Acemannan spongesstimulate alveolar bone,cementum and periodontalligament regeneration in acanine class II furcationdefect model
Chantarawaratit P, Sangvanich P, Banlunara W, Soontornvipart K,
Thunyakitpisal P. Acemannan sponges stimulate alveolar bone, cementum and
periodontal ligament regeneration in a canine class II furcation defect model.
J Periodont Res 2014; 49: 164–178. © 2013 John Wiley & Sons A/S. Published
by John Wiley & Sons Ltd
Background and Objective: Periodontal disease is a common infectious disease,
found worldwide, causing the destruction of the periodontium. The periodon-
tium is a complex structure composed of both soft and hard tissues, thus an
agent applied to regenerate the periodontium must be able to stimulate
periodontal ligament, cementum and alveolar bone regeneration. Recent studies
demonstrated that acemannan, a polysaccharide extracted from Aloe vera gel,
stimulated both soft and hard tissue healing. This study investigated effect
of acemannan as a bioactive molecule and scaffold for periodontal tissue
regeneration.
Material and Methods: Primary human periodontal ligament cells were treated
with acemannan in vitro. New DNA synthesis, expression of growth/differentia-
tion factor 5 and runt-related transcription factor 2, expression of vascular
endothelial growth factor, bone morphogenetic protein-2 and type I collagen,
alkaline phosphatase activity, and mineralized nodule formation were deter-
mined using [3H]-thymidine incorporation, reverse transcription–polymerase
chain reaction, enzyme-linked immunoabsorbent assay, biochemical assay and
alizarin red staining, respectively. In our in vivo study, premolar class II furca-
tion defects were made in four mongrel dogs. Acemannan sponges were applied
into the defects. Untreated defects were used as a negative control group. The
amount of new bone, cementum and periodontal ligament formation were eval-
uated 30 and 60 d after the operation.
Results: Acemannan significantly increased periodontal ligament cell prolifera-
tion, upregulation of growth/differentiation factor 5, runt-related transcription
factor 2, vascular endothelial growth factor, bone morphogenetic protein 2, type
I collagen and alkaline phosphatase activity, and mineral deposition as com-
pared with the untreated control group in vitro. Moreover, acemannan signifi-
cantly accelerated new alveolar bone, cementum and periodontal ligament
formation in class II furcation defects.
P. Chantarawaratit1,2,
P. Sangvanich3, W. Banlunara4,
K. Soontornvipart5,
P. Thunyakitpisal61Faculty of Dentistry, Dental Biomaterials
Program, Graduate School, Chulalongkorn
University, Bangkok, Thailand, 2Department of
Materials Science, Faculty of Science,
Chulalongkorn University, Bangkok, Thailand,3Department of Chemistry, Faculty of Science,
Chulalongkorn University, Bangkok, Thailand,4Department of Pathology, Faculty of
Veterinary Science, Chulalongkorn University,
Bangkok, Thailand, 5Department of Surgery,
Faculty of Veterinary Science, Chulalongkorn
University, Bangkok, Thailand and 6Research
Unit of Herbal Medicine and Natural Product for
Dental Application, Department of Anatomy,
Faculty of Dentistry, Chulalongkorn University,
Bangkok, Thailand
Pasutha Thunyakitpisal, Research Unit of
Herbal Medicine and Natural Product for Dental
Application, Department of Anatomy, Faculty of
Dentistry, Chulalongkorn University, Henri-
Dunant Rd, Patumwan, Bangkok 10330,
Thailand
Tel: +66817133311
Fax: +6622188870
e-mail: [email protected]
Key words: acemannan; animal study; class II
furcation defect model; periodontal ligament
cells; periodontal regeneration
Accepted for publication March 29, 2013
J Periodont Res 2014; 49: 164–178All rights reserved
© 2013 John Wiley & Sons A/S.
Published by John Wiley & Sons Ltd
JOURNAL OF PERIODONTAL RESEARCH
doi:10.1111/jre.12090
Conclusion: Our data suggest that acemannan could be a candidate biomolecule
for periodontal tissue regeneration.
Periodontal disease is a common
chronic infectious disease causing the
destruction of the periodontium: peri-
odontal ligament (PDL), alveolar
bone and cementum. Although con-
ventional scaling and root planing
therapy can halt the progression of
this disease, and results in an increase
in clinical periodontal attachment,
this treatment is only effective in the
early phase of the disease. Following
scaling and root planing, periodontal
tissue repair frequently results in a
widened PDL space and incomplete
regeneration of cementum and alveo-
lar bone (1). Therefore, the ultimate
goal of periodontal treatment is not
only to cease and prevent further peri-
odontal tissue destruction, but also to
regenerate the periodontal apparatus
(2,3).
Both anatomically and physiologi-
cally, the periodontium is a very com-
plicated organ containing both soft
tissue and hard tissue functioning
together to support the teeth in the
jaw. Therefore, the methods and
agents used in periodontal tissue
regeneration should stimulate all peri-
odontal tissue types. Polysaccharides
such as hyaluronic acid, chitosan, algi-
nate and pectin have been proposed
for use in tissue engineering and regen-
erative medicine (4–7). These natural
materials have demonstrated biocom-
patibility, biodegradability, immuno-
modulation, antimicrobial, wound
healing and osteogenic activities (4–8).Thus, they have the potential to be
used as periodontal regenerative
agents. Polysaccharides can be pre-
pared in various forms such as gels,
films, beads, sponges and scaffolds
(4–7,9). Therefore, polysaccharides
could function as either active mole-
cules or scaffolds for periodontal
regenerative therapy.
