Hindawi
BioMed Research International
Volume 2022, Article ID 2656784, 12 pages
https://doi.org/10.1155/2022/2656784
Research Article
The Immunomodulatory and Regenerative Effect of Biodentine™
on Human THP-1 Cells and Dental Pulp Stem Cells: In
Vitro Study
Duaa Abuarqoub ,1 Nazneen Aslam ,2 Rand Zaza ,2 Hanan Jafar ,2,3
Suzan Zalloum ,2 Renata Atoom ,2 Walhan Alshaer ,2 Mairvat Al-Mrahleh ,2
and Abdalla Awidi 2,3
1
Department of Pharmacology and Biomedical Sciences, Faculty of Pharmacy and Medical Sciences, University of Petra,
Amman, Jordan
2
Cell Therapy Center, The University of Jordan, Amman, Jordan
3
School of Medicine, The University of Jordan, Amman, Jordan
Correspondence should be addressed to Duaa Abuarqoub; duaa.abuarqoub@uop.edu.jo
and Abdalla Awidi; abdalla.awidi@gmail.com
Received 12 May 2022; Revised 9 June 2022; Accepted 18 August 2022; Published 2 September 2022
Academic Editor: Bruna Sinjari
Copyright © 2022 Duaa Abuarqoub et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
Background. Pulp tissue affected by deep caries and trauma can be protected by vital pulp therapies in which pulp regeneration
success depends on the degree of pulp inflammation and the presence of regenerative signals. Reparative dentinogenesis
requires dental pulp stem cell (DPSC) activity which can be stimulated by many bioactive molecules to repair the dentine,
mediating a balance between the inflammatory response and the reparative events. Therefore, this study was performed in
order to investigate the immune-inflammatory effect of Biodentine capping material on DPSCs and macrophages. Method.
THP-1, a human monocytic cell line, was differentiated to macrophages, and flow cytometry was used to analyze the
expressions of specific macrophage markers. LPS-mediated infection was created for macrophages and DPSCs followed by
treatment with Biodentine. CBA array was used to investigate the cytokine secretion followed by qPCR. Migration potential of
treated DPSCs was also determined. Results. Our results showed that THP-1 cell line was successfully differentiated into
macrophages as shown by surface marker expression. CBA array and qPCR results showed that Biodentine-treated DPSCs and
macrophages upregulated anti-inflammatory cytokines and downregulated proinflammatory cytokines. Also, Biodentine
enhances the migration potential of treated DPSCs. Conclusion. Biodentine capping material mediated the polarization of M1
to M2 macrophages suggestive of tissue repair properties of macrophages and enhanced the anti-inflammatory cytokines of
DPSCs responsible for dentine-pulp regeneration.
1. Introduction
Pulp tissue is the most important tissue for the development
of the tooth, providing strength and vitality. Unfortunately,
the pulp might get inflamed or lose its functionality and
structural integrity when exposed to an external stimulus
such as traumas, deep caries, and attrition or restorative
treatments. As a result of such exposures, dental pulp cells
start to differentiate into odontoblasts which are responsible
for the reparative dentine formation, through increasing the
secretion of dentine matrix proteins and inducing dentine
mineralization [1]. However, when teeth lose their pulps,
2
they also lose the sensation of environmental changes. Moreover, pulpless teeth start to lose their potential to regenerate
the dentine which makes the progression of caries easier and
unremarkable [2]. The pulp capping and pulpotomy named
as “vital pulp therapy” play a major role in preserving and
protecting the vital pulp from any external stimulus; hence,
the protected pulp would be able to perform its function
properly by forming the reparative dentine bridges which
is an indicator of the success of pulp therapy [3].
Capping materials are designed to stimulate the dentinogenesis process in vital pulp therapy. These materials are
required to be biocompatible, retain high physiochemical
standards, and stimulate the formation of dentine and the
differentiation of dental pulp cells [4]. Calcium hydroxide
(CH) was the first pulp capping biomaterial to be announced
in the clinical field of dentistry [5]. It showed high capacity
to stimulate dentine regeneration and has antimicrobial features. Nonetheless, the use of CH has become limited in the
practice due to its high solubility in the oral fluids and its
inefficient sealing properties. Moreover, CH fails to adhere
to the native dentine, which leads to formation of tunnels
in dentine bridges [5, 6].
Recently, a new biomaterial has been introduced to the
capping materials called mineral trioxide aggregate (MTA).
