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ORIGINAL ARTICLE
248
a
Former Resident,
b
Professor,
c
Assistant Professor,
d
Full-time
Lecturer, Department of Orthodontics, Dental Hospital, East-West
Neo Medical Center.
Corresponding author:
Jong-Hyun Nahm.
Department of Orthodontics, Dental Hospital, East-West Neo
Medical Center, 149, Sangil-dong, Gangdong-gu, Seoul 134-
727, Korea.
+82 2 440 6205; e-mail, orthopia@unitel.co.kr.
Received January 30, 2008; Last Revision June 8, 2009;
Accepted June 13, 2009.
DOI:10.4041/kjod.2009.39.4.248
Effects of compressive stress on the expression of M-CSF,
IL-1
β
, RANKL and OPG mRNA in periodontal ligament cells
Ji-Woong Kim, DMD, MSD,
a
Ki-Soo Lee, DMD, MSD, PhD,
b
Jong-Hyun Nahm, DMD, MSD, PhD,
c
Yoon-Goo Kang, DMD, MSD, PhD
d
Objective: The aim of this study was to determine if human PDL cells can produce osteoclastogenic mRNA
and examine how compressive stress affects the expression of osteoclastogenic mRNA in human PDL
cells. Methods: Human PDL cells were obtained from biscupids extracted for orthodontic treatment. The
compressive force was adjusted by increasing the number of cover glasses. PDL cells were subjected to
a compressive force of 0.5, 1.0, 2.0, 3.0 or 4.0 g/cm
2
for 0.5, 1.5, 6, 24 or 48 hours. Reverse transcription
polymerase chain reaction (RT-PCR) analysis was performed to examine levels of M-CSF, IL-1β, RANKL,
OPG mRNA expression. Results: Human PDL cells could produce M-CSF mRNA. Human PDL cells under
compressive stress showed increased M-CSF, IL-1β and RANKL mRNAs expression in a force (up to 2
g/cm
2
) and time-dependent manner. However, OPG mRNA expression was constant regardless of the level
and duration of stress. Conclusions: Continuous compressive stress induced the mRNA expression of os-
teoclastogenic cytokines including M-CSF, RANKL, IL-1β in PDL cells. Together with an unchanged OPG
mRNA level, these results suggest that compressive stress-induced osteoclastogenesis in vivo is partly
controlled by M-CSF, RANKL and IL-1β expression in PDL cells.
(Korean J Orthod 2009;39(4):248-256)
Key words: Human PDL cell, Mechanical stress, Osteoclastogenesis
INTRODUCTION
Orthodontic tooth movement occurs during the se-
quential periodontal tissue remodeling, especially al-
veolar bone, induced by therapeutic mechanical stress.
1
It is a generally accepted that the periodontal ligament
tissue plays a key role in tooth movement as a re-
sponse to an applied mechanical stress, due to parad-
ental tissue remodeling including bone resorption and
formation. “Ankylosed teeth”, in which the cementum
of the tooth root is connected directly to the alveolar
bone, cannot be moved by therapeutic mechanical
stress due to the lack of a periodontal ligament.
2
Osteoclastogenesis has been an important subject in
the field of bone cell biology for a long time. Recent-
ly, the molecular determinants of osteoclastogenesis
were identified. Membrane-bound proteins, receptor ac-
tivator of nuclear factor
κ
B ligand (RANKL), and
soluble macrophage colony-stimulating factor (M-CSF)
are considered essential factors for osteoclastogenesis
produced by osteoblasts and bone marrow stromal
cells.
3-6
In contrast, osteoprotegerin (OPG), a soluble
tumor necrosis factor (TNF) receptor homolog, was
found to inhibit osteclastogenesis by competing with
the binding of RANKL to the RANK (receptor of
RANKL).
7
Vol. 39, No. 4, 2009. Korean J Orthod
Effects of compressive force on the periodontal ligament cells
249
Fig 1. Method used to apply a compressive stress.