Acemannan is a biodegradable poly-
saccharide composed of b-(1,4)-acety-lated polymannose extracted from
Aloe vera gel. Acemannan has been
shown to stimulate gingival fibroblast,
dental pulp fibroblast, cementoblast
and bone marrow stromal cell prolifer-
ation and differentiation in vitro (10–13). In vivo, acemannan enhanced oral
ulcer and oral aphthous ulcer healing,
reparative dentin formation and bone
formation (10–12,14). Based on its
bioactivity in inducing soft and hard
tissue healing, acemannan is a candi-
date for use in periodontal tissue
regeneration. However, the effect of
acemannan on the regeneration of the
periodontium has not been investi-
gated. In this study, the effect of
acemannan on the proliferation of
periodontal ligament cells (PDLCs)
and their differentiation to hard tissue
forming cells was investigated. The
effect of acemannan sponges on new
PDL, alveolar bone and cementum
formation in a canine furcation defect
model was also evaluated.
Material and methods
Isolation and characterization of
acemannan
Aloe vera (A. barbadensis Miller) was
obtained from a local herbal supplier
in Thailand. Aloe vera was identified
by Assoc. Prof. Dr. Suchada Sukrong
(Department of Pharmacognosy and
Pharmaceutical Botany, Faculty of
Pharmaceutical Sciences, Chulalongk-
orn University). The specimen (no.
051101) was deposited in the Museum
of Natural Medicines, Faculty of
Pharmaceutical Sciences, Chulalongk-
orn University (Bangkok, Thailand).
Acemannan was isolated and char-
acterized as previously described with
some modifications (11,15). Briefly,
fresh mature Aloe vera leaves were
washed and the skin removed. The
Aloe vera parenchyma were washed in
running tap water for 30 min, and
soaked in distilled water for 30 min.
The parenchyma gels were blended
using a homogenizer and centrifuged
at 18,890 g for 60 min at 4°C. The
supernatant was collected and mixed
with absolute alcohol at a 1 : 3 ratio.
The precipitated white opaque parti-
cles were collected by centrifugation
at 12,090 g for 30 min at 4°C. After
lyophilization, the pellets were ground
and kept dry until use.
The molecular weight of the ground
powder was analyzed using high-
performance liquid chromatography
connected to a reflective index detector
(RID-10A; Shimadzu, Shimadzu Cor-
poration, Tokyo, Japan). The separa-
tion was performed with a Shodex
Sugar KS-804 column and compared
with Shodex standard P-82 (Showa
Denko K.K., Yokohama, Japan). The
monosaccharide compositions were
analyzed using gas chromatography-
mass spectroscopy and 13C-NMR spec-
troscopy as previously described
(16,17). The data obtained were compa-
rable to that of previous studies, indi-
cating that the polysaccharide extracted
from freshAloe vera gel was acemannan
(15–17). The yield of acemannan
extraction was approximately 0.2%.
Cell culture
All study protocols were approved by
the Human Research Ethics Commit-
tee of the Faculty of Dentistry, Chul-
alongkorn University. PDLCs were
isolated from third molars extracted
from healthy young donors. The teeth
were washed 3 9 with phosphate-
buffered saline (PBS). PDL tissue was
removed using sterile surgical blades
from the middle one-third of the root
surface to avoid gingival and apical
tissue contamination (18,19). The iso-
lated tissue was cut into 1–2 mm3
pieces, placed into 60 mm culture
dishes, and incubated with growth
medium (Dulbecco’s modified Eagle’s
medium supplemented with 10% fetal
bovine serum, 10,000 IU/mL penicil-
lin G sodium, 100,000 lg/mL strepto-
mycin sulfate, 25 lg/mL amphotericin
B and 1% L-glutamine) at 37°C, in an
atmosphere containing 5% CO2. The
growth medium was replaced every
Acemannan and periodontal regeneration 165
other day. When the outgrown cells
reached confluence, the cells were sub-
cultured using 0.25% trypsin-EDTA
solution. All experiments were per-
formed using cells from the third to
the fifth passage. All cell culture
media were purchased from Gibco
BRLTM (InvitrogenTM, Grand Island,
NY, USA).
DNA synthesis assay
New DNA synthesis was investigated
using an [3H]-thymidine incorporation
assay (20). Briefly, PDLCs (5 9 104
cells/well) were seeded into 24-well
cell culture plates and cultured in
growth medium for 16 h. The growth
medium was then removed and the
cells were cultured in serum-free
growth medium for 3 h, and treated
with 0.25, 0.5, 1.0, 2.0 or 4.0 mg/mL
acemannan for 24 h. After 20 h, the
cells were labeled with 0.25 lCi/wellof [3H]-thymidine (Amersham Bio-
sciences, Little Chalfont, UK). Cells
treated with the same volume of med-
ium without acemannan served as a
control group. After 24 h, the cells
were washed 3 9 with PBS, fixed with
10% trichloroacetic acid, washed with
5% trichloroacetic acid twice, and sol-
ubilized in 0.5 M NaOH overnight.
After neutralization with 0.5 M HCl,
the lysate was thoroughly mixed with
2 mL of scintillation fluid (Opti-
PhaseHiSafe; Fisher Scientific, Milton
Keynes, UK). The amount of beta
radiation was determined using a
liquid scintillation counter (Wallac,
Turku, Finland). The assay was
carried out in three independent
experiments.
RNA isolation and RT-PCR analysis
PDLCs were cultured in osteogenic
medium (growth medium supple-
mented with 50 lg/mL L-ascorbic acid,
10 mM glycerophosphate, and 100 nM
dexamethasone) with acemannan at
the concentrations described above for
24 h. Cells treated with osteogenic
medium without acemannan were
included as a control group. After
24 h, total cellular RNA was collected
(Total RNA mini kit; Geneaid, Taipei,
China). Total RNA (5 lg) was
converted to cDNA. Then the target
cDNA was amplified (Prime RT Pre-
mix and Prime Taq Premix; Genet Bio,
Chungnam, Korea). The sense and
antisense primer sequences used for
GAPDH, growth/differentiation factor
5 (GDF-5) and runt-related transcrip-
tion factor 2 (Runx2) are shown in
Table 1.