In comparison with CH, MTA showed more favorable characteristics such as self-setting ability that improves the production of less porous dentine bridges with high thickness
in a very fast rate [7]. Yet, from the clinical point of view,
MTA showed some drawbacks and limitations. MTA is
composed of tricalcium aluminate which is responsible for
the discoloration of tooth after surgery [8]. Moreover, it
has a long setting time, which renders the practical use of
MTA inefficient [9].
Biodentine (BD) is a new bioactive dentine substitute
composed of calcium silicate and possesses similar mechanical
properties as dentine. The high density, low porosity, quick
setting time, good biocompatibility, beneficial impact on the
critical pulp cells, and capacity to promote reparative and tertiary dentine production are all characteristics of the BD
cement [10, 11]. Similar to MTA, Biodentine (BD) can be
applied in both dental crown and root treatments [12, 13].
The main uses of Biodentine are direct pulp capping and
pulpotomy [14], root-end filling [12], cervical and radicular
restorations [13], dentine regeneration, and sealing the communications between pulp space and periodontal ligament
[12]. However, BD is superior to calcium hydroxide in terms
of its physical and mechanical properties, including low porosity, high compressive strength, low solubility, high density,
and superior capacity to seal to dentine [11]. BD’s bridge is
produced in a very well-arranged pattern, which is localized
and organized at the damage site. Additionally, the quality of
the produced dentine was significantly better than that of calcium hydroxide, as the orthodentin organization of Biodentine’s dentine bridges was seen with very clear visible dentine
tubules. Additionally, cells effectively secreting the structure
displayed osteopontin and DSP expression, two important
regulators of reparative dentine development, in addition to
the formation of new blood vessels inside the dentine bridges,
resulting in the generation of vasodentine [6, 15].
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For in vitro cultures, Biodentine (BD) showed low cytotoxic effects and increased proliferation potential in cultures
of pulp cells, osteoblasts, and periodontal ligaments [16–19].
Similar to MTA, in vivo studies showed that Biodentine
initiated sufficient biological response, comparable to MTA.
On the other side, Biodentine induces a moderate immunological response but plays a key role in modulating this
inflammatory response over time [11, 20].
Generally, the pulp tissue of a healthy tooth is directly
involved in the immunoreactivity with other immune cells
such as macrophages, which originated from monocytes that
are highly distributed through the pulp tissue in quiescent
state. The use of capping biomaterials to treat caries can elicit
immunological reaction, starting the inflammatory response
and harboring of macrophages into the inflammation site
[20–22]. The direct contact of macrophages with the biomaterial that is used in the filling process stimulates these
immune cells to produce more cytokines leading to strong
inflammation [23, 24]. The secretion of cytokines represents
processes in repair and destruction [25]. The first step of
inflammation after the use of the filling material is the secretion of proinflammatory cytokines, interleukin-1 (IL-1),
interleukin-6 (IL-6), interleukin-1beta (IL-1β), tumor necrosis factor (TNF), monocyte chemoattractant protein (MCP),
and macrophage inflammatory protein1 (MIP1) [24].
Hence, the analysis of the toxicological and immunological effect of BD is highly important in order to understand
the immune-inflammatory effects of BD. Very few studies
have investigated the immunological effect of BD on
immune cells. Thus, the significance of our study is aiming
to explore the immunological effects of BD when cocultured
directly with human THP-1 derived macrophage immune
cells, where this cell line is considered an ideal cell model
to study the inflammatory response of BD by measuring
the expression and secretion levels of released cytokines.
Additionally, this study is aimed at evaluating the impact
of BD on the migration, inflammation, and regeneration of
pulp tissue, when BD was cocultured directly with dental
pulp progenitor stem cells (DPSCs). Our null hypothesis
was established that there was no difference in the immunomodulatory effect and regeneration potential of cells after
exposure to Biodentine (BD).
2. Materials and Methods
2.1. Study Design. Two different cell types were used: THP-1
human monocytic cell line and dental pulp progenitor stem
cells (DPSCs) for inflammation and regeneration experiments, as shown in Figure 1.
2.2. Cell Culture of THP-1. THP-1 human monocytic cell
line (ATCC, USA) was cultured as previously described
[26], in RPMI 1640 media (Hyclone, USA) containing 20%
fetal bovine serum (Gibco, USA) in addition to 4.5 g/l DGlucose (Sigma, USA) in a 5% CO2 incubator at 37°C; media
exchange was performed every 2-3 days.
2.2.1. Differentiation of THP-1 into Macrophages. The
differentiation of THP-1 into macrophages was done as
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Dental pulp stem cells
(DPSCs)
THP-1 cells
Sample collection; third molar
teeth.
