Periodontal regeneration: a challenge for the tissue engineer?

Insights and Advancements in Periodontal Tissue Engineering and Bone Regeneration

The regeneration of periodontal bone defects continues to be an essential therapeutic concern in dental biomaterials. Numerous biomaterials have been utilized in this sector so far. However, the immune response and vascularity in defect regions may be disregarded when evaluating the effectiveness of biomaterials for bone repair. Among several regenerative treatments, the most recent technique of in situ tissue engineering stands out for its ability to replicate endogenous restorative processes by combining scaffold with particular growth factors. Regenerative medicine solutions that combine biomaterials/scaffolds, cells, and bioactive substances have attracted significant interest, particularly for bone repair and regeneration. Dental stem cells (DSCs) share the same progenitor and immunomodulatory properties as other types of MSCs, and because they are easily isolable, they are regarded as desirable therapeutic agents in regenerative dentistry. Recent research has demonstrated that DSCs sown on newly designed synthetic bio-material scaffolds preserve their proliferative capacity while exhibiting increased differentiation and immuno-suppressive capabilities. As researchers discovered how short peptide sequences modify the adhesion and proliferative capacities of scaffolds by activating or inhibiting conventional osteogenic pathways, the scaffolds became more effective at priming MSCs. In this review, the many components of tissue engineering applied to bone engineering will be examined, and the impact of biomaterials on periodontal regeneration and bone cellular biology/molecular genetics will be addressed and updated.

Can vitamins improve periodontal wound healing/regeneration?

Periodontitis is a complex inflammatory disorder of the tooth supporting structures, associated with microbial dysbiosis, and linked to a number if systemic conditions. Untreated it can result in an irreversible damage to the periodontal structures and eventually teeth loss. Regeneration of the lost periodontium requires an orchestration of a number of biological events on cellular and molecular level. In this context, a set of vitamins have been advocated, relying their beneficial physiological effects, to endorse the biological regenerative events of the periodontium on cellular and molecular levels. The aim of the present article is to elaborate on the question whether or not vitamins improve wound healing/regeneration, summarizing the current evidence from in vitro, animal and clinical studies, thereby shedding light on the knowledge gap in this field and highlighting future research needs. Although the present review demonstrates the current heterogeneity in the available evidence and knowledge gaps, findings suggest that vitamins, especially A, B, E, and CoQ10, as well as vitamin combinations, could exert positive attributes on the periodontal outcomes in adjunct to surgical or nonsurgical periodontal therapy.

Three-dimensional-printed scaffolds for periodontal regeneration: A systematic review

Background

As current ethical codes preclude determining whether the clinical improvements obtained with the use of three-dimensional (3D)-printed scaffolds represent true periodontal regeneration, the histological proof of evidence for regeneration must be demonstrated in animal models. Thus, this systematic review investigated the regenerative potential of 3D-printed scaffolds in animal models of periodontal defects.

Materials and Methods

A systematic search was performed in four databases (Medline, Embase, Web of Science, and Scopus) to identify preclinical controlled studies that investigated the use of 3D-printed scaffolds for periodontal regeneration. Studies limited to periodontal defects treated with 3D scaffolds were eligible for inclusion. The primary outcome was periodontal regeneration, assessed histologically as new bone, cementum, and periodontal ligament (PDL). This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Quality was assessed according to the SRYCLE score.

Results

Six studies met the inclusion criteria. Scaffolds were designed using computer-aided design software. While the absence of a scaffold resulted in defects repaired mainly with fibrous connective tissue, the use of nonguiding 3D scaffolds promoted some bone formation. Notably, the regeneration of cementum and functional PDL fibers perpendicularly inserted into the root surface and the alveolar bone was limited to the defects treated with multi-compartment fiber-guiding or ion-containing 3D scaffolds. Nevertheless, the quality of the evidence was limited due to the unclear risk of bias.

Conclusions

Despite the limitations of the available evidence, the current data suggest that the use of printed multi-compartment fiber-guiding or ion-containing 3D scaffolds improves periodontal regeneration in animal models.

Evaluation of efficacy of simvastatin in bone regeneration following local application in third molar extraction socket: A randomized control trial

Aims and Objectives

The aim of this study is to study the efficacy of simvastatin in bone regeneration following the local application in third molar extraction sockets.

Materials and Methods

This is a randomized controlled trial done on 50 patients involving 100 third molar teeth extraction sockets. The patients were randomly divided based on the placement of simvastatin. Extraction sockets which were treated with simvastatin were considered study sockets and without simvastatin were considered control sockets. The study socket was assigned for the placement of simvastatin (10 mg) powder along with gelfoam as carrier moistened with normal saline solution and control socket was assigned for the placement of gelfoam moistened with saline. Intraoral periapical radiographs were taken on the 1st, 4th, 8th, and 12th weeks, and mean gray scale values indicating bone density were evaluated for both the groups. Cone-beam computed tomography (CBCT) was taken by the end of the 12th week to further evaluate the osseous regeneration. Patients were compared and evaluated for bone density, pain, and swelling. Pain and swelling were evaluated on postoperative days 1 and 7.

Results

The mean gray-level histogram values (bone density) were statistically highly significant in the study group compared to the control group in the 1st, 4th, 8th, and 12th weeks, and CBCT also showed statistically significant difference between the control and study group by the end of the 12th week.

Conclusion

The present data suggest that the local application of simvastatin promotes and enhances bone formation in the extraction sockets, which provides a very cost-effective way for faster bone regeneration.

Decellularized Matrix Induced Spontaneous Odontogenic and Osteogenic Differentiation in Periodontal Cells

The regeneration of periodontal tissues is a decisive factor in the treatment of periodontitis. Currently, to achieve complete periodontal regeneration, many studies have evaluated the effectiveness of decellularized tissue-engineered constructs on periodontal regeneration. We studied the possibilities of osteogenic and odontogenic differentiation of periodontal progenitor and stem cells (SCs) of the periosteum and periodontal ligament, in decellularized tooth matrix (dTM) and periodontal ligament (dPDL), in 2D and 3D culture. The cell culture of periodontal cells without decellularized matrices was used as control. On the 14th day of cultivation of PDLSCs, PSCs, and PDLSCs + PSCs on dTM and/or dPDL scaffolds in 2D conditions, in all scaffold variants, a dense monolayer of spindle-shaped cells was intensely stained for markers of osteogenic differentiation, such as osteopontin and osteocalcin. Periodontal cells in the collagen I hydrogel (3D-dimensional culture) were more diverse in shape and, in combination of dTM and dPDL, in addition to osteogenic expression, expressed dentin sialophosphoprotein, an odontogenic differentiation marker. Thus, collagen I hydrogel contributed to the formation of conditions similar to those in vivo, and the combination of dTM with dPDL apparently formed a microenvironment that promoted osteogenic and odontogenic differentiation of periodontal cells.