The amplification cycles were com-
posed of 94°C for 30 s, 56°C for 30 s
and 72°C for 1 min. After 30 cycles,
the PCR products were separated by
electrophoresis on 1.5% agarose gel
(570 bp for GDF-5, 229 bp for
Runx2 and 307 bp for GADPH).
Vascular endothelial growth factor,
bone morphogenetic protein 2 and
type I collagen measurement
Vascular endothelial growth factor
(VEGF), bone morphogenetic protein
2 (BMP-2), and type I collagen levels
were measured according to the
manufacturers’ instructions (VEGF
and BMP-2; R&D Systems, Minne-
apolis, MN, USA; type I collagen;
Takara Bio Inc., Shiga, Japan).
Briefly, PDLCs (5 9 104 cells) were
seeded in 24-well plates and grown
to 80% confluence. Then the
medium was replaced by osteogenic
medium containing the same concen-
trations of acemannan as described
above. Cells treated with medium
without acemannan were included as
a control group. Culture supernatant
was collected for VEGF, BMP-2 and
type I collagen level determination.
The sensitivities of the ELISA kits
for VEGF, BMP-2 and type I colla-
gen are 5 pg/mL, 11 pg/mL and
10 ng/mL, respectively. The assay
was carried out in three independent
experiments.
Alkaline phosphatase activity assay
PDLCs were prepared and treated
with acemannan as described above.
Alkaline phosphatase (ALPase) activ-
ity was determined after 72 h. The
cells were washed 3 9 with PBS, and
incubated with glycine buffer (100 mM
glycine, 2 mM MgCl2, pH 10.5) con-
taining 0.35 mg/mL p-nitrophenyl-
phosphate (Sigma-Aldrich, St. Louis,
MO, USA) at 30°C for 30 min. The
reaction was terminated with 1 M
NaOH. ALPase activity was reported
in terms of p-nitrophenol production
which was measured at 405 nm and
normalized to total cellular protein
(nmol p-nitrophenol/min per lg) (21).
Mineralization staining
PDLCs were prepared and treated
with acemannan as described above.
Mineral deposition by cultured
PDLCs was determined by alizarin
red (AR) staining after 9 and 18 d.
The cells were washed 3 9 with PBS,
fixed with 70% ethanol, and stained
with 2% AR (pH 4; Wako Pure
Chemical Industries, Osaka, Japan).
After photographing the staining
results, the stained mineral nodules
were destained with 100 mM cetylpy-
ridinium chloride for 15 min. The
absorbance of the released stain was
measured at 570 nm (12,22).
Preparation of acemannan sponges
Acemannan sponges were prepared by
direct lyophilization as previously
described (23). Briefly, 5% and 10%
acemannan solutions (w/v) were fro-
zen at �80°C for 16 h, lyophilized for
16 h and exposed to ultraviolet light
for 1 h. The 5% and 10% acemannan
Table 1. Nucleotide sequence of sense and antisense primers of GAPDH, GDF-5 and
Runx2
Gene Company name Primer
GAPDH Bio Basic Inc. forward GTCATCCATGACAACTTTGG
reverse GGAAGGCCATGCCAGTGACG
GDF-5 Sigma Genosys forward CTCCTCACTTTCTTGCTTTGG
reverse CCTCCAACTTCACGCTGCTGT
Runx2 Bio Basic Inc forward TCTTCACAAATCCTCCCC
reverse TGGATTAAAAGGACTTGGTG
166 Chantarawaratit et al.
solutions generated 10 mg and 20 mg
acemannan sponges, respectively. The
sponges were kept in a desiccator at
room temperature until used.
Scanning electron microscopy and
pore size analysis
Acemannan spongeswere sputter coated
with gold-palladium and analyzed under
scanning electron microscopy (SEM;
JSM-5410LV; JEOL, Tokyo, Japan).
Samples were analyzed in both longitu-
dinal and transverse planes. Thirty pores
were randomly selected. Pore diameter,
circularity and pore size were mea-
sured using the IMAGE PRO-PLUS pro-
gram, version 6.0 (MediaCybernetics,
Rockville, MD, USA). Because the
pore shapes were predominantly ellip-
tical, the pore diameter was calcu-
lated by the average of the longest
and shortest axis of each pore. Circu-
larity was the ratio between the short-
est and the longest axis of each pore
(24).
Biocompatibility evaluation
According to ISO, both extract test
and direct contact assays were used as
in vitro cytotoxicity tests (25,26). For
the extract test, acemannan sponges
were incubated in growth medium
(1 sponge/2 mL) at 37°C with gentle
agitation. The conditioned media were
collected at 1 and 3 d of immersion.
PDLCs (5 9 104 cells) were seeded
in 24-well plates and incubated until
80% confluent. The growth medium
was removed and the cells were washed
with PBS. The cells were then incu-
bated with conditioned media for 72 h.
Cells incubated with growth medium
were used as a control group. Subse-
quently an 3-[4,5-dimethylthiazol-2-
yl]-2,5-diphenyl tetrazolium bromide
(MTT) viability test was performed as
described (27). Briefly, the cells were
washed twice with PBS and incubated
with 0.5 mg/mL MTT solution for
10 min. The formazan crystals were
dissolved in dimethyl sulfoxide and the
optical density was determined by
measuring the light absorbance at
570 nm. The background absorbance
of dimethyl sulfoxide was subtracted
from the sample absorbance (26).
For the direct contact assay,
sponges were soaked in growth med-
ium for 4 h. Then the sponges were
placed in center of each well in 12-
well culture plates. PDLCs (8 9 104)
were seeded around the sponges. Cell
morphology was observed under the
phase contrast microscope at 0, 4, 24,
48 and 72 h after seeding (25).
