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Blood, Vol. 93 No. 1 (January 1), 1999:
pp. 149-156
Selective Transendothelial Migration of Hematopoietic Progenitor
Cells: A Role in Homing of Progenitor Cells
By
Kiyotoshi Imai,
Masanobu Kobayashi,
Jingxin Wang,
Yoichi Ohiro,
Jun-ichi Hamada,
Yuko Cho,
Masahiro Imamura,
Manabu Musashi,
Takeshi Kondo,
Masuo Hosokawa, and
Masahiro Asaka
From the Laboratory of Pathology, Laboratory of Cell Biology, Cancer
Institute, the Department of Pediatrics, the Department of Gerontology
and Oncology, The Third Department of Internal Medicine, Hokkaido
University School of Medicine, Sapporo, Japan.
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ABSTRACT |
To elucidate the mechanisms by which hematopoietic progenitor cells
transmigrate via the bone marrow (BM) endothelial cells, we first
established endothelial cell lines from BM and lung, and BM fibroblast
cell lines; then we established an in vitro model of transendothelial
migration of hematopoietic progenitor cells in the presence of
chemoattractants secreted by BM fibroblast cells. The BM endothelial
cells expressed vascular cell adhesion molecule-1 (VCAM-1), but the
lung endothelial cells did not. The BM fibroblast cells secreted
chemoattractants including stroma cell-derived factor
(SDF)-1, which could attract hematopoietic progenitor
cells to BM and activate the adhesion molecules expressed on
hematopoietic progenitor cells after rolling along the endothelial cells. Anti-SDF-1 antibody inhibited the transendothelial migration of
a hematopoietic progenitor cell line, FDCP-2. FDCP-2 that expressed very late activation antigen-4 (VLA-4) and normal progenitor cells transmigrated through BM endothelial cells but not lung endothelial cells, even if in the presence of chemoattractants produced by BM
fibroblasts. Both anti-VLA-4 and anti-VCAM-1 antibodies inhibited the
transendothelial migration of FDCP-2 cells and normal hematopoietic progenitor cells. These findings suggest that the transendothelial migration of hematopoietic progenitor cells is characteristic of BM
endothelial cells, and that VLA-4/VCAM-1 and SDF-1 play important roles
in the transendothelial migration and, consequently, homing of
hematopoietic progenitor cells to BM.
© 1999 by The American Society of Hematology.
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INTRODUCTION |
MECHANISMS OF migration of leukocytes
from peripheral blood (PB) to extra-vascular tissues have been
extensively examined, and the transendothelial migration cascade system
is now being proposed as a mechanism for leukocytes'
migration.1-7 This migration cascade system consists of
rolling along the vessel wall, activation of adhesion molecules by
cytokines and chemokines, firm adhesion to endothelial cells via the
activation of adhesion molecules, and transendothelial migration.
Transendothelial migration of hematopoietic progenitor cells occurs
during mobilization of hematopoietic progenitor cells into PB, which is
induced by cytokine-administration and/or chemotherapy, and it
occurs when intravenously transplanted hematopoietic progenitor cells
home to bone marrow (BM). It is believed that transendothelial
migration of hematopoietic progenitor cells occurs through a similar
cascade to that of leukocytes. It has recently been
reported that the interaction of leukocyte function-associated antigen
(LFA)-1 and intercellular adhesion molecule (ICAM)-1
played important roles in the transendothelial migration of
CD34+ hematopoietic cells.8 In their study, the
transendothelial migration was examined in the absence of any
chemoattractant or chemokine in the lower chambers of transwell plates;
in other words, the transendothelial migration of progenitor cells in
their experimental model was not BM-oriented but rather random.
Furthermore, it was not determined whether transendothelial migration
of hematopoietic progenitor cells was characteristic of BM endothelial
cells. Therefore, mechanisms of transendothelial migration of
hematopoietic progenitor cells into BM are still poorly understood. In
this study, we established endothelial cell lines from BM and lung, and
BM fibroblast cell lines. Then, we established an in vitro
transendothelial chemotactic migration model in the presence of
chemoattractants produced by BM fibroblasts. Using this model, we
examined whether hematopoietic progenitor cells selectively
transmigrate through the BM endothelial cells compared with the lung
endothelial cells, and then determined the roles of adhesion molecules
and chemoattractants responsible for the transendothelial migration of
hematopoietic progenitor cells.
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MATERIALS AND METHODS |
Reagents.
Anti-Thy 1.2, anti-mouse CD45R/B220 (Ly-5), anti-mouse granulocytes,
and anti-mouse E-selectin antibodies were purchased from Pharmingen
(San Diego, CA). Anti-mouse L-selectin antibody was purchased from
Serotec Ltd (Oxford, UK). Anti-macrophage/CD11b antibody was purchased
from Boehringer Mannheim Biochemica (Tokyo, Japan). Anti-mouse vascular
cell adhesion molecule-1 (VCAM-1), anti-mouse very late activation
antigen-4 (VLA-4) antibodies were purchased from Southern Biotechnology
Associates, Inc (Birmingham, AL). Anti-mouse CD11a (LFA-1) and
anti-mouse CD54 (ICAM-1) antibodies were purchased from Genzyme
(Cambridge, MA). Anti-factor VIII antibody was purchased from
Cosmo-Bio (Tokyo, Japan). Goat 1 F(ab )2 anti-rat
IgG-fluorescein was purchased from Leinco Technologies, Inc (Ballwin,
MO). Anti-stroma cell-derived factor (SDF)-1 antibody was purchased from Santa Cruz Biotechnology, Inc (Santa Cruz, CA).