Bioactive Inorganic Materials for Dental Applications: A Narrative Review

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

Porphyromonas gingivalis lipopolysaccharide enhances the proliferation of human periodontal ligament cells via upregulation of cyclin D1, cyclin A and cyclin B1

Human periodontal ligament cells (hPDLCs) play a notable role in periodontal tissue homeostasis and regeneration. However, the effect of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) on the proliferation of hPDLCs remains unclear. The present study investigated the effects of Pg-LPS on the proliferation profile of hPDLCs, and the involvement of cyclins and cyclin-dependent kinases in the process. hPDLCs were treated with Pg-LPS, and cell proliferation and cycle were detected using Cell Counting Kit-8 assays and flow cytometry. The mRNA expression levels of the cyclins and cyclin-dependent kinases (CDKs), including cyclins A, B1, D1 and D2 and CDK1, 2 and 4, were detected using reverse transcription-quantitative PCR. The protein expression levels of cyclins A, B1 and D1 were analysed using western blotting. The proliferation of hPDLCs was significantly increased after treatment with Pg-LPS at the concentrations of 0.001, 0.01, 0.1, 1 and 10 µg/ml for 24, 36 and 48 h compared with the cells cultured without LPS (P<0.01). The proliferation index of hPDLCs was significantly enhanced after treatment with Pg-LPS (0.0001, 0.001, 0.01, 0.1, 1 and 10 µg/ml) for 24 h (P<0.01). However, the S-phase fraction (SPF) only significantly increased after treatment with Pg-LPS at 0.01 µg/ml for 24 h (P<0.05), while the G₂/M-phase fraction increased (P<0.01) and the G₀/G₁-phase fraction decreased (P<0.01) compared with the controls. The proliferation index and SPF increased, peaked at 24 h and then decreased at 48 h in both Pg-LPS-stimulated and control groups. Notably, Pg-LPS significantly upregulated the expression levels of cyclins D1, A and B1 after 24 h compared with those in the controls. Overall, the present study indicated that Pg-LPS may enhance the proliferation of hPDLCs, potentially through upregulation of cyclins D1, A and B1.

Scaffolds in Periodontal Regenerative Treatment

Successful periodontal regeneration requires the hierarchical reorganization of multiple tissues including periodontal ligament, cementum, alveolar bone, and gingiva. The limitation of conventional regenerative therapies has been attracting research interest in tissue engineering-based periodontal therapies where progenitor cells, scaffolds, and bioactive molecules are delivered. Scaffolds offer not only structural support but also provide geometrical clue to guide cell fate. Additionally, functionalization improves bioactive properties to the scaffold. Various scaffold designs have been proposed for periodontal regeneration. These include the fabrication of biomimetic periodontal extracellular matrix, multiphasic scaffolds with tissue-specific layers, and personalized 3D printed scaffolds. This review summarizes the basic concept as well as the recent advancement of scaffold designing and fabrication for periodontal regeneration and provides an insight of future clinical translation.

Adipose-Derived Stromal Cells and Mineralized Extracellular Matrix Delivery by a Human Decellularized Amniotic Membrane in Periodontal Tissue Engineering

Periodontitis is a prevalent disease characterized by the loss of periodontal supporting tissues, bone, periodontal ligament, and cementum. The application of a bone tissue engineering strategy with Decellularized Human Amniotic Membrane (DAM) with adipose-derived stromal cells (ASCs) has shown to be convenient and valuable. This study aims to investigate the treatments of a rat periodontal furcation defect model with DAM, ASCs, and a mineralized extracellular matrix (ECM). Rat ASCs were expanded, cultivated on DAM, and with a bone differentiation medium for four weeks, deposited ECM on DAM. Periodontal healing for four weeks was evaluated by micro-computed tomography and histological analysis after treatments with DAM, ASCs, and ECM and compared to untreated defects on five consecutive horizontal levels, from gingival to apical. The results demonstrate that DAM preserves its structure during cultivation and healing periods, supporting cell attachment, permeation, bone deposition on DAM, and periodontal regeneration. DAM and DAM+ASCs enhance bone healing compared to the control on the gingival level. In conclusion, DAM with ASC or without cells and the ECM ensures bone tissue healing. The membrane supported neovascularization and promoted osteoconduction.

3 D nano bilayered spatially and functionally graded scaffold impregnated bromelain conjugated magnesium doped hydroxyapatite nanoparticle for periodontal regeneration

Chronic periodontal disease affect the tissues supporting around the teeth like gingival tissue, connective tissue, alveolar bone and periodontal ligaments. Hitherto, periodontal treatment was targeted to selectively repopulate the defect site with cell that has capability to regenerate lost tissue by promoting the concept of guided tissue regeneration but it requires second surgery due to non- biodegradability. The use of polymeric biodegradable nanofibrous coated scaffold that have the ability to deliver bioactives required for regeneration to occur is relatively a newer concept. The functionalization of polymeric scaffold with Bromelain and magnesium doped hydroxyapatite nanoparticle enhanced the mechanical, physico-chemical, thermal and biological properties of the scaffold by imitating the intricate extracellular matrix (ECM) architecture which provided the necessary bioactive cues that offered control over cellular functions by showing antibacterial potential, hemocompatibility and increasing the proliferation and migration rate in vitro. In addition, in ovo chicken chorioallantoic membrane assay and ex vivo aortic ring assay confirmed the efficacy of the developed scaffold by encouraging angiogenesis required for maintaining its viability after implanting onto the infected area. Further, the scaffold positively interacted with the host and actively contributed to the process of tissue regeneration in vivo in Wistar rat model.

Regenerative potential of cultured gingival fibroblasts in treatment of periodontal intrabony defects (randomized clinical and biochemical trial)

BACKGROUND

Defective cellular elements constitute an important challenge to achieve predictable periodontal regeneration. In an attempt to improve the cellularity of periodontal defects, gingival fibroblasts were implanted without their associated extracellular elements in periodontal defects to expose them to periodontal tissue mediators. In order to investigate the regenerative potential of gingival fibroblasts translocated into periodontal defects, the present study was designed to clinically and biochemically investigate the use of gingival fibroblasts (GF) and their associated mesenchymal stem cells (GMSC) in the treatment of intrabony periodontal defects.

METHODS

A total of 20 subjects were randomly divided into two groups (n = 20). Group I: ten patients were included with ten intrabony periodontal defects that received β-calcium triphosphate (β-TCP) followed by collagen membrane defect coverage, while group II: (10 patients) ten periodontal defects received cultured gingival fibroblasts (GF) on the β-TCP scaffold and covered by a collagen membrane. The clinical evaluation was carried out at the beginning and at 6 months. Gingival crevicular fluid (GCF) samples were collected directly from the test sites for the quantitative measurement of PDGF-BB and BMP-2 using the ELISA kit at 1, 7, 14, and 21 days after surgery.

RESULTS

Group II reported a significantly greater reduction in vertical pocket depth (VPD) and CAL gain compared with group I after 6 months. Radiographic bone gain was statistically higher in group II compared with group I. A significantly higher concentration of PDGF-BB was observed in group II on days 1, 3, and 7 compared with group I.

CONCLUSIONS

Translocation of gingival fibroblasts from gingival tissue to periodontal defects could be a promising option that increases cellular elements with regeneration potential. The concept of total isolation of gingival fibroblasts using occlusive membranes must be re-evaluated.

