Persistence of murine myeloid leukaemic cells in long-term bone marrow cultures

Patterns of growth in long-term bone marrow culture were compared for a number of murine myeloid leukaemias. A leukaemic pattern of haematopoiesis was maintained in culture for a period of at least 15 weeks for one of the lines. However in the other five murine myeloid leukaemic lines studies, the leukaemic cells appeared not to survive in culture and normal haematopoiesis was established. Transplantation of cells from these established cultures at weeks 7 or 11 into syngeneic recipients revealed that leukaemic cells were present. Thus leukaemic cells seem to persist in long-term bone marrow cultures even in morphologically normal cultures.     

Expression of AC133 and CD117 on candidate normal stem cell populations in childhood B-cell precursor acute lymphoblastic leukaemia

To identify residual candidate normal progenitor/stem cell populations in childhood B-cell precursor acute lymphoblastic leukaemia (ALL), expression of AC133 and CD117 was analysed on the leukaemic cell clone and on immature B-lineage-negative CD34+CD19- bone marrow cells. 10/25 patients (40%) had no detectable expression of AC133 within the leukaemic cell clone. 24/26 patients (92%) lacked expression of CD117 on the leukaemic blast cell population. In contrast, a distinct AC133-positive cell population was found in 8/8 children with AC133-negative ALL and a CD117-positive cell population could be identified in 12/12 children with CD117-negative ALL, within the CD34+CD19- progenitor/stem cell compartment. These observations provide further evidence that in B-cell precursor ALL, unlike in acute myelogenous leukaemia, it may be possible to distinguish residual normal progenitor/stem cells from the leukaemic cell clone.     

Interleukin 2 interacts with myeloid growth factors in serum-free long-term bone marrow culture

Summary. IL2 infusion may benefit patients with haematological malignancies by lowering the disease burden. However, conflicting data have been reported on IL2 effects on myelopoiesis, in vitro as well as in vivo. In the present study we investigated the ability of IL2 to act on committed and primitive bone marrow progenitor cells in defined serum-free (SF) culture conditions which avoid many technical biases such as interference by exogenous stimulating or inhibiting factors. Low doses of IL2 (0·1–1000 U/ml) were studied without or in combination with recombinant IL3, GM-CSF and erythropoietin, in SF long-term marrow culture (LTMC). We report data in favour of an inhibitory activity of IL2 limited to committed progenitors and excluding more primitive haemopoietic stem cells, as shown by an alteration of CFU-GM proliferation during the first 5 weeks of LTMC., decreasing with time, unaffected BFU-E and increased nucleated cell production. Beyond week 5, no difference was observed between IL2 supplemented cultures and the SF control cultures. In parallel, IL2 induced the adherence of fibroblastic cells and their progeny. In addition to the inhibitory effect, IL2 appeared to limit the stimulating effect on granulopoiesis and erythropoiesis of myeloid growth factors (GF) such as combination of IL3, GM-CSF and EPO. Indeed, in SF-LTMC conditions, IL2 inhibitory effect is effective on CFU-GM production throughout the 7 weeks of LTMC and on BFU-E during the first 2 weeks only. These data confirm the interaction of IL2 with other GFs in the complex interplay of the cytokine network.     

格列卫治疗单倍体骨髓移植后复发的难治性急性淋巴细胞白血病缓解 1例报告

目的：探讨格列卫治疗Ph^1阳性儿童急性淋巴细胞性白血病单倍体骨髓移植后复发的疗效。方法：用格列卫，300mg，1次／d，顿服治疗1例单倍体骨髓移植后复发难治性急性淋巴细胞白血病。治疗前后观察血常规、骨髓象、BCR／ABL融合基因。结果：治疗4周后达完全缓解，BCR／ABL基因转阴。结论：格列卫治疗Ph^1阳性儿童急性淋巴细胞性白血病单倍体骨髓移植后复发有效。     

Selective expansion of normal haemopoietic progenitors from chronic myelogenous leukaemia marrow