Pre-cultured PDL cells were compressed continuously
using a different number of round-shaped cover glas-
ses. Round-shaped cover glasses were placed over a
confluent cell layer in each well of a 6-well plate. The
amount of compressive force was adjusted by increas-
ing or decreasing the number of cover glasses placed.
Cultured cells derived from the PDL, mostly fibro-
blasts, can express and produce the cytokines asso-
ciated with osteoclastogenesis. Hasegawa et al
8
re-
ported that PDL cells derived from deciduous and per-
manent teeth synthesized both RANKL and OPG, and
could regulate the differentiation of osteoclasts. It was
also reported that PDL cells secrete M-CSF in re-
sponse to TNF-
α
stimulation.
9
Wada et al
10
showed
that human PDL fibroblastic cells have the capacity to
produce and secrete OPG. Furthermore, it was reported
that inflammatory cytokines, such as PGE2, IL-1
α
,
IL-1
β
, IL-6 and TNF-
α
, are produced by mechan-
ically stimulated PDL cells.
11-13
Previous reports showed that PDL cells can partic-
ipate in osteoclastogenesis but the production of the re-
lated cytokines in PDL cells has not been fully charac-
terized. In particular, for M-CSF and IL-1
β
, their pro-
duction in mechanically stimulated PDL cells has not
been documented. This study examined the mode of
osteoclastogenetic cytokine production including MCSF,
RANKL, IL-1
β
and OPG in PDL cells in response to
compressive mechanical stimulation.
MATERIAL AND METHODS
Primary human PDL cells
Biscupids extracted from 5 patients for orthodontic
reasons were used in this study. Informed consent was
obtained from all volunteers. Immediately after ex-
traction, the teeth were placed in
α
-MEM containing
15% FBS (Sigma-aldrich, St. Louis, MO, USA) and
3-fold-reinforced antibiotics (Antibiotics and Antimy-
cotics, Gibco BRL, Grand Island, NY, USA) in a 50
ml conical tube (Corning, NY, USA). Using a No. 15
surgical blade, a piece of PDL was obtained exclu-
sively from the middle of the tooth roots in order to
exclude the intermixture of gingivae and dental
pulp.
9,10
The PDL tissue obtained was treated with 1.10
unit/ml dispase (Gibco BRL, Grand Island, NY, USA)
and 264 unit/ml collagenase (Collagenase Type II;
Gibco BRL, Grand Island, NY, USA) for 1 hour at
37
o
C. After washing with
α
-MEM, ligament samples
were cultured on a 100 mm primary culture dish
(Corning, NY, USA) in
α
-MEM containing 15% FBS
and antibiotics. The cells proliferating from the extracts
were passaged. For all experiments, PDL cells from
the 4
th
to 8
th
passages were used.
Cell culture
All PDL cells were cultured in
α
-MEM containing
15% FBS and antibiotics at 37
o
C in a 5% CO
2
incubator. The culture medium was changed twice a
week throughout the experiment.
Application of compressive stress
After sufficient cultivation, PDL cells from each pa-
tient were transferred to 6-well plates. Each well of a
6-well plate contained 1 × 10
6
PDL cells. Two days
later, the PDL cells were allowed to adhere to the well
plate base, and PDL cells were compressed con-
tinuously using the uniform compression method illus-
trated in Fig 1.
Briefly, round-shaped cover glasses (30 mm diame-
ter, Marienfeld, Louda-Könlgshofen, Germany) were
placed over a confluent cell layer in each well of a
6-well plate. Each cover glass weighed 0.245 gm. The
compressive force was adjusted by increasing or de-
Kim JW, Lee KS, Nahm JH, Kang YG
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Table 1. Primers used for RT-PCR
Annealing
Sp e c ific it y Olig onucle otide sequ ence (5'-3') Accession no. Product (BP )
temperatu re (
o
C)
M-CSF DSO
TM
prim er NM _00 0757 N.A 63
IL- 1
β
DSO
TM
prim er NM _00 0576 N.A 63
RANK L AGC AGA GAA AGC GAT GG T AF0 19047 341 58
GGG TAT GAG AAC TTG GGA TT
OPG TCA AGC AGG AGT GCA ATC G U943 32 342 57
AGA ATG CCT CCT CAC ACA GG
GAPDH CGG AGT CAA CGG ATT TGG TCG TA T N M_002046 306 56
AGC CTT CTC CAT GGT GGT GAA GAC
Sequence of DSO
TM
primer is not shown according to patent protection law.
