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 Previous Article | Table of Contents | Next Article 
Blood, Vol. 91 No. 1 (January 1), 1998:
pp. 37-45
Multilineage Hematopoietic Recovery by a Single Injection of
Pegylated Recombinant Human Megakaryocyte Growth and Development
Factor in Myelosuppressed Mice
By
Kazunori Shibuya,
Hiromichi Akahori,
Kazumi Takahashi,
Emiko Tahara,
Takashi Kato, and
Hiroshi Miyazaki
From the Pharmaceutical Research Laboratory, Kirin Brewery Co,
Takasaki, Japan.
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ABSTRACT |
Previous studies have shown that daily multiple administration of
pegylated recombinant human megakaryocyte growth and development factor
(PEG-rHuMGDF) markedly stimulates thrombopoiesis and effectively
ameliorates thrombocytopenia, and in most cases anemia and neutropenia,
in myelosuppressed animals. In this study, we evaluated the effects of
a single intravenous injection of PEG-rHuMGDF on hematopoietic recovery
after sublethal total-body irradiation in mice. A single injection of
PEG-rHuMGDF (1 to 640 µg/kg) 1 hour after irradiation accelerated
platelet, red blood cell (RBC), and white blood cell (WBC) recovery in
a dose-dependent fashion. In the bone marrow of vehicle-treated mice,
megakaryocytic, erythroid, and myeloid progenitors, as well as day 12
colony-forming unit-spleen (CFU-S), were dramatically decreased much
earlier than the nadirs of peripheral blood cells, whereas
megakaryocytes were modestly decreased. Treatment with PEG-rHuMGDF (80
µg/kg, an optimal dose) 1 hour after irradiation resulted in more
rapid recovery of these four hematopoietic progenitors and also
significantly facilitated megakaryocyte recovery. In addition, the same
PEG-rHuMGDF administration schedule expanded bone marrow cells capable
of rescuing lethally irradiated recipient mice. As the interval between
irradiation and PEG-rHuMGDF treatment was longer, its effects on
hematopoietic recovery were attenuated. In contrast to the effects of
PEG-rHuMGDF, a single injection of recombinant human granulocyte
colony-stimulating factor (rhG-CSF) 1 hour after irradiation
exclusively accelerated WBC recovery, but only to a similar extent as
PEG-rHuMGDF (80 µg/kg) treatment even when rhG-CSF doses were
escalated to 1,000 µg/kg. This appeared related to different
pharmacokinetics of these two factors after a single injection in
irradiated mice. The concentrations of PEG-rHuMGDF after injection
persisted in the plasma for a longer time compared with rhG-CSF. These
results indicate that a single injection of PEG-rHuMGDF at an early
time after irradiation is able to effectively improve thrombocytopenia,
anemia, and leukopenia with concomitant accelerated recovery of both
primitive and committed hematopoietic progenitors in irradiated mice.
Our data also show that compared with the rhG-CSF shown to exert
multilineage effects on hematopoiesis, PEG-rHuMGDF has more
wide-ranging effects on peripheral blood cell recovery.
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INTRODUCTION |
THROMBOPOIETIN (TPO), also termed the
c-Mpl ligand, is the recently isolated hematopoietic factor that
primarily regulates megakaryocytopoiesis and platelet
production.1-6 Results from in vitro studies have shown
that TPO stimulates the growth of committed megakaryocyte progenitors
(colony-forming unit-megakaryocyte [CFU-MK]), progressive maturation
of megakaryocytes, and proplatelet formation.3,7-14 In
addition to acting on megakaryocytopoiesis, TPO enhances the growth of
committed erythroid progenitors15,16 and primitive
hematopoietic progenitors.17-20 In vivo administration of
either glycosylated TPO or pegylated recombinant human megakaryocyte
growth and development factor (PEG-rHuMGDF), a pegylated, truncated
molecule related to TPO, dramatically increases circulating platelets
with little or no influence on red blood cells (RBCs) and white blood
cells (WBCs) and markedly expands CFU-MK and megakaryocytes in the bone
marrow of normal animals.3,21-24
In chemotherapy- and/or irradiation-induced myelosuppression in
animals, treatment with TPO or PEG-rHuMGDF has a profound effect on
thrombocytopenia, effectively reducing the platelet nadir and
accelerating platelet recovery.25-31 Moreover, TPO or
PEG-rHuMGDF significantly improves neutropenia and anemia associated
with myelosuppression.25-33 In bone marrow transplantation
models, PEG-rHuMGDF administration34,35 or transplantation
of bone marrow cells from TPO-pretreated donor mice36
facilitates platelet recovery.
It has been reported that a single injection of pegylated murine MGDF
into normal mice causes dose-dependent and significant increases in
megakaryocyte number, size, and ploidy in the bone
marrow.24 One study using PEG-rHuMGDF has shown that a
single injection of PEG-rHuMGDF is sufficient to increase circulating
platelet counts.25 On the other hand, multiple-injection
protocols have been used in all of the experiments to investigate the
effects of TPO or PEG-rHuMGDF on hematopoietic recovery in
myelosuppressed animals. Our previous study has shown that in
chemotherapy-induced myelosuppressed mice, treatment with PEG-rHuMGDF
once per week (on days 1 and 8) after chemotherapy on day 0 is almost
as effective as daily multiple injections of PEG-rHuMGDF from day 1 in
improving thrombocytopenia.31 This suggests that a
single injection of PEG-rHuMGDF may have a significant effect on
thrombocytopenia in myelosuppressed mice.
In this study, we therefore explored whether a single administration of
PEG-rHuMGDF is able to improve impaired hematopoiesis in irradiated
mice. Our data show that a single injection of PEG-rHuMGDF into
irradiated mice at an early time after irradiation greatly accelerates
the recovery of circulating platelets and significantly enhances the
recovery of RBCs and WBCs, accompanied by accelerated recovery of both
primitive and committed hematopoietic progenitors in the bone marrow.
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MATERIALS AND METHODS |
Animals.
Male BALB/c mice aged 8 weeks were purchased from Charles River Japan
Inc (Atsugi, Japan). Mice were housed in autoclaved cages, and were
maintained in an air-conditioned, specific pathogen-free animal room
regulated at a temperature of 21° to 23°C and a relative humidity
of 50% to 60%. The 12-hour lighting cycle began with lights on at 8
AM. Mice were given sterilized commercial rodent chow and
water ad libitum. All experiments in this study were approved by the
Institutional Animal Care and Use Committee of our laboratory.
Cytokines.
