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Biomedical subjects

L B To

Publications and source records attributed to L B To.

At least 37 records · Page 2Linked to original sources
PubMed1998

Establishment of a reproducible model of chronic-phase chronic myeloid leukemia in NOD/SCID mice using blood-derived mononuclear or CD34+ cells.

An animal model of chronic myeloid leukemia (CML) will help characterize leukemic and normal stem cells and also help evaluate experimental therapies in this disease. We have established a model of CML in the NOD/SCID mouse. Infusion of > or = 4 x 10(7) chronic-phase CML peripheral blood cells results in engraftment levels of > or = 1% in the bone marrow (BM) of 84% of mice. Engraftment of the spleen was seen in 60% of mice with BM engraftment. Intraperitoneal injection of recombinant stem cell factor produced a higher level of leukemic engraftment without increasing Philadelphia-negative engraftment. Granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor did not increase the level of leukemic or residual normal engraftment. Assessment of differential engraftment of normal and leukemic cells by fluorescence in situ hybridization analysis with bcr and abl probes showed that a median of 35% (range, 5% to 91%) of engrafted cells present in the murine BM were leukemic. BM engraftment was multilineage with myeloid, B-cell, and T-cell engraftment, whereas T cells were the predominant cell type in the spleen. BM morphology showed evidence of eosinophilia and increased megakaryocytes. We also assessed the ability of selected CD34+ CML blood cells to engraft NOD/SCID mice and showed engraftment with cell doses of 7 to 10 x 10(6) cells. CD34- cells failed to engraft at cell doses of 1.2 to 5 x 10(7). CD34+ cells produced myeloid and B-cell engraftment with high levels of CD34+ cells detected. Thus, normal and leukemic stem cells are present in CD34+ blood cells from CML patients at diagnosis and lead to development of the typical features of CML in murine BM. This model is suitable to evaluate therapy in CML.

Animals↗
PubMed1998

Granulocyte colony-stimulating factor (G-CSF) dose-dependent efficacy in peripheral blood stem cell mobilization in patients who had failed initial mobilization with chemotherapy and G-CSF.

For 10 consecutive patients in our unit who did not show a significant rise in blood progenitor cells within 14 days following chemotherapy and G-CSF, we increased the G-CSF dose from 5 to 10 microg/kg/day (n = 9) or from 10 to 15 microg/kg/day (n = 1). As a result, there were significant increases in total yield as well as yield per apheresis of mononuclear cells, CD34+ cells and CFU-GM (P < 0.025, <0.01 and <0.005, respectively). After G-CSF dose escalation, six of the 10 patients had sufficient CD34+ cells for performing transplantation. These results demonstrate a dose-dependent response of progenitor cell mobilization by G-CSF when used in combination with chemotherapy. Moreover, increasing the dose of G-CSF as late as the third week of mobilization may still provide sufficient cell yield even with patients who did not show a significant mobilization with conventional doses of G-CSF.

Adolescent↗
PubMed1998

Rapid hematopoietic recovery after multicycle high-dose chemotherapy: enhancement of filgrastim-induced progenitor-cell mobilization by recombinant human stem-cell factor.

PURPOSE: To assess the mobilization potential and safety of recombinant human stem-cell factor (SCF) when coadministered with filgrastim to untreated women with poor-prognosis breast cancer. PATIENTS AND METHODS: Eligible women had breast cancer with 10 or more positive axillary nodes, or estrogen receptor-negative tumor with 4 positive nodes, or stage III disease. Patients were randomized to receive SCF plus filgrastim or filgrastim alone. Filgrastim 12 microg/kg daily was administered for 6 days by continuous subcutaneous infusion. SCF was administered by daily subcutaneous injection at 5, 10, or 15 microg/kg concurrent with filgrastim for 7 days, or 10 microg/kg daily starting 3 days before filgrastim for a total of 10 days (SCF pretreatment). Apheresis was performed on days 5, 6, and 7 of filgrastim administration. Patients then had three cycles of epirubicin 200 mg/m2 and cyclophosphamide 4 g/m2 every 28 days, each supported by one third of the apheresis product. RESULTS: Sixty-two women were treated. Greater yields occurred in patients who received SCF 10 microg/kg daily plus filgastim than those who received filgrastim alone (P=.013 for CD34+ cells; P=.07 for granulocyte-macrophage colony-forming cells [GM-CFCs]). The difference was more marked with SCF-pretreatment than concurrent SCF. Fewer aphereses were required to reach the predetermined target of peripheral-blood progenitor/stem cells (PBPCs) in women who received SCF. SCF was generally well tolerated. Hematologic recovery was rapid after each of the three cycles of chemotherapy. There was no difference in recovery between the different treatment groups. CONCLUSION: Mobilization of PBPCs by filgrastim is significantly enhanced by coadministration of SCF, and commencing SCF before filgrastim can optimize this effect. SCF has the potential to reduce the number of aphereses required to collect a target number of PBPCs.

