Keywords
grape seed extract - proanthocyanidins - bone remodeling - human health
Introduction
In recent years, the grape has explored its bioactive compounds, such as proanthocyanidins
and phenolic acid, that are found in the skin, pulp, and seed.[1] The grape seed extract (GSE) has attracted the attention of the food industry and
public health organizations.[2] GSE has potential health benefits because of rich proanthocyanidins,[3] approximately 74 to 78%,[4] and it possesses anti-inflammatory, antioxidant,[5] antiapoptotic and pro-proliferative properties.[6] Besides its potential, the GSE is considered safe for humans, because it does not
show any toxicity effects like changing the hematological parameter and organ changes.[7] By that A GSE has been recognized by the Food and Drug Administration as Generally
Recognized as Safe and is sold commercially as a dietary supplement, and is listed
in the Everything Added to Food in the United States data.[8]
In dentistry, the GSE has been proved to prevent dental caries[9]
[10] by covering the acquired enamel pellicle and preventing bacterial adhesion to performed
biofilm[11] and antibacterial in the root canal during endodontic treatment.[12] The GSE also has been promoted as periodontitis medication because it is able to
reduce oxidative stress and inflammation.[13] In clinical randomized clinical trials, the GSE significantly reduced the probing
depth and increased the attachment level.[14] Recent research has shown GSE's influence in bone remodeling process in postorthodontic
relapse prevention by inhibiting osteoclastogenesis.[15] Bone remodeling is an active and dynamic process between bone resorption by osteoclasts
and bone formation by osteoblasts that works in balance to maintain mineral homeostasis
in the body.[16] It is no exception that prevention of postorthodontic relapse also requires adequate
bone remodeling, which is an important factor in maintaining bone thickness. During
orthodontic tooth movement, bone resorption occurs in the pressure area, due to osteoclast
activation, and bone formation in the pull area, due to osteoblast formation.[17] Not only alveolar bone remodeling but also the changes that include periodontal
ligament metabolism[18] and neural regulation occurr.[19] This process should occur in a balanced manner until the teeth on the arch is achieved.
The undesirable thing is that excessive resorption occurs without being followed by
the bone formation in the tension area of the teeth involved. More importantly, the
height of the alveolar bone and the thickness of the cortical bone must be maintained.[20]
The current data showed that with the consumption of 200 to 400 mg per day of GSE
as food supplementation, no physiological or clinical abnormality was changed, and
it was declared safe for consumption.[21] The safety is related to high proanthocyanidins and safe to gastrointestinal mucosa.[22]
[23] The proanthocyanidins exerted an antioxidant and anti-inflammatory effect by inhibiting
the production of a pro-inflammation cytokine through the inhibition of nuclear factor
kappa B (NF-kB)[24] and the C-reactive protein (CRP).[25]
[26] Recent research also provided that the supplementation of GSE containing high proanthocyanidins
has great benefits for humans by providing antioxidative stress and anti-inflammation,[27] improving bone health such as preventing bone loss,[28] inhibiting bone resorption by inhibiting osteoclastogenesis through NF-kB and c-Jun
N-terminal kinase (JNK) signaling,[29] inhibiting advance glycation end product,[30] increasing bone formation by increase bone mineral and density,[31] upregulating bone growth factors, such as bone morphogenetic protein 7 (BMP-7),[30] and increasing implant osseointegration.[28] On the other hand, the GSE also provides a protective effect against osteoarthritis
in the knee.[32] With various potentials regarding GSE for various bone remodeling markers, due to
limitations and explanations of the exact mechanism of GSE for alveolar bone, jaw
bone, and skeletal bone remodeling, especially in treatment-related like postorthodontic
relapse prevention, dental implant, periodontal treatment, or dental surgery, this
scoping review was conducted to further explain the mechanism and provide an opportunity
for further research to be performed.
Methods
Review Methodology
This scoping review of published studies on the effect of GSE on bone remodeling was
conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis
(PRISMA) 2020 guidelines. The focus question in this review was, “How does GSE affect
bone remodeling (alveolar bone, jaw bone and skeletal bone)?