PEG-rHuMGDF was expressed in Escherichia coli using a plasmid
that encodes a truncated mpl ligand related to TPO including the
Mpl-binding amino-terminal domain, and then was purified to
homogeneity. The molecule was further derivatized with polyethylene
glycol. Filgrastim (rhG-CSF) expressed in E coli was prepared
at Kirin Brewery Co (Tokyo, Japan).
Study design.
Before treatment with hematopoietic factors or vehicle, mice were
exposed to total-body irradiation at a dose of 3.5 Gy with an x-ray
apparatus (MBR-1520R; Hitachi, Tokyo, Japan). At various times after
irradiation, mice were given a single intravenous injection of various
doses of PEG-rHuMGDF, rhG-CSF, or vehicle (acetate-buffered solution)
in a volume of 0.1 mL. Each experimental group consisted of five or six
mice. Peripheral blood samples were obtained from the retro-orbital
plexus using 75-mm heparinized capillary tubes (Funakoshi
Pharmaceutical Co, Tokyo, Japan). Complete blood cell counts were
performed with the Sysmex automatic microcell counter F-800 (Toa
Medical Electronics, Kobe, Japan). Reticulocyte counts were determined
as previously described.23
In vitro progenitor cell assays.
Bone marrow cells were harvested from mice by flushing the femoral
contents with modified CATCH medium.37 CFU-MK
cultures were performed according to the method previously
described37 with minor modifications. Briefly, an
appropriate number of marrow cells were cultured in the presence of 30
ng recombinant mouse interleukin-3 ([rmIL-3] Kirin Brewery
Co)23 and 20 ng PEG-rHuMGDF in 1 mL Iscove's modified
Dulbecco's medium (Sigma, St Louis, MO) containing 0.3% Noble agar
(Difco, Detroit, MI), 10% fetal calf serum ([FCS] GIBCO, Grand
Island, NY), 2 mmol/L glutamine, 1 mmol/L sodium pyruvate, and 50
µmol/L 2-mercaptoethanol (Merck, Darmstadt, Germany) in a 35-mm
tissue culture dish (Nunc, Naperville, IL) at 37°C in a humidified
atmosphere of 5% CO2. After 7 days of culture, agar disks
were detached from the culture dishes, placed onto glass slides, and
stained with acetylcholinesterase (AchE) according to the method of
Jackson.38 CFU-MK-derived colonies were defined as
colonies with at least three megakaryocytes. Cultures of
CFU-granulocyte-macrophage (CFU-GM) and burst-forming unit-erythroid
(BFU-E) were performed with a methylcellulose method. Briefly, an
appropriate number of marrow cells were cultured with 16 IU recombinant
human erythropoietin (Kirin Brewery Co)23 and 5 ng rmIL-3
in 1 mL  -medium (Flow Laboratories, McLean, VA) containing 0.88%
methylcellulose (Shinetsu Kagaku Kogyo, Tokyo, Japan), 30% FCS, 1%
bovine serum albumin (Sigma), and 50 µmol/L 2-mercaptoethanol in a
35-mm tissue culture dish. After 7 days of culture, GM colonies ( 50
cells) or erythroid colonies (200 cells) were counted as CFU-GM- or
BFU-E-derived colonies, respectively, using an inverted light
microscope. The total number of each hematopoietic progenitor cell per
femur was calculated as follows: the number of colonies generated per
dish was multiplied by the total number of cells obtained from one
femur divided by the number of cells seeded per dish.
Day 12 CFU-spleen assay.
Day 12 CFU-spleen (CFU-S) was assayed according to the method of Till
and McCulloch.39 Briefly, bone marrow cells derived from
mice treated postirradiation with PEG-rHuMGDF or vehicle were washed
and suspended in -medium, and aliquots of the cells were injected
into recipients that had been irradiated at a lethal dose of 8.5 Gy.
Twelve days after inoculation, the recipients were killed, and their
spleens were removed and fixed with Bouin's solution. Colonies on the
surface of the spleen were then counted as day 12 CFU-S. The total
number of day 12 CFU-S per femur was calculated as follows: the number
of day 12 CFU-S generated per spleen was multiplied by the total number
of cells obtained from one femur divided by the number of cells
injected per mouse.
Measurement of the number of marrow megakaryocytes.
Bone marrow cells were plated at 105 cells per well in
96-well immunoplates (Nunc) and fixed in 100 µL 0.1-mol/L phosphate
buffer (PB), pH 6.0, containing 2.5% glutaraldehyde (Wako Pure
Chemicals, Osaka, Japan) for 10 minutes at room temperature. After
fixation, the plates were centrifuged at 120g for 5 minutes and
the supernatant of each well was removed by aspiration, taking care not
to disturb the cell pellet. A volume of 100 µL 0.1-mol/L PB was added
to each well, and the plates were centrifuged as before. This washing
procedure was repeated twice. Subsequently, the cell pellets were
stained with AchE. The number of AchE-positive cells was counted as for
megakaryocytes using an inverted light microscope. The total number of
megakaryocytes per femur was calculated as follows: the number of
AchE-positive megakaryocytes per well was multiplied by the total
number of cells obtained from one-femur divided by the number of cells
plated per well.
Bone marrow transplantation experiments.
Mice were intravenously given one dose of PEG-rHuMGDF (80 µg/kg) or
vehicle 1 hour after total-body irradiation at a dose of 3.5 Gy. Two
days later, the femoral bone marrow cells were collected, washed, and
resuspended in -medium. Aliquots of cells (106 cells per
mouse) were inoculated intravenously into the lateral tail vein of
syngeneic recipient mice that had been irradiated at a lethal dose of
8.5 Gy (six mice per experimental group), and then the survival of the
transplanted mice was monitored for 90 days.
Enzyme-linked immunosorbent assays.
Plasma levels of PEG-rHuMGDF and rhG-CSF after a single injection in
irradiated mice were measured by sandwich enzyme-linked immunosorbent
assays (ELISAs) previously established for endogenous human
TPO40 and endogenous human G-CSF,41
respectively. One hour after irradiation, mice received a single
intravenous injection of PEG-rHuMGDF (80 µg/kg) or rhG-CSF (1,000
µg/kg), and blood was then collected at different times within 72
hours after injection to prepare plasma samples. Cytokine standards
(PEG-rHuMGDF and rhG-CSF) and test samples were assayed by the
above-mentioned sandwich ELISAs, and all samples were analyzed in
duplicate. Cytokine concentrations in test plasma were calculated by
regression analysis from standard curves obtained with serially diluted
cytokine standards. The limit of detection for each cytokine in mouse
serum was 100 to 200 pg/mL.