Adult↗
PubMed1997

Spontaneous regression of relapsed non-Hodgkin's lymphoma in a patient who received an autologous transplant for primary resistant disease.

Poor prognosis malignant lymphoma is often treated with autologous bone marrow transplantation. Relapse after transplantation is usually associated with disease progression and resistance to further therapy. We present a case in which a 50-year-old patient relapsed with multiple pulmonary metastases shortly after peripheral blood stem cell transplantation. Remarkably, this relapse remitted spontaneously. This may provide valuable insights into tumour cell biology and mechanisms by which stem cell mobilisation may alter this.

Bone Marrow Transplantation↗
PubMed1997

Peripheral blood is a source of BCR-ABL-negative pre-progenitors in early chronic phase chronic myeloid leukemia.

Manipulation of autologous bone marrow cells (BM) for transplantation in chronic myeloid leukemia (CML) to enrich for normal cells is a novel approach that may improve survival for patients not suitable for allogeneic transplantation. Limitations of this technique include the reported low frequency of normal stem cells in CML and the difficulties in obtaining sufficient BM for manipulation. To address these problems we compared the apheresis product with the diagnostic bone marrow at diagnosis as a source of primitive BCR/ABL-negative progenitors. We analyzed the CD34+ HLA-DR- and CD34+CD38(-) populations in five CML patients to evaluate the frequency of BCR-ABL-negative progenitors and pre-progenitors in these populations. Progenitor analysis was performed by RT-PCR of individual hemopoietic colonies from a standard CFU-GM assay. Analysis of pre-progenitors involved RT-PCR of secondary colonies derived from a stroma-free pre-CFU assay. Our results show variable levels of BCR-ABL-negative progenitors in the 34+DR- population but very low levels of BCR-ABL-negative progenitors in the 34+38- population in blood. Analysis of pre-progenitors from the 34+DR- fraction of peripheral blood (PB) and BM showed 80-100% and 85-100% of colonies were BCR-ABL negative at days 14 and 28, respectively. Analysis of pre-progenitors from the 34+38- fraction of PB and BM showed 23-100% and 42-100% of colonies were BCR-ABL negative at days 14 and 28, respectively. In summary, pre-progenitors from the 34+DR- and 34+38- populations are predominantly BCR-ABL negative in both marrow and blood at diagnosis. Apheresis product collected at diagnosis is a more abundant sources of BCR-ABL-negative pre-progenitors than BM. Thus, apheresis product could potentially be utilized as a source of BCR-ABL-negative stem cells in CML.

ADP-ribosyl Cyclase↗
PubMed1997

Detection of minimal residual disease in an AML patient with trisomy 8 using interphase fish.

Patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) often exhibit clonal chromosomal abnormalities. Using a probe for the centromeric region of chromosome 8, fluorescence in situ hybridization (FISH) on interphase cells was used to detect trisomy 8 in an AML patient whose leukemia was characterised by the karyotype 47, XY, +8, del(9) (q21.1q32). We have demonstrated using FISH the presence of the trisomy at all stages of the patient's disease course (including remission, peripheral blood cell harvest and relapse), whereas conventional karyoptypic analysis was only able to detect the trisomy at diagnosis and clinical relapse. We have also shown using immunophenotyping, cell sorting and FISH, that the trisomic cells in this patient were restricted to the CD34+ subset of blood and bone marrow and could not be found in the CD 34-, T or B cell compartment. Overall we have shown FISH to be a rapid, quantitative method for the detection of cells with numerical chromosome abnormalities. FISH analysis of interphase cells provides valuable information on the status of the whole population, rather than just cycling cells, and can be applied successfully to monitor the level of leukemic cells.

