Periodontal tissue regeneration by signaling molecule(s): what role does basic fibroblast growth factor (FGF-2) have in periodontal therapy?

Stem Cells in Dentistry: Types of Intra- and Extraoral Tissue-Derived Stem Cells and Clinical Applications

Stem cells are undifferentiated cells, capable of renewing themselves, with the capacity to produce different cell types to regenerate missing tissues and treat diseases. Oral facial tissues have been identified as a source and therapeutic target for stem cells with clinical interest in dentistry. This narrative review report targets on the several extraoral- and intraoral-derived stem cells that can be applied in dentistry. In addition, stem cell origins are suggested in what concerns their ability to differentiate as well as their particular distinguishing quality of convenience and immunomodulatory for regenerative dentistry. The development of bioengineered teeth to replace the patient's missing teeth was also possible because of stem cell technologies. This review will also focus our attention on the clinical application of stem cells in dentistry. In recent years, a variety of articles reported the advantages of stem cell-based procedures in regenerative treatments. The regeneration of lost oral tissue is the target of stem cell research. Owing to the fact that bone imperfections that ensue after tooth loss can result in further bone loss which limit the success of dental implants and prosthodontic therapies, the rehabilitation of alveolar ridge height is prosthodontists' principal interest. The development of bioengineered teeth to replace the patient's missing teeth was also possible because of stem cell technologies. In addition, a “dental stem cell banking” is available for regenerative treatments in the future. The main features of stem cells in the future of dentistry should be understood by clinicians.

Dose-dependent effect of radiation on resorbable blast material titanium implants: an experimental study in rabbits

BACKGROUND

Radiotherapy is a commonly used treatment modality in head and neck cancer; however, it also negatively affects healthy structures. Direct damage to oral soft and hard tissue frequently occurs with radiotherapy. In this study, we aimed to evaluate the effect of radiotherapy on bone surrounding titanium dental implants via biomechanical and molecular methods.

MATERIALS AND METHODS

Fifty-four implants were inserted in the left tibiae of 18 adult male New Zealand rabbits (3 implants in each rabbit). After 4 weeks of the implant surgery, the left tibiae of 12 rabbits were subjected to a single dose of irradiation (15 Gy or 30 Gy). Four weeks after the irradiation, rabbits were sacrificed and removal torque test was done for the biomechanical evaluation. Bone morphogenetic protein-2 (Bmp-2) and fibroblast growth factor-2 (Fgf-2) expression analyses were performed with Real-time PCR. Statistical analysis was done using SPSS.

RESULTS

The control group showed significantly higher removal torque value than the 15 and 30 Gy irradiation groups, and the 15 Gy irradiation group had higher removal torque value than the 30 Gy irradiation group (p < .001). The 15 Gy and 30 Gy irradiation groups had significantly lower Bmp-2 and Fgf-2 mRNA expressions than the control group (p < .001). In addition, the 30 Gy irradiation group had significantly lower Bmp-2 (p < .01) and Fgf-2 mRNA expressions (p < .001) than the 15 Gy group.

CONCLUSION

Radiotherapy with 15 and 30 Gy doses can adversely affect osseointegration of implants by reducing the quality of bone and impairing the bone-to-implant contact. The mechanism of action seems to be related to alterations in Bmp-2 and Fgf-2 mRNA expressions.

Morinda citrifolia Leaf Extract Enhances Osteogenic Differentiation Through Activation of Wnt/β-Catenin Signaling

Morinda citrifolia (Noni) leaf is an herbal medicine with application in the domestic treatment of a broad range of conditions, including bone fracture and luxation. However, the basic mechanism underlying the stimulation of osteogenic differentiation by Noni leaf extract remains poorly understood. This study aimed to examine the effect of this extract on osteogenic differentiation and the mechanism by which Noni leaf extract enhances osteogenic differentiation. Aqueous extract of Noni leaves was prepared, and rutin and kaempferol-3-O-rutinoside were identified to be two of its major components. C2C12 and human periodontal ligament (hPDL) cells were used to study the effect of Noni. Noni did not show cytotoxicity at a concentration range of 0.015%-1.0% (w/v%) and significantly enhanced the activity of alkaline phosphatase (ALP) and expression levels of osteoblast differentiation markers, including Runx2, ALP, osterix, and osteocalcin, bone morphogenetic protein 2, Wnt3a, and β-catenin. In addition, Noni enhanced the matrix mineralization of hPDL cells. In the signaling pathways, Noni increased the phosphorylation levels of Akt and GSK3β and nuclear translocation and transcriptional activity of β-catenin, which were attenuated by the addition of Dkk-1, a Wnt inhibitor, or LY294002, a PI3K inhibitor. These results suggest that Noni leaf extract enhances osteogenic differentiation through the PI3K/Akt-dependent activation of Wnt/β-catenin signaling. Noni leaf extract might be a novel alternative medicine for bone and periodontal regeneration in patients with periodontal diseases.

Evaluation of Recombinant Human FGF-2 and PDGF-BB in Periodontal Regeneration: A Systematic Review and Meta-Analysis

The prognosis for successful treatment of periodontal diseases is generally poor. Current therapeutic strategies often fail to regenerate infected periodontium. Recently an alternative strategy has been developed that combines conventional treatment with the application of recombinant human growth factors (rhGFs). But ambiguities in existed studies on the clinical efficacy of rhGFs do not permit either the identification of the specific growth factors effective for therapeutic interventions or the optimal concentration of them. Neither is it known whether the same rhGF can stimulate regeneration of both soft tissue and bone, or whether different patient populations call for differential use of the growth factors. In order to explore these issues, a meta-analysis was carried out. Particular attention was given to the therapeutic impact of fibroblast growth factor 2(FGF-2) and platelet derived growth factor BB (PDGF-BB). Our findings indicate that 0.3% rhFGF-2 and 0.3 mg/ml rhPDGF-BB show a greater capacity for periodontal regeneration than other concentrations and superiority to control groups with statistical significance. In the case of patients suffering only from gingival recession, however, the application of rhPDGF-BB produces no significant regenerative advantage. The findings of this study can potentially endow clinicians with guidelines for the appropriate application of these two rhGFs.

F-spondin negatively regulates dental follicle differentiation through the inhibition of TGF-β activity

OBJECTIVE

F-spondin is an extracellular matrix (ECM) protein that belongs to the thrombospondin type I repeat superfamily and is a negative regulator of bone mass. We have previously shown that f-spondin is specifically expressed in the dental follicle (DF), which gives rise to the periodontal ligament (PDL) during the tooth root formation stage. To investigate the molecular mechanism of PDL formation, we investigated the function of f-spondin in DF differentiation.

DESIGN

The expression patterning of f-spondin in the developing tooth germ was compared with that of periodontal ligament-related genes, including runx2, type I collagen and periostin, by in situ hybridization analysis. To investigate the function of f-spondin during periodontal ligament formation, an f-spondin adenovirus was infected into the bell stage of the developing tooth germ, and the effect on dental differentiation was analyzed.