CD34⁺ and CD34⁺ DR^? cells from the bone marrow (BM) of chronic-phase chronic myelogenous leukaemia (CML) patients at diagnosis were tested for their colony-forming ability in response to early and intermediate-late colony stimulating factors (CSFs). Molecular analysis revealed that 55.6 ± 9% SD of CD34⁺DR^? colonies, in which actin and ABL mRNA were detectable, expressed the product of the BCR-ABL gene. The percentage and the clonogenic efficiency of CML DR^? cells were significantly lower than those of comparable DR^? cells from normal donors. However, clonogenic assays using recombinant human CSFs demonstrated a remarkable proliferation of CML cells when stimulated by SCF, IL-11 and IL-3, used as single factors in the presence of erythropoietin (EPO) and was almost entirely due to erythroid progenitors. Conversely, optimal stimulation of CD34⁺DR^? cells from normal donors required co-incubation with three or more CSFs. Stroma-noncontact long-term cultures were then established in the presence of exogenous CSFs and human irradiated allogeneic stromal layers or the murine stromal cell line M2-10B4, engineered to produce G-CSF and IL-3. In these cultures the combination of SCF and IL-3 induced a 25.4 ± 5 SD, 40 ± 6 SD and 20.5 ± 6 SD fold increase of colony-forming unit cells (CFU-C), at weeks 2, 4 and 5, respectively. At the same time-points the number of primitive long-term culture initiating cells (LTC-IC) showed a 4 ± 2 SD, 3.3 ± 1.5 SD and 2.3 ± 1 SD fold increase compared to baseline values. BCR-ABL mRNA analysis of single colonies demonstrated that 27 ± 9% SD and 7 ± 3% SD CFU-C at weeks 4 and 5, respectively, expressed the fusion gene, whereas leukaemic LTC-IC disappeared from the culture by week 2. These results suggest that leukaemic CD34⁺DR^? cells have a different pattern of response to CSFs than normal cells. In addition, we established culture conditions which allow selective expansion of benign haemopoietic cells coexisting with leukaemic progenitors.     

Selective secretion of chemoattractants for haemopoietic progenitor cells by bone marrow endothelial cells: a possible role in homing of haemopoietic progenitor cells to bone marrow

To elucidate the mechanisms by which haemopoietic progenitor cells lodge in the bone marrow, we examined the secretion of chemoattractants for haemopoietic progenitor cells by bone marrow and lung endothelial cells. The bone marrow endothelial cells, but not lung endothelial cells, secreted chemoattractants for the haemopoietic progenitor cell line, FDCP-2, and normal haemopoietic progenitor cells. Checkerboard analysis demonstrated that the conditioned medium of the bone marrow endothelial cells had chemotactic activity and random motility-stimulating activity. The bone marrow endothelial cells expressed stromal-cell-derived factor-1 (SDF-1) mRNA and produced SDF-1 protein, whereas the lung endothelial cells did not. Adhesion of FDCP-2 cells to the bone marrow endothelial cells was partially inhibited by anti-SDF-1 antibody. These findings suggest that the chemoattractants for haemopoietic progenitor cells including SDF-1 and random motility-stimulating factor(s) selectively secreted by the bone marrow endothelial cells may contribute to the homing of haemopoietic progenitor cells to bone marrow.     

Haemopoiesis in long-term bone marrow cultures. A review.

Bone marrow-derived adherent cell layers, containing endothelial cells, fat cells and macrophages will support prolonged haemopoiesis in vitro. Evidence suggests that the adherent layer is acting as an in vitro haemopoietic inductive environment for stem cell proliferation and differentiation into the variety of committed progenitor cells of the granulocytic, erythroid, megakaryocytic and lymphoid lineages. Using this system we have analysed the factors controlling proliferation of stem cells (CFU-S), differentiation and maturation of granulocyte/macrophage precursor cells (CFU-C), leukaemic transformation by chemicals and viruses, the role of environment versus stem cells in the aetiology of haemopoietic aplasias and the possible usefulness of long-term cultures for bone marrow transplantation.     