Acute Disease↗
PubMed1997

Ex vivo culture of peripheral blood CD34+ cells: effects of hematopoietic growth factors on production of neutrophilic precursors.

A major potential application for ex vivo culture of hematopoietic progenitor cells is the treatment of cytopenia following high-dose chemotherapy and hematopoietic transplantation. We have previously postulated that infusion of a sufficient number of neutrophil postprogenitor cells generated by ex vivo culture of CD34+ cells may be able to abrogate neutropenia. In this article, we describe further development of an efficient stromal-free, cytokine-dependent, static culture system for generation of these cells. Our previous studies indicated that maximal production of nucleated cells and myeloid progenitor cells from PB CD34+ cells occurred with multiple hematopoietic growth factor (HGF), notably the 6-HGF combination of interleukin (IL)-1, IL-3, IL-6, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage-CSF (GM-CSF), and stem cell factor (SCF). In the present study, we determine the contribution of each of these 6 HGF in generation of neutrophilic precursors. SCF, G-CSF, and IL-3 were found to be the most important HGF for production of neutrophilic cells. The 4-HGF combination of IL-3, IL-6, G-CSF, and SCF was optimized by performing dose-response experiments and shown to be as potent as 6 HGF for production of nascent CFU-GM and neutrophilic precursors.

Antigens, CD34↗
PubMed1996

Apoptosis of hemopoietic cells by the human granulocyte-macrophage colony-stimulating factor mutant E21R.

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) binds to a high-affinity heterodimeric receptor composed of a specific alpha chain and a common beta chain (beta(c)), which is shared with the receptors for interleukins 3 and 5. Hemopoietic cell survival requires GM-CSF binding this high-affinity receptor. We have recently developed the GM-CSF mutant E21R, which selectively binds to the alpha chain and behaves as a competitive GM-CSF antagonist. We have now examined the role of E21R on the survival of hemopoietic cells and found that E21R causes apoptosis (programmed cell death) of normal and malignant cells directly in the absence of GM-CSF. The direct apoptotic effect of E21R occurred in a dose- and time-dependent manner. Apoptosis by E21R was dependent on cells expressing the high-affinity GM-CSF receptor and could be blocked by GM-CSF. Significantly, apoptosis of the cells occurred even in the presence of the survival factors granulocyte CSF and stem cell factor but was prevented by engagement of beta(c) with interleukin 3. The initiation of apoptosis required phosphorylation, transcriptional activity, and protein synthesis. These findings support a model whereby binding of E21R to the alpha chain leads to apoptosis, while beta(c) plays an important role in cell survival. This model may be applicable to other multimeric cytokine receptors and offers a novel approach for the treatment of human leukemia.

Acute Disease↗
PubMed1996

Comparison of myeloma cell contamination of bone marrow and peripheral blood stem cell harvests.

lt could be speculated for patients with myeloma and other lymphoproliferative disorders that peripheral blood stem cells may be preferable to bone marrow for autologous transplantation because they may be less contaminated by neoplastic cells. To test this possibility, the immunoglobulin heavy chain gene rearrangement and limiting dilution polymerase chain reaction were used to sensitively quantify myeloma cells in bone marrow and peripheral blood stem cell collections, taken at a similar time, from eight patients with multiple myeloma. Levels of residual disease in the peripheral blood stem cell harvests were variable and did not reflect the tumour burden in the marrow. Peripheral blood stem cells contained 1.7 to 23700-fold fewer myeloma cells compared with the bone marrow and would have resulted in reinfusion of 0.08 to 59480-fold fewer myeloma cells based on total reinfused CFU-GM and 0.24 to 24700-fold fewer myeloma cells based on total reinfused nucleated cells. Assuming that the proportion of clonogenic myeloma cells is equivalent, peripheral blood stem cells may be better than bone marrow as a source of haemopoietic stem cells for transplantation in multiple myeloma. The clinical followup suggested that patients transplanted with peripheral blood stem cells containing a low number of myeloma cells had better disease control than those transplanted with peripheral blood stem cells containing a high number.