RESULTS

F-spondin was specifically expressed in the DF of the developing tooth germ; by contrast, type I collagen, runx2 and periostin were expressed in the DF and in the alveolar bone. F-spondin-overexpresssing tooth germ exhibited a reduction in gene expression of periostin and type I collagen in the DF. By contrast, the knockdown of f-spondin in primary DF cells increased the expression of these genes. Treatment with recombinant f-spondin protein functionally inhibited periostin expression induced by transforming growth factor-β (TGF-β).

CONCLUSION

Our data indicated that f-spondin inhibits the differentiation of DF cells into periodontal ligament cells by inhibiting TGF-β. These data suggested that f-spondin negatively regulates PDL differentiation which may play an important role in the immature phenotype of DF.

Role of PIN1 on in vivo periodontal tissue and in vitro cells

BACKGROUND

Although expression of peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (PIN1) was reported in bone tissue, the precise role of PIN1 in periodontal tissue and cells remain unclear.

MATERIAL & METHODS

To elucidate the roles of PIN1 in periodontal tissue, its expression in periodontal tissue and cells, and effects on in vitro 4 osteoblast differentiation and the underlying signaling mechanisms were evaluated.

RESULTS

PIN1 was expressed in mouse periodontal tissues including periodontal ligament cells (PDLCs), cementoblasts and osteoblasts at the developing root formation stage (postnatal, PN14) and functional stage of tooth (PN28). Treatment of PIN1 inhibitor juglone, and gene silencing by RNA interference promoted osteoblast differentiation in PDLCs and cementoblasts, whereas the overexpression of PIN1 inhibited. Moreover, osteogenic medium-induced activation of AMPK, mTOR, Akt, ERK, p38 and NF-jB pathways were enhanced by PIN1 siRNA, but attenuated by PIN1 overexpression. Runx2 expressions were induced by PIN1 siRNA, but downregulated by PIN1 overexpression.

CONCLUSION

In summary, this study is the first to demonstrate that PIN1 is expressed in developing periodontal tissue, and in vitro PDLCs and cementoblasts. PIN1 inhibition stimulates osteoblast differentiation, and thus may play an important role in periodontal regeneration.

Effects of diode laser irradiation and fibroblast growth factor on periodontal healing of replanted teeth after extended extra-oral dry time

AIM

The search for effective protocols to reduce the incidence of root resorption and allow periodontal ligament repair is still challenging, given the unpredictable outcome of late tooth replantation. The aim of this study was to assess the effects of both high-power diode laser irradiation (DL) and basic fibroblast growth factor (FGF) on the periodontal healing of replanted teeth after extended extra-oral dry time.

METHODS

Maxillary incisors of 50 male rats were extracted and assigned to three experimental and two control groups (n = 10). DL: root surfaces treated with DL (810 nm, continuous mode, 1.0 W, 30 s), FGF: topical application of FGF gel to the root surface and in the alveolar wound, DL + FGF: DL and topical application of FGF gel, C+: no treatment after extraction and immediate replantation and C-: no treatment after extraction and replantation after 60 min. In the experimental groups, the specimens were kept dry for 60 min, the pulps were removed and the canals were filled with calcium hydroxide paste prior to tooth replantation. The animals were euthanized after 60 days. The specimens were processed for radiographic, histological and immunohistochemical analyses.

RESULTS

The radiographic analysis showed fewer resorptive areas in DL + FGF (P < 0.05). The histological and immunohistochemical analyses showed that the DL group had lower mean values of ankylosis, replacement and inflammatory resorption when compared to C-, not differing statistically from C+. DL + FGF produced significantly more collagen fibers (type I and type III) than C-, not differing from C+ in the case of type I fibers (P < 0.05).

CONCLUSIONS

DL, with or without FGF, reduced the occurrence of external root resorption and ankylosis. Periodontal healing was favored and some fiber reinsertion occurred only when FGF was used.

Effects of fibroblast growth factor-2 on cell proliferation of cementoblasts

Background/purpose

Fibroblast growth factor (FGF)-2 is known as a signaling molecule that induces tissue regeneration. Little is known about the effect of FGF-2 on cementoblasts for periodontal and periapical regeneration. The aim of this study was to investigate the effects of FGF-2 on murine immortalized cementoblast cell line (OCCM.30).

Materials and methods

Cell growth and proliferation was judged by using alamar blue reduction assay. Flow cytometry analysis was used to evaluate Stro-1 positive cells expression with or without FGF-2. Western blot was used to evaluate the expression of phosphorylated serine–threonine kinase Akt (p-Akt) and extracellular signal-regulated protein kinase (p-ERK) in cementoblasts.

Results

FGF-2 was found to increase cell growth in a dose-dependent manner (P < 0.05). The concentration of 10 ng/mL FGF-2 enhanced cell proliferation in a time-dependent manner (P < 0.05). In addition, 10 ng/mL FGF-2 significantly increased the number of Stro-1 positive cells in the first 24 hours (P < 0.05). Moreover, 10 ng/mL FGF-2 was found to upregulate p-Akt and p-ERK in a time-dependent manner (P < 0.05).

Conclusion

Taken together, FGF-2 could increase cementoblast growth, proliferation, and Stro-1 positive cells. These enhancements are associated with the upregulation of p-Akt and p-ERK expression. The application of FGF-2 may provide benefit for periodontal and periapical regeneration during the early phase of wound healing.

A Novel Regenerative Technique Combining Bone Morphogenetic Protein-2 With Fibroblast Growth Factor-2 for Circumferential Defects in Dog Incisors

BACKGROUND

Periodontal regeneration of incisors is necessary for esthetic recovery. A novel regenerative method combining bone morphogenetic protein (BMP)-2 and fibroblast growth factor (FGF)-2 was developed. The purpose of this study is to evaluate periodontal healing, including root coverage, in circumferential defects of incisors.

METHODS

Fifty incisors in five beagles were used. After circumferential defects were surgically created, each group, consisting of ten recipient sites, received: 1) a double layer with FGF-2 (2 μg)/collagen as inner layer and BMP-2 (4 μg)/collagen as outer layer (FB-DL group); 2) collagen impregnated with both FGF-2 (2 μg) and BMP-2 (4 μg) (FB-M group); 3) BMP-2 (4 μg)/collagen (B group); 4) FGF-2 (4 μg)/collagen (F group); or 5) collagen (C group). Dogs were sacrificed 8 weeks post-surgery, and healing was evaluated histologically.

RESULTS

The three groups treated with BMP-2 showed enhanced new bone formation compared with control and F groups (P < 0.05). Furthermore, connective tissue attachment with cementum regeneration in the FB-DL group was significantly greater than in FB-M and B groups (P <0.05). Ankylosis in the FB-DL group was significantly less than in FB-M and B groups (P <0.05). Gingival recession was inhibited significantly better in FB-DL and FB-M groups compared with control and B groups.