Detection of minimal residual leukemia after bone marrow transplantation in patients with chronic myeloid leukemia using the polymerase chain reaction

We have utilized the polymerase chain reaction (PCR) to sensitively detect the minimal residual leukemia in 24 patients who were hematologically normal and were negative for Ph1 chromosome after bone marrow transplantation (BMT). None of the patient showed breakpoint cluster region (BCR) gene rearrangement by Southern blot analysis, however, PCR technique revealed the bcr/abl mRNA in 13 of 24 patients. In patients who received CY + TBI as a conditioning regimen, 6 out of 8 patients were detected bcr/abl mRNA by PCR. On the other hand, patients who received high dose AraC+ CY + TBI or busulfan + CY as a conditioning, bcr/abl mRNA was detected in 4 out of 9 patients and 1 out of 5 patients, respectively. There was no clear association between the presence or absence of graft versus host disease and the detection of bcr/abl mRNA by PCR.     

The coiled-coil domain and Tyr177 of bcr are required to induce a murine chronic myelogenous leukemia-like disease by bcr/abl

The bcr/abl fusion in chronic myelogenous leukemia (CML) creates a chimeric tyrosine kinase with dramatically different properties than intact c-abl. In P210 bcr/abl, the bcr portion includes a coiled-coil oligomerization domain (amino acids 1-63) and a grb2-binding site at tyrosine 177 (Tyr177) that are critical for fibroblast transformation, but give variable results in other cell lines. To investigate the role of the coiled-coil domain and Tyr177 in promoting CML, 4 P210 bcr/abl-derived mutants containing different bcr domains fused to abl were constructed. All 4 mutants, Delta(1-63) bcr/abl, (1-63) bcr/abl, Tyr177Phe bcr/abl, and (1-210) bcr/abl exhibited elevated tyrosine kinase activity and conferred factor-independent growth in cell lines. In contrast, differences in the transforming potential of the 4 mutants occurred in our mouse model, in which all mice receiving P210 bcr/abl-expressing bone marrow cells exclusively develop a myeloproliferative disease (MPD) resembling human CML. Of the 4 mutants assayed, only 1-210 bcr/abl, containing both the coiled-coil domain and Tyr177, induced MPD. Unlike full-length P210, this mutant also caused a simultaneous B-cell acute lymphocytic leukemia (ALL). The other 3 mutants, (1-63) bcr/abl, Tyr177Phe bcr/abl, and Delta(1-63) bcr/abl, failed to induce an MPD but instead caused T-cell ALL. These results show that both the bcr coiled-coil domain and Tyr177 are required for MPD induction by bcr/abl and provide the basis for investigating downstream signaling pathways that lead to CML.     

老年白血病bcr/abl融合基因的表达及其临床意义

目的　观察bcr/abl融合基因在老年白血病的表达及其临床意义。　 方法 　应用逆转录聚合酶链反应 (RT PCR)一步法检测 62例老年白血病患者bcr/abl融合基因的表达。　 结果 　 62例患者中bcr/abl融合基因阳性 5 3例 ,阳性率 85 5 % ,其中急性淋巴细胞白血病 (ALL) 17例 ,阳性 9例 (5 2 9% ) ;慢性粒细胞白血病 (CML)45例 ,阳性 44例 (97 88% )。DOCP方案治疗 7例bcr/abl ALL患者完全缓解 (CR)率 2 8 6% ,6例bcr/abl-ALL患者CR率 66 7% (P <0 0 1)。　 结论　bcr/abl融合基因检测有助于CML和ALL的临床诊断、治疗选择、微小残留病变 (MRD)监测以及预后判断 ;老年ALLbcr/abl融合基因阳性率较高 ,可能是其治疗效果较差的原因之一 ;bcr/abl ALL患者CR率明显低于bcr/abl-ALL患者 ;RT PCR一步法特异性好、敏感性高、简便快速 ,尤其适用于MRD的临床监测。     

Proliferation of myeloid progenitor cells in human long-term bone marrow cultures is stimulated by interleukin-1 beta