Isolation of dental pulp stem cells
(DPSCs).
Treatment of DPSCs by LPS and
biodentine (BD).
Quantification of inflammatory
cytokines cytometric beads array
(CBA)
Gene expression (RT-qPCR)
Wound healing assay
Cell Culture of THP-1.
Differentiation of THP-1 into
macrophages
Characterization by flow/
cytometry: Monocytes vs
macrophages.
Activation of macrophages by LPS
and BD.
Expression profile of macrophages
by flow cytometry after BD
activation
Quantification of inflammatory
cytokines cytometric beads array
(CBA)
Gene expression (RT-qPCR)
Figure 1: Study design of the work plan.
previously described [26]. Briefly, 2 × 105 cells/ml of monocytic THP-1 cells were cultured in 24-well tissue culture
plates (SPL, Korea) for 24 h. Following that, the differentiation was done by treating cells with 100 nM phorbol 12myristate 12-acetate (PMA, Bio-Techne, USA) for the next
24 h. Cell adherence is an indicator of successful differentiation into macrophages; therefore, nonadherent cells were
aspirated from the culture.
2.2.2. Characterization by Flow Cytometry: Monocytes vs.
Macrophages. In order to determine the variation in the
immunophenotyping characteristics, the expression of several cell surface markers was measured before and after the
differentiation of THP-1 into macrophages. Therefore, cells
were collected and stained with the following markers:
CD68-FITC (eBioscience, USA), CD14-PE-cy7 (BD Biosciences, USA), CD206-PE (BD Biosciences, USA), CD11b-PE
(Bioscience, USA), HLA-DR-PerCPCy5.5 (BD Biosciences,
USA), SSEA1-FITC (BD Biosciences, USA), CD117-PE (BD
Biosciences, USA), CD49f-PE (eBioscience, USA), CD29APC (BD, USA), and CD45-FITC (BD Biosciences, USA).
FACSDiva 8 software and FACSCanto II (BD Biosciences,
USA) were used to acquire the samples. Data were analyzed
by using FlowLogic software (version 7.3, Australia).
2.2.3. Activation of Macrophages by LPS and Biodentine. The
differentiated macrophages were activated by treating cells
with 1 μg/ml lipopolysaccharide (LPS, Santa Cruz) for 24 h.
Following that, medium was aspirated and fresh media containing 2 mg/ml of Biodentine were added for the next 24 h.
Untreated cells were used as control. After that, media and
cells were collected from both treated and control cells.
2.2.4. Expression Profile of Macrophages by Flow Cytometry
after Biodentine Activation. To explore the effect of Biodentine on the immunophenotype of LPS-treated macrophages,
surface marker expression profile was evaluated by flow
cytometry.
First, cells were harvested, collected, and stained with the
following fluorinated antibodies: CD68-FITC (eBioscience,
USA), CD14-PE-cy7 (BD Biosciences, USA), CD206-PE
(BD Biosciences, USA), CD49F-PE (eBioscience, USA),
CD29-APC (BD, USA), CD11b-PE (eBioscience, USA),
HLA-DR-PerCPCy5.5 (BD Biosciences, USA), CD117-PE
(BD Biosciences, USA), CD45-FITC (BD Biosciences,
USA), and SSEA-FITC (BD Biosciences, USA), for 30 min
at room temperature. Samples were acquired and analyzed
with FACSDiva software version 8 on a FACSCanto II (BD
Biosciences, USA) and FlowLogic software 7.3.
2.3. Isolation of Dental Pulp Stem Cells (DPSCs)
2.3.1. Sample Collection. Human impacted third molars were
collected from healthy donors aged 24-, 25-, and 29-year-old
(N = 3). All donors were healthy without any medical complications. Additionally, the collected teeth were healthy
(not infected) and free of any dental caries, and the redness
of the pulp is an indicator of its viability.
2.3.2. Cell Culture of DPSCs. Dental pulp stem cells
(DPSCs) were isolated from human third molars, as previously described [27]. The obtained DPSC cells were incubated in a 5% CO2 incubator at 37°C, until reaching 7080% confluence.
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Table 1: Primer set of inflammatory cytokines.