The Population, Intervention, Comparison, Outcome statement used for this study is
the population included in all the studies investigating the potential effect of GSE
on bone remodeling, including alveolar bone, jaw bones, and skeletal bone. Intervention
is defined as the various dose and administrations of GSE. Any comparison (placebo
or no control) was included. All clinical outcomes related to bone remodeling markers
by in vivo research were included.
Information Sources
A comprehensive literature search was conducted on the following databases: PubMed,
Scopus document, Science Direct, Web of Science, Embase, and manual search for all
studies published.
Search Strategy
The keyword as [(grape seed) or (grape seed extract)] AND [(bone) or (bone remodeling)]
were used in the research. Results were limited to studies published in English and
in vivo studies. Review articles were not included in this review.
Study Design and Selection Process
All studies on those databases and fitting the criteria below were grouped together,
and any duplicates were removed. The remaining studies were then filtered according
to the title and the abstract. Studies that did not match were excluded at this stage.
The remaining studies were screened at the final stage according to their full text,
and those that did not meet the inclusion criteria were excluded. Mendeley reference manager was used to organize the study titles and abstracts and identify duplicates.[33] This process was conducted by four independent investigators: EDW, AT, IGAWA, and
MDCS. In the case of disagreements, the investigators reached their decision through
discussion.
The inclusion criteria for this review included clinical or in vivo studies about GSE, studies describing its potential effect on bone remodeling, the
dose of the treatment, and the marker analyzed. This process, documented by Microsoft
Excel for Windows, was performed in the following order: the name of the first author,
publication year, country, study design, and results.
Results
Study Selection
After using a combination of keywords, 659 articles were found in the three databases.
The titles were screened, and the duplicates were removed, resulting in 82 remaining
articles. After reading the abstracts, all 82 articles were included in the next step
of assessing the full text for eligibility. After this process, only 26 articles analyzed
the effect of supplementation of GSE to the alveolar bone (7 articles), jaw bones
(4 articles), skeletal bone (long and flat bone) (6 articles), and in the bone disease
model (9 articles; [Fig. 1]).
Fig. 1 Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flowchart.
Study Characteristics
Twenty-six studies revealed the potential effect of GSE on the alveolar bone, including
maxilla,[15] interpremaxillary,[34] alveolar bone in a molar area,[35]
[36]
[37] and incisive area[38]
[39] the mandibular jaw bone[40]
[41] and condyle[31]
[42] skeletal bone including the femur,[28]
[43] calvaria,[28] and tibia.[28]
[44]
[45]
[46]
[47] In the disease model, femur,[48]
[49]
[50]
[51]
[52] tibia,[53]
[54] and knee were used.[55]
[56]
The study of supplementations of GSE was mostly performed in Wistar rats,[15]
[31]
[35]
[36]
[37]
[38]
[40]
[41]
[42]
[43]
[44]
[45]
[46]
[47]
[49]
[50]
[54]
[55] Sprague-Dawley rat,[34] rabbits,[39]
[51]
[52] and mice.[28]
[48]
[56]
The GSE Effect on Alveolar Bone
The GSE was administered per-orally in various doses, ranging from 0.1 mL, 0.5 mL.kg,
12.5 mg/mL, 50 mg/kg, 100 mg/kg, and 200 mg/kg. The orthodontic intervention was performed
like coil springs, helical springs, and orthodontic wire. The periodontal intervention
related to alveolar bone was placed with silk and a braided suture in the cervical
of the teeth. And in other studies, tooth extraction was performed.
All the interventions showed increased bone remodeling, marked with increased osteocalcin
and osteoblast; decreased receptor activator of NF-kB ligand (RANKL), osteoprotegerin
(OPG), osteoblast; decreased inflammatory responses marker with decreased serum malonaldehyde
(MDA) and gingival tissue level, inflammatory cell, matrix metalloproteinase 8 (MMP-8)
and hypoxia-inducible factor 1α (HIF-1α); increased anti-inflammatory response marked
by an increase in the glutathione (GSH) level; and decreased alveolar bone resorption
and alveolar bone loss marked by decreased osteoclast and increased bone morphological
protein 2 (BMP-2; [Table 1]).