To study the effect of interleukin-1 (IL-1) beta on the proliferation of hematopoietic progenitor cells (HPC) in long-term bone marrow cultures (LTBMC), stromal cell layers were established from normal human bone marrow. Autologous cryopreserved mononuclear phagocyte- and T-lymphocyte-depleted bone marrow cells were reinoculated on the stromal layers in fresh culture medium, with or without the addition of human IL-1 beta (30 U/mL). Once a week, half of the culture supernatant was replaced with fresh culture medium with or without IL-1, and all nonadherent cells were returned to the flasks. At weekly intervals during a period of 5 weeks, one culture was sacrificed to determine the total number of cells and hematopoietic progenitor cells, present in the adherent and the nonadherent cell fractions. In IL-1-stimulated cultures, the number of cells recovered during a period of 5 weeks exceeded the number of cells in unstimulated control cultures by 1.5 times. This difference was attributed to a twofold increase in the number of adherent cells. The number of HPC recovered from IL-1- stimulated cultures was not different from that recovered from controls. The levels of colony-stimulating activity (CSA) in supernatants from IL-1-stimulated cultures were significantly higher than those in supernatants from control cultures. These results indicate that IL-1 enhances the recovery of cells in LTBMC by stimulating the proliferation of HPC with the concurrent release of CSA from stromal cells, without diminishing the number of HPC.     

Isolation and culture of endothelial cells from human bone marrow

Summary : Adhesive interactions between haemopoietic progenitor cells and bone marrow sinusoidal endothelium are potentially important in the homing of these cells back to re-establish haemopoiesis following stem cell transplantation. A simple method for the isolation and culture of human bone marrow endothelial cells is described using bone marrow aspirates obtained from patients undergoing bone marrow harvests for autologous or syngeneic bone marrow transplantation. The method is based on the selective binding of the lectin Ulex europaeus agglutinin-1 (UEA-1) to endothelial cells. Magnetic Dynabeads coupled with UEA-1 were incubated with single cell suspensions of bone marrow following red cell lysis, and bound cells were isolated with a magnet. The isolated cells demonstrated positive immunofluorescence staining for von Willebrand factor. Cells were plated onto tissue culture flasks coated with extracellular matrix derived from human umbilical vein endothelial cells in an endothelial serum-free medium together with 5% fetal calf serum for 24h. Cells were then cultured in endothelial serum-free growth medium supplemented with 5% fetal calf serum, endothelial cell growth supplemented with 5% fetal calf serum, endothlial cell growth supplement and heparin. After 2–4 weeks in culture, two morphologically different cell populations can be identified. One has a polygonal spindle-shaped morphology with a rapid growth rat, the other a rounded morphology and a slow growth rate. Both population have a vasiculated cytoplasm. Positive immunostaining of the cells was demonstrated with a number of endothelial cell markers including von Willebrand factor, and antibodies to ICAM-1, VCAM-1, E-wlectin, CD31 and BMA120. Weibel-Palade bodies were observed by electron microscopy.
Culture of these cells will allow detailed in vitro studies of adhesion mechanisms in the homing of haemopoietic progenitor cells.     

Functional studies of bone marrow haemopoietic and stromal cells in the myelodysplastic syndrome (MDS)

Long-term bone marrow culture (LTBMC) was used to investigate the proliferative behaviour of marrow cells from a spectrum of cases of the myelodysplastic syndrome (MDS), and the results compared with those obtained in the conventional short-term clonal assay. Two broad patterns of growth were revealed in LTBMC. In one group the incidence of haemopoietic progenitor cells steadily declined to abnormally low levels at 4 weeks, while in a second group they were maintained near normal levels for periods of up to 7 weeks. These growth patterns, which were not predictable from clonogenic assays on the marrow cells prior to LTBMC, or from the morphology of the bone marrow, may reflect the stage of evolution of the disease. Further studies of clonality are required to establish whether or not patients exhibiting the second pattern have a potentiality to harbour residual normal haemopoiesis. LTBMC was also used to study the function of MDS marrow stroma in terms of its ability to sustain the growth of normal haemopoietic progenitor cells. Although the phenotype of the cultured adherent cell layer, obtained from some patients, was atypical, no consistent functional defect of MDS stroma could be identified by studying the level of haemopoiesis reached by normal cells seeded into MDS stroma.     