Gene
IL-10
IL-1β
TGF-β
IL12-p40
TNF-α
IL-6
IL-8
PPIA “cyclophilin A”
F
R
GCCAAGCCTTGTCTGAGATGATCC
CAGAAGTACCTGAGCTCGCC
GCGCGAGATCCTCTCCATTT
CATCTGCCTCTTCTTGTGGGT
CATCTGCCTCTTCTTGTGGGT
GGCACTGGCAGAAAACAACC
CTGGCCGTGGCTCTCTTG
TCCTGGCATCTTGTCCATG
CATTCTTCACCTGCTCCACGGCC
AGATTCGTAGCTGGATGCCG
AGGTCCAGCATGAACATGGG
GACTGGGTCCGAGGGATCTT
GACTGGGTCCGAGGGATCTT
GCAAGTCTCCTCATTGAATCC
CCTTGGCAAAACTGCACCTT
CCATCCAACCACTCAGTCTTG
2.3.3. Treatment of Dental Pulp Stem Cells (DPSCs) by LPS
and Biodentine (BD). DPSCs were activated by using lipopolysaccharide (1 μg/ml LPS, Santa Cruz) for 24 h. Then,
culture medium was replaced with fresh media containing
2 mg/ml of BD for further 24 h. Untreated cells were used
as control cells. After the incubation period, media and cells
were collected from both groups and stored at −80°C.
2.4. Quantification of Inflammatory Cytokine Cytometric
Bead Array (CBA). To evaluate the impact of Biodentine
(BD) on the secretion of cytokines from macrophages and
DPSCs, a panel of cytokines containing IL-6, IL-8, IL-10,
TNF-α, IL-1β, and IL-12p70 was utilized and the corresponding proteins were measured via human inflammatory
cytokine CBA (BD Biosciences, USA) by flow cytometry.
Samples were analyzed as previously described [26].
2.5. Gene Expression (RT-qPCR). To measure the impact of
Biodentine (BD) on the expression of cytokines of treated
macrophage cells and DPSCs on gene level, qPCR was
performed.
First, BD-treated cells either THP-1 macrophages or
DPSCs and their control cells were harvested and collected
by using 0.25% trypsin EDTA (Gibco, USA). Then, RNA
was extracted from treated cells and their control by using
Trizol-hybrid method (Qiagen, USA). Q-PCR analyses were
performed, as previously described [26]. Q-PCR was performed by using CFX96 (Bio-Rad, Hercules, CA, USA),
with the following conditions: denaturing 95°C for 10 s,
annealing 60°C for 15 s, and extension 72°C for 10 s, and
repeated in a 35-PCR cycle. The fold change of the target
gene was normalized compared to the differentiated macrophages (THP-1 cells stimulated with PMA only). Additionally, for DPSC-treated cell fold change of the target gene
was normalized to DPSCs, which is not activated by LPS.
The specific primer set used for analysis is listed in
Table 1. Gene fold regulation was calculated by using the
following equations:
Activated sample : ∆Ct = Ct GOI − Ct HKG,
Reference sample : ∆Ct = Ct GOI − Ct HKG,
∆∆Ct = ∆CtTreated sample −∆CtReference sample :
Gene fold regulation = 2−∆∆Ct :
ð1Þ
GOI stands for gene of interest, and HKG stands for
housekeeping gene.
2.6. Migration Experiment
2.6.1. Wound Healing Assay (Scratch Assay). The wound
healing assay was performed as previously described [28].
Briefly, 2 × 105 of DPSC cells (at P3) were seeded into 6well culture plates (TPP, USA) until reaching 100% confluent monolayer. A starvation step was followed by adding
serum-free medium to the 100% confluent cells for 24 h.
Then, a scratch was made on the confluent layer of cells.
Then, inflicted monolayers were washed with PBS to remove
cell debris and then treated with 2 mg/ml of α-MEM containing Biodentine, in addition to the cell culture medium
which is used as a control for 24 h. The inflicted cultured
cells were observed using an inverted microscope (Axio
Vert, Zeiss, Germany) to detect the differences in closure
pattern at two different time points 0 and 24 h.
2.7. Statistical Analysis. The results were analyzed by GraphPad Prism and Microsoft Windows Excel to determine the
statistical differences among all assays. For the expression
profile of undifferentiated and differentiated cells (flow
cytometry markers), t-test was performed between groups
and statistical analysis was calculated for each marker. Additionally, the t-test was used for the secreted cytokines at protein level and gene fold regulation between the treated and
control groups (significance assumed for ∗∗∗∗ p < 0:00005,
∗∗∗
p < 0:0005, ∗∗ p < 0:005, and ∗ p < 0:05).
