures were incubated at 37°C in a fully humidified atmosphere supplemented with 5% CO2. Colonies were counted under an inverted microscope after 7 or 10 days. The research was divided into four groups: 1. control group; 2. PMPs(10μg/ml); 3. PMPs(50μg/ml); 4. PMPs(100μg/ml). The colony formation was enhanced with PMPs and is dependently stimulated with PMPs. The number of colonies in the group of PMPs(100μg/ml) is more than that of other groups. The number of colonies in control group, PMPs(10μg/ml), PMPs(50μg/ml) and PMPs(100μg/ml) are 57.4±3.2, 65.6±5.6, 77.1±1.7 and 87.8±5.0 per 1×105 respectively. These increases in different groups were statistically significant when compared with control group(p<0.05). To sum up, PMPs can affect the cloning efficiency of CFU-GM of umbilical cord hematopoietic stem cells and the efficiencies are depended on the concentration of PMPs.

Functional Analysis of Leukemia-Associated PTPN11 Mutations in Primary Hematopoietic Cells.

The PTPN11 gene encodes SHP-2, a non-receptor protein tyrosine phosphatase (PTPase) that relays signals from activated growth factor receptors to p21ras (Ras), Src family kinases, and other signaling molecules. Germ-line, missense mutations in PTPN11 account for approximately 50% of cases of the human developmental disorder Noonan Syndrome (NS). More recently, PTPN11 mutations have been identified in approximately 35% of children with juvenile myelomonocytic leukemia (JMML) without NS and have also been detected in other lymphoid and myeloid malignancies. Interestingly, almost all of these leukemia-associated mutations introduce amino acid substitutions within the N-SH2 domain of SHP-2 that are largely distinct from those found in NS. We have assessed the functional consequences of leukemia-associated PTPN11 mutations in primary hematopoietic cells. Expression of an E76K mutant SHP-2 in murine fetal liver and bone marrow cells confers a hypersensitive pattern of colony-forming unit granulocyte-macrophage (CFU-GM) colony growth in response to granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 3 (IL-3). Specifically, cells expressing E76K mutant SHP-2 display enhanced colony growth at low concentrations of growth factor compared to cells expressing wild-type (WT) SHP-2 protein. Mutant colonies are significantly larger with an abnormal, spreading morphology. E76K-expressing cells also form CFU-GM colonies in the absence of growth factor. The catalytic activity of the E76K mutant is required for aberrant colony growth as expressing the E76K mutation in the context of defective phosphatase activity (C463S) abolishes hypersensitive CFU-GM growth. Mutant E76K expression also enhances the growth of immature progenitor cells with high repopulating potential (HPP-CFC and LPP-CFC) in response to GM-CSF and IL-3 and perturbs erythroid progenitor colony growth. In addition, expressing the E76K mutation results in more pronounced growth factor hypersensitivity than another leukemia-associated SHP-2 mutation (D61Y), and both of these mutations confer a stronger hematopoietic phenotype than the common N308S substitution found in patients with NS.

Expression of hematopoietic inhibitory factors in mouse fibroblasts, macrophages and endothelial cells.

Pure bone marrow fibroblasts, macrophages and endothelial cells were cultured in Iscove-modified Dulbecco's medium. RT-PCR was used to determine the expression of inhibitory cytokine mRNAs in these cell types. Serum-free conditioned medium was collected from each cell type and ultrafiltration was performed with a centriprep 10. The retentate contained substances whose molecular weights were >10 kD, whilst the filtrate contained substances with molecular weights <10 kD. The effect of conditioned media and their components on colony forming unit-granulocyte-macrophage (CFU-GM) were investigated. The results showed: (1) six cytokines, MIP-1alpha, MIP-2, TGF-beta, TNF-alpha, IFN-gamma and Tbeta(4), inhibited the growth of CFU-GM when murine WEHI-3 conditioned medium was added to the culture system as a source of colony stimulation. (2) The original endothelial cell conditioned medium (E-CM) did not affect the production of CFU-GM, but the >10 kD component of E-CM increased its production, and the <10 kD component decreased it. Both fibroblast conditioned medium (F-CM) and the >10 kD component of F-CM stimulated proliferation of CFU-GM, but the <10 kD component suppressed it. All three components of macrophage conditioned medium (M-CM) inhibited the growth of CFU-GM. (3) Expression of four of the mRNAs, namely MIP-2, TNF-alpha, INF-gamma and Tbeta(4), was seen in all three types of stromal cells, while TGF-beta mRNA was only seen in endothelial cells and macrophages, and MIP-1alpha mRNA in endothelial cells and fibroblasts. The inhibitors TGF-beta, MIP-1alpha, and Tbeta(4)have an inhibitory effect on the growth of CFU-GM, but TNF-alpha, INF-gamma and MIP-2 do not.