Statistical analysis.
All data represent the mean ± SEM. The statistical significance of
differences in the number of platelets, RBCs, WBCs, and hematopoietic
progenitor cells between vehicle- and PEG-rHuMGDF-treated groups was
assessed by Dunnett's multiple comparison test. The statistical
significance of differences in megakaryocyte number between vehicle-
and PEG-rHuMGDF-treated groups was assessed by Student's
t-test.
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RESULTS |
A single injection of PEG-rHuMGDF significantly improves pancytopenia
in irradiated mice.
We examined the effects of a single intravenous injection of
PEG-rHuMGDF at doses of 1 to 640 µg/kg on the recovery of peripheral
blood cell counts in mice exposed to sublethal total-body irradiation.
The data shown in Fig 1 were obtained with PEG-rHuMGDF administration
1 hour after irradiation. In
vehicle-treated controls, the platelet nadir occurred on day 8 at
approximately 11% of normal levels, and platelet numbers then began to
increase but did not return to normal levels by day 18 (Fig 1A). A
single injection of PEG-rHuMGDF had a dose-dependent, marked effect on
thrombocytopenia in irradiated mice. The platelet nadir on day 8 was
significantly reduced by treatment with at least 8 µg/kg PEG-rHuMGDF
compared with the vehicle (P < .01; Fig 1A). Treatment with
PEG-rHuMGDF even at the lowest dose (1 µg/kg) resulted in faster
recovery of platelet counts after day 8 compared with the time-matched
vehicle treatment (P < .01). When higher doses of
PEG-rHuMGDF (80 or 640 µg/kg) were administered, platelet counts
returned to basal levels as early as day 10 (Fig 1A). Based on these
results, we chose 80 µg/kg as a single optimal dose.
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| Fig 1.
Effects of a single injection of PEG-rHuMGDF on
peripheral blood cell recovery in irradiated myelosuppressed mice. One
hour after irradiation at a dose of 3.5 Gy, mice were intravenously
given 1 ( ), 8 ( ), 80 ( ), or 640 ( ) µg/kg PEG-rHuMGDF, or
vehicle ( ). The data represent 1 of 2 separate experiments.
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Irradiation treatment produced moderate anemia with a nadir on days 12
through 15 (Fig 1B). A single injection of PEG-rHuMGDF caused a
dose-dependent recovery of RBCs in irradiated mice. Treatment with even
the lowest dose of PEG-rHuMGDF (1 µg/kg) resulted in a significant
reduction in the RBC nadir (P < .05; Fig 1B). A single
injection of PEG-rHuMGDF also accelerated reticulocyte recovery in a
dose-dependent fashion, indicating enhanced RBC production by
PEG-rHuMGDF treatment (data not shown).
Irradiated mice exhibited severe leukopenia, as well (Fig 1C). Although
PEG-rHuMGDF treatment had no effect on the WBC nadir, a single
injection of at least 80 µg/kg PEG-rHuMGDF modestly but significantly
accelerated WBC recovery compared with the time-matched vehicle
treatment (P < .01; Fig 1C).
To determine the effective administration schedules for PEG-rHuMGDF,
mice were given a single injection of an optimal dose of PEG-rHuMGDF
(80 µg/kg) at different times (within 60 hours) after irradiation
(Fig 2). The earlier PEG-rHuMGDF was administered,
the better the improvement of
thrombocytopenia was achieved (Fig 2A). Thus, PEG-rHuMGDF treatment 1
hour after irradiation was most effective in improving
thrombocytopenia. PEG-rHuMGDF treatment at an earlier time after
irradiation was required for a significant reduction in the platelet
nadir on day 8, compared with a significant platelet recovery after day
8. Platelet nadir counts were significantly reduced with PEG-rHuMGDF
treatment within the first 24 hours after irradiation
(P < .01; Fig 2A). On the other hand, mice receiving a
single dose of PEG-rHuMGDF 48 hours after irradiation had significantly
higher platelet counts on day 12 (P < .05) and day 15
(P < .01) compared with vehicle-treated, time-matched
control mice, although PEG-rHuMGDF treatment 60 hours after irradiation
no longer had a significant effect on platelet counts (Fig 2A). Similar
to the effects on platelet counts, PEG-rHuMGDF treatment 1 hour
after irradiation was most effective for recovery of both RBCs and WBCs
(Fig 2B and C).
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| Fig 2.
Effects of the interval between irradiation and a single
injection of PEG-rHuMGDF on peripheral blood cell recovery in
irradiated myelosuppressed mice. Mice were irradiated at a dose of 3.5
Gy and intravenously given 80 µg/kg PEG-rHuMGDF 1 ( ), 12 (), 24
(), 36 (), 48 (), or 60 ( ) hours after irradiation, or
vehicle () 1 hour after irradiation. The data represent 1 of 2
separate experiments.
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PEG-rHuMGDF treatment accelerates the recovery of hematopoietic
progenitors and megakaryocytes in the bone marrow.
We next examined the effects of a single injection of PEG-rHuMGDF on
the recovery of megakaryocytes and various hematopoietic progenitor
cells in the bone marrow of irradiated mice. Total-body irradiation had
a mild effect on megakaryocytes in the femur, as compared with its
influence on hematopoietic progenitor cells (Fig 3). In vehicle-treated
controls, megakaryocytes gradually decreased after irradiation and
reached approximately 60% of normal levels by day
5. A single injection of PEG-rHuMGDF 1 hour
after irradiation significantly increased the number of
megakaryocytes on day 5 (P < .01; Fig 3).
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| Fig 3.
Effects of a single injection of PEG-rHuMGDF on
megakaryocyte recovery after irradiation in mice. Mice were irradiated
at a dose of 3.5 Gy and intravenously given 80 µg/kg PEG-rHuMGDF
() or vehicle () 1 hour after irradiation. The number of
megakaryocytes in the femur of the mice before total-body irradiation
and at indicated times after irradiation was examined.
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In the femur of vehicle-treated mice, drastic decreases in the number
of CFU-MK, BFU-E, CFU-GM, and day 12 CFU-S were noted by 12 hours, much
earlier than the nadirs for peripheral blood cells, and continued on
day 3 (Fig 4). A single injection of PEG-rHuMGDF 80 µg/kg 1 hour
after irradiation resulted in significantly accelerated recovery of
CFU-MK, BFU-E, and CFU-GM by day 3, and of day 12 CFU-S by day 2 (Fig
4). However, an injection of PEG-rHuMGDF 24 and 48 hours after
irradiation had little or no effect on any of four hematopoietic
progenitors tested (Fig 4).