CONCLUSION

These data support development of a double-layer method combining BMP-2 and FGF-2 as a therapeutic approach to periodontal regeneration at incisors with horizontal circumferential defects.

Periodontal regeneration with 0.3% basic fibroblast growth factor (FGF-2) for a patient with aggressive periodontitis: a case report

This case report describes the clinical efficacy of treatment with basic fibroblast growth factor (FGF-2) for periodontal regeneration. A patient with aggressive periodontitis participated in a clinical trial involving administration of 0.3% FGF-2 in comparison with a placebo control. To evaluate the efficacy of FGF-2, standardized radiographs were taken before surgery and at 12, 24, and 36 weeks after FGF-2 treatment. The rate of increase in alveolar bone height was 86.9% at 36 weeks. The 6-year postoperative radiograph showed significant development of alveolar bone in comparison with the first visit. FGF-2 treatment may be effective for periodontal regeneration in cases of aggressive periodontitis. (J Oral Sci 58, 137-140, 2016).

A Randomized Clinical Trial Evaluating rh-FGF-2/β-TCP in Periodontal Defects

Biological mediators have been used to enhance periodontal regeneration. The aim of this prospective randomized controlled study was to evaluate the safety and effectiveness of 3 doses of fibroblast growth factor 2 (FGF-2) when combined with a β-tricalcium phosphate (β-TCP) scaffold carrier placed in vertical infrabony periodontal defects in adult patients. In this double-blinded, dose-verification, externally monitored clinical study, 88 patients who required surgical intervention to treat a qualifying infrabony periodontal defect were randomized to 1 of 4 treatment groups—β-TCP alone (control) and 0.1% recombinant human FGF-2 (rh-FGF-2), 0.3% rh-FGF-2, and 0.4% rh-FGF-2 with β-TCP—following scaling and root planing of the tooth prior to a surgical appointment. Flap surgery was performed with EDTA conditioning of the root prior to device implantation. There were no statistically significant differences in patient demographics and baseline characteristics among the 4 treatment groups. When a composite outcome of gain in clinical attachment of 1.5 mm was used with a linear bone growth of 2.5 mm, a dose response pattern detected a plateau in the 0.3% and 0.4% rh-FGF-2/β-TCP groups with significant improvements over control and 0.1% rh-FGF-2/β-TCP groups. The success rate at 6 mo was 71% in the 2 higher-concentration groups, as compared with 45% in the control and lowest treatment groups. Percentage bone fill in the 2 higher-concentration groups was 75% and 71%, compared with 63% and 61% in the control and lowest treatment group. No increases in specific antibody to rh-FGF-2 were detected, and no serious adverse events related to the products were reported. The results from this multicenter trial demonstrated that the treatment of infrabony vertical periodontal defects can be enhanced with the addition of rh-FGF-2/β-TCP ( ClinicalTrials.gov NCT01728844).

Smoking and gingivitis: focus on inducible nitric oxide synthase, nitric oxide and basic fibroblast growth factor

BACKGROUND

Periodontal disease pathogenesis has been associated with smoking. Gingivitis is a mild and reversible form of periodontal disease and it tends to progress to periodontitis only in susceptible individuals. In the present study, we aimed to examine the impact of smoking on host responses in gingivitis and to evaluate and compare the inducible nitric oxide synthase (iNOS) activity in gingival tissue and NO and basic fibroblast growth factor (bFGF) levels in the gingival crevicular fluid of patients with gingivitis and healthy individuals.

MATERIAL AND METHODS

Forty-one participants were assigned to the gingivitis-smoker (n = 13), gingivitis (n = 13), healthy-smoker (n = 7) and healthy groups (n = 8). Clinical indices were recorded; gingival biopsy and gingival crevicular fluid samples were obtained from papillary regions. iNOS expression was evaluated by immunohistochemical staining. The immunoreactive cells were semiquantitatively assessed. For the quantitative determination of nitrite and nitrate in gingival crevicular fluid, the NO assay kit was used. The amount of bFGF in gingival crevicular fluid was determined by enzyme-linked immunosorbent assay.

RESULTS

The gingivitis-smoker group demonstrated a stronger iNOS expression than the non-smoker gingivitis group. iNOS expression intensity was lower in the non-smoker healthy group compared to that in healthy-smokers. No significant gingival crevicular fluid NO and bFGF level changes were observed between groups. Among patients with gingivitis, a positive correlation was detected between gingival crevicular fluid NO and bFGF levels (r = 0.806, p = 0.001).

CONCLUSIONS

Our data suggest that smoking has significant effects on iNOS expression but not on gingival crevicular fluid NO or bFGF levels in healthy and patients with gingivitis. However, our results suggest that bFGF might be involved in the regulation of NO production via iNOS.

Biologic Agents for Periodontal Regeneration and Implant Site Development

The advancement of molecular mediators or biologic agents has increased tremendously during the last decade in periodontology and dental implantology. Implant site development and reconstruction of the lost periodontium represent main fields in which these molecular mediators have been employed and investigated. Different growth factors trigger different reactions in the tissues of the periodontium at various cellular levels. Proliferation, migration, and differentiation constitute the main target areas of these molecular mediators. It was the purpose of this comprehensive review to describe the origin and rationale, evidence, and the most current understanding of the following biologic agents: Recombinant Human Platelet-Derived Growth Factor-BB (rhPDGF-BB), Enamel Matrix Derivate (EMD), Platelet-Rich Plasma (PRP) and Platelet-Rich Fibrin (PRF), Recombinant Human Fibroblast Growth Factor-2 (rhFGF-2), Bone Morphogenic Proteins (BMPs, BMP-2 and BMP-7), Teriparatide PTH, and Growth Differential Factor-5 (GDF-5).

FGF2 gene activated matrices promote proliferation of bone marrow stromal cells

BACKGROUND

In this study, we report on the results from the development and early in vitro testing of a gene activated matrix encoding basic human fibroblast growth factor 2 (FGF2) in bone marrow stromal cells (BMSCs).

METHODS

Polyethylenimine (PEI), a cationic polymer, was utilized as a gene delivery vector and collagen scaffolds were used as the carrier to deliver the PEI-pDNA nano-sized complexes (nanoplexes) encoding the FGF2 protein. Initially, the BMSCs were transfected in vitro with the PEI-pFGF2 nanoplexes, prepared at a N/P ratio of 10, with cells alone and naked DNA as controls. This was followed by transfection experiments using collagen scaffold containing complexes, with the scaffold alone as a control. The transfection efficacy of the nanoplexes was assessed using ELISA for the determination of FGF2 protein expressed by the transfected cells. The functionality of transfection was assessed by evaluating cellular recruitment, attachment, and proliferation of BMSCs on the scaffold using imaging techniques.