In vivo study
Four young adult mongrel dogs (12 mo
of age) were obtained from the Faculty
of Veterinary Science, Chulalongkorn
University, Bangkok, Thailand. The
protocol for the animal study was
approved by the Animal Ethics Com-
mittee of the Faculty of Veterinary
Science, Chulalongkorn University.
The animals were adapted to a 12-h
light/12-h dark cycle for 2 wk before
the operation. During the experiment,
the animals had access to food and
water ad libitum. Two weeks before
the operation, all subjects received
scaling and root planing. Cefazolin
(first generation cephalosporin) 25
mg/kg IV was used for pre-
operative antibiotics prophylaxis.
Sedation was achieved using propofol
1–4 mg/kg and maintained with iso-
flurane (2% in 100% oxygen). The
operation area was locally anesthe-
tized using 2% lidocaine with
1 : 100,000 norepinephrine.
Class II furcation defects were cre-
ated in the furcation areas of the
maxillary and mandibular second and
third premolars (P2 and P3) of each
dog for a total of 32 defects (28,29).
Briefly, a mucoperiosteal flap was
raised. The alveolar crest in the
furcation area was vertically reduced
5 mm from the cemento-enamel junc-
tion using atraumatic osteotomy. The
mesial and distal roots served as
the mesial and distal walls of the
defect, respectively. The bucco-lingual
depth of the defect was approximately
two-thirds the diameter of the tooth
crown. The average width and depth
of the defects was 5 and 3 mm,
respectively. All PDL tissue and
cementum were removed from the
root surface of the defect area using
a curette. Reference notches were
placed in the mesial and distal roots
at the base of the defect using a
0.25 mm diameter round bur
(Fig. 1A).
In each dog, the defects randomly
received one of the following treat-
ments: (i) blood clot in an untreated
defect (negative control); (ii) 10 mg
acemannan sponge (5% w/v); (iii)
20 mg acemannan sponge (10% w/v);
and (iv) sham/no operation as a refer-
ence of the normal anatomy of the
periodontium. The flap was reposi-
tioned and sutured with absorbable
sutures (FSSB, Jestetten, Germany).
The animals received postoperative
antibiotic and analgesic treatment
twice a day using cefazolin 12.5 mg/kg
and carprofen 2.2 mg/kg, respectively.
Two dogs were killed 30 and 60 d
after the operation. Jaw blocks of the
premolar regions, including bone, teeth
and soft tissue, were removed, fixed in
10% neutral formalin buffer, and
demineralized with 4% nitric acid in
10% neutral formalin buffer. Tissue
dehydration was carried out using
ethanol–acetone dehydration and sam-
ples were routinely embedded in paraf-
fin. Five micrometer sections were
prepared from each tissue block in a
lingual–buccal direction.
Histomorphometric analysis
Histomorphometric analysis was per-
formed following the method of
Kosen et al. (30) with some modifica-
tions. Five sections were selected from
each specimen. The first section was
from the mid-point of the furcation
defect and the rest were obtained
every 120 lm in a buccal direction
from the initial section. The selected
sections were stained with hematoxy-
lin and eosin and photographed using
the OLIVIA program (Olympus, Tokyo,
Japan).
The following five histomorphomet-
ric measurements were determined for
each stained section using the IMAGE
PRO-PLUS program, version 6 (Media-
Cybernetics, Rockville, MD, USA)
(Fig. 1C).
1. Defect area: the total area from
the furcation to the apical border
of the notches on the mesial and
distal roots.
Acemannan and periodontal regeneration 167
2. New bone: the percentage of newly
formed alveolar bone area in rela-
tion to the defect area (a).
3. Defect length: the length of the
root surface located between the
notches on the mesial and the dis-
tal roots (b).
4. New cementum: the percentage of
the length of the newly formed
amorphous substance, cementoid-
like tissue or cementum-like tissue
on the root surface in relation to
the defect length (c, d).
5. New PDL length: the percentage
of the length of fibrous tissue
between newly formed cementum
and alveolar bone in relation to
the defect length (e, f).
Statistical analysis
The data were collected and analyzed
using the SPSS program for Windows,
version 17.0 (SPSS, Chicago, IL,
USA). The results were expressed as
mean � standard error. One-way
analysis of variance and Dunnett
multiple comparisons were performed
in this study. Values of p < 0.05 were
considered as statistically significant.
Results
Acemannan-induced periodontal
ligament cell proliferation and
mRNA expression of runt-related
transcription factor 2 and growth/
differentiation factor 5
The [3H]-thymidine incorporation
assay showed that after 24 h, aceman-
nan at concentrations of 2 and 4 mg/
mL significantly increased new DNA
synthesis in PDLCs compared with
the negative control group (p < 0.05;
Fig. 2A). Acemannan at a concentra-
tion of 4 mg/mL exhibited the maxi-
mum effect on DNA synthesis, which
was approximately three-fold that of
the untreated group.
Acemannan at concentrations of 1, 2
and 4 mg/mL significantly upregulated
the mRNA level of Runx2 1.18, 1.17
and 1.25-fold, respectively, compared
with the untreated group (Fig. 2B).
Acemannan also significantly increased
the mRNA level of GDF-5. Aceman-
nan at 1 mg/mL showed the maximum
effect, an approximately 1.48-fold
increase compared with the negative
control group (Fig. 2C).