The therapeutic role of bone marrow stem cell local injection in rat experimental periodontitis

Mesenchymal stem cell therapy brings hope for regenerating damaged periodontal tissues. The present study aimed to investigate the therapeutic role of local bone marrow stem cell (BMSC) injection in ligation-induced periodontitis and the underlying mechanisms. Alveolar bone lesion was induced by placing ligatures subgingivally around the bilateral maxillary second molars for 28 days. The alveolar bone lesion was confirmed by micro-CT analysis and bone histomorphometry. Allogeneic BMSC transplantation was carried out at 28 day after ligation. The survival state of the transplanted BMSC was observed by bioluminescent imaging. The implantation of the BMSC into the gingival tissues and periodontal ligament was confirmed by green fluorescent protein (GFP) immunohistochemical staining. The expression level of pro-inflammatory, tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and receptor activator of nuclear factor-κ B ligand (RANKL) and osteoprotegerin (OPG) in periodontal tissues were evaluated by immunohistochemical staining and real-time PCR. Significant reverse of alveolar bone lesion was observed after BMSC transplantation. The expression of TNF-α and IL-1β was down-regulated by BMSC transplantation. The number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the periodontal ligament was reduced, and the increased RANKL expression and decreased OPG expression were also reversed after BMSC transplantation. It is concluded that allogeneic BMSC local injection could inhibit the inflammation of the periodontitis tissue and promote periodontal tissue regeneration.

Fabrication and Characterization of Chitosan-Collagen Membrane from Barramundi (Lates Calcarifer) Scales for Guided Tissue Regeneration

OBJECTIVES

 The aim of this study was to evaluate the synthesis, mechanical strength, and morphology of chitosan-collagen membranes from barramundi scales for guided tissue regeneration technique.

MATERIALS AND METHODS

 Collagen was extracted from barramundi scales by immersion in acetic acid. The resulting wet collagen was later dried. The membrane was fabricated by mixing chitosan with collagen from barramundi scales. Membrane characterization parameters were measured using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and mechanical property.

RESULTS

 The FTIR spectrum showed the typical peak of the mixture of chitosan and collagen. The tensile strength and elongation at break of the membrane in dry condition were 0.28 MPa and 8.53%, respectively, while in the wet condition these were 0.12 MPa and 25.6%. The membrane porosity test result was 38.85%; SEM result showed a porous membrane surface with size varying around 16 to 100 µm.

CONCLUSION

 The chitosan-collagen membrane from the barramundi scale showed the fibrous membrane surface that has ideal porous size as guided tissue regeneration membrane and the lower mechanical strength.

Modifications of Polymeric Membranes Used in Guided Tissue and Bone Regeneration

Guided tissue/bone regeneration (GTR/GBR) is a widely used procedure in contemporary dentistry. To achieve the required results of tissue regeneration, soft tissues that reproduce quickly are separated from the slow-growing bone tissue by membranes. Many types of membranes are currently in use, but none of them fulfil all of the desired features. To address this issue, further research on developing new membranes with better separation characteristics, such as membrane modification, is needed. Many of the current innovative modified materials are still in the phase of in vitro and experimental studies. A collective review on new trends in membrane modification to GTR/GBR is needed due to the widespread use of polymeric membranes and the constant development in the field of dentistry. Therefore, the aim of this review was to present an overview of polymeric membrane modifications to the GTR/GBR reported in the literature. The authors searched databases, including PubMed, SCOPUS, Web of Science, and OVID, for relevant studies that were published during 1999-2019. The following keywords were used: guided tissue regeneration, membranes, coating, and modification. A total of 17 papers were included in this review. Furthermore, the articles were divided into three groups that were based on the type of membrane modification: antibiotic coating, ion-use modifications, and others modifications, thus providing an overview of current existing knowledge in the field and encouraging further research. The results of included studies on modified barrier membranes seem to be promising, both in terms of safety and benefits for patients. However, modifications result in a large spectrum of effects. Further clinical studies are needed on a large group of patients to clearly confirm the effects that were observed in animal and in vitro studies.

The impact of simvastatin intervention on the healing of bone, soft tissue, and TMJ cartilage in dentistry: a systematic review and meta-analysis

The review aimed at assessing the osteopromotive potential as well as soft tissue and temporomandibular joint (TMJ) cartilage healing properties of simvastatin by summarizing its efficacy on the current dental treatment of periodontal bone and soft tissue defects, and temporomandibular joint (TMJ) arthritis from the available animals and human studies. An electronic search was performed on MEDLINE, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) using a combination of keywords. A hand search was undertaken on seven oral surgery journals. No limitation of publication year in the English language was placed. Controlled randomized animal and human clinical trials, as well as prospective comparative studies, were included. Data on the comparison of topical/systemic simvastatin on bone healing in intrabony and furcation defects, extraction sockets, distraction osteogenesis, as well as soft tissue healing in mucogingival grafting procedures and cartilage protection in TMJ arthritis were extracted from all the eligible studies. Studies with a minimum of ten participants and follow up at least 6 months were included. Ten animal studies and six clinical studies were included in this study. All the animal studies included a minimum of eight sites per group assessed clinically, histologically, and radiographically. All human studies included clinical and radiological evaluation. The results of the review show that simvastatin administration displays positive treatment outcomes in the full range of therapies investigated in the oral regions such as periodontal infection control, periodontal and alveolar bone regeneration, soft tissue grafting, TMJ inflammation reduction, and cartilage repair. Its mechanism includes stimulating bone formation, promoting soft tissue healing, increasing articular and condylar cartilage thickness, as well as reducing inflammation at surgical sites in TMJ disorders. Simvastatin administration is beneficial to the healing of oral bone and cartilage. More studies are desired to determine its potential in soft tissue healing.

Effect of Adipose-Derived Stem Cells and Their Exo as Adjunctive Therapy to Nonsurgical Periodontal Treatment: A Histologic and Histomorphometric Study in Rats

Scaling and root planing (SRP) is of limited value in many cases, so adjunctive treatment was applied to augment its outcome. Adipose-derived stem/stromal cells (ADSCs) were investigated in periodontal regeneration with promising results. However, they have safety concerns. The exosomes (Exo.), which are extracellular vesicles mediating the action of stem/stromal cells, represent a new approach to overcome these concerns. Ligature-induced periodontitis was induced in 50 rats for 14 days, and they were divided into control (5 healthy rats for histologic comparison), SRP group, ADSCs group, and Exo. group, with evaluation intervals at 2 days, and 2 and 4 weeks, including 5 rats in each interval for each group. The specimens were evaluated for histologic description (H&E), histochemical study (Masson trichrome), and histomorphometric study, to evaluate the area % of newly formed tissues. The Exo. group revealed the best results in all intervals with significantly higher area % of newly formed tissues, followed by ADSCs and, finally, SRP. Both Exo. and ADSCs showed organized newly formed tissues with the Exo. group obtaining comparable histologic results to the normal, healthy tissues by 4 weeks. Adipose-derived stem/stromal cells and their Exo. represent a promising adjunctive treatment to SRP.