Table 1
The effect of GSE administration on the alveolar bone of animals
|
Animals
|
Bone location
|
Bone intervention
|
GSE treatment
|
Comparison
|
Treatment outcome
|
References
|
|
Doses
|
Duration
|
|
Rat—Wistar
|
Maxillary central incisive
|
An orthodontic force with Stainless steel 3-spin coil spring
|
12.5 mg/mL
|
Once a day for 1/3/7/14 days
|
Without GSE treatment
|
Lower osteoclast number
|
[15]
|
|
Rat—Sprague-Dawley
|
Inter-premaxillary suture
|
An orthodontic force with helical springs steel wire
|
100 mg/kg
|
15 days
|
Without GSE treatment
|
Higher new bone formation
|
[34]
|
|
Rat—Wistar albino
|
Mandibular first molar
|
Ligature induced periodontitis using 0.5 mm orthodontic wire
|
50 mg/kg
|
Once every 3 days for 1/7/28 days
|
Saline solution
|
Lower MDA serum level
|
[35]
|
|
Lower MDA gingival tissue level
|
|
Higher GSH level
|
|
Lower inflammatory cells
|
|
Lower alveolar bone resorption
|
|
Rat—Wistar
|
Mandibular first molar
|
Ligature induced periodontitis using silk suture
|
100 mg/kg
200 mg/kg
|
Once a day for 30 days
|
Saline solution
|
Higher number of osteoblasts
|
[36]
|
|
Lower number of osteoclasts
|
|
Lower alveolar bone loss
|
|
Lower MMP-8 expression
|
|
Lower HIF-1α expression
|
|
Rat—Wistar
|
Maxillary first molar
|
Ligature induced periodontitis braided silk
|
50 mg/kg
100 mg/kg
|
Once a day for 14 days
|
Without GSE treatment
|
Lower alveolar bone loss
|
[37]
|
|
Higher osteocalcin
|
|
Rat—Wistar
|
Mandibular first incisor
|
Tooth extraction
|
0.1 mL
|
Once time
|
Without GSE treatment
|
Higher of osteoblast
|
[38]
|
|
Rabbit—New Zealand
|
Maxillary first incisor
|
Tooth extraction
|
0.5 mL/kg
|
Once time
|
Hemostatic sponge
|
Higher of BMP-2
|
[39]
|
Abbreviations: BMP-2, bone morphogenetic protein 2; GSE, grape seed extract; HIF-1
α, hypoxia-inducible factor 1α; MDA, malonaldehyde; MMP-8, matrix metalloproteinase
8.
The GSE Effect on Jaw Bone
The supplementation of GSE affected mandibular bone by 3 mg dose once a week for 3
and 6 weeks. The cortical and trabecular bone marked an increase in density and bone
mineral content, calcium, phosphate, and improved bone strength ([Table 2]).
Table 2
The effect of GSE administration on the jaw bone of animal
|
Animals
|
Bone location
|
Bone intervention
|
GSE treatment
|
Comparison
|
Treatment outcome
|
References
|
|
Doses
|
Duration
|
|
Rat—Wistar
|
Mandibular
|
Standard diet with GSE supplementation
|
3 mg
|
21 days
|
Standard diet
|
Higher trabecular high density
|
[40]
|
|
Higher bone mineral content
|
|
Higher cortical bone density
|
|
Higher bone mineral content
|
|
Higher bone strength
|
|
Rat—Wistar
|
Mandibular condyle
|
Standard diet with GSE supplementation
|
3 mg
|
21 days
|
Standard diet
|
Higher bone cortical density
|
[31]
|
|
Higher bone total density
|
|
Rat—Wistar
|
Mandibular condyle
|
Low calcium diet with GSE supplementation
|
3 mg
|
21 days
|
Low calcium diet
|
Higher cortical bone density
|
[42]
|
|
Higher trabecular bone mineral content
|
|
Rat—Wistar
|
Mandibular
|
Combination low and high calcium diet with GSE supplementation
|
3 mg
|
42 days
|
Combination low and high calcium diet
|
Higher cortical bone density
|
[41]
|
|
Higher trabecular bone mineral content
|
Abbreviation: GSE, grape seed extract.
The GSE Effect on Skeletal Bone
The supplementation of GSE affected the femur, calvaria, and tibia bone with osteotomy,
defect and implant placement. The dose was 10 to 100 mg/kg. The bone remodeling showed
bone healing and improvement after the defect, increased callus formation, bone volume,
and increased torque of implant removal ([Table 3]).