3. Results
3.1. Differentiation of THP-1 Cells into Macrophages. To
confirm the success of differentiation from monocytes into
macrophages, surface marker expression profile was evaluated by flow cytometry. The expression profile of differentiated macrophages was distinguished from THP-1 monocytic
cells. As shown in (Figure 2 and Table 2), the expression of
the following markers CD11b, CD68, CD206, SSEA1,
HLA-DR, CD14, CD117, CD29, CD45, and CD49f was significantly upregulated in the differentiated macrophages
compared to THP1-monocytes (p < 0:05).
3.2. Activation of Differentiated Macrophages by LPS and
Biodentine. Differentiated macrophages were activated by
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CD11b
CD68
CD206
SSEA1
HLA-DR
CD14
CD117
CD29
CD45
CD49F
THP-1 Monocytes
THP-1 Macrophages
(a)
Fluorescence intensity (FI)
5000
⁎
4000
3000
⁎
2000
⁎
1000
⁎
⁎
⁎
⁎
CD
H 206
LA
-D
R
CD
1
CD 4
11
7
CD
29
CD
45
CD
6
CD 8
11
SS b
EA
CD 1
49
f
0
⁎
THP-1
Macrophages
(b)
Figure 2: Flow cytometric (a) histograms and (b) statistical analysis of the expression of surface markers of THP-1 monocytes and PMATHP-1-treated cells (macrophages) (∗ p < 0:05).
using LPS. Remarkably, CD68, CD11b, CD29, and CD14
were upregulated significantly after the activation of macrophages by LPS, while CD49f and HLA-DR were downregulated. Moreover, SSEA1 and CD206 showed no or
negligible activation (Figure 3 and Table 2). However, after
treating activated macrophages with Biodentine (BD), the
expression profile of the obtained macrophages was evident.
CD29, CD45, and SSEA1 were downregulated compared to
the control untreated macrophages, whereas CD14, CD117,
and CD49f were slightly upregulated. Furthermore, CD68,
CD11b, CD206, and HLA-DR showed negligible activation
(Figure 4 and Table 2).
3.3. Cytometric Bead Array (CBA) and Gene Expression
3.3.1. For Treated Macrophages. For BD-treated activated
macrophages, IL-12p70, IL-1β, and TNF-α were downregulated compared to the untreated control cells in a significant
manner (p < ∗∗∗ , p < ∗∗∗ , and p < ∗∗∗∗ ), whereas IL-6 and IL10 were upregulated significantly in BD-treated macrophage
cells compared to the untreated control cells (p < ∗∗ , p < ∗∗ ).
However, BD-treated macrophages showed the same expression levels of secreted IL-8 cytokines without statistical significance when compared to the control cells (Figure 5).
Table 2: Flow cytometric results of macrophages’ expression
percentages (%) for surface markers for all groups.
THP-1 (%) Macrophages (%) BD (%) Control (%)
SSEA1
CD206
HLA-DR
CD14
CD117
CD29
CD45
CD49f
CD68
CD11b
24.76
2.83
4.04
87.53
0.24
97.41
92.06
90.49
9.93
87.52
44.28
3.52
36.82
96.04
0.64
98.04
99.19
99.91
37.67
69.86
47.48
8.32
24.73
98.80
5.62
98.06
91.65
97.80
94.66
98.92
63.16
6.71
13.98
99.53
1.84
98.93
97.49
99.37
94.96
97.17
At the gene level, our data showed a significant increase
in the expression of the IL-10 and TGF-β compared to the
control untreated group (p < ∗∗∗ , p < ∗ ), while for IL-1β,
IL-6, and IL-, a significant downregulation was detected in
Biodentine-treated macrophages compared to the control
untreated cells (p < ∗∗∗ , p < ∗∗ , and p < ∗ ). For TNF-α and
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CD11b
CD68
SSEA1
CD206
HLA-DR
CD14
CD117
CD29
CD45
CD49F
Macrophages
Macrophages + LPS
(a)
Fluorescence intensity (FI)
5000
⁎
4000
3000
2000
⁎
⁎
1000
⁎
⁎
H
CD
2
LA 06
-D
R
CD
1
CD 4
11
7
CD
29
CD
45
CD
6
CD 8
11
SS b
EA
CD 1
49
f
0
Macrophages
Macrophages + LPS
(b)
Figure 3: Flow cytometric histograms (a) and the analysis of the fluorescence intensity (b) of the expression of surface markers of
differentiated macrophages compared to LPS-activated differentiated macrophages (∗ p < 0:05).
IL-12P40, no significant difference was observed among the
treated group and their control cells (Figure 6).