Dynabeads M-450 coated with sheep anti-rat IgG antibody was purchased
from Dynal Inc (Great Neck, NY). Acetylated low-density lipoprotein
labeled with 1,1-dioctadecyl-3,3,3,3-tetramethylindo-carbocyanine perchlorate (DiI-acetylated-LDL) was purchased from Paesel GmbH (Hanau,
Germany).
Cell lines.
A murine interleukin-3 (IL-3)-dependent hematopoietic progenitor cell
line, FDCP-2, was maintained in RPMI 1640 medium supplemented with 10%
fetal calf serum (FCS) and 20% WEHI-3B (an IL-3-producing murine
myelomonocytic cell line) cell-conditioned medium.
Establishment of BM endothelial cell lines, fibroblast cell lines,
and a lung endothelial cell line.
Six- to 12-week-old female BDF1 mice were purchased from Japan Charles
River (Kanagawa, Japan). Single-cell suspensions of the BM were
obtained from femurs by flushing the marrow with ice-cold RPMI 1640 medium and 10% FCS using a 21-gauge needle. Primary stromal layers
were established according to the method described previously.9 Briefly, the cells were plated at a density of 2 × 106 cells/mL in 25-cm2 flasks in RPMI
1640 medium supplemented with 10% FCS in a humidified incubator at 5%
CO2 at 37°C. The cultures were fed every 3 to 4 days by
changing half the medium. After 3 to 5 weeks of culture, confluent
stromal layers were formed. The stromal cells were obtained by
trypsinization, and 2 × 106 cells were seeded in 5 mL of
RPMI 1640 medium supplemented with 10% FCS in 6-well culture plates.
The cells were incubated at 37°C in a CO2 incubator for 2 days until the cells were 40% to 60% confluent. Transfections were
performed using a LIPOFECTIN reagent (GIBCO-BRL Life Technologies,
Tokyo, Japan) as previously described.10 SV40 vector
(pMK16) constructed by Gluzman et al11 and pGEM-SR NEO
were mixed with the LIPOFECTIN reagent. The LIPOFECTIN reagent-DNA
complexes were overlaid onto the sub-confluent stromal layers in
serum-free RPMI-1640 medium. The cells were incubated for 24 hours at
37°C in a CO2 incubator and the medium was exchanged with
fresh RPMI-1640 medium supplemented with 10% FCS and 800 µg/mL of
G418. Four days after transfection, the cells were collected by
EDTA/trypsin-treatment and then washed with RPMI-1640 medium supplemented with 10% FCS. Transformed BM adherent cells were maintained in RPMI-1640 medium with 10% FCS and G418. A single cell
was suspended in 100 µL of fresh medium and cultured in 96-well plates. The medium was changed every 3 to 4 days. When the colonies developed in wells, they were removed by EDTA/trypsin-treatment and
placed in 5 mL RPMI-1640 medium supplemented with 10% FCS in
25-cm2 plastic flasks. When the cells were confluent,
aliquots of the cells were passed through three to four dilutions every
week. The cells maintained for more than 20 passages were selected as immortalized cells and examined for expression of SV40 large T antigen.
Established cell lines were designated as STR-1, STR-2, STR-3, and
following ascending numbers up to STR-12. A lung endothelial cell line
expressing SV40 large T antigen was also established from a lung
endothelial cell line, LE1, by transfection with SV40 vector (pMK16) and designated as LE1SVO.12,13 LE1
cells have been reported to be factor VIII+ and able to
uptake diI-acetylated LDL.12 LE1SVO cells, BM endothelial cell lines, and BM fibroblast cell lines were maintained in RPMI 1640 medium supplemented with 10% FCS.
Characteristics of BM endothelial and fibroblast cell lines.
BM endothelial and fibroblast cell lines were cytochemically analyzed
for peroxidase, alkaline phosphatase, and a-naphthyl acetate esterase
as described previously.14 Briefly, the established cell
lines were cultured in chambered slides, washed with phosphate-buffered saline (PBS), and fixed with ethanol for 10 minutes and stained. Expression of SV40 large T antigen was examined with anti-T antigen antibody using a VECSTATIN ABC kit according to the manufacturer's recommendation (Funakoshi, Tokyo, Japan). Expression of factor VIII was
examined with anti-factor VIII antibody by the use of a confocal laser
microscopy. Uptake of LDL was examined according to the previously
described methods.15 Briefly, the cells were incubated with
diI-acetylated LDL (10 mg/mL) at 37°C in the culture medium for 4 hours. The medium was removed, and after thorough washing the cells
were fixed with 3% formaldehyde in PBS and evaluated for LDL uptake
under a confocal laser microscopy. Expression of adhesion molecules and
differentiation antigens was evaluated by fluorescence-activated cell
sorter (FACS) analysis. Three (STR-4, STR-10, and STR-12) of the cell
lines that were Mac-1 , factor VIII+, and
able to uptake LDL were selected as BM endothelial cell lines, and
another one (STR-2) that was Mac-1, factor
VIII, and not able to uptake LDL was selected as a BM
fibroblast cell line.