creasing the number of cover glasses. Because the di-
ameter of a well in a 6-well culture plate is approx-
imately 35 mm, the periphery of each well was not
fully covered by the cover glass. However, the un-
covered area was minor and did not appear to affect
the results of the study. The PDL cells were subjected
to a compressive force of 0.5, 1, 2, 3 or 4 g/cm
2
(total
given force was 3.43, 7.015, 14.21, 21.315, 28.175 gm,
which was 0.49, 1.01, 2.01, 3.01, 3.99 g/cm
2
) for 0.5,
1.5, 6, 24 or 48 hours. The PDL cells without com-
pressive stimulation served as the control group.
RNA extraction and first-strand comple-
mentary DNA synthesis
After each culture period, the total RNA was ex-
tracted from each culture. After removing the culture
medium, the PDL cells from each well were homogen-
ized using Trizol reagent (Invitrogen Co., Carlsbad,
CA, USA). After homogenization, 0.2 ml of chloro-
form (Sigma-aldrich, St. Louis, MO, USA) per 1 ml of
Trizol reagent was added. The samples were centri-
fuged at 4
o
C, 12,000 rpm for 15 minutes. An aqueous
phase was transferred to a fresh tube, and 0.5 ml of
isopropyl alcohol (Sigma-aldrich, St. Louis, MO, USA)
per 1 ml of Trizol reagent was added. The samples
were centrifuged again under the same conditions.
Removing the supernatant, the RNA pellets were wash-
ed with 75% alcohol (Sigma-aldrich, St. Louis, MO,
USA), and dried for 5 to 10 minutes. The RNA was
dissolved in 0.1% diethyl pyrocarbonate (DEPC) water
(Fermentas, Glen Burnie, MD, USA).
For complementary DNA synthesis, a mixture of 500
ng mRNA, 2
μ
l of 10
μ
M Oligo dT (Fermentas, Glen
Burnie, MD, USA) and 3
μ
l DEPC water was in-
cubated at 80
o
C for 3 minutes, and chilled on ice for
2 minutes. Subsequently, 4
μ
l of 5X RT buffer
(Fermentas, Glen Burnie, MD, USA), 20 units of
RNase inhibitor (Fermentas, Glen Burnie, MD, USA),
200 units of RevertAid
TM
M-MuLV RT (Fermentas
Inc., Glen Burnie, MD, USA) and 4
μ
l of 2.5 mM
dNTP Mix (Fermentas, Glen Burnie, MD, USA) were
added to the mixture and incubated at 42
o
C for 90
minutes.
Reverse transcription polymerase chain re-
action assays
First-stranded complementary DNA was subjected to
polymerase chain reaction (PCR) amplification using
gene specific PCR primers. PCR for M-CSF and IL-1
β
was carried out using a GeneXP
TM
kit (Seegene, Seoul,
Korea). Each 10
μ
l reaction mixture contained 2
μ
l of
5X Human CYTO-X DSO
TM
primer, 5
μ
l of 2X mas-
ter mix and 20 ng of cDNA. Each cycle consisted of
the following: heat denaturation at 94
o
C for 30s, an-
nealing at 63
o
C for 90s and extension at 72
o
C for 90s.
PCR amplification can only start if all two parts of the
DSO
TM
(Dual Specificity Oligonucleotide; Seegene,
Seoul, Korea) primer bind to cDNA, which result in
Vol. 39, No. 4, 2009. Korean J Orthod
Effects of compressive force on the periodontal ligament cells
251
Fig 2. Compressive stress up-regulated M-CSF and
IL-1β mRNAs expression in PDL cells. A, RT-PCR
analysis of PDL cells. The PDL cells were loaded at
different compressive stress (0, 0.5, 1, 2, 3 or 4 g/cm
2
)
for 48 hours; B, Densitometry analysis. The results are
expressed as the mean ratio to GAPDH expression o
f
five independent experiments. M-CSF and IL-1β
mRNAs expression at 2 g/cm
2
was significantly differ-
ent compared to those of the control.