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| Fig 4.
Effects of a single injection of PEG-rHuMGDF on the
recovery of various hematopoietic progenitor cells after irradiation in
mice. Mice were intravenously given 80 µg/kg PEG-rHuMGDF 1 (), 24
(), or 48 () hours after irradiation, or vehicle () 1 hour
after irradiation. The number of CFU-MK, BFU-E, CFU-GM, and day 12
CFU-S in femoral bone marrow before irradiation and at indicated times
after irradiation was examined using the respective adequate progenitor
assays. The number of CFU-MK, BFU-E, CFU-GM, and day 12 CFU-S per femur
in untreated normal mice was 2,340 ± 314, 1,030 ± 474, 9,900 ±
1,772, and 2,436 ± 407, respectively. *P < .05, **P
< .01: significantly greater than vehicle-treated, time-matched
controls.
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We further examined whether PEG-rHuMGDF treatment enhances the recovery
of bone marrow hematopoietic progenitor cells with in vivo repopulating
ability. One hour after irradiation, donor mice were treated with a
single injection of PEG-rHuMGDF (80 µg/kg) or vehicle. Two days
later, their femoral bone marrow cells were prepared and inoculated
into lethally irradiated recipient mice. Transplantation of bone marrow
cells derived from PEG-rHuMGDF-treated donor mice resulted in a 70%
survival of recipient mice at 90 days. In contrast, all recipient mice
that received bone marrow cells derived from vehicle-treated donor mice
or no transplantation died by 14 or 17 days after transplantation,
respectively (Fig 5).
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| Fig 5.
Effects of a single injection of PEG-rHuMGDF on the
expansion of bone marrow cells capable of surviving in lethally
irradiated mice. One hour after irradiation at a dose of 3.5 Gy, mice
were intravenously given 80 µg/kg PEG-rHuMGDF () or vehicle ().
Two days later, the mice were killed and their bone marrow cells
(106 cells per mouse) were intravenously injected into
syngeneic recipient mice that had been lethally irradiated at a dose of
8.5 Gy. One group of lethally irradiated mice received no
transplantation of bone marrow cells ().
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Comparison of the effects of a single injection of PEG-rHuMGDF and
rhG-CSF in irradiated mice.
The above-mentioned results indicate multilineage effects of
PEG-rHuMGDF. It has already been shown that in addition to the effects
on committed granulocyte precursors, G-CSF acts on primitive
hematopoietic progenitors,42 and that G-CSF treatment
accelerates the recovery of not only WBCs (or neutrophils) but also
RBCs and platelets in myelosuppressed mice,33,43 indicating
multilineage effects of G-CSF. Therefore, we compared the effects of a
single injection of PEG-rHuMGDF 80 µg/kg and different doses of
rhG-CSF 1 hour after irradiation on the recovery of peripheral blood
cells in irradiated mice. A single injection of rhG-CSF at any dose up
to 1,000 µg/kg could not reduce the WBC nadir, but higher doses of
rhG-CSF significantly accelerated the WBC recovery as compared with the
time-matched, vehicle treatment (P < .01 at 250 µg/kg on
days 8 and 10 and P < .01 at 1,000 µg/kg on days 8
through 18; Fig 6C). However, even if rhG-CSF 1,000 µg/kg was used,
its effects on WBC recovery were modest, being only comparable to the
effects of PEG-rHuMGDF (Fig 6C). Moreover, a single injection of
rhG-CSF had only minimal effects on the recovery of both platelets and
RBCs in irradiated mice (Fig 6A and B).
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| Fig 6.
Comparison of the effects of a single injection of
rhG-CSF and PEG-rHuMGDF on the recovery of peripheral blood cells in
irradiated mice. One hour after irradiation at a dose of 3.5 Gy, mice
were intravenously given 80 µg/kg PEG-rHuMGDF () or 10 (), 50
(), 250 (), or 1,000 () µg/kg rhG-CSF, or vehicle ().
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One possibility was thought to be that the different effects of
PEG-rHuMGDF and rhG-CSF on pancytopenia are due to different
pharmacokinetics of these two cytokines in irradiated mice. Therefore,
we examined the time course of PEG-rHuMGDF and rhG-CSF concentrations
in the plasma of mice that received a single intravenous injection of
PEG-rHuMGDF 80 µg/kg or rhG-CSF 1,000 µg/kg 1 hour after
irradiation. PEG-rHuMGDF concentrations decreased more slowly compared
with rhG-CSF, and still remained at detectable levels (~540 pg/mL) 60
hours after injection (Fig 7). However, although a much higher dose of
rhG-CSF was administered to irradiated mice, rhG-CSF concentrations
decreased to approximately 510 pg/mL 24 hours after injection, and
afterward to undetectable levels (Fig 7). These data indicate a more
prolonged presence of injected PEG-rHuMGDF in the peripheral blood of
irradiated mice.
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| Fig 7.
Plasma concentration profiles of PEG-rHuMGDF and rhG-CSF
after a single injection in irradiated mice. One hour after
irradiation, mice received a single intravenous injection of 80 µg/kg
PEG-rHuMGDF () or 1,000 µg/kg rhG-CSF (). Plasma samples were
prepared from blood drawn from mice at the indicated times after
injection, and were assayed by sandwich ELISA for each cytokine. Each
point represents the mean value from 4 mice.
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DISCUSSION |
Previous studies have demonstrated that daily multiple injections of
human or murine TPO or PEG-rHuMGDF starting the day after
myelosuppressive treatment cause a dose-dependent improvement of
thrombocytopenia, anemia, and leukopenia (or neutropenia) in
myelosuppressed animals.25-31 Our previous study has shown
that a daily multiple-injection schedule of PEG-rHuMGDF is not
necessarily required for accelerated platelet recovery after
myelosuppressive chemotherapy in mice.31 In this study, we
therefore examined whether a single injection of PEG-rHuMGDF enhances
hematopoietic recovery after irradiation in mice. Treatment with a
single dose of PEG-rHuMGDF 1 hour after irradiation reduced the
severity of thrombocytopenia and accelerated platelet recovery in a
dose-dependent fashion, thereby shortening the duration of
thrombocytopenia, in irradiated mice. Such effects of a single
injection of PEG-rHuMGDF seem comparable to those of daily multiple
injections of PEG-rHuMGDF or TPO as previously
reported.25-31
A single dose of PEG-rHuMGDF at an early time after irradiation
significantly accelerated RBC and WBC recovery, as well. The effects of
a single injection of PEG-rHuMGDF on peripheral blood cells other than
platelets are similar to results from previous studies using multiple
injections of murine or human TPO or PEG-rHuMGDF in myelosuppressed
animals.26-33 As already reported for multiple
administrations of murine TPO30,32,33 or
PEG-rHuMGDF,27,31 a single injection of PEG-rHuMGDF
significantly enhanced erythroid and myeloid progenitor recovery.