FACS analysis.
A total of 1 × 105 cells was incubated for 30 minutes on
ice with first antibodies and then incubated with second antibodies for
45 minutes on ice. The cells were analyzed by the use of a FACScan
(Becton Dickinson, San Jose, CA).
Preparation of conditioned medium.
STR-2 cells were grown to confluence in a tissue culture flask. After
being washed twice with PBS, the cells were incubated for 48 hours in
serum-free RPMI medium, and then conditioned medium was collected,
filtrated through a 0.25-µm Milipore filter (Gelman Science, Ann Arbor, MI), stored at 4°C and used for the following experiments.
Semi-purification of normal progenitor cells.
Ten- to 15-week-old male BDF1 mice were obtained from Charles River
Japan. Single-cell suspensions were prepared from pooled femurs of
mice, which had been injected with 150 mg/kg of 5-fluorouracil (5-FU;
Kyowa Hakko Kogyo Co, Tokyo, Japan) intravenously (IV) 2 days before
examination (day 2 post-5-FU marrow cells) to enrich the noncycling
hematopoietic primitive progenitor cells. Lineage-negative (Lin) day 2 post 5-FU marrow cells were isolated as
described previously.16 Briefly, mononuclear cells were
separated by density centrifugation on Ficoll-Paque (specific gravity,
1.077) from the day 2 post 5-FU marrow cells. They were then incubated
at 4°C for 45 minutes in a mixture of anti-Thy 1.2, anti-B220,
anti-Gr-1, and anti-Mac-1/CD11b antibodies. After washing twice, the
cells were incubated with sheep anti-rat IgG (Fc)-conjugated
immunomagnetic beads at 4°C for 45 minutes. Lineage-specific
antigen-positive cells were removed by a magnetic particle concentrator
(Dynal), and Lin cells were recovered.
Adhesion assay.
FDCP-2 cells were incubated with 5 µmol/L acetoxymethyl
ester-2,7-bis-(2-carboxyethyl)-5-(and 6)-carboxyfluorescein
(BCECF-AM) (Wako, Tokyo, Japan) for 1 hour. After washing three times
with RPMI-1640 medium, BCECF-AM-labeled cells were placed on STR-4 cells and allowed to adhere for 2 hours. Nonadherent cells were removed
by three washes with RPMI-1640 medium. After lysing with 1% Triton X-100 (Junsei Chemical Co, Ltd, Tokyo,
Japan)-PBS, the plates were read on an ELISA reader
(BioRad, Richmond, CA) at a wave length of 520 nm. Percentages of
adherent cells were calculated by the following formula: % Adherent
Cells = (Optical Density [OD] Values of Adherent
Cells/OD Values of Total Cells) × 100.
Chemotactic migration assay.
To examine the chemotactic activities and random motility-stimulating
activities in the conditioned medium of BM fibroblasts, the micropore
filter assay was performed according to the previously described
methods.17 In transwell plates, tissue-culture-treated micropore filters with 5-µm pores were placed to separate the upper
and lower chambers. Six hundred microliters of STR-2 cell-conditioned medium was placed in the lower chambers (Transwell;
Costar, Cambridge, MA). Suspensions (100 µL) of FDCP-2
cells at an appropriate concentration were placed in the upper
chambers. After 4 hours of incubation, transmigrated cells into the
lower chambers were counted under an inverted microscope at least in
three areas. To evaluate the chemotactic activity for
progenitor cells of SDF-1 in STR-2 cell-conditioned medium, anti-SDF-1
antibody was added in the upper chambers at up to 2 µg/mL.
Transendothelial migration assays.
For the transendothelial migration assay, 2 × 105 STR-4,
STR-10, STR-12, and LE1SVO cells were seeded on micropore filters. After 4 days, the confluent monolayers were formed and were suitable for transendothelial migration assay. To assess the integrity of lung
and BM endothelial cell monolayers grown on micropore filters, FDCP-2
cells (1 × 104) and semi-purified murine BM progenitor
cells (5 × 104) were seeded in the upper chambers and
incubated for 4 hours in the absence of STR-2 cell-conditioned medium
in the lower chambers. Without any conditioned medium, the cells seeded
on endothelial cell monolayers did not transmigrate into the lower
chambers within 4 hours. We also examined the integrity of endothelial
cell monolayers by diffusion assay using BCECF-AM. Diffusion of
BCECF-AM through both STR-4 and LE1SVO cell monolayers was always less
than 8% within 4 hours. FDCP-2 cells transmigrated into the lower
chambers were counted under an inverted microscope at more than three
areas. Normal BM progenitor cells transmigrated into the lower chambers were counted by colony assays using the total cells transmigrated into
the lower chambers.
For blocking the migration, FDCP-2 cells or normal BM
Lin cells were simultaneously seeded on endothelial cell
monolayers with various anti-adhesion molecule antibodies. To evaluate
the role of SDF-1 in this transendothelial migration assays,
anti-SDF-1 antibody was added in the upper chambers at up to 8 µg/mL.