Fig 3. Compressive stress up-regulated M-CSF and
IL-1β mRNAs expression in a time dependent
manner. A, RT-PCR analysis of PDL cells. The PDL
cells were loaded at a constant compressive stress (2
g/cm
2
) for 0, 0.5, 1.5, 6, 24 or 48 hours; B, Densi-
tometry analysis. The results are expressed as the
mean ratio to GAPDH expression of five independent
experiments. M-CSF and IL-1β mRNAs expression
was significantly different from the control after 6
hours and 24 hours, respectively.
higher specificity and sensitivity than when using the
usual primer.
In PCR for RANKL and OPG, 2X PCR Master Mix
(Fermentas, Glen Burnie, MD, USA) was used for the
reaction. Each 50
μ
l reaction mixture contained 20
pmol of the sense and antisense PCR primers, 200 ng
of cDNA and 25
μ
l of 2X PCR Master Mix. Each cy-
cle consisted of the following: denaturation at 94
o
C for
30s, annealing at a temperature optimized for each pri-
mer pair (Table 1) for 90s and extension at 74
o
C for
90s.
The PCR products were electrophoresed and vi-
sualized on a 2% agarose gel containing ethidium bro-
mide with UV light illumination. The relative intensity
of the gel bands was measured using Scion Image
(Scion, Frederick, MD, USA) for Windows XP.
Statistical treatment
Statistical significance was evaluated by analysis of
variance (ANOVA) and a multiple-comparison test
(Scheffé's test) using SPSS V.13 (SPSS inc., Chicago,
IL, USA). A p value
<
0.05 was considered signi-
ficant. The values are expressed as the mean ± SD.
RESULTS
Effects of various compressive stress and
duration on the expression of M-CSF and
IL-1β mRNAs
The expression of M-CSF and IL-1
β
mRNAs in hu-
man PDL cells was assessed after applying various
mechanical compressive stresses for various durations.
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Fig 4. Compressive stress up-regulated RANKL mRNA
expression in PDL cells. In contrast, OPG mRNA ex-
pression did not change. A, RT-PCR analysis of PDL
cells. The PDL cells were loaded at different com-
pressive stresses (0, 0.5, 1, 2, 3 or 4 g/cm
2
) for 48
hours; B, Densitometry analysis. The results are ex-
pressed as the mean ratio to GAPDH expression o
f
five independent experiments. RANKL mRNA ex-
pression was significantly different from the control at
2 g/cm
2
. In contrast, OPG mRNA expression was con-
stant throughout the experiment.
Fig 5. Compressive stress up-regulated RANKL mRN
A
expression in a time dependent manner. In contrast,
OPG mRNA expression did not change. A, RT-PCR
analysis of PDL cells. The PDL cells were loaded at a
constant compressive stress (2 g/cm
2
) for 0, 0.5, 1.5,
6, 24 or 48 hours; B, Densitometry analysis. The re-
sults are expressed as the mean ratio to GAPDH ex-
pression of five independent experiments. RANKL
mRNA expression was significantly different from the
control after 6 hours. In contrast, OPG mRNA ex-
pression was constant throughout the experiment.
PDL cells under compression showed an increase in
M-CSF and IL-1
β
mRNAs expression in a force-de-
pendent manner up to 2 g/cm
2
, but the expression de-
creased after applying 3 g/cm
2
. The expression of M-
CSF and IL-1
β
mRNAs in the experimental groups
reached a maximum of 1.7- and 1.5-fold, respectively,
at a compressive load of 2 g/cm
2
, and were signifi-
cantly different from those of the control group which
was without compressive stress (0 g/cm
2
) (Fig 2).