Interleukin-10 inhibits in vitro hematopoietic suppression and production of interferon-gamma and tumor necrosis factor-alpha by peripheral blood mononuclear cells from patients with aplastic anemia.

Mononuclear cells (MNC) from patients with aplastic anemia (AA) can inhibit hematopoietic colony formation from normal bone marrow (BM) cells. Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) are considered as soluble mediators of BM suppression in AA. Because of its cytokine synthesis inhibiting action, interleukin-10 (IL-10) could be a potentially useful molecule to modulate the hematopoietic effects of MNC from patients with AA. Using coculture experiments we studied the effect of recombinant human IL-10 (rhIL-10) on the in vitro hematopoietic suppression by peripheral blood (PB) MNC from AA patients. PBMNC (5 x 10(5)/ml) from seven patients with AA caused a 40-100% reduction of normal burst-forming unit-erythroid (BFU-E) growth and a 38-91% reduction of colony-forming unit-granulocyte/macrophage (CFU-GM) growth, respectively, in semisolid cocultures. IL-10 was highly effective in reversing growth inhibition in these cocultures. Addition of 10 ng/ml IL-10 to cocultures significantly restored growth of BFU-E in all seven cases and growth of CFU-GM in five of seven cases, respectively. The effect was dose dependent and correlated with decreased IFN-gamma and TNF-alpha production in suspension cultures. Using intracellular cytokine staining it was found that increased TNF-alpha production in AA cells was derived from both CD4+ and CD8+ cells, whereas aberrant IFN-gamma synthesis was only detected in CD8+ cells. IL-10 is effective in reversing in vitro hematopoietic suppression by PBMNC from AA patients. These results suggest therapeutic evaluation of rhIL-10 in patients with AA.

Effect of oxysterols on hematopoietic progenitor cells

Oxysterols are hydroxylated derivatives of cholesterol detected in blood, cells, and tissues. They exhibit a number of biologic activities, including inhibition of cellular proliferation and cytotoxicity associated with induction of apoptosis. Given the important regulatory role of apoptosis in hematopoiesis, we investigated the effects of oxysterols on human hematopoietic progenitor cells (HPCs). Colony-forming unit granulocyte-macrophage (CFU-GM) from human bone marrow and umbilical cord blood (UCB) were grown in the presence of varying concentrations of three different oxysterols-7-keto-cholesterol, 7-beta-hydroxycholesterol, and 25-hydroxycholesterol (25-OHC). Similarly, the effect of oxysterols on HL60 and CD34+ cells was investigated using annexin V staining and flow cytometry to measure apoptosis. Reduction of nitroblue tetrazolium was used to assess differentiative status of HL60 cells. CFU-GM derived from human bone marrow were inhibited by all three oxysterols tested, with 25-OHC being the most potent. In comparison, CFU-GM derived from UCB were less sensitive to the effects of all the oxysterols tested, with statistically significant inhibition observed only in the presence of 25-OHC. Oxysterol treatment of HL60 cells inhibited cell growth and increased the number of annexin V+ and nitroblue tetrazolium+ cells. The percentage of viable, CD34+ annexin V+ cells also was increased with oxysterol treatment of purified HPCs in liquid culture. These experiments indicate that oxysterol inhibition of CFU-GM and HL60 cell growth can be attributed to induction of apoptosis and/or differentiation. These investigations revealed that oxysterols are a new class of inhibitors of HPC proliferation of potential relevance in vivo and in vitro.