Previous in vitro studies have shown that although TPO alone has no
influence on terminal differentiation in myelopoiesis and
erythropoiesis, it can synergize with other cytokines to enhance the
development of early progenitor cells other than CFU-MK. For example,
TPO enhances the proliferation of erythroid progenitors in the presence
of erythropoietin15,16,32 and proliferation of primitive
multipotent progenitors in synergy with early-acting cytokines such as
IL-3 or stem cell factor.17-20 Considering these in vitro
results, administered PEG-rHuMGDF may interact with other endogenous
cytokines to stimulate expansion of erythroid and myeloid progenitors,
resulting in the accelerated recovery of RBCs and WBCs we observed.
The interval between PEG-rHuMGDF and irradiation is critical to the
effects of PEG-rHuMGDF on pancytopenia in irradiated mice. By delaying
the start of PEG-rHuMGDF treatment after irradiation, its therapeutic
effects were lessened. A single injection 60 hours after irradiation
had no effects on either the platelet nadir or platelet recovery.
Although the explanation for the necessity of earlier administration of
PEG-rHuMGDF is unclear at present, it is possible that at an earlier
time after irradiation, more residual hematopoietic progenitors in the
bone marrow respond to PEG-rHuMGDF, leading to accelerated peripheral
blood cell recovery. Our results on the timing of a single injection of
PEG-rHuMGDF are consistent with a previous report showing that an
injection of adenovirus vector encoding TPO on the same day of
chemotherapy and irradiation effectively accelerates platelet recovery
in mice, but has little effect on thrombocytopenia when the vector
administration is delayed by 3 days.44 Similarly, it has
been reported that, like PEG-rHuMGDF treatment in this study,
administration of G-CSF,43,45 IL-6,46 or
IL-1147 to myelosuppressed mice immediately
after myelosuppressive treatment is most effective for improving
impaired hematopoiesis.
Hematologic analyses of mice engineered to lack either the TPO receptor
(c-Mpl)48,49 or TPO49 have revealed substantial
effects of TPO on the development of both primitive and various
committed hematopoietic progenitors. Indeed, results from in vitro
studies have shown that TPO stimulates proliferation of not only
CFU-MK3,7-13 but also primitive hematopoietic
progenitors17-20 and committed erythroid
progenitors.15,16 Similar to the in vitro effects, in vivo
administration of TPO or PEG-rHuMGDF expands the number of multipotent
progenitors and various committed progenitors, including CFU-MK, in the
bone marrow of normal mice23 and monkeys.21 The
multilineage effects of TPO or PEG-rHuMGDF have been shown in
myelosuppressed animals. Multiple injections of TPO or PEG-rHuMGDF
enhance the recovery of both multipotent27,31,33 and
committed27,30-33 progenitors. Our data show that a single
injection of PEG-rHuMGDF markedly enhances the recovery of CFU-MK,
BFU-E, CFU-GM, day 12 CFU-S, and primitive hematopoietic progenitors
with in vivo repopulating ability in the femur of irradiated mice.
Thus, a single injection of PEG-rHuMGDF is sufficient to accelerate
multilineage progenitor recovery. Recent studies have shown that TPO
prevents apoptosis of murine primitive hematopoietic
progenitors50 and a human megakaryocytic cell
line.51 Therefore, it is possible that a single
administration of PEG-rHuMGDF suppresses apoptosis of both primitive
multipotent and lineage-restricted progenitors in the bone marrow of
irradiated mice, leading to an expansion of a wide range of
hematopoietic progenitors. It is also possible that PEG-rHuMGDF
exogenously administered acts in concert with elevated levels of other
cytokines endogenously produced in response to myelosuppression to
enhance hematopoietic progenitor recovery. It remains unknown whether
the enhanced recovery of multipotent primitive progenitors contributes
to the enhanced recovery of peripheral blood cells.
In this study, the number of megakaryocytes in the femur was gradually
and modestly decreased after irradiation, clearly different from the
drastic decreases in hematopoietic progenitors examined. These data are
in agreement with a previous report showing that megakaryocytes are
relatively radioresistant.52 A single injection of
PEG-rHuMGDF into irradiated mice resulted in a significant enhancement
of megakaryocyte numbers on day 5 after irradiation as compared with
vehicle treatment. However, the size of megakaryocytes in
PEG-rHuMGDF-treated mice on day 5 was smaller than in vehicle-treated
controls (data not shown), suggesting generation of immature
megakaryocytes from CFU-MK by PEG-rHuMGDF administration.
It has been shown that G-CSF stimulates primitive hematopoietic
progenitors other than committed granulocyte progenitors in
vitro.42 Treatment with G-CSF has a significant effect on
the recovery of WBCs (or neutrophils), RBCs, and platelets after
myelosuppressive treatment in mice.33,43,46 In this study,
we therefore compared the therapeutic effects of a single injection of
PEG-rHuMGDF and rhG-CSF 1 hour after irradiation in mice. Our data show
that, unlike PEG-rHuMGDF treatment, a single injection of rhG-CSF to
irradiated mice exerts a dominant effect on WBC recovery but has
minimal effects on platelet and RBC recovery. It is conceivable that
these different effects of PEG-rHuMGDF and rhG-CSF on peripheral blood
cell recovery are due to different intrinsic properties. Further, our
data suggest that compared with rhG-CSF, more prolonged circulating
plasma levels of PEG-rHuMGDF after a single injection may be related to
more widespread, pronounced effects of PEG-rHuMGDF on peripheral blood
cell recovery. Previous studies have shown that PEG-rHuMGDF has much
more potent platelet-promoting activity in normal mice, as compared
with nonpegylated rHuMGDF.23,26 These findings together
with our data suggest that pegylation results in a longer half-life of
rHuMGDF in the circulation, thereby increasing its in vivo biologic
activity.
In conclusion, our study has shown that a single injection of
PEG-rHuMGDF in irradiated mice at an early time after irradiation
markedly accelerates the recovery of both primitive and committed
hematopoietic progenitors and effectively improves pancytopenia,
including thrombocytopenia. Our data suggest that a single injection of
PEG-rHuMGDF may be a clinically effective administration schedule.
| |
FOOTNOTES |
Submitted March 27, 1997;
accepted August 21, 1997.