3.3.2. Cytometric Bead Array (CBA) and Gene Expression for
Treated DPSCs. Flow cytometric results of CBA for BDtreated activated DPSCs cells showed that IL-10 and IL12p70 were significantly upregulated compared to the control untreated cells (p < ∗∗ , p < ∗∗∗ ), while IL-1β and IL-6
were downregulated significantly when compared to the
control untreated cells (p < ∗∗ , p < ∗ ), whereas for TNF-α
and IL-8, a nonsignificant expression was found as compared to the control cells (Figure 7).
From gene expression analysis, we can conclude that
Biodentine-treated DPSCs demonstrate a significant downregulation of IL-6, IL-8, and IL-1β (p < ∗∗∗∗ , p < ∗ , p < ∗∗∗∗
) as compared to untreated cells, while IL-10, TGF-β, and
TNF-α were significantly upregulated in comparison to control cells (p < ∗∗ , p < ∗∗ , p < ∗∗∗ ). On the other hand, IL12P40 did not show any significant difference (Figure 8).
3.4. Migration: Wound Healing (Scratch Assay). The migration potential of BD-treated DPSCs (2 mg/ml of Biodentine)
was performed by evaluating the wound infliction closure
under the microscope. Interestingly, Biodentine was able to
stimulate the healing process of inflicted DPSCs by decreasing the width of the wound (Figure 9).
4. Discussion
In vital pulp therapy, both inflammation and dentine-pulp
regeneration are important processes in order to conserve
the functionality and to maintain the viability of pulp tissue
when the capping material is used in clinical application
[30]. After the first step of inflammation, progenitor cells
such as dental pulp stem cells (DPSCs) are required to start
the regeneration of dentine-pulp complex [31], as these
DPSCs are known with their high potential to regenerate
and repair the dentine matrix [32, 33]. Therefore, the success
of pulp regeneration relies on the presence of progenitor’s
cells that are responsible for pulp regeneration and the control of inflammation [30].
This study has evaluated the immunomodulatory effect
of Biodentine (BD) pulp capping material on THP-1 macrophages and its role in stimulating the dentine-pulp
regeneration when exposed to DPSCs (Progenitor cells)
of the pulp tissue.
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CD11b
CD68
CD206
SSEA1
HLA-DR
CD14
CD117
CD29
CD45
CD49F
Macrophages
Macrophages + BD
(a)
Fluorescence intensity (FI)
5000
4000
3000
2000
⁎
⁎
1000
⁎
⁎
⁎
CD
H 206
LA
-D
R
CD
14
CD
11
7
CD
29
CD
4
CD 5
49
CD f
6
CD 8
11
SS b
EA
1
0
BD
CONTROL
(b)
Figure 4: Flow cytometric (a) histograms and (b) the analysis of the fluorescence intensity of macrophages’ expression markers after
treatment with Biodentine (BD) for 24 h, compared to the control untreated macrophages (∗ p < 0:05).
⁎⁎
IL-6
20
40
20
0
50
0
pg/ml
TNF-𝛼
400
300
40
20
BD-treated cells Control
IL-12p70
⁎⁎⁎
200
100
⁎⁎⁎⁎
0
0
BD-treated cells Control
20
0
60
150
⁎⁎⁎
30
BD-treated cells Control
IL-1𝛽
200
⁎⁎
10
0
BD-treated cells Control
pg/ml
40
pg/ml
pg/ml
pg/ml
40
IL-10
50
60
60
100
IL-8
80
pg/ml
80
BD-treated cells Control
BD-treated cells Control
Figure 5: Measurement of the expression level of cytokines secreted by macrophage cells, activated with lipopolysaccharides, then treated
with Biodentine (BD), compared to the control untreated group by using CBA by flow cytometry (∗∗∗∗ p < 0:00005, ∗∗∗ p < 0:0005, ∗∗ p <
0:005, and ∗ p < 0:05).