Table 3
The effect of GSE administration on the skeletal bone of an animal
|
Animals
|
Bone location
|
Bone intervention
|
GSE treatment
|
Comparison
|
Treatment outcome
|
References
|
|
Doses
|
Duration
|
|
Wistar rats—Albino
|
Femur shaft
|
Osteotomy
|
100 mg/kg
|
10/20/30 days
|
Nonfracture and standard diet
|
Higher bone improvement
|
[43]
|
|
Higher bone healing
|
|
Higher bone strength
|
|
Mice—C57BL/6 J
|
Calvaria
|
Bone defect
|
10 mg/mL/kg
|
13 weeks
|
Pure water
|
Higher bone density
|
[28]
|
|
Femur
|
Lower bone defect volume
|
|
Tibia
|
Implant placement
|
Higher new bone formation
|
|
Higher removal torque of implant
|
|
Rat—Wistar
|
Tibia
|
Combination standard diet and low calcium diet and GSE supplementation
|
3 mg
|
3 weeks
|
Combination standard diet and low calcium diet and tap water
|
Higher trabecular bone density
|
[44]
|
|
Higher trabecular bone mineral
|
|
Rat—Wistar
|
Tibia
|
Combination standard diet and low calcium diet and GSE supplementation
|
3 mg
|
3 weeks
|
Combination standard diet and low calcium diet and tap water
|
Higher cortical bone mineral
|
[45]
|
|
Higher calcium and phosphate content
|
|
Rat—Wistar
|
Tibia
|
Combination standard low and high calcium diet and GSE supplementation
|
3 mg
|
3 weeks
|
Combination standard low and high calcium diet and tap water
|
Higher trabecular bone density
|
[46]
|
|
Higher trabecular bone mineral
|
|
Rat—Wistar
|
Tibia
|
Combination standard low and high calcium diet and GSE supplementation
|
3 mg
|
3 weeks
|
Combination standard low and high calcium diet and tap water
|
Higher cortical cone density
|
[47]
|
|
Higher cortical bone mineral
|
|
Higher bone strength
|
Abbreviation: GSE, grape seed extract.
The GSE Effect on the Skeletal Bone with Disease
The supplementation of GSE also showed a good response for bone remodeling in bone
diseases like bone inflammation by lipopolysaccharide (LPS), osteonecrosis, arthritis,
and osteoporosis. GSE doses vary from 12 mL/kg to 300 mg/kg.
The GSE increased the Rcan 3, Runx2, and Sox6 expressions, osteocalcin, phosphor and
calcium content, bone volume and density, and also thickness of trabecula during bone
formation. However, the GSE also inhibited bone resorption through a decreased number
of osteoclast and inflammation process. The inflammation process reduced the 8-oxo-2'-deoxyguanosine,
Superoxide dismutase (SOD), Glutahione (GSH), Malondialdehyde (MDA), Caspase 3, and
interleukin-1β (IL-1β) values. While it was related to bone destruction, it decreased
nitro tyrosine, RANK, NFATc1, LRP, Tcf3, and MMP-13 expression ([Table 4]).