Plants and Their Bioactive Constituents in Mesenchymal Stem Cell-Based Periodontal Regeneration: A Novel Prospective

Periodontitis is a common chronic inflammatory disease, which causes the destruction of both the soft and mineralized tissues. However, current treatments such as bone graft materials, barrier membranes, and protein products all have difficulties in regenerating the complete periodontal tissue structure. Stem cell-based tissue engineering has now emerged as one of the most effective treatments for the patients suffering from periodontal diseases. Plants not only can be substrates for life processes, but also contain hormones or functional molecules. Numbers of preclinical studies have revealed that products from plant can be successfully applied in modulating proliferation and differentiation of human mesenchymal stem cells. Plant-derived substances can induce stem cells osteogenic differentiation, and they also possess angiogenic potency. Furthermore, in the field of tissue engineering, plant-derived compounds or plant extracts can be incorporated with biomaterials or utilized as biomaterials for cell transplantation. So it is speculated that botanical products may become a new perspective in stem cell-based periodontal regeneration. However, the lack of achieving predict clinical efficacy and quality control has been the major impediment to its extensive application. This review gives an overview of the prospect of applying different plant-derived substances in various human mesenchymal stem cells-based periodontal regeneration.

Human β-defensin 3-combined gold nanoparticles for enhancement of osteogenic differentiation of human periodontal ligament cells in inflammatory microenvironments

Objective

It is a great challenge to absorb and conduct biophysicochemical interactions at the nano-bio interface. Peptides are emerging as versatile materials whose function can be programmed to perform specific tasks. Peptides combined nanoparticles might be utilized as a new approach of treatment. Human β-defensin 3 (hBD3), possesses both antimicrobial and proregeneration properties. Gold nanoparticles (AuNPs) have shown promising applications in the field of tissue engineering. However, the coordinating effects of AuNPs and hBD3 on human periodontal ligament cells (hPDLCs) remain unknown. In this study, we systematically investigated whether AuNPs and hBD3 would be able to coordinate and enhance the osteogenic differentiation of hPDLCs in inflammatory microenvironments, and the underlying mechanisms was explored.

Methods

hPDLCs were stimulated with E. coli-LPS, hBD3 and AuNPs. Alkaline phosphatase (ALP) and alizarin red S staining were used to observe the effects of hBD3 and AuNPs on the osteogenic differentiation of hPDLCs. Real-time PCR and western blot were performed to evaluate the osteogenic differentiation and Wnt/β-catenin signaling pathway related gene and protein expression.

Results

In the inflammatory microenvironments stimulated by E. coli-LPS, we found that AuNPs and hBD3 increased the proliferation of hPDLCs slightly. In addition, hBD3-combined AuNPs could significantly enhance ALP activities and mineral deposition in vitro. Meanwhile, we observed that the osteogenic differentiation-related gene and protein expressions of ALP, collagenase-I (COL-1) and runt-related transcription factor 2 (Runx-2) were remarkably upregulated in the presence of hBD3 and AuNPs. Moreover, hBD3-combined AuNPs strongly activated the Wnt/β-catenin signaling pathway and upregulated the gene and protein expression of β-catenin and cyclin D1. Furthermore, hBD3-combined AuNPs induced osteogenesis, which could be reversed by the Wnt/β-catenin signaling pathway inhibitor (ICG-001).

Conclusion

The present study demonstrated that hBD3 combined AuNPs could significantly promote the osteogenic differentiation of hPDLCs in inflammatory microenvironments via activating the Wnt/β-catenin signaling pathway.

Stromal Cell-Derived Factor-1 Accelerates Cartilage Defect Repairing by Recruiting Bone Marrow Mesenchymal Stem Cells and Promoting Chondrogenic Differentiation<sup/>

Chemokine stromal cell-derived factor-1 (SDF-1) is a powerful chemoattractant for the localization of CXCR4-positive bone marrow mesenchymal stem cells (BMSCs) into the bone marrow. We studied the effects of SDF-1 on the cartilage defect repair by recruiting BMSCs and promoting its chondrogenic differentiation in vitro and in vivo. Chemotaxis analysis with Transwell plate showed that SDF-1 could recruit BMSCs through SDF-1/CXCR4 axis. Real-time polymerase chain reaction, enzyme-linked immunosorbent assays, and Western blot results suggested that the levels of type II collagen and GAG were increased after incubating BMSCs with SDF-1 compared with the without SDF-1 group. More positive BrdU-labeled BMSCs were detected at the cartilage defect region in the SDF-1 + poly [lactide-co-glycolide] (PLGA) scaffold group (SP) in which those animals showed a smooth and transparent cartilage tissue with a strong staining of toluidine blue and type II collagen compared with the no-SDF-1 groups. ICRS score suggested that the repair effect in the SDF-1 + PLGA-treated animals was improved compared with PLGA scaffold group alone at 4 and 8 weeks after surgery; the repair effect from the SDF + PLGA-treated animals was significantly improved compared with the PLGA alone at 12 weeks after surgery. Our in vitro and in vivo results indicated the following: (1) SDF-1 could recruit the BMSCs into cartilage defect area. (2) SDF-1 induces BMSCs expressing type II collagen and GAG, which may accelerate the BMSCs transforming into chondrocytes under the cartilage microenvironment in vivo. (3) PLGA scaffold attached with SDF-1 remarkably promoted the cartilage defect repairing. The defected cartilage was filled with transparent cartilage 12 weeks after the surgery, which shared a similar structure with the adjacent normal cartilage. Taken together, this research provides a new strategy for cartilage defect repairing.

Potential of electrospun chitosan fibers as a surface layer in functionally graded GTR membrane for periodontal regeneration

OBJECTIVE

The regeneration of periodontal tissues lost as a consequence of destructive periodontal disease remains a challenge for clinicians. Guided tissue regeneration (GTR) has emerged as the most widely practiced regenerative procedure. Aim of this study was to electrospin chitosan (CH) membranes with a low or high degree of fiber orientation and examines their suitability for use as a surface layer in GTR membranes, which can ease integration with the periodontal tissue by controlling the direction of cell growth.

METHODS

A solution of CH-doped with polyethylene oxide (PEO) (ratio 95:5) was prepared for electrospinning. Characterization was performed for biophysiochemical and mechanical properties by means of scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, swelling ratio, tensile testing and monitoring degradation using pH analysis, weight profile, ultraviolet-visible (UV-vis) spectroscopy and FTIR analysis. Obtained fibers were also assessed for viability and matrix deposition using human osteosarcoma (MG63) and human embryonic stem cell-derived mesenchymal progenitor (hES-MP) cells.

RESULTS

Random and aligned CH fibers were obtained. FTIR analysis showed neat CH spectral profile before and after electrospinning. Electropsun mats were conducive to cellular attachment and viability increased with time. The fibers supported matrix deposition by hES-MPs. Histological sections showed cellular infiltration as well.

SIGNIFICANCE

The surface layer would act as seal to prevent junctional epithelium from falling into the defect site and hence maintain space for bone regeneration.