RESULTS

BMSCs transfected with the PEI-pFGF2 nanoplexes (either alone or within the scaffold) led to higher expression of FGF2, compared to controls. Scanning electron microscopy and confocal imaging confirmed the recruitment and attachment of BMSCs to scaffolds containing the PEI-pFGF2 nanoplexes. Confocal microscopy showed a significantly higher number of proliferating cells within PEI-pFGF2 nanoplex-loaded scaffolds than with empty scaffolds.

CONCLUSIONS

This first in vitro evaluation in BMSCs provides evidence that gene activated matrices (GAMs) encoding the FGF2 protein may have strong translational potential for clinical applications that require enhanced osseous and periodontal tissue regeneration.

PLAP-1/Asporin Positively Regulates FGF-2 Activity

PLAP-1 is an extracellular matrix protein that is predominantly expressed in the periodontal ligament within periodontal tissue. It was previously revealed that PLAP-1 negatively regulates bone morphogenetic protein 2 and transforming growth factor β activity through direct interactions. However, the interaction between PLAP-1 and other growth factors has not been defined. Here, we revealed that PLAP-1 positively regulates the activity of fibroblast growth factor 2 (FGF-2), a critical growth factor in tissue homeostasis and repair. In this study, we isolated mouse embryonic fibroblasts (MEFs) from Plap-1(-/-) mice generated in our laboratory. Interestingly, Plap-1(-/-) MEFs exhibited enhanced responses to bone morphogenetic protein 2 but defective responses to FGF-2, and Plap-1 transfection into Plap-1(-/-) MEFs rescued these defective responses. In addition, binding assays revealed that PLAP-1 promotes FGF-2-FGF receptor 1 (FGFR1) complex formation by direct binding to FGF-2. Immunocytochemistry analyses revealed colocalization of PLAP-1 and FGF-2 in wild-type MEFs and reduced colocalization of FGF-2 and FGFR1 in Plap-1(-/-) MEFs compared with wild-type MEFs. Taken together, PLAP-1 positively regulates FGF-2 activity through a direct interaction. Extracellular matrix-growth factor interactions have considerable effects; thus, this approach may be useful in several regenerative medicine applications.

FGF-2 induces the proliferation of human periodontal ligament cells and modulates their osteoblastic phenotype by affecting Runx2 expression in the presence and absence of osteogenic inducers

The exact phenotype of human periodontal ligament cells (hPDLCs) remains a controversial area. Basic fibroblast growth factor (FGF-2) exhibits various functions and its effect on hPDLCs is also controversial. Therefore, the present study examined the effect of FGF-2 on the growth and osteoblastic phenotype of hPDLCs with or without osteogenic inducers (dexamethasone and β-glycerophosphate). FGF-2 was added to defined growth culture medium and osteogenic inductive culture medium. Cell proliferation, osteogenic differentiation and mineralization were measured. The selected differentiation markers, Runx2, collagen type I, α1 (Col1a1), osteocalcin (OCN) and epidermal growth factor receptor (EGFR), were investigated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Runx2 and OCN protein expression was measured by western blotting. FGF-2 significantly increased the proliferation of hPDLCs, but did not affect alkaline phosphatase activity. RT-qPCR analysis revealed enhanced mRNA expression of Runx2, OCN and EGFR, but suppressed Col1a1 gene expression in the absence of osteogenic inducers, whereas all these gene levels had no clear trend in their presence. The Runx2 protein expression was clearly increased, but the OCN protein level showed no evident trend. The mineralization assay demonstrated that FGF-2 inhibited mineralized matrix deposition with osteogenic inducers. These results suggested that FGF-2 induces the growth of immature hPDLCs, which is a competitive inhibitor of epithelial downgrowth, and suppresses their differentiation into mineralized tissue by affecting Runx2 expression. Therefore, this may lead to the acceleration of periodontal regeneration.

Recruitment of mesenchymal stem cells by stromal cell-derived factor 1α in pulp cells from deciduous teeth

Dental pulp cells (DPCs), including dental pulp (DP) stem cells, play a role in dentine repair under certain conditions caused by bacterial infections associated with caries, tooth fracture and injury. Mesenchymal stem cells (MSCs) have also been shown to be involved in this process of repair. However, the mechanisms through which MSCs are recruited to the DP have not yet been elucidated. Therefore, the aim of the present in vitro study was to investigate whether stromal cell-derived factor 1α (SDF1)-C-X-C chemokine receptor type 4 (CXCR4) signaling is involved in tissue repair in the DP of deciduous teeth. A single-cell clone from DPCs (SDP11) and UE7T-13 cells were used as pulp cells and MSCs, respectively. The MG-63 and HuO9 cells, two osteosarcoma cell lines, were used as positive control cells. Reverse transcription polymerase chain reaction (RT-PCR) revealed that all cell lines (SDP11, UE7T-13 MG-63 and HuO9) were positive for both SDF1 and CXCR4 mRNA expression. Moreover, immunocytochemical analysis indicated that SDF1 and CXCR4 proteins were expressed in the SDP11 and UE7T-13 cells. SDF1 was also detected in the cell lysates (CLs) and conditioned medium (CM) collected from the SDP11 and UE7T-13 cells, and AMD3100, a specific antagonist of CXCR4, inhibited the migration of the UE7T-13 cells; this migration was induced by treatment with CM, which was collected from the SDP11 cells. In addition, real-time PCR showed that the expression of SDF1 in the SDP11 cells was inhibited by treatment with 20 ng/ml fibroblast growth factor (FGF)-2, and exposure to AZD4547, an inhibitor of the FGF receptor, blocked this inhibition. Collectively, these data suggest that SDF1 produced by DP plays an important role in homeostasis, repair and regeneration via the recruitment of MSCs.

Attachment and Differentiation of Human Umbilical Cord Stem Cells on to the Tooth Root Surface with and without the Use of Fibroblast Growth Factor-An In Vitro Study

Background and Objectives

The purpose of this first of its kind study was to analyse the growth, development and attachment of cultured human umbilical cord stem cells alone or supplemented with basic Fibroblast Growth Factor (bFGF) on both healthy and periodontally diseased tooth surfaces in vitro.

Methods

Four groups of 12 root surface scaffolds each were classified as Group I- healthy root surfaces; Group II- periodontally diseased; Group III- Healthy with bFGF and Group IV- periodontally diseased root with bFGF. bFGF was applied in the concentration of 8 ng/ml on to the surface followed by incubation of cultured human umbilical cord stem cells (hUCMSCs) on the scaffolds. Scanning electron microscopy observations were made on 14^th and 21^st days to assess the proliferation and morphology of cells attached on the tooth surface.