M-CSF and IL-1
β
mRNAs expression was similar to
that of the control group at 0.5 hour of 2 g/cm
2
com-
pression but a time-dependent increase was evident af-
ter 6 and 24 hours, respectively, for up to 48 hours
(Fig 3).
Effects of various compressive forces and
duration on the expression of RANKL and
OPG mRNAs
Expression of RANKL and OPG mRNA in human
PDL cells was assessed after applying various com-
pressive mechanical stresses for various durations. PDL
cells under compression showed increased RANKL
mRNA expression in a force-dependent manner up to
2 g/cm
2
, but expression was decreased after 3 g/cm
2
.
The expression of RANKL mRNA in the experimental
groups reached a maximum of 2.1-fold at 2 g/cm
2
, and
was significantly different from those of the control
group (Fig 4). RANKL mRNA expression was similar
to that of the control group after 0.5 hours of 2 g/cm
2
compression. However, an increase was evident after 6
hours, and it increased in a time-dependent manner for
Vol. 39, No. 4, 2009. Korean J Orthod
Effects of compressive force on the periodontal ligament cells
253
up to 48 hours (Fig 5). In contrast, OPG mRNA ex-
pression did not change, regardless of the amount of
compressive force applied and the duration of com-
pression (Figs 4 and 5).
DISCUSSION
In this study, human PDL cells were cultured under
various levels of compressive stress for different peri-
ods to determine the effects of mechanical stress on
the expression of M-CSF mRNA in PDL cells. A RT-
PCR assay was used to analyze target mRNA
expression.
Generally, PDL includes multipopulation cells con-
sisting mainly of fibroblasts with high alkaline phos-
phatase activity,
14
and fibroblasts from PDL share
many physiological characteristics with osteoblasts.
15,16
Some studies already described methods to isolate PDL
cells from PDL, and an almost identical method was
used in this study. It is possible that osteoblastic cells
in the PDL subpopulation transduce mechanical stress.
However, the effects of other types of PDL cells were
negligible in this experiment because most cells in the
population in this culture system were spindle-shaped
fibroblastic cells.
Many researchers have already examined the effects
of mechanical stress on PDL cells. Various methods
have been used to impart mechanical stress to cultured
cells in the manner of tension, compression and fluid
shear stress, etc.
17-26
Among the manner of mechanical
stress, compressive stress was used to confirm the role
of PDL cell in the tissue remodeling process of the
compressive side during orthodontic tooth movement
with particular focus on osteoclastogenesis. Hydrostatic
compression,
22,23
reverse-tension compression,
24
and di-
rect contact compression methods
19,25,26
were used to
provide compressive stress on cultured cells. The direct
contact compression method appeared to mimic most
in vivo systems in orthodontic treatment because a stat-
ic compressive force is applied to the tooth in daily or-
thodontic practice and that PDL tissue is compressed
directly between two hard structures, bone and cemen-
tum. Therefore, this study adopted the direct contact
compression method, which provides a compression
force by squeezing the cells between two hard surfa-
ces, the culture dish surface and cover glass.
Kanzaki et al.
19
used glass cylinder and lead gran-
ules to provide compression stimulation. They placed a
glass cylinder over a confluent cultured PDL cell layer
and adjusted the compressive force by adding lead
granules to the cylinder. Similarly, Yamaguchi et al.
25
applied compressive stimulation by placing a 30 mm
cell disk over a confluent cell layer followed by a
glass cylinder on top of it. They also used lead gran-
ules to control the amount of compressive force by
placing them into the glass cylinder. The present meth-
od used only cover glasses in order to simplify the
equipment. In addition, by stacking same diameter
glasses, a more uniform force could be delivered to the
underlying cells than the lead granules, which can roll
around in the glass cylinder. In addition, the cover
glass weight was small enough (0.245 g) to control the
force in a more accurate manner.
The M-CSF and RANKL evaluated in this study are
essential factors for osteoclastogenesis produced by os-
teoblasts and bone marrow stromal cells.
3-6
M-CSF is
essential for not only the proliferation of osteoclast
progenitors, but also for differentiation into mature os-
teoclasts and survival in vitro.