Colony assay.
Colony assay was performed according to the previously described
methods.18 Briefly, 1 × 104 cells or the
whole transmigrated cells were plated in a mixture of Iscove's
modified Dulbecco's medium (IMDM), 20% FCS, 0.3% agar, and colony-stimulating factors (CSFs) including 10 ng/mL of
granulocyte-CSF (G-CSF), 10 ng/mL of IL-1  , 10 ng/mL of IL-3, 10 ng/mL of IL-6, and 10 ng/mL of stem cell factor (SCF). Eleven to 14 days after incubation in a highly humidified CO2 incubator
at 37°C, numbers of colonies (containing more than 40 cells) were
counted.
Reverse transcriptase-polymerase chain reaction (RT-PCR).
Total RNA was extracted from STR-2, STR-4, STR-10, STR-12 cells, and
LE1SVO cells using TRIzol (GIBCO-BRL, Gaithersburg, MD) and then
treated with 0.1 U/mL of DNAse I Amp Grade (GIBCO-BRL) for 15 minutes
at room temperature to exclude contaminated genomic DNA. Each RNA
sample (5 µg) was subjected to cDNA synthesis in 50 µL of reaction
mixture containing 75 mmol/L KCl, 50 mmol/L Tris-HCl (pH 8.3), 3 mmol/L
MgCl2, 10 mmol/L dithiothreitol, 0.5 mmol/L each dNTP, 2 µmol/L random primer, and 1,000 U AMLV reverse transcriptase
(GIBCO-BRL). PCR amplification of cDNA was performed in 50 µL of
reaction mixture containing 50 mmol/L KCl, 10 mmol/L Tris-HCl (pH 9.0),
2.5 mmol/L MgCl2, 0.1% Triton X-100, 200 µmol/L each
dNTP, 10 µmol/L each specific primers, and 1 U Taq polymerase (GIBCO-BRL). PCR was performed in a DNA thermal cycler
(Barnstead/Thermolyne, Dubuque, IA) at 25, 30, and 35 cycles (94°C
for 1 minute, 60°C for 1 minute, and 72°C for 2 minutes). The PCR
product (9 µL) was subjected to electrophoresis on 1% agarose gels
and stained with ethidium bromide. Primer sequences were as follows:
SDF-1: forward primer: 5-gctctgcatcagtgacggtaaac-3, reverse primer: 5-caatatcgtaccatatgctatggcc-3; -actin: forward primer:
5-agggaaatcgtgcgtgacatcaaa-3, reverse primer:
5-actcatcgtactcctgcttgctga-3.
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RESULTS |
Characteristics of established cell lines.
When cultured on tissue culture dishes in RPMI-1640 medium supplemented
with 10% FCS, STR-4, STR-10, STR-12, and LE1SVO cells were initially
spindle-shaped and then developed cobblestone monolayers (Fig
1). Cytochemical staining showed that
STR-2, STR-4, STR-10, and STR-12 cells were alkaline
phosphatase+, -naphtyl butyrate+,
peroxidase, and periodic acid-Schiff
(PAS) (Table 1). Staining
with anti-factor VIII antibody showed that STR-4, STR-10, STR-12, and
LE1SVO cells were mostly positive (Fig 2).
Furthermore, STR-4, STR-10, STR-12, and LE1SVO cells demonstrated uptake of diI-acetylated-LDL after 4 hours of incubation (Fig 2). STR-2
cells were factor VIII and did not uptake
diI-1-acetylated-LDL (Fig 2).
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| Fig 1.
Morphology of STR-2, STR-4, STR-10, STR-12, and LE1SVO
cells. (A) LE1SVO; (B) STR-2; (C) STR-4; (D) STR-10; (E) STR-12
(original magnification × 400 under an inverted
microscope).
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| Fig 2.
Uptake of DiI-Ac-LDL and staining by anti-factor VIII
antibody. (A and F) LE1SVO; (B and G) STR-2; (C and H) STR-4; (D and I)
STR-10; (E and J) STR-12. (A through E) The cells were incubated with
anti-factor VIII antibody and fluorescein-conjugated second antibody,
and then examined under a confocal laser microscope (original
magnification × 100). (F through J) The cells were incubated with
DiI-acetylated LDL (10 mg/mL) at 37°C for 4 hours. After thorough
washing, the cells were fixed and then evaluated for LDL uptake under a
confocal laser microscope (original
magnification × 100).
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Expression of adhesion molecules was examined before and after
stimulating with 100 ng/mL of IL-1 by FACS analysis (Fig
3). Unstimulated STR-4, STR-10, and STR-12
cells expressed only VCAM-1 but not E-selectin, ICAM-1, or L-selectin.
IL-1 induced the very weak expression of E-selectin and L-selectin
on STR-4, STR-10, and STR-12 cells but no ICAM-1. Unstimulated LE1SVO
cells expressed no VCAM-1, ICAM-1, L-selectin, or E-selectin.
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| Fig 3.
Expression of adhesion molecules on LE1SVO and STR cell
lines. (Dotted line), second antibody alone, (fine solid line),
unstimulated, (solid line), stimulated with IL-1.
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Chemotactic activity in STR-2 cell-conditioned medium.