Results

Cultured hUCMSCs demonstrated adhesion to tooth root scaffold. All the groups showed a significant increase in the number of cell attachment from 14^th day to 21^st day. The groups with bFGF showed a significant increase in attachment of cells when compared to the groups without bFGF. The cells showed an increase in number of flat cells from 14th day to 21st day in all the groups indicating an increased maturity of cells. Periodontally diseased groups had less maturity of cells than healthy groups. The groups supplemented with bFGF, had more mature cells than the groups without bFGF.

Conclusions

hUCMSCs have the propensity to differentiate into cells that have the capacity to bind to root surfaces. hUCMSCs incubated with bFGF showed better proliferation and attachment to tooth root surfaces. The role of hUCMSCs can be further explored for periodontal regeneration.

Periodontal ligament stem cells: current status, concerns, and future prospects

Periodontal ligament stem cells (PDLSCs), which reside in the perivascular space of the periodontium, possess characteristics of mesenchymal stem cells and are a promising tool for periodontal regeneration. Recently, great progress has been made in PDLSC transplantation. Investigators are attempting to maximize the proliferation and differentiation potential of PDLSCs by modifying culture conditions and applying growth factors. Nevertheless, problems remain. First, incomparability among different studies must be minimized by establishing standard guidelines for culture and identification of PDLSCs. Notably, attention should be paid to the biological safety of PDLSC transplantation. The present review updates the latest findings regarding PDLSCs and discusses standard criteria for culture and identification of PDLSCs. Finally, the review calls for careful consideration of PDLSC transplantation safety.

Tissue engineering for bone regeneration and osseointegration in the oral cavity

OBJECTIVE

The focus of this review is to summarize recent advances on regenerative technologies (scaffolding matrices, cell/gene therapy and biologic drug delivery) to promote reconstruction of tooth and dental implant-associated bone defects.

METHODS

An overview of scaffolds developed for application in bone regeneration is presented with an emphasis on identifying the primary criteria required for optimized scaffold design for the purpose of regenerating physiologically functional osseous tissues. Growth factors and other biologics with clinical potential for osteogenesis are examined, with a comprehensive assessment of pre-clinical and clinical studies. Potential novel improvements to current matrix-based delivery platforms for increased control of growth factor spatiotemporal release kinetics are highlighting including recent advancements in stem cell and gene therapy.

RESULTS

An analysis of existing scaffold materials, their strategic design for tissue regeneration, and use of growth factors for improved bone formation in oral regenerative therapies results in the identification of current limitations and required improvements to continue moving the field of bone tissue engineering forward into the clinical arena.

SIGNIFICANCE

Development of optimized scaffolding matrices for the predictable regeneration of structurally and physiologically functional osseous tissues is still an elusive goal. The introduction of growth factor biologics and cells has the potential to improve the biomimetic properties and regenerative potential of scaffold-based delivery platforms for next-generation patient-specific treatments with greater clinical outcome predictability.

Similar in vitro effects and pulp regeneration in ectopic tooth transplantation by basic fibroblast growth factor and granulocyte-colony stimulating factor

OBJECTIVES

Granulocyte-colony stimulating factor (G-CSF) has been shown to have combinatorial trophic effects with dental pulp stem cells for pulp regeneration. The aim of this investigation is to examine the effects of basic fibroblast growth factor (bFGF) in vitro and in vivo compared with those of G-CSF and to assess the potential utility of bFGF as an alternative to G-CSF for pulp regeneration.

MATERIALS AND METHODS

Five different types of cells were examined in the in vitro effects of bFGF on cell migration, proliferation, anti-apoptosis, neurite outgrowth, angiogenesis, and odontogenesis compared with those of G-CSF. The in vivo regenerative potential of pulp tissue including vasculogenesis and odontoblastic differentiation was also compared using an ectopic tooth transplantation model.

RESULTS

Basic fibroblast growth factor was similar to G-CSF in high migration, proliferation and anti-apoptotic effects and angiogenic and neurite outgrowth stimulatory activities in vitro. There was no significant difference between bFGF and G-CSF in the regenerative potential in vivo.

CONCLUSIONS

The potential utility of bFGF for pulp regeneration is demonstrated as a homing/migration factor similar to the influence of G-CSF.

TGF-β1 and FGF2 stimulate the epithelial-mesenchymal transition of HERS cells through a MEK-dependent mechanism

Hertwig's epithelial root sheath (HERS) cells participate in cementum formation through epithelial-mesenchymal transition (EMT). Previous studies have shown that transforming growth factor beta 1 (TGF-β1) and fibroblast growth factor 2 (FGF2) are involved in inducing EMT. However, their involvement in HERS cell transition remains elusive. In this study, we confirmed that HERS cells underwent EMT during the formation of acellular cementum. We found that both TGF-β1 and FGF2 stimulated the EMT of HERS cells. The TGF-β1 regulated the differentiation of HERS cells into periodontal ligament fibroblast-like cells, and FGF2 directed the differentiation of HERS cells into cementoblast-like cells. Treatment with TGF-β1 or FGF2 inhibitor could effectively suppress HERS cells differential transition. Combined stimulation with both TGF-β1 and FGF-2 did not synergistically accelerate the EMT of HERS. Moreover, TGF-β1/FGF2-mediated EMT of HERS cells was reversed by the MEK1/2 inhibitor U0126. These results suggest that TGF-β1 and FGF2 induce the EMT of HERS through a MAPK/ERK-dependent signaling pathway. They also exert their different tendency of cellular differentiation during tooth root formation. This study further expands our knowledge of tooth root morphogenesis and provides more evidence for the use of alternative cell sources in clinical treatment of periodontal diseases.

Multiphasic scaffolds for periodontal tissue engineering

For a successful clinical outcome, periodontal regeneration requires the coordinated response of multiple soft and hard tissues (periodontal ligament, gingiva, cementum, and bone) during the wound-healing process. Tissue-engineered constructs for regeneration of the periodontium must be of a complex 3-dimensional shape and adequate size and demonstrate biomechanical stability over time. A critical requirement is the ability to promote the formation of functional periodontal attachment between regenerated alveolar bone, and newly formed cementum on the root surface. This review outlines the current advances in multiphasic scaffold fabrication and how these scaffolds can be combined with cell- and growth factor-based approaches to form tissue-engineered constructs capable of recapitulating the complex temporal and spatial wound-healing events that will lead to predictable periodontal regeneration. This can be achieved through a variety of approaches, with promising strategies characterized by the use of scaffolds that can deliver and stabilize cells capable of cementogenesis onto the root surface, provide biomechanical cues that encourage perpendicular alignment of periodontal fibers to the root surface, and provide osteogenic cues and appropriate space to facilitate bone regeneration. Progress on the development of multiphasic constructs for periodontal tissue engineering is in the early stages of development, and these constructs need to be tested in large animal models and, ultimately, human clinical trials.