Address reprint requests to Hiroshi Miyazaki, PhD, Pharmaceutical
Research Laboratory, Kirin Brewery Co, Ltd, 3 Miyahara-cho, Takasaki,
Gunma 370-12, Japan.
The publication costs of this article were defrayed in part by page
charge payment. This article must therefore be hereby marked
"advertisement" in accordance with 18 U.S.C. section 1734 solely
to indicate this fact.
| |
ACKNOWLEDGMENT |
We thank Miyuki Kato, Yuko Nitta, and Masumi Ida for excellent
technical assistance.
| |
REFERENCES |
1.
de Sauvage FJ,
Hass PE,
Spencer SD,
Malloy BE,
Gurney AL,
Spencer SA,
Darbonne WC,
Henzel WJ,
Wong SC,
Kuang W-J,
Oles KJ,
Hultgren B,
Solberg LAJ,
Goeddel DV,
Eaton DL:
Stimulation of megakaryocytopoiesis and thrombopoiesis by the c-MPL ligand.
Nature
369:533,
1994[Medline]
[Order article via Infotrieve]
2.
Lok S,
Kashansky K,
Holly RD,
Kuijper JL,
Lofton-Day CE,
Oort PJ,
Grant FJ,
Heipel MD,
Burkhead SK,
Kramer JM,
Bell LA,
Sprecher CA,
Blumberg H,
Johnson R,
Prunkard D,
Ching AFT,
Mathewes SL,
Bailey MC,
Forstrom JW,
Buddle MM,
Osborn SG,
Evans SJ,
Sheppard PO,
Presnell SR,
O'Hara PJ,
Hagen FS,
Roth GJ,
Foster DC:
Cloning and expression of murine thrombopoietin cDNA and stimulation of platelet production in vivo.
Nature
369:565,
1994[Medline]
[Order article via Infotrieve]
3.
Kaushansky K,
Lok S,
Holly RD,
Broudy VC,
Lin N,
Bailey MC,
Fortrom JW,
Buddle MM,
Oort PJ,
Hagen FS,
Roth GJ,
Papayannopoulou T,
Foster DC:
Promotion of megakaryocyte progenitor expansion and differentiation by the c-MPL ligand thrombopoietin.
Nature
369:568,
1994[Medline]
[Order article via Infotrieve]
4.
Bartley TD,
Bogenberger J,
Hunt P,
Li Y-S,
Lu HS,
Martin F,
Chang M-S,
Samal B,
Nichol JL,
Swift S,
Johnson MJ,
Hsu R-Y,
Parker VP,
Suggs S,
Skrine JD,
Mereweher LA,
Clogston C,
Hsu E,
Hokom MM,
Hornkohl A,
Choi E,
Pangelinan M,
Sun Y,
Mar V,
McNinch J,
Simonet L,
Jakobsen F,
Xie C,
Shutter J,
Chute H,
Basu R,
Selander L,
Trollinger D,
Sieu L,
Padilla D,
Trail G,
Xu W,
Castillo JD,
Biron J,
Cole S,
Hu MC-T,
Pancifici R,
Ponting I,
Saris C,
Wen D,
Yung YP,
Lin H,
Bosselman RA:
Identification and cloning of a megakaryocyte growth and development factor that is a ligand for the cytokine receptor MPL.
Cell
77:1117,
1994[Medline]
[Order article via Infotrieve]
5.
Kuter DL,
Beeler DL,
Rosenberg RD:
The purification of megapoietin: A physiological regulator of megakaryocyte growth and platelet production.
Proc Natl Acad Sci USA
91:11104,
1994[Abstract/Free Full Text]
6.
Kato T,
Ogami K,
Shimada Y,
Iwamatsu A,
Sohma Y,
Akahori H,
Horie K,
Kokubo A,
Kudo Y,
Maeda E,
Kobayashi K,
Ohashi H,
Ozawa T,
Inoue H,
Kawamura K,
Miyazaki H:
Purification and characterization of thrombopoietin.
J Biochem
118:229,
1995[Abstract/Free Full Text]
7.
Banu N,
Wang JF,
Deng BJ,
Groopman JE,
Avraham H:
Modulation of megakaryocytopoiesis by thrombopoietin: The c-Mpl ligand.
Blood
86:1331,
1995[Abstract/Free Full Text]
8.
Debili N,
Wendling F,
Katz A,
Guichard J,
Breton-Gorius J,
Hunt P,
Vainchenker W:
The Mpl-ligand or thrombopoietin or megakaryocyte growth and differentiative factor has both direct proliferative and differentiative activities on human megakaryocyte progenitors.
Blood
86:2516,
1995[Abstract/Free Full Text]
9.
Nichol JL,
Hokom MM,
Hornkohl A,
Sheridan WP,
Ohashi H,
Kato T,
Li YS,
Bartley TD,
Choi E,
Bogenberger J,
Skrine JD,
Knudten A,
Chen J,
Trail G,
Sleeman L,
Cole S,
Grampp G,
Hunt P:
Megakaryocyte growth and development factor Analyses of in vitro effects on human megakaryopoiesis and endogenous serum levels during chemotherapy-induced thrombocytopenia.
J Clin Invest
95:2973,
1995
10.
Kaushansky K,
Broudy VC,
Lin N,
Jorgensen MJ,
McCarty J,
Fox N,
Zucker-Franklin D,
Lofton-Day C:
Thrombopoietin, the Mpl ligand, is essential for full megakaryocyte development.
Proc Natl Acad Sci USA
92:3234,
1995[Abstract/Free Full Text]
11.
Broudy VC,
Lin NL,
Kaushansky K:
Thrombopoietin (c-mpl ligand) acts synergistically with erythropoietin, stem cell factor, and interleukin-11 to enhance murine megakaryocyte colony growth and increases megakaryocyte ploidy in vitro.
Blood
85:1719,
1995[Abstract/Free Full Text]
12.
Nishihira H,
Toyoda Y,
Miyazaki H,
Kigasawa H,
Ohsaki E:
Growth of macroscopic human megakaryocyte colonies from cord blood in culture with recombinant human thrombopoietin (c-mpl ligand) and the effects of gestational age on frequency of colonies.
Br J Haematol
92:23,
1996[Medline]
[Order article via Infotrieve]
13.
Kato T,
Horie K,
Hagiwara T,
Maeda E,
Tsumura H,
Ohashi H,
Miyazaki H:
GpIIb/IIIa+ subpopulation of rat megakaryocyte progenitor cells exhibits high responsiveness to human thrombopoietin.