Acemannan enhanced vascular
endothelial growth factor, type I
collagen and bone morphogenetic
protein 2 expression
After 24 h of incubation, acemannan
at concentrations of 2 and 4 mg/mL
significantly increased the expression
of VEGF 1.93- and 1.72-fold, respec-
tively, compared with the control
group, while slightly increasing the
expression of BMP-2 and type I colla-
gen. However, after 48 and 72 h,
acemannan significantly enhanced
expression of type I collagen and
BMP-2, respectively, compared with
the control group. Acemannan exhib-
ited a dose-dependent upregulation of
type I collagen and BMP-2. Aceman-
nan at concentrations of 2 and 4 mg/
mL exhibited the maximum effect on
BMP-2 and type I collagen expres-
sion, respectively (Fig. 3).
Acemannan stimulated alkaline
phosphatase activity and mineral
deposition
After 72 h of treatment, acemannan at
concentrations of 2 and 4 mg/mL sig-
nificantly enhanced PDLC ALPase
activity 1.39- and 1.63-fold, respectively
(Fig. 4A). AR staining indicated that,
by 9 and 18 d, acemannan induced
mineral deposition by PDLCs. More
intense AR staining was observed in
the acemannan-treated groups com-
pared with the negative control group.
The increase in mineralized nodules
occurred in a dose-dependent manner.
The greatest mineralization was
observed at a concentration of 4 mg/
mL (Fig. 4B and 4C).
Characterization and
biocompatibility of acemannan
sponges
SEM evaluation revealed that the
concentration of acemannan used in
A
C
D
B
Fig. 1. Class II furcation defect. Schematic illustration of the class II furcation defects (A).
A defect created at the premolar furcation area (B). Histomorphometric measurements
performed in hematoxylin and eosin sections (C). The formulas used to calculate new
cementum formation, new bone formation, and PDL length (D). (a) New bone; (b) defect
length; (c, d) new cementum; and (e, f) new PDL. PDL, periodontal ligament.
168 Chantarawaratit et al.
the preparation of acemannan sponges
determined their pore diameter and
pore size. Increased concentration of
acemannan resulted in larger pore
diameters and pore areas (Fig. 5A).
The pore geometry of both the 5%
and 10% acemannan sponges was
generally elliptical (Table 2). TheMTT
assay and direct contact assay results
indicated that the acemannan sponges
were biocompatible with PDLCs. The
acemannan sponge extracts signifi-
cantly enhanced cell proliferation com-
pared with the control group (Fig. 5B).
Moreover, the direct contact test
showed that PDLs migrated towards,
and proliferated around, the aceman-
nan sponges (Fig. 5C).
Acemannan-induced periodontal
regeneration in a class II furcation
defect model
Following surgery, all dogs recovered
uneventfully and gained weight over
the experimental period (data not
shown). The animals were examined
for inflammation and foreign body
interaction 30 and 60 d after the oper-
ation, and neither was detected in
either control or acemannan-treated
groups.
Histological analysis revealed that
30 d after treatment, the defects were
partly filled with alveolar bone. The
negative control and acemannan-
treated groups all demonstrated new
alveolar bone, cementum and PDL
formation (Fig. 6A–C). These tissues
extended from the pre-existing bone,
cementum and PDL at the base of the
defect. However, the amount of new
bone and cementum was much greater
in the acemannan-treated groups than
in the control group. Serial histologi-
cal sections demonstrated that bone
formation progressed from the mid-
point of the furcation defect in a buc-
cal direction. Sixty days post-surgery,
all groups demonstrated more alveo-
lar bone, cementum and PDL forma-
tion than that seen after 30 d
(Fig. 6D–F). Marked periodontal
regeneration, including new bone,
cementum, and PDL, was detected in
the acemannan-treated groups.
Examining the newly formed bone
at 30 d post-surgery more closely
revealed woven bone with narrow tra-
beculae lined with osteoblasts. The tra-
beculae contained irregularly arranged
osteocytes (Fig. 7A–C). Sixty days
post-surgery, more new lamellar bone
formation containing osteons and
Haversian canal patterns was observed
in the control and acemannan-treated
groups (Fig. 7D–F). Thin cellular
cementum and cementoid-like tissue
partially covered the root surface after
30 d (Fig. 8A, a–c). The newly formed
PDL was characterized by a cell-rich
and vascularized dense connective
tissue between the root surface and
new bone. The PDL fibers were loose,
A
B
C
Fig. 2. Acemannan-induced PDLC proliferation and the Runx2 and GDF-5 mRNA
expression in PDLCs after 24 h. Acemannan significantly enhanced PDLC proliferation at
concentrations of 2 and 4 mg/mL (A). Acemannan at concentrations of 1, 2 and 4 mg/mL
significantly upregulated mRNA expression of Runx2 (B). Acemannan at concentrations
of 0.25, 0.5, 1, 2 and 4 mg/mL significantly upregulated mRNA level of GDF-5 (C). GAP-
DH served as internal control. *Compared with the untreated group; p < 0.05, n = 3.
GDF-5, growth/differentiation factor 5; PDLC, periodontal ligament cell; Runx2, runt-
related transcription factor 2.
Acemannan and periodontal regeneration 169
poorly organized and irregularly orien-
tated (Fig. 8B, a–c). Sharpey’s fibers
inserted into both the new cementum
and alveolar bone were observed in
some specimens by 30 d after the oper-
ation (Fig. 8B, b). At 60 d post-
treatment, the width and length of the
cementum in the acemannan-treated
groups was greater than that of the
untreated group (8A, d–f). The PDL
fibers were denser and better organized
compared with the specimens at 30 d
(8B, d–f). However, the PDL space of
all groups was wider than that of the
pre-existing space.
The histomorphometric analysis
indicated that the application of
acemannan to the furcation defects
induced greater periodontal tissue
regeneration than in the control group
(Fig. 9). There were significant differ-
ences in the mean percentage of new
bone formation between the aceman-
nan-treated groups and untreated
control group at 30 and 60 d post-
implantation (Fig. 9A). Acemannan
also significantly induced cementum
and PDL formation after 60 d of
treatment (Fig. 9B and 9C). At 60 d
post-surgery, the values of new bone,
cementum, and PDL length formation
found in the 10 mg acemannan
sponge-treated group were slightly
higher than those of the 20 mg group.