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IL-6
0.3
IL-8
0.4
IL-10
4
⁎⁎⁎
2
⁎
0.1
1
Control
BD-Treatedcells
IL12-P40
0.4
TNF-𝛼
1.0
⁎⁎⁎⁎
0.8
0.1
0.6
0.4
BD-Treatedcells
Untreated cells
Control
0.2
0.1
0.2
0.0
BD-Treatedcells
Control
⁎
0.3
Gene fold
Gene fold
Gene fold
0.2
⁎⁎⁎
TGF-𝛽
0.4
0.3
0.10
0.00
BD-Treatedcells
Control
0.15
0.05
0
0.0
BD-Treatedcells
Gene fold
Gene fold
Gene fold
Gene fold
0.2
0.1
0.0
0.20
3
0.3
⁎⁎
0.2
IL-1𝛽
0.25
0.0
0.0
BD-Treatedcells
Control
BD-Treatedcells
Control
Figure 6: Measurement of the expression level of cytokines secreted by macrophage cells, activated with lipopolysaccharides [29], then
treated with Biodentine (BD), compared to the control untreated group at the gene level by using qPCR (∗∗∗∗ p < 0:00005, ∗∗∗ p < 0:0005,
∗∗
p < 0:005, and ∗ p < 0:05).
IL-6
100
40
pg/ml
40
20
BD-Treated DPSCs Untreated DPSCs
BD-Treated DPSCs
100
I
IL-1𝛽
pg/ml
⁎⁎
40
20
⁎⁎⁎
50
80
40
60
30
40
TNF-𝛼
20
10
0
0
BD-Treated DPSCs Untreated DPSC
BD-Treated DPSCs Untreated DPSCs
IL-12p70
20
0
40
Untreated DPSCs
pg/ml
80
60
0
0
0
pg/ml
IL-10
20
20
60
⁎⁎
80
60
pg/ml
IL-8
60
⁎
pg/ml
80
BD-Treated DPSCs
Untreated DPSC
BD-Treated DPSCs Untreated DPSC
Figure 7: Measurement of the expression level of cytokines secreted by DPSCs, activated with LPS, and treated with Biodentine (BD),
compared to the untreated control group, by using CBA by flow cytometry (∗∗∗∗ p < 0:00005, ∗∗∗ p < 0:0005, ∗∗ p < 0:005, and ∗ p < 0:05).
For THP-1 cells, our data showed the successful differentiation of these monocytes into macrophages based on the
cell surface markers’ expression as analyzed by flow cytometry, and these results are in alignment with a previous study
[34]. Macrophages are important innate immune cells that
are associated with two distinct types: a proinflammatory
subset M1with prototypic macrophage functions such as
inflammatory cytokine production and bactericidal activity
and an anti-inflammatory subset M2 linked with wound
healing and tissue repair processes [35]. It has been investigated that classically activated macrophages (M1) produce
IL-6, IL-1, and TNF-α while alternatively activated (M2)
macrophages produce IL-10 and TGF-β and are thought to
be associated with tissue repair [36]. Therefore, in order to
activate these macrophage cells, macrophages were treated
with lipopolysaccharide [29] to mimic a situation where
macrophages are encountered with pathogen-associated
molecular patterns (PAMPs) that are responsible for the initiation of immunological responses [37].
In our study, the secretion of both IL-6 and IL-10 at the
protein level was significantly increased, while that of IL-1β,
Il-12p70, and TNF-α was significantly downregulated in
LPS-activated macrophages that are treated with Biodentine
compared to the untreated macrophages. At the gene level,
we found that Biodentine-treated macrophages exhibited a
downregulation of proinflammatory cytokines such as IL-8,
IL-6, and IL-1β and an upregulation of anti-inflammatory
cytokines, IL-10 and TGF-β.
In order to determine the immunological responses in
in vitro culture, cells were exposed to the treatment; then,
BioMed Research International
9
IL-10
IL-8
IL-6
25
IL-1𝛽
40
15
50
⁎⁎
5
20
10
0
0
BD-Treated DPSCs
BD-Treated DPSCs
Untreated DPSCs
IL-12p40
8
2.0
TNF-𝛼
4
0.5
2
0.0
0
BD-Treated DPSCs
Untreated DPSCs
Untreated DPSCs
BD-Treated DPSCs
Untreated DPSCs
⁎⁎
8
Gene fold
Gene fold
1.0
⁎⁎⁎⁎
TGF-𝛽
10
⁎⁎
6
1.5
20
0
BD-Treated DPSCs
Untreated DPSCs
30
10
⁎⁎⁎⁎
0
Gene fold
⁎
Gene fold
10
10
Gene fold
15
5
40
30
Gene fold
Gene fold
20
6
4
2
0
BD-Treated DPSCs
Untreated DPSCs
BD-Treated DPSCs
Untreated DPSCs
Figure 8: Measurement of the expression level of cytokines secreted by DPSCs, activated with LPS, and treated with Biodentine (BD) and
compared to the untreated control group, at the gene level by using qPCR. (∗∗∗∗ p < 0:00005, ∗∗∗ p < 0:0005, ∗∗ p < 0:005, and ∗ p < 0:05).