27
In contrast, OPG was
reported to inhibit osteclastogenesis competing with the
binding of RANKL to the RANK. IL-1
β
is a proin-
flammatory cytokine that stimulates M-CSF and PGE
2
production,
28
and up-regulated PGE
2
mediates RANKL
expression in PDL cells under a static compressive
stress.
19
However, there is some controversy regarding the
effects of M-CSF in osteoclastogenesis. Although M-
CSF is an essential factor for the formation of osteo-
clasts, it also has been reported that the addition of
M-CSF to a culture inhibits osteoclast formation.
Udagawa et al.
3
reported that M-CSF, while stimulat-
ing murine osteoclast survival, did not induce pit-form-
ing activity. Perkins et al.
29
showed that the addition of
exogenous M-CSF to a co-culture of mouse spleen
cells and ST2 cells caused a dose-dependent decrease
in the number of osteoclasts formed, and was accom-
panied by an increase in the number of macrophages.
Recently, Yasuda et al.
30
reported that a high concen-
tration of M-CSF (
>
40 ng/ml) suppressed osteoclast
formation in murine spleen cell cultures stimulated
Kim JW, Lee KS, Nahm JH, Kang YG
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with soluble RANKL. Considering that these studies
examined osteoclast formation in animal models, spe-
cies differences and different requirements for M-CSF
between the different culture systems can account for
these divergent findings.
Through RT-PCR assays, PDL cells under a com-
pressive stress showed increased M-CSF, IL-1
β
and
RANKL mRNAs expression in a force- (up to 2 g/
cm
2
) and time-dependent manner, but OPG mRNA ex-
pression was constant regardless of the amount of
compressive stress or duration of compression. This
can be explained by the fact that PDL cells under
compressive stress regulate bone remodeling through
an increase in the production of osteoclastogenetic cy-
tokines but not OPG. In addition, compressive stress-
induced intracellular changes are not involved in OPG
mRNA expression. However, it was reported that ten-
sion type stimulation up-regulates OPG mRNA ex-
pression.
31,32
Therefore compression and tension stim-
ulation appears to have separate signal transduction
pathways.
These results partly coincide with previous reports.
Kanzaki et al.
19
reported that compressive stress up to
2 g/cm
2
up-regulated RANKL mRNA in a time-de-
pendent manner. They also measured the level of OPG
and reported no change. Nishijima et al.
26
examined
levels of RANKL and OPG in gingival crevicular fluid
during orthodontic tooth movement and found that the
RANKL level was elevated while the OPG level was
decreased. They also performed an in vitro study and
reported that compression stressed PDL cells increased
the secretion of RANKL in a time-dependent manner
but decreased the secretion of OPG in a time-depend-
ent manner. Nakajima et al.
33
carried out a similar
compressive stimulation study on PDL cells. They also
reported that RANKL production was elevated in a
time and force-dependent manner up to 4 g/cm
2
, the
maximal force that they used. On the other hand, they
reported an increase in OPG production in com-
pression-stressed PDL cells. Overall, it appears that
compressive stress up-regulates RANKL mRNA and
increases the production of RANKL in PDL cells.
However, for OPG, there are discrepancies between
studies, which will need more investigation to establish
the mode of OPG production in PDL cells.
With the exception of Nakajima et al.'s
33
study, oth-
er studies examining compressive stress effects on
PDL cells reported that a 2 g/cm
2
force is the optimal
level of force that can elicit a maximal PDL cell
response.
19,23,26
These results also support the optimal
force level of 2 g/cm
2
. At an applied force magnitude
of 3 g/cm
2
, the level of M-CSF, IL-1
β
and RANKL
mRNA expression decreased. This is probably due to
the 3 g/cm
2
applied force being too heavy making cell
survival difficult. Indeed, a microscopic observation af-
ter applying 4 g/cm
2
showed that the compressive
stress was so heavy that PDL cells were partially dam-
aged and?the number of cells decreased (data not
shown). Nakao et al.
23
suggested that 2 g/cm
2
was suit-
able but 7.0 g/cm
2
was too heavy for cell survival.