Discussion
Tissue engineering and regenerative
medicine in combination with peri-
odontal therapy can be used to over-
come the limitations of conventional
treatment and regenerate new peri-
odontal tissue. The PDL is a fibrous
connective tissue connecting the alve-
olar bone and tooth root cementum.
In addition to anchoring the teeth
in the jaw, the PDL is a key contribu-
tor of the cells involved in periodon-
tal regeneration (31). Many studies
have demonstrated that the PDL con-
tains stem cells that participate in
periodontal tissue homeostasis and
regeneration. These cell populations
contain progenitors of the fibroblast
and osteoblast/cementoblast cell lin-
eages, which are involved in periodon-
tium regeneration. Under suitable
inductive conditions, PDLCs prolifer-
ate and differentiate to osteoblast-like
and cementoblast-like cells, express
bone-associated protein markers and
generate mineralized nodules and
ectopic hard tissue (32,33). These data
suggest that PDLCs have the poten-
tial to regenerate all types of peri-
odontal tissues.
In the present study, acemannan
functioned as a bioactive molecule,
stimulating PDLC proliferation, expres-
sion of Runx2, GDF-5, BMP-2,
VEGF, type I collagen, ALPase activ-
ity, and mineral deposition. Runx2 is
a transcription factor considered to
be a regulator of osteoblast/cemento-
blast differentiation and function
(34,35). BMP-2, GDF-5 and VEGF
are important growth factors for peri-
odontal tissue healing and regenera-
tion. BMP-2 is one of the most potent
growth factors inducing osteogenic/
cementogenic differentiation (36–38).GDF-5 has been demonstrated
A
B
C
Fig. 3. Acemannan promoted the expression of VEGF, type I collagen, and BMP-2. (A)
Acemannan significantly induced VEGF expression at 24 h, (B) type I collagen at 48 h
and (C) BMP-2 at 72 h. *Compared to the untreated group; p < 0.05, n = 3. BMP-2, bone
morphogenetic protein 2; VEGF, vascular endothelial growth factor.
170 Chantarawaratit et al.
to stimulate PDL development, new
cementum formation and bone regen-
eration (39,40). GDF-5 and its recep-
tor have been detected in PDLCs
(41). Intrabony defects treated with
BMP-2 or GDF-5 exhibited enhanced
periodontal healing/regeneration with
new alveolar bone, cementum and
PDL formation (37,39,42). VEGF has
been shown to induce angiogenesis by
increasing endothelial cell prolifera-
tion and migration (43). BMP-2 and
VEGF have been observed to stimu-
late dental follicle cells to differenti-
ate toward an osteoblast/cementoblast
phenotype (44,45). Therefore, aceman-
nan may accelerate periodontal tissue
healing/regeneration by stimulating
PDLC expression of BMP-2, GDF-5
and VEGF.
In addition to enhanced growth
factor synthesis, acemannan induced
the expression of type I collagen,
ALPase activity and mineral deposi-
tion by PDLCs. Type I collagen is the
predominant extracellular matrix pro-
tein in the PDL, cementum and alveo-
lar bone (46,47), providing physical
support and acting as a template
for mineral deposition in hard tissue.
A
C
B
Fig. 4. Acemannan increased ALPase activity and mineral deposition. Acemannan significantly enhanced periodontal ligament cell
ALPase activity after 72 h of incubation at concentrations of 2 and 4 mg/mL (A). *denotes statistical difference with the untreated group;
p < 0.05, n = 3. Acemannan increased periodontal ligament cell mineral deposition at 9 and 18 d (B, C). The 0.5, 1, 2 and 4 mg/mL
acemannan-treated groups had larger and more intensely stained areas than the untreated group. By quantitative alizarin red staining, the
0.5, 1, 2 and 4 mg/mL acemannan-treated groups significantly promoted mineralization. *,#Compared with the untreated group at the 9th
and 18th day of incubation, respectively, p < 0.05, n = 9. ALPase, alkaline phosphatase.
Acemannan and periodontal regeneration 171
ALPase is an osteogenic/cementogenic
differentiation early phase marker
(48). Increased levels of ALPase activ-
ity in periodontal tissues correlated
with periodontal tissue regeneration
(49,50). Mineral deposition is a
unique characteristic of hard tissue
forming cells. Our data suggest that
acemannan can induce extracellular
matrix synthesis and the differenti-
ation of PDLCs into hard tissue
forming cells, osteoblasts and ce-
mentoblasts, which generate bone and
cementum, respectively.
Although our in vitro results indi-
cated acemannan induced PDLC
Table 2. Characteristic of the sponge pores
Parameters 5% Acemannan sponge 10% Acemannan sponge
Pore diameter (lm) 167.95 � 36.17 189.35 � 69.42
Circularity 0.72 � 0.16 0.58 � 0.2
Pore size/area (lm2) 1.843E4 � 7.105E3 2.7552E4 � 1.9867E4
A
C
Ba
a b c
d e f
b
c d
Fig. 5. Scanning electron microscopy analysis of the 5% (a, c) and 10% (b, d) acemannan sponges. Note the increased pore size in the
10% sponges (A). The acemannan sponge extracts significantly increased periodontal ligament cell proliferation (MTT assay) *Compared
with the untreated group; p < 0.05, n = 3. (B). Acemannan sponge biocompatibility with periodontal ligament cell. Direct contact test of
the 5% (a–c) and 10% (d–f) acemannan sponges was analyzed via the phase contrast microscope at 0 (a, d), 24 (b, e), and 72 h (c, f) after
seeding. #Sponge (C).