Chemotactic activity for FDCP-2 cells in STR-2 cell-conditioned medium
was examined by checkerboard analysis. The results summarized in Table
2 show that FDCP-2 cells migrated into the lower chamber when attracted by STR-2 cell-conditioned medium in a
dose-dependent manner. Furthermore, even if concentrations of the
conditioned medium in the upper chambers were intensified higher than
those in the lower chambers, the numbers of migrated FDCP-2 cells
increased. These results suggest that STR-2 cells secreted chemotactic
factor(s) and also random motility-stimulating factor(s). Chemotactic
activity of STR-2 cell-conditioned medium for FDCP-2 cells was
abrogated by anti-SDF-1 antibody in a dose-dependent manner (Fig
4). STR-2 cells as well as BM endothelial
cells expressed SDF-1 mRNA (Fig 5). LE1SVO
cells did not express SDF-1 mRNA. These findings suggest that
chemotactic activity found in STR-2 cell-conditioned medium was mostly
attributable to SDF-1.
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| Fig 4.
Effects of anti-SDF-1 antibody on chemotactic activity.
FDCP-2 cells were placed in the upper chambers of Transwell plates with
or without anti-SDF-1 antibody at the indicated concentrations. Six
hundred microliters of STR-2 cell-conditioned medium was placed in the
lower chambers. After 4 hours of incubation, transmigrated cells into
the lower chambers were counted under an inverted microscope. Results
were shown as the mean ± SD of data obtained from three different
experiments.
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Transendothelial migration of FDCP-2.
To elucidate the mechanisms by which hematopoietic progenitor cells in
PB lodge in BM, we established an in vitro transendothelial migration
model, where the conditioned medium of BM fibroblasts was placed in the
lower chambers of transwell plates, and micropore filters coated with
endothelial cell monolayers were placed in the interspace of the lower
and upper chambers. The results are shown in Fig 6A through
D. In this assay, FDCP-2 cells were
attracted to the lower chambers by STR-2 cell-conditioned medium. We
found that FDCP-2 cells transmigrated through BM endothelial cells
(STR-4, STR-10, and STR-12 cells) but not STR-2 cells or LE1SVO cells (Fig 6A).
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| Fig 6.
Transendothelial migration of FDCP-2 cells. (A)
Transmigration of FDCP-2 cells through LE1SVO and STR cell lines; (B)
effects of anti-VLA-4 and anti-VCAM-1 antibodies on the
transmigration of FDCP-2 cells through STR-4 cells; (C) adhesion of
FDCP-2 cells to STR-4 cells; (D) effects of anti-SDF-1 antibody on the
transmigration of FDCP-2 cells through STR-4 cells. Results were shown
as the mean ± SD of data obtained from three different experiments.
*P < .01.
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Anti-VCAM-1 antibody almost completely inhibited the transendothelial
migration of FDCP-2 cells. Anti-VLA-4 antibody also inhibited the
migration. Anti-E-selectin, anti-ICAM-1 antibodies, and control rat
IgG showed no effect on the transendothelial migration of FDCP-2 cells
through STR-4 cells (Fig 6B). Inhibition of transendothelial migration
by anti-VLA-4 and anti-VCAM-1 antibodies was also observed in the
experiments using STR-10 and STR-12 cells as monolayers. Because
anti-VLA-4 and anti-VCAM-1 antibodies slightly but not significantly
inhibited the adhesion of FDCP-2 cells to STR-4 cells (Fig 6C),
inhibition of the transendothelial migration of FDCP-2 cells by these
antibodies was not ascribed to the inhibition of adhesion. Anti-SDF-1
antibody inhibited the transendothelial migration of FDCP-2 cells
through STR-4 cells in a dose-dependent manner (Fig 6D). Inhibition of
transendothelial migration by anti-SDF-1 antibody was also observed in
the experiments using STR-10 and STR-12 cells as monolayers (data not
shown). These findings suggest that both SDF-1 and VCAM-1/VLA-4 are
necessary for the transendothelial migration of hematopoietic
progenitor cells.
Transendothelial migration of normal hematopoietic progenitor cells.
Table 3 shows the numbers of transmigrated
Lin cells and colony-forming unit granulocyte-macrophage
(CFU-GM). Normal CFU-GM did not transmigrate through LE1SVO cell
monolayers, whereas they transmigrated through STR-4, STR-10, and
STR-12 cell monolayers in the presence of STR-2 cell-conditioned
medium. Both anti-VLA-4 and anti-VCAM-1 antibodies significantly
inhibited the transendothelial migration of normal CFU-GM (Table 3).
Anti-ICAM-1 and anti-E-selectin antibodies as well as control rat IgG
had no effect on the transendothelial migration (data not shown).