Bone marrow endothelial cells secrete thymosin β4 and AcSDKP

Bone marrow endothelial cells are the essential component of the bone marrow microenvironment. They produce many kinds of cytokines, including stimulators and inhibitors. Many researchers have suggested that in the presence of endothelial cell layer, CD34+CD38- cells are capable of expansion. The ability of the endothelial cell layer to protect hematopoietic stem cells from extensive differentiation may be related to the inhibitors derived from endothelial cells. The aim of the present study was to determine whether the inhibitors thymosin beta4 and AcSDKP are elaborated by murine bone marrow endothelial cells. Murine bone marrow endothelial cells (mBMECs) were cultured in serum-free conditioned medium. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to analyze the differential expression of the thymosin-beta gene, and reverse phase high-performance chromatography (HPLC) and mass spectroscopy were used to determine the concentration of thymosin beta4 (Tbeta4) and AcSDKP in EC lysate and in the medium (mBMEC-CM). Colony-forming unit granulocyte-macrophage (CFU-GM) colony assays were used to examine the effect of components (mw 3-10 kD, <3 kD) of mBMEC-CM, thymosin beta4, and AcSDKP on the proliferation of hematopoietic cells.mBMECs expressed Tbeta4 mRNA. In EC lysate and mBMEC-CM, Tbeta4 and AcSDKP were detected. After adding protease inhibitors, the concentration of Tbeta4 in EC lysate increased significantly, while the concentration of AcSDKP decreased. mBMEC-CM (mw 3-10 kD) had no effect on the formation of CFU-GM. However, mBMEC-CM (mw <3 kD) could inhibit the growth of CFU-GM. Tbeta4 (10(-11) approximately 10(-7)mol/L) and AcSDKP (10(-11) approximately 10(-5)mol/L) had dose-dependent inhibitory effects on the growth of CFU-GM. Angiotensin converting enzyme (ACE), the enzyme degrading AcSDKP, could partially eliminate the inhibitory effect of mBMEC-CM (mw <3 kD) on CFU-GM.BMECs express and secrete Tbeta4 and AcSDKP. Tbeta4 exists in the 3-10 kD component of mBMEC-CM, while AcSDKP exists in the <3 kD component of ECCM. Both components exert inhibitory effects on the proliferation of hematopoietic progenitors.

Influence of Photofrin® on the Hematopoietic Accessory Function of Murine Peritoneal Cells

The porphyrin photochemotherapeutic agent Photofrin® stimulates hematopoietic activity within the bone marrow (BM) and spleens of normal mice. We found that the intraperitoneal (i.p.) administration of Photofrin® also caused a 3–4 fold increase in peritoneal cell (PC) numbers, particularly cells bearing granulocyte surface antigens. Little granulocyte-macrophage progenitor activity was detectable within the PC population of control and Photofrin®-injected mice suggesting that Photofrin® had elicited an influx of inflammatory cells into the region. In contrast to cells from control animals, PC obtained 6 h to 168 h after the i.p. injection of Photofrin® exhibited a consistently inferior capacity to support the growth of BM colony forming units granulocyte-macrophage (CFU-GM). When PC from control or Photofrin®-treated mice were added to the BM culture system in the presence of defined growth factors there was no effect on the number of colonies formed. This finding indicated that negative regulatory elements were not responsible for the reduced hematopoietic accessory activity exhibited by PC from Photofrin®-treated mice. Supernatants conditioned by PC from Photofrin®-injected mice poorly supported BM CFU-GM growth in vitro and in contrast to PC supernatants prepared from control mice did not contain detectable amounts of granulocyte-macrophage colony stimulating factor (GM-CSF). The cellular changes which occur within the peritoneal cavity represent bystander events not directly related to the hematostimulatory action of Photofrin®.

Value of colony forming unit-granulocyte macrophage assay in predicting relapse in acute myeloid leukaemia.

To evaluate the validity of the colony forming unit-granulocyte macrophage (CFU-GM) assay for predicting relapse in patients with acute myeloid leukaemia (AML). The study population comprised 32 patients with AML in remission, followed for a median of 18 months. A mean of four studies was carried out per patient. Three patterns of in vitro growth based on the number of CFU-GM in normal bone marrow were defined: 1 = normal (normal number of CFU-GM and a cluster:colony ratio < 2); 2 = hypoplastic (low number of CFU-GM and a cluster:colony ratio < 2); 3 = anomalous (low or normal number of CFU-GM and a cluster:colony ratio > 2). Eleven patients relapsed, all of whom had previously displayed an abnormal CFU-GM pattern: anomalous in nine and hypoplastic in two. The remaining 25 patients were in complete remission at the time of writing, 16 of whom had a normal growth pattern. The other nine had anomalous (eight patients) or hypoplastic (one patient) growth. The latter may be false positive results. The in vitro growth pattern was not constant during follow up analysis. All 15 patients in whom the growth pattern switched from abnormal to normal remain in complete remission. By contrast, of the five cases in whom the pattern changed from normal to abnormal, three have relapsed and the other two had other indicators of relapse. The growth pattern remained unchanged in the remaining 16 patients. The present data show that the sequential investigation of the CFU-GM growth pattern may be of value in predicting relapse in patients with AML.

