title: Myelopoietin, a chimeric agonist of human interleukin 3 and granulocyte colony-stimulating factor receptors, mobilizes CD34+ cells that rapidly engraft lethally x-irradiated nonhuman primates.
abstract: Myelopoietin (MPO), a multifunctional agonist of interleukin 3 and granulocyte colony-stimulating factor (G-CSF) receptors, was evaluated for its ability to mobilize hematopoietic colony-forming cells (CFC) and CD34+ cells relative to control cytokines in normal nonhuman primates. Additionally, the engraftment potential of MPO-mobilized CD34+ cells was assessed in lethally irradiated rhesus monkeys. Normal rhesus monkeys were administered either MPO (200 microg/kg/day), daniplestim (a high-affinity interleukin 3 receptor agonist) (100 microg/kg/day), G-CSF (100 microg/kg/day), or daniplestim coadministered with G-CSF (100 microg/kg/day each), subcutaneously for 10 consecutive days. The mobilization kinetics were characterized by peripheral blood (PB) complete blood counts, hematopoietic CFC [granulocyte-macrophage CFC (GM-CFC), megakaryocyte CFC (MK-CFC)], and the immunophenotype (CD34+ cells) of PB nucleated cells prior to and on day 3 to days 7, 10, 12, and 14, and at intervals up to day 28 following initiation of cytokine administration. A single large-volume leukapheresis was conducted on day 5 in an additional cohort (n = 10) of MPO-mobilized animals. Eight of these animals were transplanted with two doses of CD34+ cells/kg. A maximum 10-fold increase in PB leukocytes (white blood cells) (from baseline 7.8-12.3 x 10(3)/microL to approximately 90 x 10(3)/microL) was observed over day 7 to day 10 in the MPO, G-CSF, or daniplestim+G-CSF cohorts, whereas daniplestim alone stimulated a less than onefold increase. A sustained, maximal rise in PB-derived GM-CFC/mL was observed over day 4 to day 10 for the MPO-treated cohort, whereas the daniplestim+G-CSF, G-CSF alone, and daniplestim alone treated cohorts were characterized by a mean peak value on days 7, 6, and 18, respectively. Mean peak values for PB-derived GM-CFC/mL were greater for MPO (5,427/mL) than for daniplestim+G-CSF (3,534/mL), G-CSF alone (3,437/mL), or daniplestim alone (155/mL) treated cohorts. Mean peak values for CD34+ cells/mL were noted within day 4 to day 5 of cytokine administration: MPO (255/microL, day 5), daniplestim+G-CSF (47/microL, day 5), G-CSF (182/microL, day 4), and daniplestim (96/microL, day 5). Analysis of the mobilization data as area under the curve indicated that for total CFCs, GM-CFC, MK-CFC, or CD34+ cells, the MPO-treated areas under the curve were greater than those for all other experimental cohorts. A single, large-volume (3.0 x blood volume) leukapheresis at day 5 of MPO administration (PB: CD34+ cell/microL = 438 +/- 140, CFC/mL = 5,170 +/- 140) resulted in collection of sufficient CD34+ cells (4.31 x 10(6)/kg +/- 1.08) and/or total CFCs (33.8 x 10(4)/kg +/- 8.34) for autologous transplantation of the lethally irradiated host. The immunoselected CD34+ cells were transfused into autologous recipients (n = 8) at cell doses of 2 x 10(6)/kg (n = 5), and 4 x 10(6)/kg (n = 3) on the day of apheresis. Successful engraftment occurred with each cell dose. The data demonstrated that MPO is an effective and efficient mobilizer of PB progenitor cells and CD34+ cells, such that a single leukapheresis procedure results in collection of sufficient stem cells for transplantation and long term engraftment of lethally irradiated hosts.
authors.affiliation: Greenebaum Cancer Center, Baltimore, MD 21201, USA. tmacvitt@umaryland.edu
authors.forename: T J
authors.initials: TJ
authors.lastname: MacVittie
authors.forename: A M
authors.initials: AM
authors.lastname: Farese
authors.forename: T A
authors.initials: TA
authors.lastname: Davis
authors.forename: L B
authors.initials: LB
authors.lastname: Lind
authors.forename: J P
authors.initials: JP
authors.lastname: McKearn
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism*; D019540:Area Under Curve; D001772:Blood Cell Count / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004338:Drug Combinations; D000069585:Filgrastim; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000031:analogs & derivatives; D007962:Leukocytes / Q000166:cytology / Q000187:drug effects; D008253:Macaca mulatta; D008297:Male; D010446:Peptide Fragments; D010455:Peptides / Q000494:pharmacology; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000819:agonists*; D016185:Receptors, Interleukin-3 / Q000819:agonists*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D011994:Recombinant Proteins; D013997:Time Factors; D019172:Transplantation Conditioning
chemical_list: D018952:Antigens, CD34; D004338:Drug Combinations; D007377:Interleukin-3; D010446:Peptide Fragments; D010455:Peptides; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; C093340:daniplestim; D000069585:Filgrastim