Regenerative periodontal therapy: 30 years of lessons learned and unlearned

In this review, we reflect upon advances and hindrances encountered over the last three decades in the development of strategies for periodontal regeneration. In this soul-searching pursuit we focus on revisiting lessons learned that should guide us in the quest for the reconstruction of the lost periodontium. We also examine beliefs and traditions that should be unlearned so that we can continue to advance the field. This learned/unlearned body of knowledge is consolidated into core principles to help us to develop new therapeutic approaches to benefit our patients and ultimately our society.

Periodontology: past, present, perspectives

Periodontitis is an infectious disease that affects the tooth-supporting tissues and exhibits a wide range of clinical, microbiological and immunological manifestations. The disease is associated with and is probably caused by a multifaceted dynamic interaction of specific infectious agents, host immune responses, harmful environmental exposure and genetic susceptibility factors. This volume of Periodontology 2000 covers key subdisciplines of periodontology, ranging from etiopathogeny to therapy, with emphasis on diagnosis, classification, epidemiology, risk factors, microbiology, immunology, systemic complications, anti-infective therapy, reparative treatment, self-care and affordability issues. Learned and unlearned concepts of periodontitis over the past 50 years have shaped our current understanding of the etiology of the disease and of clinical practice.

A role for c-Kit in the maintenance of undifferentiated human mesenchymal stromal cells

The multipotency of human mesenchymal stromal cells (hMSCs) and the feasibility of deriving these cells from periodontal ligament hold promise for stem cell-based tissue engineering. However, the regulation of adult hMSCs activity is not well understood. The present study investigated the c-Kit surface receptor and downstream gene expression in hMSCs. The c-Kit-positive population showed increased colony-forming ability rather than differentiation potential. The knockdown of c-Kit and/or stem cell factor (SCF) genes enhanced alkaline phosphatase activity and also upregulated osteoblast- and adipocyte-specific genes, including osteocalcin, runt-related transcription factor 2, osteopontin, peroxisome proliferator-activated receptor-γ, and lipoprotein lipase. Stimulation with growth factors, including fibroblast growth factor-2, transforming growth factor-β1, and enamel matrix derivative significantly suppressed the mRNA expression of c-Kit. These results support an emerging understanding of the roles of the c-Kit/SCF signal in maintaining the undifferentiated stage of hMSCs by inhibiting the expression of lineage-specific genes in hMSCs and regulating the effect of growth factors on the proliferation and differentiation of hMSCs. The modulation of c-Kit/SCF signaling might contribute to future regenerative approaches in controlling both the stemness and differentiation properties of hMSCs.

Tissue engineering in periodontal tissue

Periodontitis, a recognized disease worldwide, is bacterial infection-induced inflammation of the periodontal tissues that results in loss of alveolar bone. Once it occurs, damaged tissue cannot be restored to its original form, even if decontaminating treatments are performed. For more than half a century, studies have been conducted to investigate true periodontal regeneration. Periodontal regeneration is the complete reconstruction of the damaged attachment apparatus, which contains both hard tissue (alveolar bone and cementum) and soft tissue (periodontal ligament). Several treatments, including bone grafts, guided tissue regeneration with physical barriers for epithelial cells, and growth factors have been approved for clinical use; however, their indications and outcomes are limited. To overcome these limitations, the concept of "tissue engineering" was introduced. Combination treatment using cells, growth factors, and scaffolds, has been studied in experimental animal models, and some studies have been translated into clinical trials. In this review, we focus on recent progressive tissue engineering studies and discuss future perspectives on periodontal regeneration.

Cooperative effects of FGF-2 and VEGF-A in periodontal ligament cells

We previously demonstrated that topical application of fibroblast growth factor (FGF)-2 enhanced periodontal tissue regeneration. Although angiogenesis is a crucial event for tissue regeneration, the mechanism(s) by which topically applied FGF-2 induces angiogenesis in periodontal tissues has not been fully clarified. In this study, we investigated whether FGF-2 could induce vascular endothelial growth factor (VEGF)-A expression in periodontal ligament (PDL) cells and whether cell-to-cell interactions between PDL cells and endothelial cells could stimulate angiogenesis. FGF-2 induced VEGF-A secretion from MPDL22 cells (mouse periodontal ligament cell line) in a dose-dependent manner. Transwell and wound-healing assays revealed that co-stimulation with FGF-2 plus VEGF-A synergistically stimulated the migration of MPDL22 cells. Interestingly, co-culture of MPDL22 cells with bEnd5 cells (mouse endothelial cell line) also stimulated VEGF-A production from MPDL22 cells and tube formation by bEnd5 cells. Furthermore, time-lapse analysis revealed that MPDL22 cells migrated close to the tube-forming bEnd5 cells, mimicking pericytes. Thus, FGF-2 induces VEGF-A expression in PDL cells and induces angiogenesis in combination with VEGF-A. Cell-to-cell interactions with PDL cells also facilitate angiogenesis.

Identification of novel amelogenin-binding proteins by proteomics analysis

Emdogain (enamel matrix derivative, EMD) is well recognized in periodontology. It is used in periodontal surgery to regenerate cementum, periodontal ligament, and alveolar bone. However, the precise molecular mechanisms underlying periodontal regeneration are still unclear. In this study, we investigated the proteins bound to amelogenin, which are suggested to play a pivotal role in promoting periodontal tissue regeneration. To identify new molecules that interact with amelogenin and are involved in osteoblast activation, we employed coupling affinity chromatography with proteomic analysis in fractionated SaOS-2 osteoblastic cell lysate. In SaOS-2 cells, many of the amelogenin-interacting proteins in the cytoplasm were mainly cytoskeletal proteins and several chaperone molecules of heat shock protein 70 (HSP70) family. On the other hand, the proteomic profiles of amelogenin-interacting proteins in the membrane fraction of the cell extracts were quite different from those of the cytosolic-fraction. They were mainly endoplasmic reticulum (ER)-associated proteins, with lesser quantities of mitochondrial proteins and nucleoprotein. Among the identified amelogenin-interacting proteins, we validated the biological interaction of amelogenin with glucose-regulated protein 78 (Grp78/Bip), which was identified in both cytosolic and membrane-enriched fractions. Confocal co-localization experiment strongly suggested that Grp78/Bip could be an amelogenin receptor candidate. Further biological evaluations were examined by Grp78/Bip knockdown analysis with and without amelogenin. Within the limits of the present study, the interaction of amelogenin with Grp78/Bip contributed to cell proliferation, rather than correlate with the osteogenic differentiation in SaOS-2 cells. Although the biological significance of other interactions are not yet explored, these findings suggest that the differential effects of amelogenin-derived osteoblast activation could be of potential clinical significance for understanding the cellular and molecular bases of amelogenin-induced periodontal tissue regeneration.