Anti-SDF-1 antibody inhibited the tarnsendothelial migration of
CFU-GM.
| |
DISCUSSION |
Normal adult hematopoiesis is restricted within the BM extravascular
spaces separated by BM endothelial cells and basement membrane from
intravascular spaces.19 Hematopoietic progenitor cells in
BM transmigrate through BM endothelial cells from extravascular spaces
into intravascular spaces, and those transplanted into PB transmigrate
through BM endothelial cells from intravascular spaces to extravascular
spaces. Transendothelial migration of hematopoietic progenitor cells is
thought to be through a similar transmigration cascade to the one
proposed for leukocytes, such as rolling, secretion of cytokines
and/or chemokines, activation of adhesion molecules, firm
adhesion, and transendothelial migration.1,3,5
In this study, we showed that BM endothelial cells but not lung
endothelial cells express VCAM-1 and that hematopoietic progenitor cells transmigrate through the BM endothelial cells, but not the lung
endothelial cells, via the interaction between VLA-4 and VCAM-1. These
results indicate that hematopoietic progenitor cells transmigrate into
BM in an organ-specific manner, and that VLA-4/VCAM-1 play important
roles in the homing of hematopoietic progenitor cells to BM. Both
hematopoietic progenitor cells and endothelial cells express various
adhesion molecules, including the integrin family and Ig super
family.2,3,19,20 Previously it was reported that VLA-4,
VLA-5, and LFA-1 expressed on hematopoietic progenitor cells were
functionally important in hematopoiesis.21-24 Because VLA-5
is a classical fibronectin receptor and binds to the RGD site of
fibronectin,25 it may play important roles in transmigration through basement membranes. VLA-4 binds to the CS-1 site
of fibronectin as well as a member of the Ig superfamily, VCAM-1.26 Previous reports showed that the VLA4/VCAM-1
adhesion pathway played important roles in the homing of hematopoietic progenitor cells to BM.27-31 On the other hand,
E-selectin, platelet endothelial cellular adhesion
molecule (PECAM)-1, CD34, ELAM-1, ICAM-1, and VCAM-1 expressed on BM
endothelial cells have been also reported to play important roles in
hematopoiesis.32 The recent report by Schweitzer et
al33 showed that E-selectin and VCAM-1 were expressed on
endothelial cells of only hematopoietic tissues. Their findings are in
accordance with ours that VCAM-1 was expressed only on the BM
endothelial cells but not on the lung endothelial cells. Henninger et
al34 reported in similar findings that there were
significant differences in the expression of ICAM-1 and VCAM-1 among
different tissues. In contrast to our findings, Mohle et
al8 recently reported that LFA-1/ICAM-1 played important
roles in transendothelial migration of hematopoietic progenitor cells.
The discrepancy between their results and ours could be explained by
the difference of adhesion molecules expressed on endothelial cells.
The BM endothelial cells in our experiment expressed VCAM-1
constitutively but not ICAM-1, whereas their endothelial cells
expressed ICAM-1 but not VCAM-1. Alternatively, all of our endothelial
cell lines secreted chemoattractants including SDF-1 (Fig 3), which may
have activated the adhesion molecules expressed on progenitors,
especially VLA-4, and allowed the interaction between VLA-4 and VCAM-1
in our in vitro model. In fact, anti-SDF-1 antibody inhibited the
transendothelial migration of FDCP-2 cells in a dose-dependent manner,
suggesting that SDF-1 is necessary for transendothelial migration of
hematopoietic progenitor cells. However, SDF-1 alone is not sufficient
for the transendothelial migration of progenitor cells because FDCP-2
cells do not transmigrate through STR-2 cells that secrete SDF-1.
Furthermore, chemoattractants secreted by BM endothelial cells may
stimulate the expression of VCAM-1 on BM endothelial cells in an
autocrine manner. This may explain why the BM endothelial cells but not
the lung endothelial cells expressed VCAM-1 without any stimulation.
We examined the transendothelial migration in the presence of
BM-fibroblast-conditioned medium that contained random
motility-stimulating factor(s) and chemoattractant(s) including SDF-1
to make a similar situation in vitro to that of BM in vivo. Recently,
Yong et al35 have reported that transmigration of
CD34+ cells across endothelium was mediated by PECAM-1
(CD31). However, none of the chemoattractant was used in their
transmigration experiments, which suggests that the transmigration of
CD34+ cells in their experiment reflects the random
migration rather than the chemotaxis. The difference in the assay
system may account for the difference of adhesion molecules responsible
for the transmigration of progenitor cells. STR-2 cells secreted SDF-1,
which was reported to induce chemotaxis and transendothelial migration
of progenitor cells.36-38 Aiuti et
al37 have reported that SDF-1 induced the transendothelial migration of progenitor cells through mouse
endothelial cells that did not express VCAM-1. Their experiments were
performed by the use of human BM cells and a mouse endothelioma cell
line. Therefore, the discrepancy between our results and their results may be explained by the differences of the endothelial cell lines used
for the transendothelial migration assay. In addition, the motility-stimulating factor(s) other than SDF-1 contained in STR-2 cell-conditioned medium may influence the transendothelial migration. The nature of this random motility-stimulating activity is now under
investigation. SDF-1 or SDF-1 plus random motility-stimulating activity
secreted by BM fibroblasts may play important roles in attracting
hematopoietic progenitor cells to BM.
| |
ACKNOWLEDGMENT |
We thank M. Yanome for assistance in preparing the manuscript.
| |
FOOTNOTES |
Submitted October 3, 1997;
accepted September 3, 1998.
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.
Address reprint requests to Masanobu Kobayashi, MD, Laboratory of
Pathology, Cancer Institute, Hokkaido University School of Medicine.
