Allogeneic peripheral blood stem cell transplantation following CD34+ enrichment by density gradient separation.

GVHD is a significant cause of morbidity and mortality following allogeneic peripheral blood stem cell transplantation (AlloPBSC). CD34+ cell selection could reduce GVHD by negative selection of T cells. In an attempt to reduce the T cell content of alloPBSC we carried out a trial in which 11 patients with hematologic malignancies received alloPBSC from HLA-matched siblings following density gradient separation using an isotonic colloidal silica solution (BDS 60; Dendreon Corporation). Cyclosporine and methylprednisone were used for GVHD prophylaxis. The mean yield of CD34+ cells was 69 +/- 15.6% with a purity of 2.9 +/- 1.7%. The mean number of CD3+ cells infused was 1.0 +/- 1.2 x 107/kg, representing a 1.3 log depletion. A high risk of acute GVHD was observed: grade II-IV in 7/11 (64%) and grade III-IV GVHD in 5/11 (45%) patients. Nine of the 11 (82%) patients died with a median survival of 68 days. Cytokine expression in PBSC was compared pre and post processing. Interferon-gamma was detected only following density gradient separation while IL-8 expression increased 3- to 6-fold post processing. Therefore, processing with this device may augment production of pro-inflammatory cytokines. Bone Marrow Transplantation (2000) 25, 1223-1228.

Ex vivo cultured megakaryocytes express functional glycoprotein IIb-IIIa receptors and are capable of adenovirus-mediated transgene expression.

Investigation of the molecular basis of megakaryocyte (MK) and platelet biology has been limited by an inadequate source of genetically manipulable cells exhibiting physiologic MK and platelet functions. We hypothesized that ex vivo cultured MKs would exhibit agonist inducible glycoprotein (GP) IIb-IIIa activation characteristic of blood platelets and that these cultured MKs would be capable of transgene expression. Microscopic and flow cytometric analyses confirmed that human hematopoietic stem cells cultured in the presence of pegylated recombinant human MK growth and development factor (PEG-rHuMGDF) differentiated into morphologic and phenotypic MKs over 2 weeks. Cultured MKs expressed functional GPIIb-IIIa receptors as assessed by agonist inducible soluble fibrinogen and PAC1 binding. The specificity and kinetics of fibrinogen binding to MK GPIIb-IIIa receptors were similar to those described for blood platelets. The reversibility and internalization of ligands bound to MK GPIIb-IIIa also shared similarities with those observed in platelets. Cultured MKs were transduced with an adenoviral vector encoding green fluorescence protein (GFP) or beta-galactosidase (beta-gal). Efficiency of gene transfer increased with increasing multiplicities of infection and incubation time, with 45% of MKs expressing GFP 72 hours after viral infection. Transduced MKs remained capable of agonist induced GPIIb-IIIa activation. Thus, ex vivo cultured MKs (1) express agonist responsive GPIIb-IIIa receptors, (2) are capable of expressing transgenes, and (3) may prove useful for investigation of the molecular basis of MK differentiation and GPIIb-IIIa function.

A functional granulocyte colony-stimulating factor receptor is required for normal chemoattractant-induced neutrophil activation.

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor that is widely used to treat neutropenia. In addition to stimulating polymorphonuclear neutrophil (PMN) production, G-CSF may have significant effects on PMN function. Because G-CSF receptor (G-CSFR)-deficient mice do not have the expected neutrophilia after administration of human interleukin-8 (IL-8), we examined the effect of the loss of G-CSFR on IL-8-stimulated PMN function. Compared with wild-type PMNs, PMNs isolated from G-CSFR-deficient mice demonstrated markedly decreased chemotaxis to IL-8. PMN emigration into the skin of G-CSFR-deficient mice in response to IL-8 was also impaired. Significant chemotaxis defects were also seen in response to N-formyl-methionyl-leucyl-phenylalanine, zymosan-activated serum, or macrophage inflammatory protein-2. The defective chemotactic response to IL-8 does not appear to be due to impaired chemoattractant receptor function, as the number of IL-8 receptors and chemoattractant-induced calcium influx, actin polymerization, and release of gelatinase B were comparable to those of wild-type PMNs. Chemoattractant-induced adhesion of G-CSFR-deficient PMNs was significantly impaired, suggesting a defect in beta2-integrin activation. Collectively, these data demonstrate that selective defects in PMN activation are present in G-CSFR-deficient mice and indicate that G-CSF plays an important role in regulating PMN chemokine responsiveness.

Specific signals generated by the cytoplasmic domain of the granulocyte colony-stimulating factor (G-CSF) receptor are not required for G-CSF-dependent granulocytic differentiation.

Granulocyte colony-stimulating factor (G-CSF) is the principal growth factor regulating the production of neutrophils, yet its role in lineage commitment and terminal differentiation of hematopoietic progenitor cells is controversial. In this study, we describe a system to study the role of G-CSF receptor (G-CSFR) signals in granulocytic differentiation using retroviral transduction of G-CSFR-deficient, primary hematopoietic progenitor cells. We show that ectopic expression of wild-type G-CSFR in hematopoietic progenitor cells supports G-CSF-dependent differentiation of these cells into mature granulocytes, macrophages, megakaryocytes, and erythroid cells. Furthermore, we show that two mutant G-CSFR proteins, a truncation mutant that deletes the carboxy-terminal 96 amino acids and a chimeric receptor containing the extracellular and transmembrane domains of the G-CSFR fused to the cytoplasmic domain of the erythropoietin receptor, are able to support the production of morphologically mature, chloroacetate esterase-positive, Gr-1/Mac-1-positive neutrophils in response to G-CSF. These results demonstrate that ectopic expression of the G-CSFR in hematopoietic progenitor cells allows for multilineage differentiation and suggest that unique signals generated by the cytoplasmic domain of the G-CSFR are not required for G-CSF-dependent granulocytic differentiation.