Adult↗
PubMed1996

Progenitor cell yield in sequential blood stem cell mobilization in the same patients: insights into chemotherapy dose escalation and combination of haemopoietic growth factor and chemotherapy.

Between April 1988 and March 1994 a total of 23 patients with haematological or non-haematological malignancies received serial peripheral blood stem cell (PBSC) mobilization to attain sufficient harvest for PBSC transplant at our institution. There was no improvement in yield with the second mobilization for group A patients (n = 12) who had the same dose of cyclophosphamide twice as mobilizing agent. For group B patients (n = 6). who had a higher dose of cyclophosphamide with the second mobilization, there was significant increase in CFU-GM yield. CD34+ cell yield was not measured. For group C patients, who received interleukin-3 plus granulocyte-macrophage colony-stimulating factor (GM-CSF) with the first mobilization and chemotherapy plus GM-CSF with the second, there was significant increase in CFU-GM as well as CD34+ cell yield. Our results demonstrate that, at the doses studied, chemotherapy dose escalation and combining haemopoietic growth factor with chemotherapy improve progenitor cell yield in PBSC mobilization.

Adult↗
PubMed1996

Myeloma stem cells in autografting in multiple myeloma.

Autologous transplantation has been used increasingly over the last 10 years for the treatment of multiple myeloma. As is the case in other cancers treated by high-dose therapy and stem cell rescue, the contribution of occult tumor cells in the graft to relapse posttransplant remains to be resolved. In this report, we review the biology and differentiation of plasma cells in the context of their significance as an origin of relapse in multiple myeloma.

Hematopoietic Stem Cell Transplantation↗
PubMed1996

Standardization of the CFU-GM assay using hematopoietic growth factors.

The colony-forming unit-granulocyte-macrophage (CFU-GM) assay is used commonly to assess adequacy of progenitor number in bone marrow transplantation. The assay is poorly standardized, resulting in variability of results between and within laboratories. We assessed three variables that contribute to the lack of standardization. The colony-stimulating activity of human placental-conditioned medium (HPCM) was compared with combinations of recombinant hematopoietic growth factors (HGF) in 5 normal bone marrow donors. A protocol for batch testing of fetal calf serum (FCS) is described. In addition, a rigid training program has been introduced to minimize interstaff and intrastaff variability in the counting of colonies. We show that a five-factor combination of interleukin-3 (IL-3), IL-6, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), and stem cell factor (SCF) produces a mean increase of 85% in colony number. Some combinations of three HGF produce similar growth to HPCM, and all four HGF combinations are equivalent or superior to HPCM. Batch testing of FCS shows variability between batches. We show significant interstaff and intrastaff variability between a new and experienced staff member that improves following a period of training. In summary, the use of recombinant HGF in association with a rigorous program of batch testing of FCS and staff training results in a CFU-GM assay that can be standardized between laboratories.

Blood Cell Count↗
PubMed1996

Peripheral blood stem cells mobilized from patients with acute myeloid leukaemia have different platelet repopulating abilities compared with those mobilized from patients with other diseases.

Peripheral blood stem cell (PBSC) transplantation gives rapid recovery of neutrophils and platelets and sustained haemopoiesis. However in patients with acute myeloid leukaemia (AML) platelet recovery has a distinctive rapid rise and then secondary fall between 3 to 8 weeks post-transplant. This study compares platelet and neutrophil recovery after PBSC transplantation in 15 patients with AML and 29 patients with other diseases consecutively transplanted in a single unit. PBSC were collected during recovery from consolidation chemotherapy in AML patients and after cyclophosphamide or cytokine administration in the other patient groups. Mononuclear cell numbers collected were similar but CFU-GM numbers were greater from the AML patients. A significant secondary fall occurred only in the platelet count and only in AML patients. Long-term recovery of the platelet count was the same in AML as in the other patients. In AML patients, the fall was the same in the long term remitters as in those who eventually relapsed. Previous studies have not, demonstrated a difference in type of precursors mobilized by differing methods, but have not included AML patients. Megakaryocyte precursors were assayed in this study and showed no consistent differences in number between patient groups however pre-progenitor assays are not yet established especially in the megakaryocytic lineage. The possible explanation for this secondary fall in AML patients is discussed.