Periostin increases migration and proliferation of human periodontal ligament fibroblasts challenged by tumor necrosis factor -α and Porphyromonas gingivalis lipopolysaccharides

BACKGROUND

In the chronic established periodontal lesion, the proliferation and migration potential of periodontal ligament (PDL) cells are significantly compromised. Thus, the progressive loss of tissue integrity is favored and normal healing and regeneration compromised. Periostin, a known PDL marker, modulates cell-matrix interactions, cell behavior, as well as the matrix biomechanics and PDL homeostasis.

OBJECTIVE

To evaluate whether periostin restores the regenerative potential of PDL cells in terms of proliferation, migration, and activation of survival signaling pathways after being challenged by Porphyromonas gingivalis lipopolysaccharides and tumor necrosis factor alpha α.

METHODS

Human PDL (hPDL) cells were cultured under different conditions: control, periostin (50 or 100 ng/mL), and fibroblast growth factor 2 (10 ng/mL) to evaluate cell proliferation (by Ki67), cell migration (by scratch assays) and PI3K/AKT/mTOR pathway activation (by western blot analyses of total AKT, phospho-AKT and PS6). A different set of cultures was challenged by adding tumor necrosis factor alpha α (10 ng/mL) and P. gingivalis lipopolysaccharides (200 ng/mL) to evaluate the effects of periostin as described above.

RESULTS

Periostin significantly increased cell proliferation (twofold), migration (especially at earlier time points and low dose) and activation of survival signaling pathway (higher phosphorylation of AKT and PS6). Furthermore, periostin promoted similar cellular effects even after being challenged with proinflammatory cytokines and bacterial virulence factors.

CONCLUSION

Periostin acts as an important modulator of hPDL cell-matrix dynamics. It modulates hPDL proliferation, migration and PI3K/AKT/mTOR pathway. It also helps in overcoming the altered biological phenotype that chronic exposure to periodontal pathogens and proinflammatory cytokines produce in hPDL cells.

Intermittent parathyroid hormone administration improves periodontal healing in rats

BACKGROUND

Intermittent administration of parathyroid hormone (PTH) promotes new bone formation in patients with osteoporosis and bone fractures. It was shown previously that PTH also reduces periodontitis-related bone loss. The aim of this study is to evaluate the effect of treatment with PTH on periodontal healing in rats.

METHODS

Fenestration defects were created at the buccal surface of the distal root of the mandibular first molars, and both periodontal ligament (PDL) and cementum were removed. Animals were then assigned to two groups (eight animals per group): group 1: control, placebo administration; and group 2: test, human PTH (hPTH) 1-34 administration at a concentration of 40 μg/kg. For both groups, the animals were injected every 2 days, and the animals were sacrificed at 14 and 21 days after surgery. Specimens were harvested and processed for routine decalcified histologic sections. The following parameters were assessed: 1) remaining bone defect extension (RBDE); 2) newly formed bone density (NFBD); 3) total callus area (TCA); 4) osteoclast number (ON) in the callus region; and 5) newly formed dental cementum-like tissue (NFC). Birefringence of root PDL reattachment was also evaluated.

RESULTS

Birefringence analysis showed root PDL reattachment for both groups 21 days after treatment. Intermittent hPTH 1-34 administration decreased RBDE (P <0.01) and increased NFBD (P <0.01), TCA (P <0.01), area of NFC (P <0.01), and ON in the callus region (P <0.01).

CONCLUSION

Within the limits of the present study, intermittent administration of hPTH 1-34 led to an enhanced periodontal healing process compared with non-treated animals.

Effect of basic fibroblast growth factor on pluripotent marker expression and colony forming unit capacity of stem cells isolated from human exfoliated deciduous teeth

Human dental pulp of exfoliated deciduous teeth contains the population of cells that exhibited mesenchymal stem cell (MSC) characters. Though, a cell amplification process is indeed required to secure an adequate cell number for such a potential employment. Several publications suggested the alteration of MSCs upon in vitro culture, for example, the decrease in proliferation and the loss of stem cell characters. Here, we investigated an influence of basic fibroblast growth factor (bFGF) on stem cells isolated from human exfoliated deciduous teeth (SHEDs) with respect to cell proliferation, colony forming unit efficiency and stem cell marker expression in both short- and long-term cultures. For short-term bFGF treatment, SHEDs were treated with bFGF for 48 h. While, in long-term bFGF supplementation, SHEDs were maintained in culture and continuous passage upon confluence in medium supplemented with bFGF. Cells at passage (P) 5 and 10 were employed for characterization. Our results showed that short-term bFGF treatment enhanced OCT4, REX1, and NANOG mRNA expression as well as colony forming unit ability. The FGFR inhibitor pretreatment was able to attenuate the influence of bFGF on pluripotent stem cell marker expression, confirming bFGF function. In addition, cells cultured in high passage number had decreased in cell proliferation, colony forming unit capacity, and pluripotent stem cell maker mRNA expression. However, bFGF supplementation in culture medium enhanced both pluripotent stem cell marker expression and colony forming unit capacity in later passage, though the effect was not robust. Together, these results indicate that high passage number may attenuate pluripotent properties of SHEDs and bFGF supplementation could be the beneficial approach to maintain SHEDs' stemness properties.

Protein and peptide-based therapeutics in periodontal regeneration

Protein and peptide-based therapeutics provide a unique strategy for controlling highly specific and complex biologic actions that cannot be accomplished by simple devices or chemical compounds. This article reviews some of the key characteristics and summarizes the clinical effectiveness of protein and peptide-based therapeutics targeting periodontal regeneration.

EVIDENCE ACQUISITION

A literature search was conducted of randomized clinical trials and systematic reviews evaluating protein and peptide-based therapeutics for the regeneration of periodontal tissues of at least 6 months duration. Data sources included PubMed and Embase electronic databases, hand-searched journals, and the ClinicalTrials.gov registry.

EVIDENCE SYNTHESIS

Commercially marketed protein and peptide-based therapeutics for periodontal regeneration provide gains in clinical attachment level and bone formation that are comparable or superior to other regenerative approaches. Results from several clinical trials indicate that protein and peptide-based therapies can accelerate repair and regeneration when compared with other treatments and that improvements in clinical parameters continue beyond 12 months. Protein and peptide-based therapies also exhibit the capacity to increase the predictability of treatment outcomes.

CONCLUSIONS

Clinical and histologic studies support the effectiveness of protein- and peptide-based therapeutics for periodontal regeneration. Emerging evidence suggests that the delivery devices/scaffolds play a critical role in determining the effectiveness of this class of therapeutics.

Expression and purification of biologically active human FGF2 containing the b'a' domains of human PDI in Escherichia coli

Among the members of the fibroblast growth factor (FGF) family that affect the growth, differentiation, migration, and survival of many cell types, FGF2 is the most abundant in the central nervous system. Because of its wound healing effects, FGF2 has potential as a therapeutic agent. The protein is also added to the culture media to maintain stem cells. Expression and purification procedures for FGF2 that are highly efficient and low cost have been intensively investigated for the past two decades. Our current study focuses on the purification of FGF2 fused with b'a' domains of human protein disulfide isomerase to elevate overexpression, solubility, and stability with a simplified experimental procedure using only ion exchange chromatography, as well as on the confirmation of the biological activity of FGF2 on fibroblast Balb/c 3T3 cells and hippocampal neural cells.