Kita-15, Nishi-7, Kita-ku, Sapporo, 060 Japan; e-mail:
mkobaya{at}med.hokudai.ac.jp.
| |
REFERENCES |
1.
Springer TA:
Traffic signals for lymphocyte recirculation and leukocyte emigration: The multistep paradigm.
Cell
76:301, 1994[Medline]
[Order article via Infotrieve]
2.
Gumbiner BA:
Cell adhesion: The molecular basis of tissue architecture and morphogenesis.
Cell
84:345, 1996[Medline]
[Order article via Infotrieve]
3.
Carlos TM, Harlan JM:
Leukocyte-endothelial adhesion molecules.
Blood
84:2068, 1994[Abstract/Free Full Text]
4.
Papayannopoulou T, Craddock C:
Homing and trafficking of hematopoietic progenitor cells.
Acta Haematol
97:97, 1997[Medline]
[Order article via Infotrieve]
5.
Springer TA:
Traffic signals on endothelium for lymphocyte recirculation and leukocyte emigration.
Annu Rev Physiol
57:827, 1995[Medline]
[Order article via Infotrieve]
6.
Butcher EC:
Leukocyte-endothelial cell recognition: Three (or more) steps to specify and diversity.
Cell
67:1033, 1991[Medline]
[Order article via Infotrieve]
7.
Lasky LA:
Selectins: Interpreters of cell-specific carbohydrate information during inflammation.
Science
258:964, 1992[Abstract/Free Full Text]
8.
Mohle R, Moore MAS, Nachman RL, Rafii S:
Transendothelial migration of CD34+ and mature hematopoietic cells: An in vitro study using a human bone marrow endothelial cell line.
Blood
89:72, 1997[Abstract/Free Full Text]
9.
Dong Z, Wortis HH:
Function of bone marrow stromal cell lines.
J Immunol
153:1441, 1994[Abstract]
10.
Felgner PL, Gadek TR, Holm M, Roman R, Chan HW, Wenz M, Northrop JP, Ringold GM, Danielsen M:
Lipofectin: A highly efficient, lipid-mediated DNA-transfection procedure.
Proc Natl Acad Sci USA
84:7413, 1987[Abstract/Free Full Text]
11.
Gluzman Y, Frisque RJ, Sambrook J:
Origin-defective mutants of SV40.
Cold Spring Harb Symp Quant Biol
44:293, 1980
12.
Belloni PN, Carney DH, Nicolson GL:
Organ-derived microvessel endothelial cells exhibit differential responsiveness to thrombin and other growth factors.
Microvasc Res
43:20, 1992[Medline]
[Order article via Infotrieve]
13.
Hamada J, Cavanaugh PG, Lotan O, Nicolson GL:
Separable growth and migration factors for large-cell lymphoma cells secreted by microvascular endothelial cells derived from target organs for metastasis.
Br J Cancer
66:349, 1992[Medline]
[Order article via Infotrieve]
14.
Aizawa S, Taguchi M, Nakano M, Inokuchi S, Handa H, Toyama K:
Establishment of a variety of human bone marrow stromal cell lines by the recombinant SV40-adenovirus vector.
J Cell Physiol
148:245, 1991[Medline]
[Order article via Infotrieve]
15.
Rafii S, Shapiro F, Rimarachin J, Nachman RL, Ferris B, Weksler B, Moore MAS, Asch AS:
Isolation and characterization of human bone marrow microvascular endothelial cells: Hematopoietic progenitor cell adhesion.
Blood
84:10, 1994[Abstract/Free Full Text]
16.
Musashi M, Sakurada K, Kawamura K, Iwasaki H, Tsuda Y, Kobayashi M, Sasaki M, Kato K, Tanaka E, Sudo T, Asaka M, Miyazaki T:
Phorbol ester enhancement of IL-3-dependent proliferarion of primitive progenitors of mice in culture.
J Pharmacol Exp Therapeut
280:225, 1997[Abstract/Free Full Text]
17.
Hauzenberger D, Klominek J, Sundqvisk K-G:
Functional specialization of fibronectin-binding 1-integrins in T lymphocyte migration.
J Immunol
153:960, 1994[Abstract]
18.
Kobayashi M, Imamura M, Gotohda Y, Maeda S, Iwasaki H, Sakurada K, Kasai M, Hapel AJ, Miyazaki T:
Synergistic effects of interleukin-1 and interleukin-3 on the expansion of human hematopoietic progenitor cells in liquid cultures.
Blood
78:1947, 1991[Abstract/Free Full Text]
19.
Coulombel L, Auffray I, Gaugler M-H, Rosemblatt M:
Expression and function of integrins on hematopoietic progenitor cells.
Acta Haematol
97:13, 1997[Medline]
[Order article via Infotrieve]
20.
Wilson JG:
Adhesive interactions in hemopoiesis.
Acta Haematol
97:6, 1997[Medline]
[Order article via Infotrieve]
21.
Williams DA, Rios M, Stephens C, Patel VP:
Fibronectin and VLA-4 in haematopoietic stem cell microenvironment interactions.
Nature
352:438, 1991[Medline]
[Order article via Infotrieve]
22.
Miyake K, Weissmann IL, Greenberger JS, Kincade PW:
Evidence for a role of VLA-4 in lympho-hemopoiesis.