172 Chantarawaratit et al.
activity, which could lead to periodon-
tal tissue regeneration, acemannan in
solution may not be appropriate for
applying to periodontal pockets to
induce periodontal regeneration because
in solution acemannan would be
diluted by crevicular fluid. Because of
its physical properties as a polysac-
charide, acemannan can be prepared
as a sponge. SEM analysis revealed
acemannan sponges contained inter-
connected pores with diameters rang-
ing from 100 to 260 lm. This
diameter range is suitable for PDLC
attachment and growth (51). After
being inserted into a periodontal
defect, an acemannan sponge would
absorb and maintain serum or inter-
stitial fluid from the surrounding tis-
sue, which is enriched with growth
factors and nutrients that promote tis-
sue healing. We found that aceman-
nan sponges were biocompatible and
exhibited biological activity as shown
by their ability to stimulate PDLC
migration and proliferation. This sug-
gests that an acemannan sponge could
function in vivo by inducing PDLC
proliferation and activity and act as a
scaffold permitting PDLC infiltration
and growth.
Currently, the precise molecular
mechanisms governing the effects
of acemannan on cellular activity
remain unknown. Based on its struc-
ture, sugar composition and molecu-
lar weight, acemannan could bind to
a specific cell surface receptor and
then initiate downstream intracellular
signaling pathways to stimulate prolif-
eration and differentiation. Aceman-
nan induced the phosphorylation of
p38 mitogen-activated protein kinase
(MAPK) in dental pulp cells. Preincu-
bation with the specific p38 MAPK
inhibitor SB203580 resulted in a 50%
decrease in the phosphorylation level
of p38 MAPK as compared with the
acemannan-treated group (52). Peri-
odontal ligament cell proliferation,
gene expression, osteogenic differenti-
ation, and mineralization have all
been shown to be regulated by p38
MAPK (53). Therefore, acemannan
may activate periodontal ligament cell
proliferation and differentiation via
the MAPK pathway. Another possi-
ble pathway is via acemannan binding
to the mannose receptor. The man-
nose receptor family is composed of
Endo180 (CD280), the M-type phos-
pholipase A2 receptor, and the DEC-
205/gp200-MR6 subfamily. These
receptors contain C-type lectin-like
domains that recognize mannose,
fructose or N-acetylglucosamine at
the end of a polysaccharide chain
(54,55). After binding, the ligand–receptor complex is internalized and
subsequently releases the ligands
inside the cell. To better understand
the molecular mechanisms of aceman-
nan activity, future study is required.
In periodontal disease, the involve-
ment of a furcation defect is consid-
ered a complex and severe condition,
causing extensive and rapid attach-
ment loss and tooth loss. The success
of furcation defect treatment is often
limited (56,57). To demonstrate the
effect of acemannan on periodontal
regeneration, an in vivo class II furca-
tion defect model was chosen. An
advantage of a class II furcation
A B C
D E F
Fig. 6. Histology of periodontal regeneration in class II furcation defects at 30 d (A–C)
and 60 d (D–F) post-surgery of control group (A, D), 10-mg acemannan sponge group (B,
E) and 20-mg acemannan sponge group (C, F). At both time points the sponge-treated
groups showed more new bone and cementum formation than the control group. NB, new
bone; PB, pre-existing bone; black arrowhead, new cementum; white arrowhead, pre-exist-
ing cementum; white arrow, the apical limit of the defect. Scale bar = 500 lm.
Acemannan and periodontal regeneration 173
defect model is that it limits the severe
gingival recession problems often
found in class III furcation defect
models. Severe gingival recession can
result in the loss of test material from
the defect and exposure of the defect
area leading to microbial contamina-
tion (58). However, class II furcation
defect models still have limitations in
their use in periodontal regeneration
studies. The lingual wall of a class II
defect is in contact with intact alveolar
bone, cementum and PDL, which is
not the case in a class III defect. Con-
sequently, the lingual defect area has a
greater healing rate than the buccal
area. Sectioning along the mesiodistal
plane of class II furcation defects may
lead to some difficulties in interpreting
the histological results. To account for
this, we employed criteria used in a
previous study to select the sections to
be examined (30). In a buccal direc-
tion beginning at the midsection, a
section every 120 lm of each defect
was selected and measured. The mean
of the histomorphometric results
obtained from each distance was used
in the statistical analysis.
A study by Jittapiromsak et al.,
reported that a dose of 300–600 lgacemannan was effective as a direct
pulp capping material for a pinpoint
pulpal exposure area of 1 mm2 (12,59).
The volume of the class II furcation
defects in the present study was
37 mm3. For use in a three-dimen-
sional defect, we calculated that the
appropriate amount of acemannan
sponge per defect should be 11–22 mg.
Therefore, 10 and 20 mg acemannan
sponges were prepared and placed in
the defects. To minimize the effect of
bone density variations between the
upper and lower jaw, and between
each animal, every group was repre-
sented in each jaw of each animal. In
this preliminary study, a convenient
sample of dogs and defects was used to
evaluate the effect of acemannan on
periodontal regeneration in canines.
Histomorphometric analysis revealed
that in all groups, more bone than
cementum was regenerated. This may be
because cementum has no direct blood
supply, lymphatic drainage or innerva-
tion. Thus, cementum lacks sources of
important factors for remodeling, repair
and regeneration as compared with
bone, which contains a blood supply
system. Consequently, cementum repair
and regeneration is lower and more
unpredictable than bone regeneration
(20,60,61). In our histological evalua-
tion, the new cementum, which covered
the denuded root dentin surface, exhib-
ited various patterns; amorphous eosin-
ophilic substance, cementoid-like tissue
and cellular cementum. This finding
corresponds to a previous report (62).
Ankylosis is the pathological fusion
between tooth root and alveolar bone.