Acute Disease↗
PubMed1996

Increased levels of megakaryocyte progenitors in peripheral blood mobilised by chemotherapy and/or haemopoietic growth factor protocols.

We have quantitated colony-forming unit megakaryocyte, (CFU-Mk), burst-forming unit megakaryocyte, (BFU-Mk), colony-forming unit granulocyte-macrophage (CFU-GM), and CD34+ cells in 98 mobilised PB samples from 53 patients mobilised by one of six protocols, including myelosuppressive chemotherapy alone (n = 22), or in combination with recombinant haemopoietic growth factors (n = 32), and growth factors alone (n = 17) or in combination (n = 27). The frequency of megakaryocyte progenitors (total Mk = CFU-Mk + BFU-Mk) in mobilised PB (mean 356, range 0-3240/10(6)) was similar to that in steady-state BM (mean 429, range 0-3315/10(6) n = 45). The levels of total Mk in mobilised PB (mean 1509, range 0-36 099/ml) showed a mean 75-fold increase compared with steady state PB (mean 20, range 0-86/ml, n = 15). In mobilised PB the levels of CFU-Mk were significantly correlated with levels of BFU-Mk (rs = 0.71, P < 0.0001) and the levels of megakaryocyte progenitors correlated significantly with those of myeloid progenitors (rs = 0.59, P < 0.0001) and CD34+ cells (rs = 0.69, P < 0.0001). The mobilisation of megakaryocyte progenitors into the circulation in response to high-dose chemotherapy and/or haemopoietic growth factors contributes to an understanding of the rapid platelet recovery following PBSC transplantation and suggests that the measurement of megakaryocyte progenitors may be a useful indicator for platelet reconstitutive capacity.

Adult↗
PubMed1995

Adjuvant treatment of high-risk breast cancer using multicycle high-dose chemotherapy and filgrastim-mobilized peripheral blood progenitor cells.

Women with primary breast cancer associated with extensive axillary node involvement or large primary tumors have a very poor prognosis despite treatment with standard-dose adjuvant chemotherapy. In an attempt to improve the outlook of these patients, we investigated the safety and feasibility of delivering three cycles of high-dose epirubicin and cyclophosphamide supported with filgrastim-mobilized peripheral blood progenitor cells (PBPC). Fifteen previously untreated women, median age 50 (range, 30-58) years, with poor prognosis early stage breast cancer received filgrastim (12 microgram/kg daily for 6 days) prior to chemotherapy to mobilize progenitor cells. Patients were then given three cycles of epirubicin (200 mg/m2) and cyclophosphamide (4 g/m2) at planned 28-day intervals, each followed by infusion of one third of the PBPC collected and daily administration of filgrastim (5 microgram/kg s.c.). Three leukaphereses collected a median of 114.9 (range, 22.7-273.5) x 10(4) granulocyte-macrophage-colony-forming cells/kg body weight. Hemopoietic recovery was rapid after each cycle, and there was no correlation between the rate of recovery and the number of granulocyte-macrophage-colony-forming cells infused. There was a small but significant progressive delay in recovery from hematological and nonhematological toxicities across the three cycles. Left ventricular ejection fraction fell to below 50% in eight (53%) patients, but none developed congestive cardiac failure. Two patients did not complete three cycles because of insufficient PBPC for a third cycle (n = 1) and 2-mercaptoethane sodium sulfonate- related drug reaction during the second cycle (n = 1). There were no deaths during the study or during the follow-up period (median, 70 weeks; range, 50-85 weeks), and no late toxicities occurred. Therefore, we concluded that the delivery of multiple cycles of nonmyeloablative, dose-intensive chemotherapy supported by PBPC and filgrastim is safe, and may be widely applicable to a variety of common chemosensitive cancers with a poor prognosis. The efficacy of three cycles of high-dose epirubicin and cyclophosphamide is to be compared with standard-dose chemotherapy in a randomized trial in patients with high-risk, operable stage II and III breast cancer.

Adolescent↗