Exp Hematol
24:1209,
1996[Medline]
[Order article via Infotrieve]
14.
Horie K,
Miyazaki H,
Hagiwara T,
Tahara E,
Matsumoto A,
Kadoya T,
Ogami K,
Kato T:
Action of thrombopoietin at the megakaryocyte progenitor level is critical for the subsequent proplatelet production.
Exp Hematol
25:169,
1997[Medline]
[Order article via Infotrieve]
15.
Kobayashi M,
Laver JH,
Kato T,
Miyazaki H,
Ogawa M:
Recombinant human thrombopoietin (Mpl ligand) enhances proliferation of erythroid progenitors.
Blood
86:2494,
1995[Abstract/Free Full Text]
16.
Papayannopoulou T,
Brice M,
Farrer D,
Kaushansky K:
Insights into the cellular mechanisms of erythropoietin-thrombopoietin synergy.
Exp Hematol
24:660,
1996[Medline]
[Order article via Infotrieve]
17.
Ku H,
Yonemura Y,
Kaushansky K,
Ogawa M:
Thrombopoietin, the ligand for the Mpl receptor, synergizes with Steel factor and other early acting cytokines in supporting proliferation of primitive hematopoietic progenitors of mice.
Blood
87:4544,
1996[Abstract/Free Full Text]
18.
Sitnicka E,
Lin N,
Priestley GV,
Fox N,
Broudy VC,
Wolf NS,
Kaushansky K:
The effect of thrombopoietin on the proliferation and differentiation of murine hematopoietic stem cells.
Blood
87:4998,
1996[Abstract/Free Full Text]
19.
Kobayashi M,
Laver JH,
Kato T,
Miyazaki H,
Ogawa M:
Thrombopoietin supports proliferation of human primitive hematopoietic cells in synergy with Steel factor and/or interleukin-3.
Blood
88:429,
1996[Abstract/Free Full Text]
20.
Itoh R,
Katayama N,
Kato T,
Mahmud N,
Masuya M,
Ohishi K,
Minami N,
Miyazaki H,
Shiku H:
Activity of the ligand for c-mpl, thrombopoietin, in early haemopoiesis.
Br J Haematol
94:228,
1996[Medline]
[Order article via Infotrieve]
21.
Farese A,
Hunt P,
Boone T,
MacVittie T:
Recombinant human megakaryocyte growth and development factor stimulates thrombocytopoiesis in normal nonhuman primates.
Blood
86:54,
1995[Abstract/Free Full Text]
22.
Ulich TR,
Delcastillo J,
Senaldi G,
Kinstler O,
Yin SM,
Kaufman S,
Tarpley J,
Choi E,
Kirley T,
Hunt P,
Sheridan WP:
Systemic hematologic effects of PEG-rHuMGDF-induced megakaryocyte hyperplasia in mice.
Blood
87:5006,
1996[Abstract/Free Full Text]
23.
Kabaya K,
Akahori H,
Shibuya K,
Nitta Y,
Ida M,
Kusaka M,
Kato T,
Miyazaki H:
In vivo effects of pegylated recombinant human megakaryocyte growth and development factor on hematopoiesis in normal mice.
Stem Cells
14:651,
1996[Medline]
[Order article via Infotrieve]
24.
Arnold JT,
Daw NC,
Stenberg PE,
Jayawardene D,
Srivastava DK,
Jackson CW:
A single injection of pegylated murine megakaryocyte growth and development factor (MGDF) into mice is sufficient to produce a profound stimulation of megakaryocyte frequency, size, and ploidization.
Blood
89:823,
1997[Abstract/Free Full Text]
25.
Ulich TR,
del Castillo J,
Yin S,
Swift S,
Padilla D,
Senaldi G,
Bennett L,
Shutter J,
Bogenberger J,
Sun D,
Samal B,
Shimamoto G,
Lee R,
Steinbrink R,
Boone T,
Sheridan WT,
Hunt P:
Megakaryocyte growth and development factor ameliorates carboplatin-induced thrombocytopenia in mice.
Blood
86:971,
1995[Abstract/Free Full Text]
26.
Hokom MM,
Lacey D,
Kinstler OB,
Choi E,
Kaufman S,
Faust J,
Rowan C,
Dwyer E,
Nichol JL,
Grasel JW,
Steinbrink R,
Heccht R,
Winters D,
Boone T,
Hunt P:
Pegylated megakaryocyte growth and development factor abrogates the lethal thrombocytopenia associated with carboplatin and irradiation in mice.
Blood
86:4486,
1995[Abstract/Free Full Text]
27.
Farese A,
Hunt P,
Boone T,
MacVittie T:
Combined administration of recombinant human megakaryocyte growth and development factor and granulocyte colony-stimulating factor enhances multilineage hematopoietic reconstitution in nonhuman primates after radiation-induced marrow aplasia.
J Clin Invest
97:2145,
1996[Medline]
[Order article via Infotrieve]
28.
Akahori H,
Shibuya K,
Obuchi M,
Nishizawa Y,
Tsuji A,
Kabaya K,
Kusaka M,
Ohashi H,
Tsumura H,
Kato T,
Miyazaki H:
Effect of recombinant human thrombopoietin in nonhuman primates with chemotherapy-induced thrombocytopenia.
Br J Haematol
94:722,
1996[Medline]
[Order article via Infotrieve]
29.
Grossmann A,
Lenox J,
Ren HP,
Humes JM,
Forstrom JW,
Kaushansky K,
Sprugel KH:
Thrombopoietin accelerates platelet, red blood cell, and neutrophil recovery in myelosuppressed mice.
Exp Hematol
24:1238,
1996[Medline]
[Order article via Infotrieve]
30.
Kaushansky K,
Lin N,
Grossmann A,
Humes J,
Sprugel KH,
Broudy VC:
Thrombopoietin expands erythroid, granulocyte-macrophage, and megakaryocytic progenitor cells in normal and myelosuppressed mice.
Exp Hematol
24:265,
1996[Medline]
[Order article via Infotrieve]
31.
Akahori H,
Shibuya K,
Ozai M,
Ida M,
Kabaya K,
Kato T,
Miyazaki H:
Effect of pegylated recombinant human megakaryocyte growth and development factor on thrombocytopenia induced by a new myelosuppressive chemotherapy regimen in mice.
Stem Cells
14:678,
1996[Medline]
[Order article via Infotrieve]
32.
Kaushansky K,
Broudy VC,
Grossmann A,
Humes J,
Lin N,
Ren HP,
Bailey MC,
Papayannopoulou T,
Forstrom JW,
Sprugel KH:
Thrombopoietin expands erythroid progenitors, increases red cell production, and enhances erythroid recovery after myelosuppressive therapy.