J Exp Med
173:599, 1991[Abstract/Free Full Text]
23.
Kerst JM, Sanders JB, Slaper-Cortenbach ICM, Doorakker MCh, Hooibrink B, van Oers RHJ, von dem Borne AEGKr, van der Schoot CE:
41 and 51 are differentially expressed during myelopoiesis and mediate the adherence of CD34+ cells to fibronectin in an activation-dependent way.
Blood
81:344, 1993[Abstract/Free Full Text]
24.
Gunji Y, Nakamura M, Hagiwara T, Hayakawa K, Matsushita H, Osawa H, Nagayoshi K, Nakauchi H, Yanagisa M, Miura Y, Suda T:
Expression and function of adhesion molecules on human hematopoietic stem cells: CD34+ LFA-1 cells are more primitive than CD34+ LFA-1 cells.
Blood
80:429, 1992[Abstract/Free Full Text]
25.
Ruoslahti E, Pierschbacher MD:
New perspectives in cell adhesion: mRGD and integrins.
Science
238:491, 1987[Abstract/Free Full Text]
26.
Hemler ME:
Adhesive protein receptors on hemopoietic progenitors.
Immunol Today
9:109, 1988[Medline]
[Order article via Infotrieve]
27.
Tavassoli M, Hardy CL:
Molecular basis of homing of intravenously transplanted stem cells to the marrow.
Proc Natl Acad Sci USA
84:4485, 1987[Abstract/Free Full Text]
28.
Carlos TM, Schwartz BR, Kovach NL, Rosso EYM, Osborn L, Chi-Rosso G, Newman B, Lobb R, Harlan JM:
Vascular cell adhesion molecule-1 mediates lymphocyte adherence to cytokine-activated cultured human endothelial cells.
Blood
76:965, 1990[Abstract/Free Full Text]
29.
Jacobsen K, Kravitz J, Kincade PW, Osmond DG:
Adhesion receptors on bone marrow stromal cells: In vivo expression of vascular cell adhesion molecule-1 by reticular cells and sinusoidal endothelium in normal and  -irradiated mice.
Blood
87:73, 1996[Abstract/Free Full Text]
30.
Papayanopoulou T, Craddock C, Nakamoto B, Priesley GV, Wolf NS:
The VLA4/VCAM-1 adhesion pathway defines contrasting mechanisms of lodgement of transplanted murine hematopoietic progenitors between bone marrow and spleen.
Proc Natl Acad Sci USA
92:9647, 1995[Abstract/Free Full Text]
31.
Papayanopoulou T, Priestley GV, Nakamoto B:
Anti-VLA4/VCAM-1-induced mobilization requires cooperative signaling through the kit/mkit ligand pathway.
Blood
91:2231, 1998[Abstract/Free Full Text]
32.
Dercksen MW, Weimar IS, Richel DJ, Breton-Gorius J, Vainchenker W, Slaper-Cortenbach CM, Pinedo HM, von dem Bome AE, Gerritsen WR, van der Schoot CE:
The value of flow cytometric analysis of platelet glycoprotein expression of CD34+ cells measured under conditions that prevent P-selectin-mediated binding of platelets.
Blood
86:3771, 1995[Abstract/Free Full Text]
33.
Schweitzer KM, Draeger AM, van der Valk P, Thijsen SFT, Zevenbergen A, Theijsmeijer AP, van der Schoot CE, Langenhuijsen MMAC:
Constitutive expression of E-selectin and vascular cell adhesion molecule-1 on endothelial cells of hematopoietic tissues.
Am J Pathol
148:165, 1996[Abstract]
34.
Henninger DD, Panchi J, Eppihimer M, Russell J, Gerritsen M, Anderson DC, Granger DN:
Cytokine-induced VCAM-1 and ICAM-1 expression in different organs of the mouse.
J Immunol
158:1825, 1997[Abstract]
35.
Yong KL, Watts M, Thomas S, Sullivan A, Ings S, Linch DC:
Transmigration of CD34+ cells across specialized and nonspecialized endothelium prior activation by growth factors and is mediated by PECAM-1 (CD31).
Blood
91:1196, 1998[Abstract/Free Full Text]
36.
Nagasawa T, Hirota S, Tachibana K, Takakura N, Nishikawa S, Kitamura Y, Yoshida N, Kikutani H, Kishimoto T:
Defects of B-cell lymphopoiesis and bone-marrow myelopoiesis in mice lacking the CXC chemokine PBSF/SDF-1.
Nature
382:635, 1996[Medline]
[Order article via Infotrieve]
37.
Aiuti A, Webb IJ, Springer T, Gutierrez-Ramos JC:
The chemokine SDF-1 is a chemoattractant for human CD34+ hematopoietic progenitor cells and provides a new mechanism to explain the mobilization of CD34+ progenitors to peripheral blood.
J Exp Med
185:111, 1997[Abstract/Free Full Text]
38.
Kim CH, Broxmeyer HE:
In vitro behavior of hematopoietic progenitor cells under the influence of chemoattractants: Stromal cell-derived factor-1, steel factor, and the bone marrow environment.
Blood
91:110, 1998
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Abstract
Introduction