This in vitro result can be applied clinically. Although
the applied orthodontic force cannot be distributed uni-
formly on the desired tooth root surface, the area of
root surface that faces a compressive orthodontic force
according to the type of tooth movement can be esti-
mated and the desirable amount of force can be calcu-
lated by multiplying 2 g/cm
2
. The validity of this as-
sumption may be proven by another systemized clin-
ical trial investigation.
After 6 hours of 2 g/cm
2
compressive mechanical
stress, there was a significant increase in the level of
M-CSF and RANKL mRNA expression compared to
the control. However, the level of IL-1
β
mRNA ex-
pression increased significantly after 24 hours. This
means that IL-1
β
mRNA up-regulation is delayed
compared to M-CSF and RANKL. In addition, other
cytokines might mediate signal transduction during a
compressive mechanical stress. To the best of our
knowledge, there are no reports on the effect of com-
pressive stress on the expression of M-CSF and IL-1
β
mRNA. These results suggest that the expression of
M-CSF and IL-1
β
mRNA increases in a time- and
force-dependent manner (up to 2 g/cm
2
). In addition, it
appears that a compressive force directly regulates
M-CSF mRNA expression but indirectly regulates IL-1
β
mRNA expression. More signal transduction studies
will be needed to confirm the mechanism of com-
pressive force induced M-CSF and IL-1
β
mRNA
expression.
Vol. 39, No. 4, 2009. Korean J Orthod
Effects of compressive force on the periodontal ligament cells
255
CONCLUSION
Continuous compressive stress up-regulates M-CSF,
IL-1
β
and RANKL mRNA expression in cultured
hPDL cells in a force- and time-dependent manner.
However, a compressive force does not regulate OPG
mRNA expression in PDL cells. These results suggest
that a compressive stimulated PDL cells regulate osteo-
clastogenesis by up-regulating the stimulatory cytokines
but not down-regulating the OPG production. There-
fore, in orthodontic tooth movement, PDL cells partic-
ipate in bone resorption by up-regulating osteoclastoge-
netic cytokines, including M-CSF, IL-1
β
and RANKL.
- 국문초록 -
압박력이 치주인대 세포의 M-CSF, IL-1
β
, RANKL
및 OPG mRNA 발현에 미치는 영향
김지웅
a
ㆍ
이기수
b
ㆍ
남종현
c
ㆍ
강윤구
d
이 연구의 목적은 배양된 사람 치주인대 세포에서 파골세
포의 형성에 관련된 물질을 합성
,
분비할 수 있는지를 알아
보고 압박력이
M-CSF, IL-1
β
, RANKL
및
OPG mRNA
의
발현에 미치는 영향을 알아보고자 하였다
.
교정치료를 목적
으로 발치된 소구치에서 얻은 치주인대세포를 배양한 후 다
양한 크기
(0.5, 1.0, 2.0, 3.0, 4.0 g/cm
2
)
의 기계적 자극을 다
양한 기간
(0.5, 1.5, 6, 24, 48 hours)
동안 적용하고
, M-CSF,
IL-1
β
, RANKL, OPG mRNA
발현양의 변화를 검사하였다
.
각각의 실험군에서 얻어진
mRNA
에 대해 역전사 중합효소
연쇄반응검사를 시행하였다
.
검사 결과 압박력은 사람 치주
인대 세포에서
M-CSF mRNA
를 발현시켰으며
M-CSF, IL-1
β
,
RANKL mRNA
의 발현양은 자극의 크기와 기간에 따라 증가
하였다
.
그러나 압박력은 사람 치주인대 세포에서
OPG
mRNA
의 발현양에 영향을 미치지 않는 것으로 나타났다
.
이
상의 결과는 기계적 자극이 치주인대 세포에서
M-CSF, IL-1
β
,
RANKL mRNA
의 발현양을 조절함으로 파골세포의 분화에
영향을 미칠 수 있음을 시사한다
.
주요 단어
:
치주인대세포
,
기계적 자극
,
파골세포형성
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