Table 4
The effect of GSE administration on the bone disease model of animal
|
Animals
|
Bone location
|
Bone intervention
|
GSE treatment
|
Comparison
|
Treatment outcome
|
References
|
|
Doses
|
Duration
|
|
Mice—ICR
|
Femur
|
Bone inflammation with LPS
|
200 mg/kg
|
Once time a day for 8 days
|
PBS
|
Lower number of osteoclasts
|
[48]
|
|
Higher bone density
|
|
Higher trabecular thickness
|
|
Higher trabecular number
|
|
Rat—Albino
|
Femur
|
Osteoporosis model with dexamethasone
|
400 mg
|
Three time per week for 4 weeks
|
Without GSE treatment
|
Improve bone structure
|
[49]
|
|
Rats—Y59 growing
|
Femur
|
Osteoporosis model with retinoic acid
|
100 mg/kg
|
Once a day for 14 days
|
Water or alendronate
|
Increase trabecula formation and thickness
|
[50]
|
|
Increase bone mineral content and density
|
|
Rabbits - New Zealand white
|
Femur
|
Osteonecrosis model induced by high-dose methylprednisolone
|
12 mL/kg
|
Once a day for 14 days
|
PBS
|
Lower bone necrosis
|
[51]
|
|
Lower 8-oxo-2'-deoxyguanosine
|
|
Lower SOD
|
|
Lower GSH levels
|
|
Lower MDA levels
|
|
Lower apoptosis index
|
|
Lower caspase 3
|
|
Rabbit—Japanese white
|
Femoral head
|
Osteonecrosis model with Escherichia coli endotoxin and methylprednisolone
|
200ug/kg
|
3 times every 24 hours
|
Saline solution
|
Increase Bcl2 expression
|
[52]
|
|
Decreased caspase 9 expression
|
|
Mice—DBA/1J
|
Tibiotalar joint of the ankle
|
Arthritis model with complete Freund's adjuvant
|
100 mg/kg
|
3 times at the interval 24 hours
|
Without GSE treatment
|
Higher SOX6 expression
|
[53]
|
|
Higher RunX2 expression
|
|
Higher Rcan 3 expressions
|
|
Lower NFATc1 expressions
|
|
Lower nitro tyrosine expression
|
|
Lower RANK expressions
|
|
Lower LRP-4 expressions
|
|
Lower Tcf3 expressions
|
|
Rat—Wistar
|
knee joint
|
Arthritis model with sodium iodoacetate
|
100 mg/k
|
Twice weekly for 18 days
|
Saline solution
|
Lower MMP-13 expressions
|
[54]
|
|
Lower nitro tyrosine expressions
|
|
Lower IL-1β expressions
|
|
Lower number of osteoclasts
|
|
Increase phosphor and calcium content
|
|
Increase osteocalcin
|
|
Rat—Wistar
|
Knee joint
|
Arthritis by monoids acetate
|
200 mg/kg
400 mg/kg
|
once a day for 10 days
|
Without GSE treatment
|
Reduce bone loss
|
[55]
|
|
Mice—DBA/1J
|
Knee joint
|
Arthritis model with complete Freund's adjuvant
|
10 mg/kg
50 mg/kg
100 mg/kg
|
5 times per 2 days for 2.5 weeks
|
Saline solution
|
Reduce the osteoclast
|
[56]
|
|
Decreased the TNF-α
|
|
Decreased the IL-17
|
Abbreviations: GSE, grape seed extract; GSH, glutathione; ICR, Institute of Cancer
Research; IL-7, interleukin-7; LPS, lipopolysaccharide; LRP-4, lipoprotein receptor-related
protein 4; MDA, malonaldehyde; MMP-13, matrix metalloproteinase 13; PBS, Phosphate
buffer saline; TNF-α, tumor necrosis factor-alpha.
Discussion
Various studies have been reported regarding the potential of GSE for human health.
GSE supplementation with the main content of proanthocyanidins is widely used to treat
obesity,[57] especially when it comes to weight control,[26] blood glucose,[58] cholesterol,[59] and blood pressure.[60]
[61]
[62] GSE supplementation can also be used to improve and prevent cardiotoxicity, gastrointestinal
toxicity, hepatotoxicity, nephrotoxicity, and mucositis caused by cancer radiation,
like.[63] In inflammation, GSE can significantly inhibit the formation of CRP.[64] As a natural ingredient that is safe for consumption, GSE is also proven to be safe
for the liver because it can improve levels of alanine aminotransferase, aspartate
aminotransferase, and alkaline phosphatase.[65] In addition, GSE is also able to provide antibacterial properties.[66]
With various studies on the potential of existing, it seems that the potential for
bone health has not been widely disclosed, so application and testing in humans have
not been widely performed. Various in vivo studies have shown a lot of GSE potential for bone remodeling processes in the alveolar
bone, jaw, and skeletal bones. One of the potentials of GSE for bone remodeling in
the alveolar bone can be seen in various treatments in the field of dentistry, such
as orthodontic, periodontal surgery, dental implant, or oral surgery.