Clinical and Radiologic Evaluation of Regenerative Potential of NHA Paste and DBM in the Treatment of Periodontal Intra-bony Defects -A Randomized Control Trial

INTRODUCTION

Previous studies have shown that Hydroxyapatite (HA) has shown good results in the treatment of intra-osseous periodontal defects. A newer variety of HA has been designed over a period of research which has nano-sized particles and is availed in a paste consistency called Nanocrystalline Hydroxyapatite paste (NHA paste). This variation in size and surface area of NHA paste can provide better results when used in intra-bony defects.

AIM

The purpose of this study was to compare the clinical and radiographic outcomes obtained with usage of NHA paste to those obtained with Demineralized Bone Matrix (DBM) in the treatment of periodontal intra-bony defects.

MATERIAL AND METHODS

A clinical trial was carried out for a period of 12 months. A total of 26 intra-bony defects in 10 patients were divided into experimental and control sites. The experimental sites were debrided and grafted with NHA paste. The control sites were debrided and grafted with DBM-Xenograft. Probing Depth, Clinical Attachment Level (DCAL) and Gingival Margin (GM) position were recorded at baseline 3, 6, 9 and 12 months. Standardized radiographs were also documented at these recalls. The results were averaged (mean± standard deviation) for each parameter and Student t-test was used to determine intra-group statistical difference and One way analyses of variance (ANOVA) to test the difference between groups using Excel and SPSS (SPSS Inc, Chicago) software packages.

RESULTS

On completion of 12 months, the mean percentage of PD reduction achieved in the experimental and control sites was 67.45% and 69.03% respectively (p<0.05). The mean percentage of gain achieved in CAL was 63.58% and 61.42% in the experimental and control sites respectively (p<0.05). Gingival recession was seen to be non-significant in the experimental and control sites. The mean percentage of bone fill in the control group obtained was 48.16% where as the percentage of bone fill obtained in the experimental group was 48.64% (p<0.05).

CONCLUSION

Overall, both therapies led to significant improvements of the investigated parameters. The NHA paste was as effective in terms of improving clinical and radiographic parameters as DBM-Xenograft, which is an already established bone graft. There is a need for further long term controlled studies evaluating the adjunctive benefits of usage of NHA paste in the treatment of periodontal intra-bony defects.

Quercitrin for periodontal regeneration: effects on human gingival fibroblasts and mesenchymal stem cells

Periodontal disease (PD) is the result of an infection and chronic inflammation of the gingiva that may lead to its destruction and, in severe cases, alveolar bone and tooth loss. The ultimate goal of periodontal treatment is to achieve periodontal soft and hard tissues regeneration. We previously selected quercitrin, a catechol-containing flavonoid, as a potential agent for periodontal applications. In this study, we tested the ability of quercitrin to alter biomarker production involved in periodontal regeneration on primary human gingival fibroblasts (hGF) and primary human mesenchymal stem cells (hMSC) cultured under basal and inflammatory conditions. To mimic PD inflammatory status, interleukin-1 beta (IL-1β) was used. The expression of different genes related to inflammation and extracellular matrix were evaluated and prostaglandin E2 (PGE2) production was quantified in hGFs; alkaline phosphatase (ALP) activity and calcium content were analysed in hMSCs. Quercitrin decreased the release of the inflammatory mediator PGE2 and partially re-established the impaired collagen metabolism induced by IL-1β treatment in hGFs. Quercitrin also increased ALP activity and mineralization in hMSCs, thus, it increased hMSCs differentiation towards the osteoblastic lineage. These findings suggest quercitrin as a novel bioactive molecule with application to enhance both soft and hard tissue regeneration of the periodontium.

Freeze gelated porous membranes for periodontal tissue regeneration

Guided tissue regeneration (GTR) membranes have been used for the management of destructive forms of periodontal disease as a means of aiding regeneration of lost supporting tissues, including the alveolar bone, cementum, gingiva and periodontal ligaments (PDL). Currently available GTR membranes are either non-biodegradable, requiring a second surgery for removal, or biodegradable. The mechanical and biofunctional limitations of currently available membranes result in a limited and unpredictable treatment outcome in terms of periodontal tissue regeneration. In this study, porous membranes of chitosan (CH) were fabricated with or without hydroxyapatite (HA) using the simple technique of freeze gelation (FG) via two different solvents systems, acetic acid (ACa) or ascorbic acid (ASa). The aim was to prepare porous membranes to be used for GTR to improve periodontal regeneration. FG membranes were characterized for ultra-structural morphology, physiochemical properties, water uptake, degradation, mechanical properties, and biocompatibility with mature and progenitor osteogenic cells. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of hydroxyapatite and its interaction with chitosan. μCT analysis showed membranes had 85-77% porosity. Mechanical properties and degradation rate were affected by solvent type and the presence of hydroxyapatite. Culture of human osteosarcoma cells (MG63) and human embryonic stem cell-derived mesenchymal progenitors (hES-MPs) showed that all membranes supported cell proliferation and long term matrix deposition was supported by HA incorporated membranes. These CH and HA composite membranes show their potential use for GTR applications in periodontal lesions and in addition FG membranes could be further tuned to achieve characteristics desirable of a GTR membrane for periodontal regeneration.

hMSC-Derived VEGF Release Triggers the Chemoattraction of Alveolar Osteoblasts

Human mesenchymal stem cells (hMSCs) are promising candidates for regenerative periodontal strategies, due to the broad spectrum of supportive effects on cells and tissues at the site of application. Although positive effects are visible, the understanding of their underlying mechanisms still requires further elucidation. Recently, we have shown that hMSCs are capable to prompt osteogenic differentiation of alveolar osteoblasts, thereby presumably contributing to alveolar bone regeneration. Another issue that is critical in this context is the attraction of hard tissue-forming cells to regeneration sites, but it is an open question whether hMSCs can afford this. In the present manuscript, we show by life cell imaging that in interactive cocultures, hMSCs successfully trigger osteoblast chemotaxis. Gene expression analysis for hMSC-innate chemoattractive biomolecules, orchestrating this process, revealed vascular endothelial growth factor (VEGF), PgE synthase, osteoprotegerin (OPG), monocyte colony-stimulating factor, and transforming growth factor β1, which was confirmed for VEGF and OPG on the protein level. Noteworthy, we showed that only corresponding levels of VEGF but not OPG attracted alveolar osteoblasts similar to hMSC coculture, while VEGF inhibitor abolished both the VEGF and the hMSC-triggered chemoattraction. In summary, we have identified secreted OPG and VEGF proteins as potential chemoattractants, of which further characterization yielded VEGF as a causative for hMSC-directed osteoblast chemotaxis. With respect to the better understanding of potential hMSC-based periodontal regeneration strategies, we propose hMSC-derived VEGF release as a mechanism in the recruitment of hard tissue-forming cells to alveolar bone sites in need of regeneration.