Effect of basic fibroblast growth factor (FGF-2) in combination with beta tricalcium phosphate on root coverage in dog

OBJECTIVE

In root coverage treatment, periodontal regeneration in gingival recession-type defects is an important challenge for the periodontist. The aim of this study was to histometrically investigate the effect of combined use of basic fibroblast growth factor (FGF-2) and beta tricalcium phosphate (β-TCP) on root coverage in dogs.

MATERIALS AND METHODS

Sixteen adult beagle dogs were used. Buccal gingival recession defects were surgically created bilaterally in the maxillary canines. The defects in each animal were randomly assigned to: (1) an FGF-2 alone (control) group or (2) FGF-2/β-TCP (experimental) group. At 2, 4 or 8 weeks following surgery, specimens were obtained and subjected to microscopic examination and histometric assessment.

RESULTS

Inhibition of epithelial down-growth was observed in both groups. At week 2, in the newly formed connective tissue at the coronal portion, the FGF-2/β-TCP group showed significantly greater numbers of proliferating cell nuclear antigen-positive cells than the FGF-2 group (55.8 ± 4.8 vs 12.0 ± 1.4, p < 0.01). In the FGF-2/β-TCP group, new attachment was observed at 8 weeks and the extent of new bone and cementum formation was significantly greater in the FGF-2/β-TCP group than that in the FGF-2 alone group. In both groups, the dentin surface beneath the new cementum presented minor irregularities, but no replacement resorption was observed.

CONCLUSIONS

FGF-2 used in combination with β-TCP enhances formation of new bone and cementum without significant root resorption in root coverage in this dog model. This combination warrants further investigation in periodontal regeneration in root coverage treatment.

Exposure to transforming growth factor-β1 after basic fibroblast growth factor promotes the fibroblastic differentiation of human periodontal ligament stem/progenitor cell lines

Basic fibroblast growth factor (bFGF) is a cytokine that promotes the regeneration of the periodontium, the specialized tissues supporting the teeth. bFGF, does not, however, induce the synthesis of smooth muscle actin alpha 2 (ACTA2), type I collagen (COL1), or COL3, which are principal molecules in periodontal ligament (PDL) tissue, a component of the periodontium. We have suggested the feasibility of using transforming growth factor-β1 (TGFβ1) to induce fibroblastic differentiation of PDL stem/progenitor cells (PDLSCs). Here, we investigated the effect of the subsequent application of TGFβ1 after bFGF (bFGF/TGFβ1) on the differentiation of PDLSCs into fibroblastic cells. We first confirmed the expression of bFGF and TGFβ1 in rat PDL tissue and primary human PDL cells. Receptors for both bFGF and TGFβ1 were expressed in the human PDLSC lines 1-11 and 1-17. Exposure to bFGF for 2 days promoted vascular endothelial growth factor gene and protein expression in both cell lines and down-regulated the expression of ACTA2, COL1, and COL3 mRNA in both cell lines and the gene fibrillin 1 (FBN1) in cell line 1-11 alone. Furthermore, bFGF stimulated cell proliferation of these cell lines and significantly increased the number of cells in phase G2/M in the cell lines. Exposure to TGFβ1 for 2 days induced gene expression of ACTA2 and COL1 in both cell lines and FBN1 in cell line 1-11 alone. BFGF/TGFβ1 treatment significantly up-regulated ACTA2, COL1, and FBN1 expression as compared with the group treated with bFGF alone or the untreated control. This method might thus be useful for accelerating the generation and regeneration of functional periodontium.

Stem cells in dentistry--Part II: Clinical applications

New technologies that facilitate solid alveolar ridge augmentation are receiving considerable attention in the field of prosthodontics because of the growing requirement for esthetic and functional reconstruction by dental implant treatments. Recently, several studies have demonstrated potential advantages for stem-cell-based therapies in regenerative treatments. Mesenchymal stem/stromal cells (MSCs) are now an excellent candidate for tissue replacement therapies, and tissue engineering approaches and chair-side cellular grafting approaches using autologous MSCs represent the clinical state of the art for stem-cell-based alveolar bone regeneration. Basic studies have revealed that crosstalk between implanted donor cells and recipient immune cells plays a key role in determining clinical success that may involve the recently observed immunomodulatory properties of MSCs. Part II of this review first overviews progress in regenerative dentistry to consider the implications of the stem cell technology in dentistry and then highlights cutting-edge stem-cell-based alveolar bone regenerative therapies. Factors that affect stem-cell-based bone regeneration as related to the local immune response are then discussed. Additionally, pre-clinical stem cell studies for the regeneration of teeth and other oral organs as well as possible applications of MSC-based immunotherapy in dentistry are outlined. Finally, the marketing of stem cell technology in dental stem cell banks with a view toward future regenerative therapies is introduced.

Stem cell and biomaterials research in dental tissue engineering and regeneration

This review summarizes approaches used in tissue engineering and regenerative medicine, with a focus on dental applications. Dental caries and periodontal disease are the most common diseases resulting in tissue loss. To replace or regenerate new tissues, various sources of stem cells have been identified such as somatic stem cells from teeth and peridontium. Advances in biomaterial sciences including microfabrication, self-assembled biomimetic peptides, and 3-dimensional printing hold great promise for whole-organ or partial tissue regeneration to replace teeth and periodontium.

Periodontal tissue reaction to customized nano-hydroxyapatite block scaffold in one-wall intrabony defect: a histologic study in dogs

Purpose

This study evaluated histologically the tissue responses to and the effects of a customized nano-hydroxyapatite (n-HA) block bone graft on periodontal regeneration in a one-wall periodontal-defect model.

Methods

A customized block bone for filling in the standardized periodontal defect was fabricated from prefabricated n-HA powders and a polymeric sponge. Bilateral 4×4×5 mm (buccolingual width×mesiodistal width×depth), one-wall, critical-size intrabony periodontal defects were surgically created at the mandibular second and fourth premolars of five Beagle dogs. In each dog, one defect was filled with block-type HA and the other served as a sham-surgery control. The animals were sacrificed following an 8-week healing interval for clinical and histological evaluations.

Results

Although the sites that received an n-HA block showed minimal bone formation, the n-HA block was maintained within the defect with its original hexahedral shape. In addition, only a limited inflammatory reaction was observed at sites that received an n-HA block, which might have been due to the high stability of the customized block bone.

Conclusions

In the limitation of this study, customized n-HA block could provide a space for periodontal tissue engineering, with minimal inflammation.