During orthodontic treatment, tooth movement is strongly influenced by the processes
of resorption and formation of the alveolar bone. GSE supplementation in the prevention
of post orthodontic relapse provides an anti-inflammatory effect by decreasing the
production of MDA in serum and gingival tissue.[35] This decrease occurs because phenolic compounds in GSE can inhibit the formation
of reactive oxygen species (ROS) and the formation of MDA.[67] The further possible mechanism was explained through periodontitis-related alveolar
bone resorption. The MDA maybe then decrease HIF-1α and MMP-8 expression,[36] resulting in a decrease in the inflammatory response,[35] and several osteoclasts.[15]
[36] HIF-1α is one of the important factors in osteoclastogenesis, especially the hypoxia
response that occurs in orthodontics tooth movement[68] and a factor in osteoclast activation,[69] through the increased of OPG secretion to bind to RANKL.[70] On the other hand, GSE is also able to reduce RANKL and OPG, thereby reducing the
number of osteoclasts[15]
[36] and increasing the osteoblast,[36] which results in an excessive decrease in alveolar bone resorption[35] or bone loss.[37] Further, the mechanism of GSE to support bone formation was explained in the tooth
extraction model, where the alveolar bone expressed increased osteoblast, and the
bone growth factor was BMP-2[38]
[39] and osteocalcin for alveolar bone mineralization[36] ([Fig. 2]).
Fig. 2 The possible mechanism of grape seed extract supplementation for alveolar bone remodeling.
BMP-2, bone morphogenetic protein 2; HIF-1α, hypoxia-inducible factor 1α; MDA, malonaldehyde;
MMP-8, matrix metalloproteinase 8; OPG, osteoprotegerin; RANKL, receptor activator
of nuclear factor-kB ligand; ROS, reactive oxygen species.
The antioxidant properties of GSE are also responsible for increasing the formation
of GSH in serum,[35] thus supporting the formation of osteoblasts,[36] and maintaining the height of alveolar bones and preventing bone loss.[34]
[36] This increase in GSH is due to the inhibition of ROS by the phenolic compound in
GSE, which then affects the NF-κB signal pathway involved in osteoclast differentiation[71] ([Fig. 2]).
Although the exact mechanism of how GSE can affect bone remodeling is still unknown,
some previous studies have confirmed this. GSE in vivo level research has been shown to affect mandibular bone[40]
[41] and mandibular condyle.[31]
[42] GSE supplementation for 3 to 6 weeks has been shown to increase trabecular density[31]
[40] and cortical density[40]
[41]
[42]
[45] and is implicated in increasing bone strength ([Fig. 3]). Analysis of bone content also showed that levels of minerals,[40]
[41] calcium and phosphate in mandibular bones,[41]
[45] were significantly increased in the group that received GSE supplementation. The
explanation of increasing jaw density and minerals, calcium, and phosphate is not
fully understood.
Fig. 3 The possible mechanism of grape seed extract E supplementation for mandibular bones
related to its strength.
Adequate bone remodeling is also needed during bone recovery due to bone disease.
GSE supplementation was performed in some studies related to bone healing-related
disease. The in vivo model was performed by LPS to induce inflammation model,[48] osteoporosis,[49]
[50] osteonecrosis,[51]
[52] and arthritis.[53]
[54]
[55]
[56] In the bone inflammation and osteoporosis model, GSE maintained the bone structure,[49] by increasing the trabecular thickness[48]
[50] and bone mineral content.[50] The exact mechanism decreased the number of osteoclasts.[48] The proanthocyanidins are responsible for this mechanism because this active substance
is able to inhibit the osteoclast through inhibition of activation of NF-kB and JNK
signaling pathways.[29]
In the osteonecrosis model, the antioxidant properties of proanthocyanidins in GSE
take place by controlling the radicals like SOD,[51] GSH,[51] MDA,[51] and pro-apoptosis proteins like caspase 3,[51] caspase 9,[52] and Bcl2.[52] It has been researched that proanthocyanidins can inhibit mitochondrial stress and
prevent the apoptosis process by inhibiting the intrinsic apoptosis pathways.[72] In the orthodontic field, the force applied will activate the hypoxia, produce ROS,
and activate the NF-kB,[71] which may increase alveolar bone resorption for tooth movement. For this reason,
the supplementation of GSE to prevent post-orthodontic tooth movement (relapse) needs
to be explored.