Long-term culture of leukemic bone marrow primary cells in biomimetic osteoblast niche

We constructed a “biomimetic osteoblast niche” with bio-derived bone as a scaffold, on which we seeded marrow mesenchymal stem cells (MSCs) from CML patients, and induced the MSCs to differentiate into osteoblasts. Bone marrow mononuclear cells from CML patients were cultured in the biomimetic niche (3D culture system) or a 2D culture system with the induced MSCs/osteoblasts as a feeder cell layer for 2 and 5 weeks without adding exogenous cytokines. Cultured cells were analyzed regarding their phenotypes and functions using flow cytometry, colony-forming unit (CFU) assay and long-term culture-initiating cells (LTC-IC) assay. All cultured and colony cells in the LTC-IC assay were collected and analyzed by fluorescent in situ hybridization to identify Ph (bcr/abl)-positive cells. Our results showed that all parameters were higher in the 3D than in the 2D system, either at 2 or 5 weeks, i.e., regarding the number of CD34⁺ cells (8,277.00 vs. 4,490.75 or 2,276.75 vs. 786.00 per well on average, respectively), number of CD34⁺/CD38⁻ cells (1,207.50 vs. 474.25 or 497.25 vs. 114.25 per well on average, respectively), numbers of CFUs (103.33 vs. 79 or 47.0 vs. 21.67/10⁵ MNCs; 189.33 vs. 131.00 or 10.33 vs. 3.67 per well on average, respectively), frequency of LTC-ICs (2.23 × 10⁻⁵ vs. 1.40 × 10⁻⁵ or 1.86 × 10⁻⁵ vs. 0.64 × 10⁻⁵, respectively) and number of remaining LTC-ICs (2.80 vs. 2.03 or 0.46 vs. 0.07 per well on average, respectively). The Ph (bcr/abl)-positive cell fraction was reduced in both systems during culture, but in the 3D system, it was not as rapid as in the 2D system and showed a leukemic predominance. In conclusion, our “biomimetic osteoblast niche” might provide a more adaptive microenvironment for leukemic stem/progenitor cell growth. The biological characteristics of leukemic stem/progenitor cells were partially maintained. It was suggested that the 3D biomimetic niche might be a new tool for studying the behaviors of leukemic hematopoietic stem cells/hematopoietic progenitor cells in vitro.     

Prompt haemopoietic reconstitution following hyperthermia purged autologous marrow and peripheral blood stem cell transplantation in acute myeloid leukaemia.

We report a case of acute myeloid leukaemia in a 35-year-old woman where marrow and chemotherapy-mobilized peripheral blood stem cells (PBSC) were obtained in first complete remission and heat treated at 42 degrees C for 1 h to minimize the likelihood of leukaemic relapse. Transplantation of marrow and PBSC was undertaken following busulphan/cyclophosphamide conditioning 9 months after diagnosis in CR1. Hyperthermic purging did not impair the rate of engraftment and the patient was independent of blood product support by day 21. Studies on this patient's committed normal granulocyte-macrophage progenitor cells (CFU-GM) on samples from marrow and peripheral blood following treatment at 42 degrees C for 1 h, showed minimal and acceptable loss of activity comparable with the loss seen in other marrow progenitor activity treated in a similar fashion in our laboratory. We conclude that hyperthermia-purged PBSC can be used to hasten recovery in autologous haemopoietic progenitor transplantation without compromising rate of engraftment. This is part of an ongoing pilot study to evaluate the role of hyperthermic purging to reduce the risk of leukaemic relapse.     

Rapid medium perfusion rate significantly increases the productivity and longevity of human bone marrow cultures.