A comparative study of the proliferation and osteogenic differentiation of human periodontal ligament cells cultured on β-TCP ceramics and demineralized bone matrix with or without osteogenic inducers in vitro

The repair of bone defects that result from periodontal diseases remains a clinical challenge for periodontal therapy. β-tricalcium phosphate (β-TCP) ceramics are biodegradable inorganic bone substitutes with inorganic components that are similar to those of bone. Demineralized bone matrix (DBM) is an acid-extracted organic matrix derived from bone sources that consists of the collagen and matrix proteins of bone. A few studies have documented the effects of DBM on the proliferation and osteogenic differentiation of human periodontal ligament cells (hPDLCs). The aim of the present study was to investigate the effects of inorganic and organic elements of bone on the proliferation and osteogenic differentiation of hPDLCs using three-dimensional porous β-TCP ceramics and DBM with or without osteogenic inducers. Primary hPDLCs were isolated from human periodontal ligaments. The proliferation of the hPDLCs on the scaffolds in the growth culture medium was examined using a Cell-Counting kit-8 (CCK-8) and scanning electron microscopy (SEM). Alkaline phosphatase (ALP) activity and the osteogenic differentiation of the hPDLCs cultured on the β-TCP ceramics and DBM were examined in both the growth culture medium and osteogenic culture medium. Specific osteogenic differentiation markers were examined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). SEM images revealed that the cells on the β-TCP were spindle-shaped and much more spread out compared with the cells on the DBM surfaces. There were no significant differences observed in cell proliferation between the β-TCP ceramics and the DBM scaffolds. Compared with the cells that were cultured on β-TCP ceramics, the ALP activity, as well as the Runx2 and osteocalcin (OCN) mRNA levels in the hPDLCs cultured on DBM were significantly enhanced both in the growth culture medium and the osteogenic culture medium. The organic elements of bone may exhibit greater osteogenic differentiation effects on hPDLCs than the inorganic elements.

Fibrin Sealant: A Review of Its Applications in Periodontal Surgery

Aim

Fibrin sealant is a biological tissue adhesive mimicking the final stage of coagulation. It has a wide variety of application in the field of periodontics. The aim of this article was to review current applications and identify potential use of fibrin sealant in periodontal surgical procedures on an evidence-based conclusion.

Materials and methods

An online search was performed in PubMed, Google Scholar and Cochrane Library databases using keywords fibrin sealant, fibrin glue, fibrin, regeneration, wound healing, tissue adhesive, gingival recession/therapy, surgical therapy, periodontal, and periodontitis in a mutually inclusive manner. The studies were evaluated by two independent reviewers for inclusion in this literature review.

Results

Out of 196 research papers identified, 59 articles were selected by the authors for this literature review, giving preference to clinical trials related to periodontal application.

Conclusion

Use of fibrin sealant is a simple, safe, costeffective, and rapid way to fix flaps and grafts avoiding any postoperative bleeding. Fibrin sealant has the property for regeneration when used in conjunction with a barrier membrane for formation of new connective tissue attachment. It is effective in microsurgical procedures and closing flaps around implant site. They initiate early wound healing through collagen synthesis and fibroblast proliferation. Fibrin sealant may be an alternate biomaterial for periodontal surgery which may stimulate periodontal wound healing and regeneration.

How to cite this article

Jacob S, Nath S. Fibrin Sealant: A Review of Its Applications in Periodontal Surgery. Int J Experiment Dent Sci 2015;4(1):40-46.

Cementum and Periodontal Ligament Regeneration

The unique anatomy and composition of the periodontium make periodontal tissue healing and regeneration a complex process. Periodontal regeneration aims to recapitulate the crucial stages of wound healing associated with periodontal development in order to restore lost tissues to their original form and function and for regeneration to occur, healing events must progress in an ordered and programmed sequence both temporally and spatially, replicating key developmental events. A number of procedures have been employed to promote true and predictable regeneration of the periodontium. Principally, the approaches are based on the use of graft materials to compensate for the bone loss incurred as a result of periodontal disease, use of barrier membranes for guided tissue regeneration and use of bioactive molecules. More recently, the concept of tissue engineering has been integrated into research and applications of regenerative dentistry, including periodontics, to aim to manage damaged and lost oral tissues, through reconstruction and regeneration of the periodontium and alleviate the shortcomings of more conventional therapeutic options. The essential components for generating effective cellular based therapeutic strategies include a population of multi-potential progenitor cells, presence of signalling molecules/inductive morphogenic signals and a conductive extracellular matrix scaffold or appropriate delivery system. Mesenchymal stem cells are considered suitable candidates for cell-based tissue engineering strategies owing to their extensive expansion rate and potential to differentiate into cells of multiple organs and systems. Mesenchymal stem cells derived from multiple tissue sources have been investigated in pre-clinical animal studies and clinical settings for the treatment and regeneration of the periodontium.

Spatiotemporally controlled microchannels of periodontal mimic scaffolds

Physiologic bioengineering of the oral, dental, and craniofacial complex requires optimized geometric organizations of fibrous connective tissues. A computer-designed, fiber-guiding scaffold has been developed to promote tooth-supporting periodontal tissue regeneration and functional restoration despite limited printing resolution for the manufacture of submicron-scaled features. Here, we demonstrate the use of directional freeze-casting techniques to control pore directional angulations and create mimicked topographies to alveolar crest, horizontal, oblique, and apical fibers of natural periodontal ligaments. For the differing anatomic positions, the gelatin displayed varying patterns of ice growth, determined via internal pore architectures. Regardless of the freezing coordinates, the longitudinal pore arrangements resulted in submicron-scaled diameters (~50 µm), along with corresponding high biomaterial porosity (~90%). Furthermore, the horizontal + coronal ([Formula: see text]) freezing orientation facilitated the creation of similar structures to major fibers in the periodontal ligament interface. This periodontal tissue-mimicking microenvironment is a potential tissue platform for the generation of naturally oriented ligamentous tissues consistent with periodontal ligament neogenesis.

Comparative study of NMP-preloaded and dip-loaded membranes for guided bone regeneration of rabbit cranial defects

Guided bone regeneration (GBR) has been utilized for several decades for the healing of cranio-maxillofacial bone defects and, particularly in the dental field, by creating space with a barrier membrane to exclude soft tissue and encourage bone growth in the membrane-protected volume. Although the first membranes were non-resorbable, a new generation of GBR membranes aims to biodegrade and provide bioactivity for better overall results. The Inion GTR™ poly(lactide-co-glycolide) (PLGA) membrane is not only resorbable but also bioactive, since it includes N-methylpyrrolidone (NMP), which has been shown to promote bone regeneration. In this study, the effects of loading different amounts of NMP onto the membrane through chemical vapour deposition or dipping have been explored. In vitro release demonstrated that lower levels of NMP led to lower NMP concentrations and slower release, based on total NMP loaded in the membrane. The dipped membrane released almost all of the NMP within 15 min, leading to a high NMP concentration. For the in vivo studies in rabbits, 6 mm calvarial defects were created and left untreated or covered with an ePTFE membrane or PLGA membranes dipped in, or preloaded with, NMP. Evaluation of the bony regeneration revealed that the barrier membranes improved bony healing and that a decrease in NMP content improved the performance. Overall, we have demonstrated the potential of these PLGA membranes with a more favourable NMP release profile and the significance of exploring the effect of NMP on these PLGA membranes with regard to bone ingrowth. Copyright © 2014 John Wiley & Sons, Ltd.