Differential Effects of Nitric Oxide on Erythroid and Myeloid Colony Growth From CD34+ Human Bone Marrow Cells

Nitric oxide (NO) is a reactive molecule with numerous physiologic and pathophysiologic roles affecting the nervous, cardiovascular, and immune systems. In previous work, we have demonstrated that NO inhibits the growth and induces the monocytic differentiation of cells of the HL-60 cell line. We have also demonstrated that NO inhibits the growth of acute nonlymphocytic leukemia cells freshly isolated from untreated patients and increases monocytic differentiation antigens in some. In the present work, we studied the effect of NO on the growth and differentiation of normal human bone marrow cells in vitro. Mononuclear cells isolated from human bone marrow were cultured in semisolid media and treated with the NO-donating agents sodium nitroprusside (SNP) or S-nitroso-acetyl penicillamine (SNAP) (0.25 to 1 mmol/L). Both agents decreased colony-forming unit-erythroid (CFU-E) and colony-forming unit-granulocyte macrophage (CFU-GM) formation by 34% to 100%. When CD34+ cells were examined, we noted that these cells responded to SNP and SNAP differently than did the mononuclear cells. At a concentration range of 0.25 to 1 mmol/L, SNP inhibited the growth of CFU-E by 30% to 75%. However, at the same concentration range, SNP increased the number of CFU-GM by up to 94%. At concentrations of 0.25 to 1 mmol/L, SNAP inhibited the growth of CFU-E by 33% to 100%. At a concentration of 0.25 mmol/L, SNAP did not affect CFU-GM. At higher concentrations, SNAP inhibited the growth of CFU-GM. Although SNP increased intracellular levels of cGMP in bone marrow cells, increasing cGMP in cells by addition of 8-Br-cGMP (a membrane permeable cGMP analogue) did not reproduce the observed NO effects on bone marrow colonies. These results demonstrate that NO can influence the growth and differentiation of normal human bone marrow cells. NO (generated in the bone marrow microenvironment) may play an important role modulating the growth and differentiation of bone marrow cells in vivo.

Oligodeoxynucleotides Antisense to c-abl Specifically Inhibit Entry Into S-Phase of CD34+ Hematopoietic Cells and Their Differentiation to Granulocyte-Macrophage Progenitors

A number of experimental observations suggest that the proto-oncogene c-abl participates in the regulation of hematopoietic cell growth. We used an antisense strategy to study the relationship between c-abl expression and hematopoietic cell proliferation and differentiation. Purified normal human bone marrow-derived CD34+ cells were obtained by immunomagnetic selection and incubated with 18-base-unmodified antisense oligodeoxynucleotides complementary to the first six codons of the two alternative first exons of c-abl, la and lb. At the end of incubation, an aliquot of cells was assayed for clonogenic growth and the remainder was used for flow cytometric analyses. Cell kinetics were evaluated by means of both single parameter DNA and bivariate DNA/bromodeoxyuridine (BrdU) flow cytometry. Apoptosis was routinely studied by DNA flow cytometric analysis and, in some cases, also through DNA agarose gel electrophoresis for detection of oligonucleosomal DNA fragments. Expression of differentiation markers was studied by flow cytometry. Exposure to antisense oligonucleotides specifically inhibited the accumulation of c-abl mRNA in CD34+ cells. Preincubation with the c-abl antisense oligomers reduced the proportion of cells in S-phase from 19% +/- 5% (mean +/- SD) to 7% +/- 4% (P < .05), and BrdU labeling from 13% +/- 6% to 6% +/- 3% (P < .05). Flow cytometry and DNA agarose gel electrophoresis showed that treated CD34+ cells accumulated in the G0/G1 region of the DNA histogram with no evidence of either differentiation or apoptosis. By contrast, both growth factor deprivation and exposure of CD34+ cells to the tyrosine kinase inhibitor tyrphostin AG82 clearly induced apoptosis. When cells were preincubated with antisense oligonucleotides and then plated for evaluation of colony formation, this resulted in a significant inhibition of colony forming unit granulocyte-macrophage growth (from 44 +/- 15 to 22 +/- 9; P < .01) but had no effect on burst-forming unit erythroid growth (24 +/- 11 v 21 +/- 11; P < .05). These results suggest that c-abl expression is critical for entry of human CD34+ hematopoietic cells into S-phase and for their differentiation to granulocyte-macrophage progenitors. They also indicate that other tyrosine kinases besides p145c-alb are active in the prevention of apoptosis, so that inhibition of c-abl RNA accumulation arrests CD34+ cells in G0/G1 without activating programmed death.