Our study did not reveal any instances
of ankylosis in either the control or
experimental groups. Ankylosis has
been proposed to be caused by an
imbalance between new alveolar bone
and periodontal tissue formation,
A B C
D E F
Fig. 7. Histology of bone regeneration in class II furcation defects at 30 d (A–C) and 60 d
(D–F) post-surgery of control groups (A, D), 10-mg acemannan sponge groups (B, E) and
20-mg acemannan sponge groups (C, F). At 30 d of treatment, newly formed woven bone
was observed, while at 60 d, a more mature bone pattern containing osteons was found.
NB, new bone; PB, pre-existing bone.
174 Chantarawaratit et al.
which impairs or hinders periodontal
regeneration. In vivo, ankylosis is asso-
ciated with the application of recombi-
nant human BMP-2. The possible
explanation is that BMP-2 is strongly
osteoinductive with low periodontal
regeneration activity, while acemannan
can stimulate both soft and hard tissue
regeneration (10–14,63,64).In some of our samples, we found a
small space, known as slit formation,
located between newly formed cemen-
tum and denuded dentin. Although the
mechanism of slit formation is still
unclear, this phenomenon is com-
monly seen, indicating a weak cohesion
between cementum and dentin (58,
65–67). The formation of a smear layer
on the surgically denuded dentin sur-
face before new cementum synthesis
has been proposed as its cause (66,67).
Electron microscopy revealed the
smear layer as an electron-dense, gran-
ular and non-collagenous layer present
between these tissues (65,68). This
smear layer can inhibit the reattach-
ment between newly formed cementum
and dentin. Another possible cause of
slit formation is tissue shrinkage dur-
ing the paraffin sectioning process that
can break the weak attachment
between these two tissues (66). Recent
studies have shown that bone sialopro-
tein and osteopontin play a role in
adhesion between these two tissues
(69,70).
Currently, a number of bioactive
substances and techniques have been
introduced as clinical periodontal regen-
eration therapies such as GEM21,
EMDOGAIN and guided tissue
regeneration (65,66,71–74). GEM21 is
a mixture of recombinant human
platelet derived growth factor BB
and beta-tricalcium phosphate, while
EMDOGAIN is a purified extract of
porcine enamel matrix proteins, lar-
gely consisting of amelogenin. Guided
tissue regeneration is a technique that
uses membranes as a barrier to sup-
port the ingrowth of periodontal tis-
sue and inhibit the invasion of
gingival epithelium in to the periodon-
tal defect. There have been many mod-
ifications made to the membrane,
including gene, protein or cell therapy
approaches. All of these materials have
been reported as successful in animal
and clinical periodontal regeneration
studies (71,72).
Based on the source and composi-
tion of acemannan, the sponges may
be an alternative biomaterial for
patients who wish to avoid the use of
recombinant protein or have restric-
tions on the source of a material.
Moreover, in sponge form, aceman-
nan is easy to insert into periodontal
defects. An acemannan sponge can be
conveniently combined with various
types of periodontal surgery tech-
niques. Unlike a solution or gel, an
A
B
a b c
a b c
d e f
d e f
Fig. 8. Histology of cementum and PDL regeneration in class II furcation defects at 30 d
(a–c) and 60 d (d–f) post-surgery of control groups (a, d), 10-mg acemannan sponge
groups (b, e), and 20-mg acemannan sponge groups (c, f). The width and length of the
cementum in the acemannan-treated groups was greater than that of the untreated group
(A). At 60 d post-surgery, the PDL fibers were denser and more organized at 30 d post-
surgery (B). NB, new bone; PB, pre-existing bone; NC, new cementum; PC, pre-existing
cementum; PDL, PDL space; D, dentin; black arrow, Sharpey’s fibers; white arrow, the
apical limit of the defect. Scale bar = 50 lm.
Acemannan and periodontal regeneration 175
acemannan sponge remains in the
defect for several weeks and gradually
releases its bioactive molecules to pro-
mote regeneration of the surrounding
tissue. We found in our in vivo study
that the sponge itself is able to stop
excessive bleeding. The blood and tis-
sue fluid held in the sponge can be a
source of growth factors and nutrients
for tissue regeneration. The ability to
physically remain in the surgical
defect might help to decrease epithe-
lial downgrowth and provide space
for periodontal tissue regeneration.
With some modification, acemannan
can be prepared as a scaffold and be
used as a cell carrier in tissue engi-
neering techniques. However, more
animal and clinical studies regarding
the efficiency of acemannan on peri-
odontal regeneration and a compari-
son with these other materials and
techniques are required.
We note that the class II furcation
defects in our study were iatrogenically
created in healthy periodontal tissue.
Therefore, there was neither microor-
ganism invasion nor the chronic
inflammation and tissue destruction as
occurs in periodontal defects. To con-
firm our data and verify its clinical
applicability, further in vivo studies of
acemannan in bacteria-induced peri-
odontal defects should be performed.
Conclusion
In conclusion, acemannan increased
PDLC proliferation, growth factor and
extracellular matrix synthesis, differen-
tiation and mineralization in vitro,
and enhanced periodontal regeneration
in class II furcation defects. Taken
together, our data suggest that ace-
mannan could be a candidate herbal
biomolecule for periodontal tissue
regeneration.
Acknowledgements
We thank Professor Dr. Visaka Lim-
wong, Associate Professor Dr. Dolly
Methatharathip, and Dr. Kevin A.
Tompkins for their valuable sugges-
tions. This work was supported by the
Higher Education Research Promotion
and National Research University Pro-
ject of Thailand (AS549A), Thailand
Government Research Fund, Develop-
ing Research Unit in Herbal Medicine
for Oral Tissue Regeneration Fund,
and the 90th Anniversary of Chul-
alongkorn University Fund (Ratcha-
daphiseksomphot Endowment Fund).
No conflicts of interest exist.
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