In the arthritis model, the GSE plays an antioxidant property in preventing bone destruction
and inflammation through increased Sox6 expression. The SOX6 expression takes place
during bone remodeling in the arthritis model.[53] Sox6 is the major factor for healing because it is able to enhance proliferation,
inhibit apoptosis, and regulate osteogenesis-related gene expression.[73] The sox family, Sox5, Sox6, and Sox9, is involved in the activation and maintenance
of chondrogenesis during fracture healing and the enhancement of chondrogenesis by
BMP-2[74] further Sox6 expression also determined bone mineral density.[75]
The other protein that influences bone remodeling is Runt-related transcription factor
2 (Runx2).[76] This protein is essential for osteoblasts and osteoclasts differentiation.[77] Some research also mentions that upregulated Runx2 and Sox6 also contribute to bone
formation, especially for chondrocyte differentiation.[78] Related to increased runx2 expression after supplementation of GSE on the arthritis
model,[53] the supplementation also decreased the HIF-1α expression in the alveolar bone. But
the relationships between Runx2 and HIF-1α have been explained by Lin et al., 2011,
in which the inhibition of Runx2 and HIF-1α resulted in heterotopic ossification forming.[79] In alveolar bone, the Runx2 also plays similar as skeletal bone, which is a role
in osteoblast differentiation[80] and maintains the integrity of the dentogingival junction.[81]
NFATc1 expression also decreases after GSE supplementation in the arthritis model.[53] During the regeneration, GSE provides antioxidant properties due to its phenolic
compound, and this substance is able to inhibit the inflammation process. The inflammation
inhibition resulted in decreased activation of NF-κB and NFATc1.[82] By decreasing the NF-kB, proinflammatory cytokine production, like IL-1β,[54] tumor necrosis factor-alpha (TNF-α), and IL17,[56] decreases. On the other hand, the decrease in NFATc1 expression also affected STAT3
for controlling osteoclast differentiation[83] and bone metabolism[84] to prevent bone resorption[85] and bone loss.[55]
Low-density lipoprotein receptor-related protein 4 (LRP-4) also decreased after GSE
supplementation. Even the exact mechanism of LRP-4 is not fully understood, but also
the role of LRP takes place and controls bone morphogenesis.[86] Unlike MMP-13,[54] this protein regulates osteoclast number and activity, bone resorption, and bone
mass[80] and maintains mineralization in the bone.[87] By affecting all proteins during bone remodeling, the process of bone regeneration
occurs, marked by increased bone volume,[48] trabecular number and thickness,[48]
[50] and increased bone minerals like phosphor and calcium and also osteocalcin[54] ([Fig. 4]). By these various effects obtained in the in vivo model, it is promising that GSE can be applied to humans in case of bone regeneration,
not limited to skeletal bone, but also to jaw bone and alveolar bone.
Fig. 4 The possible mechanism of grape seed extract supplementation for skeletal bones related
to its strength. GSH, glutathione; LRP-4, lipoprotein receptor-related protein 4;
MDA, malonaldehyde; MMP-13, matrix metalloproteinase 13.
Conclusion
Finally, from the available data, we can conclude that the supplementation of GSE
affects the alveolar bone, jaw bones, and skeletal bone by promoting bone formation
and inhibiting bone resorption by suppressing inflammation, apoptosis pathways, and
osteoclastogenesis. It not only supports bone healing in bone inflammation and bone
remodeling in osteonecrosis, osteoporosis, and arthritis but also increases bone health
by increasing the density and mineral deposition in trabecula and cortical, as well
as increases the mineral, calcium, and phosphate deposition. The supplementation of
GSE supports bone remodeling by interfering with the inflammation proses and bone
formation by preventing bone resorption and maintaining bone health. The evidence
in this scoping review gives the opportunity to conduct further research on humans.
Future Implication
The data presented showed that the GSE has a beneficial effect on human health, particularly
in maintaining bone health. Future research should consider the supplementation of
GSE not only for bone maintenance but also for treating and supporting bone remodeling
in dentistry and orthopaedic treatment. In the field of dentistry, GSE supplementation
during the retention phase may prevent postorthodontic relapses by promoting bone
regeneration. However, the optimal supplementation dose needs to be determined to
achieve a therapeutic effect.
Limitations
This review was limited by the scarcity of high-quality studies, with most of the
available research conducted on animal models or in vivo. Additionally, the lack of information regarding the specific doses of GSE used and
the duration of the treatment represent significant issues that should be addressed
in future studies to enable a more comprehensive meta-analysis.