Long-term in vitro human hematopoietic (Dexter) cultures are limited both in their longevity (8-12 weeks) and in their cell production over time. Hematopoiesis in vivo continues unabated throughout life, suggesting that failure to obtain continuous hematopoiesis in vitro is probably due to the failure of culture conditions to accurately reproduce the in vivo state. Since bone marrow cells in vivo exist at high density and are rapidly perfused by plasma components, we examined the effects of the culture medium perfusion rate and inoculum density on longevity and productivity of human bone marrow cultures. Culture efficiency and longevity were relatively independent of the variation in inoculum density from 10(6) to 5 x 10(6) cells per ml but were significantly altered by the medium perfusion rate. Increased culture perfusion was superior to traditional Dexter schedules, with 0.5 medium volume exchange per day (3.5 volume per week) being optimal. The cultures under these conditions demonstrated an increasing rate of cell production from weeks 4 to 10, with the cell production rate doubling approximately every 2 weeks. Following weeks 10-12 in culture, the cell production rate of all cultures decayed. Production of nonadherent progenitor cells was also highest in cultures perfused at 3.5 medium volume exchanges per week, where progenitor cell production was stable from weeks 6 to 18. The nonadherent cells collected were predominantly macrophages by week 19, except for the cultures perfused at a rate of 3.5 volumes per week and seeded at 5 x 10(6) cells per ml, in which production of granulocytes remained high through week 19. Establishment of more optimal perfusion conditions supports the continuous stable generation of progenitor cells over 5 months in culture, suggesting that primitive stem cells are surviving and proliferating in these cultures.     

Monoclonal antibodies and magnetic microspheres for the depletion of leukaemic cells from bone marrow harvested for autologous transplantation

The use of a panel of monoclonal antibodies and anti-mouse immunoglobulin-coated microspheres is described for the depletion of leukaemic blasts from bone marrow. Marrow treated in this way rapidly reconstitutes haemopoietic function after high-dose consolidation chemoradiotherapy. The recovery of cells from bone marrow is similar but not identical to results obtained on removal of neuroblasts from marrow to be used for autologous transplant. This is probably a reflection of the cross-reactivity of 'anti-leukaemic' antibodies with a variety of haemopoietic progenitor cells. The study described here demonstrates the feasibility of using this method to purge leukaemic cells from bone marrow. A much larger randomised study between patients receiving either purged or non-purged bone marrow would be necessary to validate the need to remove small numbers of tumour cells from bone marrow.     

Response of myelodysplastic syndrome marrow progenitor cells to stimulation with cytokine combinations in a stroma-free long-term culture system

The effect of an ex vivo expansion culture system using multiple cytokine combinations was evaluated in 38 cases of myelodysplastic syndrome (MDS) with the aim of overcoming the defective in vitro growth of haemopoietic progenitor cells. A combination of four growth factors (GF) including SCF, IL-3, IL-6 and GM-CSF was identified as the optimal combination for expanding clonogenic progenitor cells in MDS bone marrow liquid cultures. The cultures of 50% of the patients (19/38) responded to GF stimulation (mean CFU-GM fold increase 15.65 ± 48 at week 4) and showed morphological features of normal and/or dysplastic myeloid differentiation. In 12/38 cases (31%), complete unresponsiveness to multiple cytokine stimulation was observed; a small number of patients (7/38) showed progressive leukaemic growth along the cultures with the presence of 100% immature blasts at week 4. GM-CSF and c-kit receptors, analysed by immuno-histochemistry in 10 patients, were over-expressed in responding patients and either lacking or down-regulated in non-responders. Fluorescence in situ hybridization (FISH) analysis of cultured interphase cells of nine patients (trisomy 8 in eight patients) showed a clear-cut increase in the percentage of cells with three signals in the two responding patients, thus indicating the expansion of a MDS clone.   Multiple cytokine liquid cultures seem to be able to override the refractoriness of MDS progenitor cells to GF stimulation in many cases, revealing a heterogeneity which may have prognostic implications and should be considered in ex-vivo and in vivo clinical trials with cytokine combinations.