J Clin Invest
96:1683,
1995
33.
Grossmann A,
Lenox J,
Deisher TA,
Ren HP,
Humes JM,
Kaushansky K,
Sprugel KH:
Synergistic effect of thrombopoietin and granulocyte colony-stimulating factor on neutrophil recovery in myelosuppressed mice.
Blood
88:3363,
1996[Abstract/Free Full Text]
34.
Molineux G,
Hartley CA,
McElroy P,
McCrea C,
McNiece IK:
Megakaryocyte growth and development factor stimulates enhanced platelet recovery in mice after bone marrow transplantation.
Blood
88:1509,
1996[Abstract/Free Full Text]
35.
Kabaya K,
Shibuya K,
Torii Y,
Nitta Y,
Ida M,
Akahori H,
Kato T,
Kusaka M,
Miyazaki H:
Improvement of thrombocytopenia following bone marrow transplantation by pegylated recombinant human megakaryocyte growth and development factor in mice.
Bone Marrow Transplant
18:1035,
1996[Medline]
[Order article via Infotrieve]
36.
Fibbe WE,
Heemskerk DPM,
Laterveer L,
Pruijt JFM,
Foster D,
Kaushansky K,
Willemze R:
Accelerated reconstituion of platelets and erythrocytes after syngeneic transplantation of bone marrow cells derived from thrombopoietin pretreated donor mice.
Blood
86:3308,
1995[Abstract/Free Full Text]
37.
Miyazaki H,
Inoue H,
Yanagida M,
Horie K,
Mikayama T,
Ohashi H,
Nishikawa M,
Suzuki T,
Sudo T:
Purification of rat megakaryocyte colony-forming cells using a monoclonal antibody against rat platelet glycoprotein IIb/IIIa.
Exp Hematol
20:855,
1992[Medline]
[Order article via Infotrieve]
38.
Jackson CW:
Cholinesterase as a possible marker for early cells of the megakaryocytic series.
Blood
42:413,
1973[Abstract/Free Full Text]
39.
Till J,
McCulloch E:
A direct measurement of the radiation sensitivity of normal mouse bone marrow cells.
Radiat Res
14:213,
1961[Medline]
[Order article via Infotrieve]
40.
Tahara T,
Usuki K,
Sato H,
Ohashi H,
Morita H,
Tsumura H,
Matsumoto A,
Miyazaki H,
Urabe A,
Kato T:
A sensitive sandwich ELISA for measuring thrombopoietin in human serum: Serum thrombopoietin levels in healthy volunteers and in patients with haematopoietic disorders.
Br J Haematol
93:783,
1996[Medline]
[Order article via Infotrieve]
41.
Ichikawa T,
Kuwaki T,
Tachibana K,
Yanagida M,
Matsuki S:
A highly sensitive enzyme immunoassay for G-CSF in human plasma.
Exp Hematol
23:192,
1995[Medline]
[Order article via Infotrieve]
42.
Ikebuchi K,
Ihle JN,
Hirai Y,
Wong GG,
Clark SC,
Ogawa M:
Synergistic factors for stem cell proliferation: Further studies of the target stem cells and the mechanism of stimulation by interleukin-1, interleukin-6, and granulocyte colony-stimulating factor.
Blood
72:2077,
1988
43.
Tanikawa S,
Nose M,
Yoshiko A,
Tsuneoka K,
Shikita M,
Nobuo N:
Effect of recombinant human granulocyte colony-stimulating factor on the hematopoietic recovery and survival of irradiated mice.
Blood
76:445,
1990[Abstract/Free Full Text]
44.
Ohwada A,
Rafii S,
Moore MAS,
Crystal RG:
In vivo adenovirus vector-mediated transfer of the human thrombopoietin cDNA maintains platelet levels during radiation- and chemotherapy-induced bone marrow suppression.
Blood
88:778,
1996[Abstract/Free Full Text]
45.
Sureda A,
Valls A,
Kader E,
Algara M,
Ingles-Esteve J,
Bigas A,
Jaume M,
Lacrus M,
Tobajas L,
Rutllant M,
Garcia J:
A single dose of granulocyte colony-stimulating factor modifies radiation-induced death in B6D2F1 mice.
Exp Hematol
21:1605,
1993[Medline]
[Order article via Infotrieve]
46.
Patchen ML,
MacVittie TJ,
Williams JL,
Schwartz GN,
Souza LM:
Administration of interleukin-6 stimulates multilineage hematopoiesis and accelerates recovery from radiation-induced hematopoietic depression.
Blood
77:472,
1991[Abstract/Free Full Text]
47.
Leonord JP,
Quinto CM,
Kozitza MK,
Neben TY,
Goldman SJ:
Recombinant human interleukin-11 stimulates multilineage hematopoietic recovery in mice after a myelosuppressive regimen of sublethal irradiation and carboplatin.
Blood
83:1499,
1994[Abstract/Free Full Text]
48.
Alexander WS,
Roberts AW,
Nicola NA,
Li R,
Metcalf D:
Deficiencies in progenitor cells of multiple hematopoietic lineages and defective megakaryocytopoiesis in mice lacking the thrombopoietin receptor c-Mpl.
Blood
87:2162,
1996[Abstract/Free Full Text]
49.
Carver-Moore K,
Broxmeyer HE,
Luoh S-M,
Cooper S,
Peng J,
Burstein SA,
Moore MW,
de Sauvage FJ:
Low levels of erythroid and myeloid progenitors in thrombopoietin- and c-mpl-deficient mice.
Blood
88:803,
1996[Abstract/Free Full Text]
50.
Borge OJ,
Ramsfjell V,
Veiby OP,
Murphy MJ Jr,
Lok S,
Jacobsen SEW:
Thrombopoietin, but not erythropoietin, promotes viability and inhibits apoptosis of multipotent murine hematopoietic progenitor cells in vitro.
Blood
88:2859,
1996[Abstract/Free Full Text]
51.
Ritchie A,
Vadhan-Raj S,
Broxmeyer HE:
Thrombopoietin suppresses apoptosis and behaves as a survival factor for the human growth factor-dependent cell line, M07e.
Stem Cells
14:330,
1996[Medline]
[Order article via Infotrieve]
52.
Taum G:
The megakaryocyte DNA content and platelet formation after the sublethal whole body irradiation of rats.
Blood
63:917,
1984[Abstract/Free Full Text]
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Abstract
Introduction
Abstract