Is Nitrous Oxide Safe for Bone Marrow Harvest?

Patients with non-Hodgkins lymphoma undergoing autologous bone marrow harvest were studied in a prospective, randomized fashion. All patients received a general anesthetic consisting of intravenous thiopental, fentanyl, and vecuronium and were ventilated with oxygen and isoflurane. Group I (19) patients also were ventilated with nitrous oxide (70%) whereas patients in Group II (19) did not receive nitrous oxide. Bone marrow samples were obtained at the beginning and end of the harvest. Viability of bone marrow mononuclear cells was assessed with a colony-forming unit-granulocyte macrophage (CFU-GM) assay, CFU-GM growth is a marker for myeloid progenitor cells and is dependent on intact deoxyribonucleic acid synthesis. Rate of neutrophil engraftment after autologous bone marrow transplantation was also studied. Both groups of patients were statistically similar in age, weight, anesthetic duration, CFU-GM counts at both sample draws, and the time for successful engraftment. There appears to be no difference in bone marrow viability as assayed by both CFU-GM colony growth and engraftment in human bone marrow exposed to a general anesthetic with nitrous oxide.

Analysis of the effects of tumor necrosis factor inhibitors on human hematopoiesis.

Truncated soluble fragments of tumor necrosis factor (TNF) receptors have recently been isolated from human serum and urine. These shed forms of TNF receptors bind TNF-alpha and lymphotoxin and inhibit various effects of TNF in culture. In this study, we evaluated the role of these molecules in the hematopoietic system. TNF-alpha and lymphotoxin inhibited colony forming units granulocyte-macrophage (CFU-GM) and burst forming units-erythroid (BFU-E) in a dose-dependent fashion at concentrations ranging from 1 to 5,000 U/ml and 25 to 250 U/ml, respectively. TNF-alpha exerted a similar dose-dependent inhibitory effect on a CD34 enriched marrow cell population, suggesting that its effect is not mediated through CD34 accessory cells. Its suppressive effect was partially reversed by anti-TNF-alpha neutralizing antibodies, thus proving its specificity. Two shed forms of TNF receptors, TNF binding protein (TNF-bp) and TNF receptor fusion protein (TNFR-fc), had no significant effect on CFU-GM proliferation. Both molecules, however, significantly reversed the inhibitory effect of TNF-alpha (p < 0.015 and p < 0.03, respectively), whereas they had no effect on the lymphotoxin-induced CFU-GM growth inhibition. These results indicate that TNF-bp and TNFR-fc may modulate the inhibitory effects of TNF-alpha in the hematopoietic system.

The role of macrophages in the regulation of erythroid colony growth in vitro

Depletion of macrophages from murine marrow by the use of a monoclonal anti-macrophage antibody resulted in a significant increase in the number of erythroid burst forming units (BFU-E). This increase could be neutralized by the addition back to culture of macrophages or macrophage conditioned medium indicating that the suppression was mediated by soluble factors. To further characterize this effect, the addition to culture, either alone or in combination, of interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on the growth of BFU-E and the colony-forming unit granulocyte-macrophage (CFU-GM) was examined in macrophage-containing and macrophage-depleted cultures. The addition of IL-1 alpha to culture stimulated the release of both TNF alpha and GM-CSF and acted synergistically with both cytokines, resulting in a dose-dependent suppression of BFU-E and stimulation of CFU-GM growth. The increase in CFU-GM caused by the addition of IL-1 alpha was mediated by GM-CSF but not by TNF alpha as the increase was prevented by the addition of a monoclonal anti-GM-CSF antibody but not by anti-TNF alpha. When either TNF alpha or GM-CSF was neutralized by monoclonal antibodies the addition of IL-1 alpha resulted in a significant increase in BFU-E growth. The addition of GM-CSF to culture caused a dose-dependent suppression of BFU-E that was mediated by TNF alpha, as colony number was not reduced when GM-CSF and a monoclonal anti-TNF alpha antibody were simultaneously added to culture. TNF alpha- induced suppression of BFU-E only occurred in the presence of macrophages. In macrophage-depleted cultures, a dose-dependent suppression of BFU-E could be induced if subinhibitory concentrations of IL-1 alpha or GM-CSF were simultaneously added with increasing concentrations of TNF alpha. The effects of IL-1 alpha or GM-CSF and TNF alpha were markedly synergistic so that the doses required to induce suppression when added simultaneously was only 10% of that required when either were added to culture alone. Suppression of BFU-E by GM-CSF or the combined addition of GM-CSF and TNF alpha did not require IL-1 alpha because inhibition was not neutralized by the addition of anti-IL-1 alpha antibody.