Biodentine treated-DPSCs
Control-(Untreated DPSCs)
Figure 9: Scratch assay was evaluated on DPSCs treated with Biodentine (BD) to determine the effect of Biodentine on the migration
potential of treated DPSCs, compared to the control untreated cells. Wound closure was observed under the inverted microscope
(scale bar = 100 μm).
secreted cytokines were measured in cell culture media. IL-6
is an early released cytokine secreted in a time-dependent
manner, starting at the beginning of inflammation, and
decreases with time. Thus, its secretion is accumulated in
the culture media, resulting in upregulating different signaling pathways that would affect the detected level of IL-6 [35].
Previously published in vivo studies conclude similar results
regarding the expression of IL-6 [20, 38]. Additionally, the
upregulation in the expression of IL-12 at gene level could
be explained by the posttranslational modification, as IL12p40 is a subunit of IL-12p70; thus, the activation of the
latter cytokine requires the binding of two subunits IL12p40 and IL-12p35 [39].
Interestingly, we found the same effect of Biodentine on
the DPSCs after stimulating the progenitor cells with LPS
and subsequent exposure to Biodentine. Quantification of
the released mediators showed that Biodentine-treated
DPSCs have a significant upregulation of the antiinflammatory cytokine IL-10 and a downregulation of
expression of the following proinflammatory cytokines at
both protein and gene levels, IL-6, IL-8, and IL-1β. The picture for IL-12 and TNF-α was different, as the results at protein level and gene level were in disagreement. This
discrepancy can be attributed to the inverse correlation or
posttranslational modifications [35, 40].
It has been investigated that the different isoforms of
TGF-β play multiple roles in the formation and repair of
the dentine-pulp complex since it acts as a potent regulator
for initiation and resolution of inflammatory responses [31,
41–43]. It has also been suggested that macrophage
10
polarization is also driven by TGF-β expression [44]. Similarly, IL-10, an anti-inflammatory cytokine, decreases the
production of proinflammatory cytokines such as IL-6 and
CXCL-8 which in turn suppresses the immune response
and limits the tissue damage [42]. In addition, it has been
found that IL-10 is upregulated in inflamed pulps and
odontoblast-like cells thereby not only initiating the pulp’s
response to invading bacteria but also minimizing the intensity of infections [45].
Moreover, clinically, BD was able to regenerate Biodentine bridges without any pain or inflammation; thus, it is
considered more suitable for clinical application when compared to calcium hydroxide and MTA in respect of safety
and new dentine formation in the pulp chamber and the
continuous root formation [6, 15, 46, 47]. Interestingly, our
results were consistent with these published studies.
Our results are in favor of these findings. Furthermore,
we found that DPSCs treated with Biodentine have high
migration potential at the injury site which is an indicator
for the potential of Biodentine to stimulate the regeneration
of the dentine. Hence, our null hypothesis was rejected.
This current study was performed in vitro; therefore, our
future prospects will be oriented toward understanding the
possible consequences and the therapeutic outcomes
through in vivo experiments.
5. Conclusions
Our study sheds light on the importance of choice of the
pulp capping material. It shows that Biodentine can influence complement activation by modulating the polarization
of macrophages, can initiate the anti-inflammatory response
to maintain the tissue homeostasis, and can enhance the
migration potential of the DPSCs as a successful determinant of dentine-pulp regeneration.
Data Availability
No data were used to support this study.
Ethical Approval
The study was conducted according to the guidelines of the
Declaration of Helsinki and approved by the Institutional
Review Board from the Cell Therapy Center/The University
of Jordan (IRB/06/2018) and approved on 13 March 2018.
Consent
Informed consent was obtained from all subjects involved in
the study.
Conflicts of Interest
The authors declare no conflict of interest.
Authors’ Contributions
D.A. was responsible for the conceptualization. D.A. and
R.Z. were responsible for formal analysis and data interpre-
BioMed Research International
tation. H.J. and W.A. provided the resources. D.A., R.Z.,
S.Z.R.A., and W.A. were responsible for the methodology.
D.A. handled the project administration. A.A. and D.A were
in charge of the supervision. D.A., N.A., and R.Z. contributed to the writing and editing of the paper. All authors have
read and approved the manuscript.
Acknowledgments
All authors are very thankful for all participants in our
study. This research was financially supported by the University of Petra (16/4/2022) and Cell Therapy Center, University of Jordan.
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