Factors that influence the collection and engraftment of allogeneic peripheral-blood stem cells in patients with hematologic malignancies.

PURPOSE: To determine the number of CD34+ cells associated with a high probability of rapid engraftment after allogeneic peripheral-blood stem-cell (PBSC) transplant, and to examine the relationship between certain donor characteristics and the effectiveness of PBSC mobilization. PATIENTS AND METHODS: Between December 1994 and July 1996, we treated 47 patients who had resistant hematologic neoplasms with myeloablative therapy followed by transplantation of allogeneic PBSC collected from histocompatible siblings after mobilization with granulocyte colony-stimulating factor (G-CSF). Expression of CD34 was determined by flow cytometry. RESULTS: Engraftment was rapid and similar to that observed following autologous PBSC transplant, with an absolute neutrophil count (ANC) greater than 500/microL and platelet count greater than 20,000/microL on median days +9 and +11, respectively. The pace of hematologic recovery correlated with the number of hematopoietic progenitors transplanted, so that patients who received greater than 5 x 10(6) CD34+ cells/kg recipient weight had a 95% likelihood of neutrophil and platelet recovery by day +15. Baseline (precytokine) CD34+ cells per milliliter of donor peripheral blood and total G-CSF dose (donor weight x 10 micrograms/kg) correlated with the number of CD34+ cells collected (R2 = .24 and P = .0009, and R2 = .24 and P < .0001, respectively). Donor age and sex did not effect mobilization. CONCLUSION: Following allogeneic PBSC transplant, patients who received greater than 5 x 10(6) CD34+ cells/ kg recipient weight had a high probability of rapid engraftment. Donors with low baseline levels of circulating progenitors (< 2,000 CD34+ cells/mL blood) and those who received lower total doses of G-CSF were less likely to be effectively mobilized. For donors with low baseline CD34+ counts, higher doses of G-CSF might improve mobilization. Baseline CD34+ counts and total G-CSF dose accounted for less than half of the variation in CD34+ cells collected, which indicates that other, as yet unidentified, factors play an important role in determining the effectiveness of mobilization.

Mechanism of farnesol cytotoxicity: further evidence for the role of PKC-dependent signal transduction in farnesol-induced apoptotic cell death.

Mechanism of the inhibitory effect of isoprenoid farnesol on cell proliferation has been studied in human acute leukemia CEM-C1 cells. Farnesol (20 microM) reduced the rate of radioactive label incorporation into cellular diacylglycerol (DAG) and phosphocholine, the products of degradation of phosphatidylcholine (PC), indicating inhibition of PC-specific phospholipase C after about 1 h of incubation. Inhibition of phospholipase D by farnesol at the later incubation time (about 2 h) was demonstrated by a decrease in synthesis of PC-derived phosphatidylethanol in the presence of ethanol. These effects of farnesol on PC degradation and formation of DAG were followed by apoptotic fragmentation of cellular DNA and inhibition of cell growth. Exogenous DAG reduced the level of DNA fragmentation and cell growth inhibition. Results are consistent with the involvement of cellular signal transduction in the mechanism of inhibition of cell proliferation by farnesol.

Directed cell killing (apoptosis) in human lymphoblastoid cells incubated in the presence of farnesol: effect of phosphatidylcholine.

Previously reported observations have shown that trans-trans farnesol inhibits incorporation of choline into phosphatidylcholine and reduces the growth rate of the human acute leukemia CEM-C1 cell line (Melnykovych, G., Haug, J.S. and Goldner, C.M. (1992) Biochem. Biophys. Res. Commun. 186, 543-548). These findings have now been followed up in order to establish a relationship between the inhibition of phosphatidylcholine synthesis and the ensuing cell shrinkage and cell death which takes place at higher concentrations of farnesol or upon long incubation. The present results show that after incubation in the presence of farnesol the cells decrease in viability. Their nuclear DNA becomes fragmented at internucleosomal linker regions, showing characteristic pattern of bands at 180 to 200 base-pair intervals. This farnesol-induced effect was also demonstrated by flow cytometry by staining the cellular DNA with propidium iodide and was partially reversible with phosphatidylcholine.

Differences in sensitivity to farnesol toxicity between neoplastically- and non-neoplastically-derived cells in culture.

Six neoplastically-derived cell lines and three cell lines derived from normal tissues were compared for their sensitivity to isoprenoid trans-trans farnesol. Assays of cell numbers and of protein concentrations per culture revealed greater sensitivity of neoplastic cells than of the normal cells. Similar differences were obtained from the comparison of incorporation of [methyl-3H]choline into cellular lipids, with neoplastic cells showing greater inhibition than normal cells.

Growth inhibition of leukemia cell line CEM-C1 by farnesol: effects of phosphatidylcholine and diacylglycerol.

Acute leukemia cells of the established line CEM-C1 were treated during growth in serum-free medium with various concentrations of trans-trans farnesol. At concentrations ranging from 9.0 to 31.5 microM, farnesol inhibited growth of these cells without causing cell lysis. This effect was preceded by very rapid inhibition of choline incorporation in cellular lipid fraction. The growth inhibitory effect was prevented to a large extent by incubation with phosphatidylcholine or diacylglycerol.