The Role of Macrophages in the Regulation of Erythroid Colony Growth In Vitro

Depletion of macrophages from murine marrow by the use of a monoclonal anti-macrophage antibody resulted in a significant increase in the number of erythroid burst forming units (BFU-E). This increase could be neutralized by the addition back to culture of macrophages or macrophage conditioned medium indicating that the suppression was mediated by soluble factors. To further characterize this effect, the addition to culture, either alone or in combination, of interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on the growth of BFU-E and the colony-forming unit granulocyte-macrophage (CFU-GM) was examined in macrophage-containing and macrophage-depleted cultures. The addition of IL-1 alpha to culture stimulated the release of both TNF alpha and GM-CSF and acted synergistically with both cytokines, resulting in a dose-dependent suppression of BFU-E and stimulation of CFU-GM growth. The increase in CFU-GM caused by the addition of IL-1 alpha was mediated by GM-CSF but not by TNF alpha as the increase was prevented by the addition of a monoclonal anti-GM-CSF antibody but not by anti-TNF alpha. When either TNF alpha or GM-CSF was neutralized by monoclonal antibodies the addition of IL-1 alpha resulted in a significant increase in BFU-E growth. The addition of GM-CSF to culture caused a dose-dependent suppression of BFU-E that was mediated by TNF alpha, as colony number was not reduced when GM-CSF and a monoclonal anti-TNF alpha antibody were simultaneously added to culture. TNF alpha-induced suppression of BFU-E only occurred in the presence of macrophages. In macrophage-depleted cultures, a dose-dependent suppression of BFU-E could be induced if subinhibitory concentrations of IL-1 alpha or GM-CSF were simultaneously added with increasing concentrations of TNF alpha. The effects of IL-1 alpha or GM-CSF and TNF alpha were markedly synergistic so that the doses required to induce suppression when added simultaneously was only 10% of that required when either were added to culture alone. Suppression of BFU-E by GM-CSF or the combined addition of GM-CSF and TNF alpha did not require IL-1 alpha because inhibition was not neutralized by the addition of anti-IL-1 alpha antibody.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of stem cell factor on colony growth from acquired and constitutional (Fanconi) aplastic anemia

The aim of this study was to evaluate the effect of stem cell factor (SCF) on the in vitro growth of bone marrow hematopoietic progenitors from patients with acquired severe aplastic anemia (AA) or Fanconi's anemia (FA). For this purpose, we studied 11 patients with acquired AA (5 at diagnosis, 6 after ALG treatment), 12 patients with FA, and nine normal controls. Bone marrow cells were plated in vitro for colony- forming unit granulocyte-macrophage (CFU-GM) (in the presence of granulocyte-macrophage colony-stimulating factor [GM-CSF]), and for burst-forming unit-erythroid (BFU-E) and CFU-granulocyte, erythroid, monocyte, megakaryocyte (CFU-GEMM) colonies (in the presence of erythropoietin and interleukin-3 [IL-3]), with or without 20 ng/mL of SCF. In normal controls, SCF enhanced the growth of CFU-GM colonies from 103 to 263 (median), of BFU-E from 168 to 352, and of GEMM colonies from 6 to 38/10(5) cells plated. In patients with acquired AA, SCF induced a significant enhancement of BFU-E growth (8 to 29; P = .01) and allowed the formation of GEMM colonies that were not scored in baseline culture conditions (0 to 8; P = .01). CFU-GM growth was enhanced (4 to 20), but not significantly (P = .3). This was true both for patients at diagnosis and after antilymphocyte globulin treatment. By contrast, 10 of 12 FA patients grew no CFU-GM, BFU-E, or CFU-GEMM colonies, with or without SCF. In two FA patients (one transfusion- dependent and one transfusion-independent), an enhancement of CFU-GM and/or BFU-E was observed. The lack of response of hematopoietic progenitor cells from FA patients to GM-CSF+SCF or IL-3+SCF was not dependent on a defective expression of cytokine receptor messenger RNAs. Northern blot analysis showed in marrow cells from acquired AA and FA patients the presence of normal transcripts for alpha- and beta- chains of GM-CSF/IL-3 receptor and for c-kit protein. In conclusion, SCF promotes the in vitro growth of hematopoietic progenitors in patients with acquired AA, but not in patients with FA, pointing out the intrinsic nature of the defect in the latter disorder.