Bone morphogenetic protein-9 induces PDLSCs osteogenic differentiation through the ERK and p38 signal pathways

Periodontal ligament stem cells (PDLSCs) with bone morphogenic ability are used to treat diseases such as periodontitis. Their treatment potential is increased when used in combination with proteins that induce osteogenic differentiation. For example, bone morphogenetic protein-9 (BMP9) has been found to have potent osteogenic activity. In the present study, PDLSCs were isolated from human periodontal membrane and infected with recombinant adenoviruses expressing BMP9 (Ad-BMP9). Levels of osteogenic markers such as runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCN) as well as mineralization ability were measured. The results showed that BMP9 promoted bone formation of PDLSCs. In other experiments, SB203580 and PD98059, which are inhibitors of p38 and ERK1/2, respectively, were used to determine if these kinases are involved in the osteogenic differentiation process. The resulting protein expression profiles and osteogenic markers of PDLSCs revealed that the mitogen-activated protein kinase (MAPK) signaling pathway might play an important role in the process of BMP9-induced osteogenic differentiation of PDLSCs.

Porphyromonas gingivalis LPS inhibits osteoblastic differentiation and promotes pro-inflammatory cytokine production in human periodontal ligament stem cells

OBJECTIVE

Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) induces pro-inflammatory cytokines, such as interleukin-1 β (IL-1β), IL-6, and IL-8, which induce periodontal tissue destruction. Periodontal ligament stem cells (PDLSCs) play an important role in periodontal tissue regeneration and are expected to have future applications in cellular therapies for periodontitis. However, no studies have examined the effects of P. gingivalis LPS on PDLSCs. The aim of this study was to investigate how P. gingivalis LPS affects the osteoblastic differentiation and pro-inflammatory cytokine production of PDLSCs.

DESIGN

PDLSCs were obtained from healthy adult human mandibular third molars. The identification of PDLSCs was confirmed by immunohistochemical evaluations of the mesenchymal stem cell markers STRO-1 and SSEA-4. Cell proliferation and osteoblastic differentiation were investigated by culturing the PDLSCs in a normal or osteogenic medium with P. gingivalis LPS (0, 1, or 10μg/mL) and then measuring the alkaline phosphatase (ALP) activity and the production of collagen type 1 Alpha 1 (COL1A1), osteocalcin production, and mineralisation. Additionally, we examined the production of IL-1β, IL-6, and IL-8 in the PDLSCs.

RESULTS

P. gingivalis LPS inhibited the ALP activity, COL1A1 and osteocalcin production, and mineralisation in the PDLSCs, which are positive for STRO-1 and SSEA-4. P. gingivalis LPS also promoted cell proliferation and produced IL-1β, IL-6, and IL-8.

CONCLUSIONS

This study provides the first findings that P. gingivalis LPS inhibits osteoblastic differentiation and induces pro-inflammatory cytokines in PDLSCs. These findings will help clarify the relationship between periodontitis and periodontal tissue regeneration.

Stem cells, tissue engineering and periodontal regeneration

The aim of this review is to discuss the clinical utility of stem cells in periodontal regeneration by reviewing relevant literature that assesses the periodontal-regenerative potential of stem cells. We consider and describe the main stem cell populations that have been utilized with regard to periodontal regeneration, including bone marrow-derived mesenchymal stem cells and the main dental-derived mesenchymal stem cell populations: periodontal ligament stem cells, dental pulp stem cells, stem cells from human exfoliated deciduous teeth, stem cells from apical papilla and dental follicle precursor cells. Research into the use of stem cells for tissue regeneration has the potential to significantly influence periodontal treatment strategies in the future.

Comparative Study of Human Dental Follicle Cell Sheets and Periodontal Ligament Cell Sheets for Periodontal Tissue Regeneration

Periodontal ligament cell (PDLC) sheets have been shown to contribute to periodontal tissue regeneration. Dental follicle cells (DFCs), acknowledged as the precursor cells of PDLCs, have demonstrated stemness, embryonic features, heterogeneity, and pluripotency. Therefore, we hypothesized that DFC sheets might be more effective and suitable for periodontal tissue regeneration than PDLC sheets. In this study, we compared the biological characteristics of DFC sheets and PDLC sheets in vitro. To investigate the potential for periodontal tissue regeneration in vivo, complexes composed of two types of cell sheets combined with dentin matrix were implanted subcutaneously into nude mice for 6 weeks. Our results showed that, when forming cell sheets, DFCs secreted richer extracellular matrix than PDLCs. And compared to DFCs, DFC sheets expressed high levels of calcification-related genes, including alkaline phosphatase ( alp), bone sialoprotein ( bsp), osteopontin ( opn), runt-related transcription factor ( runx2), as well as the periodontal ligament-specific genes collagen III ( col III) and periostin, while the gene expression of bsp, osteocalcin ( ocn), and opn were greatly increased in PDLC sheets, when compared to PDLCs. col I expression did not change significantly. However, cementum protein 23 ( cp-23) expression increased several fold in PDLC sheets compared to PDLCs but decreased in DFC sheets compared to DFCs. DFC and PDLC sheets were both positive for Collagen I (Col I), cementum attachment protein (CAP), ALP, BSP, OCN, and OPN protein expression, and Col I, ALP, BSP, and OPN expression were increased after cell sheets were formed. Furthermore, the levels of laminin and fibronectin were higher in DFCs and DFC sheets than that of PDLCs and PDLC sheets, respectively. In vivo, DFC and PDLC sheets could both regenerate periodontal tissue-like structures, but DFC sheets demonstrated stronger periodontal regeneration potential than PDLC sheets. Therefore, DFC sheets derived from discarded dental follicle tissue after tooth extraction may be more advantageous for clinical periodontal tissue regeneration in the future.

An autologous platelet-rich plasma stimulates periodontal ligament regeneration

BACKGROUND

Regeneration of periodontal tissues is one of the most important goals for the treatment of periodontal disease. The technology of plasma rich in growth factors provides a biologic approach for the stimulation and acceleration of tissue healing. The purpose of this study is to evaluate the biologic effects of this technology on primary human periodontal ligament fibroblasts.

METHODS

The authors studied the response of periodontal ligament cells to this pool of growth factors on cell proliferation, cell migration, secretion of several biomolecules, cell adhesion, and expression of α2 integrin. Cell proliferation and adhesion were evaluated by means of a fluorescence-based method. Cell migration was performed on culture inserts. The release of different biomolecules by periodontal ligament fibroblasts was quantified through enzyme-linked immunosorbent assay. The α2 integrin expression was assessed through Western blot.

RESULTS

This autologous technology significantly stimulated cell proliferation, migration, adhesion, and synthesis of many growth factors from cells including vascular endothelial growth factor, thrombospondin 1, connective tissue growth factor, hepatocyte growth factor, and procollagen type I. The α2 integrin expression was lower in plasma rich in growth factor-treated cells compared to non-stimulated cells, although no statistically significant differences were observed.

CONCLUSION

This plasma rich in growth factors exerts positive effects on periodontal ligament fibroblasts, which could be positive for periodontal regeneration.

Mesenchymal dental stem cells in regenerative dentistry

In the last decade, tissue engineering is a field that has been suffering an enormous expansion in the regenerative medicine and dentistry. The use of cells as mesenchymal dental stem cells of easy access for dentist and oral surgeon, immunosuppressive properties, high proliferation and capacity to differentiate into odontoblasts, cementoblasts, osteoblasts and other cells implicated in the teeth, suppose a good perspective of future in the clinical dentistry. However, is necessary advance in the known of growth factors and signalling molecules implicated in tooth development and regeneration of different structures of teeth. Furthermore, these cells need a fabulous scaffold that facility their integration, differentiation, matrix synthesis and promote multiple specific interactions between cells. In this review, we give a brief description of tooth development and anatomy, definition and classification of stem cells, with special attention of mesenchymal stem cells, commonly used in the cellular therapy for their trasdifferentiation ability, non ethical problems and acceptable results in preliminary clinical trials. In terms of tissue engineering, we provide an overview of different types of mesenchymal stem cells that have been isolated from teeth, including dental pulp stem cells (DPSCs), stem cells from human exfoliated deciduous teeth (SHEDs), periodontal ligament stem cells (PDLSCs), dental follicle progenitor stem cells (DFPCs), and stem cells from apical papilla (SCAPs), growth factors implicated in regeneration teeth and types of scaffolds for dental tissue regeneration.

Key words:Dental stem cells, regenerative dentistry, mesenchymal stem cells, tissue engineering, stem cells.

Strontium-containing mesoporous bioactive glass scaffolds with improved osteogenic/cementogenic differentiation of periodontal ligament cells for periodontal tissue engineering

To achieve the ultimate goal of periodontal tissue engineering, it is of great importance to develop bioactive scaffolds which can stimulate the osteogenic/cementogenic differentiation of periodontal ligament cells (PDLCs) for the favorable regeneration of alveolar bone, root cementum and periodontal ligament. Strontium (Sr) and Sr-containing biomaterials have been found to induce osteoblast activity. However, there has been no systematic report about the interaction between Sr or Sr-containing biomaterials and PDLCs for periodontal tissue engineering. The aims of this study were to prepare Sr-containing mesoporous bioactive glass (Sr-MBG) scaffolds and investigate whether the addition of Sr could stimulate osteogenic/cementogenic differentiation of PDLCs in a tissue-engineering scaffold system. The composition, microstructure and mesopore properties (specific surface area, nanopore volume and nanopore distribution) of Sr-MBG scaffolds were characterized. The proliferation, alkaline phosphatase (ALP) activity and osteogenesis/cementogenesis-related gene expression (ALP, Runx2, Col I, OPN and CEMP1) of PDLCs on different kinds of Sr-MBG scaffolds were systematically investigated. The results show that Sr plays an important role in influencing the mesoporous structure of MBG scaffolds in which high contents of Sr decreased the well-ordered mesopores as well as their surface area/pore volume. Sr(2+) ions could be released from Sr-MBG scaffolds in a controlled way. The incorporation of Sr into MBG scaffolds has significantly stimulated ALP activity and osteogenesis/cementogenesis-related gene expression of PDLCs. Furthermore, Sr-MBG scaffolds in a simulated body fluid environment still maintained excellent apatite-mineralization ability. The study suggests that the incorporation of Sr into MBG scaffolds is a viable way to stimulate the biological response of PDLCs. Sr-MBG scaffolds are a promising bioactive material for periodontal tissue-engineering applications.

Translational research and therapeutic applications of stem cell transplantation in periodontal regenerative medicine

Stem cells have received a great deal of interest from the research community as potential therapeutic "tools" for a variety of chronic debilitating diseases that lack clinically effective therapies. Stem cells are also of interest for the regeneration of tooth-supporting tissues that have been lost to periodontal disease. Indeed, substantial data have demonstrated that the exogenous administration of stem cells or their derivatives in preclinical animal models of periodontal defects can restore damaged tissues to their original form and function. As we discuss here, however, considerable hurdles must be overcome before these findings can be responsibly translated to novel clinical therapies. Generally, the application of stem cells for periodontal therapy in clinics will not be realized until the best cell(s) to use, the optimal dose, and an effective mode of administration are identified. In particular, we need to better understand the mechanisms of action of stem cells after transplantation in the periodontium and to learn how to preciously control stem cell fates in the pathological environment around a tooth. From a translational perspective, we outline the challenges that may vary across preclinical models for the evaluation of stem cell therapy in situations that require periodontal reconstruction and the safety issues that are related to clinical applications of human stem cells. Although clinical trials that use autologous periodontal ligament stem cells have been approved and have already been initiated, proper consideration of the technical, safety, and regulatory concerns may facilitate, rather than inhibit, the clinical translation of new therapies.

Crosstalk on cell behavior in interactive cocultures of hMSCs with various oral cell types

When prospectively applied for regenerative therapies, human bone-marrow-derived mesenchymal stem cells (hMSCs) interact with the locally residing host cells. With respect to the developmentally particular origin of oral cells, little is known about the putatively discriminative behavioral responses of hMSCs in interaction with various oral cell types, including human alveolar bone osteoblasts (hOAs), periodontal ligament fibroblasts (hPDLs), and gingival fibroblasts (hGFs). To assess the crosstalk between hMSCs and oral cells, interactive cocultures were established by combining well-characterized hMSCs with hOAs, hPDLs, or hGFs, and the behavioral hMSC aspects, that is, proliferation and gene expression, were measured by employing a 5-bromo-2'-deoxyuridine assay and real-time polymerase chain reaction, while apoptosis was quantified by in situ cell death detection kit. hMSCs expressed the typical antigen spectrum lacking CD34, CD45, CD14, CD19, and HLA-DR, while expressing CD73, CD90, and CD105, and could successfully be transformed into adipocytes, osteocytes, and chondrocytes. Monocultured control hMSCs proliferated readily, whereas a general reduction of BrdU-labeled cells was observed in cocultures. Globally, upon extending time periods, interactive coculture combinations of hMSCs with hOAs reduced both osteogenic gene and stem cell marker transcription in hMSCs, a phenomenon appearing less pronounced by combining hMSCs with hPDLs, such that the observed effects in terms of proliferation and gene expression followed the same ranking: hOAs>hGFs>hPDLs. Vice versa, in interactive hMSC cocultures, the cell survival rate was significantly increased, irrespective from the combined coculture cell counterpart. Our results show for the first time that behavior of hMSCs reflected by proliferation and gene expression was governed by interaction with various oral cells in a cell-type-discriminative manner. In addition, hMSC coculture restrains apoptosis, such that influences on cell behavior appear as a crosstalk. In summary, interactive cocultures render the basis for a prospective prediction of mutual cell behavior in hMSC-based oral tissue regeneration disclosing that oral cells shift hMSC behavior from proliferation to differentiation and apoptosis-repressing features.

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.

Human periodontal ligament cells reaction on a novel hydroxyapatite-collagen scaffold

BACKGROUND

Periodontal tissue regeneration presents a highly promising method for restoring periodontal structures. The development of a suitable bioactive scaffold that promotes cell proliferation and differentiation is critical in periodontal tissue engineering. The aim of this study was to evaluate the biocompatibility of a novel 3-dimensional hydroxyapatite-collagen scaffold with human periodontal ligament (hPDL) cell culture.

METHODS

The scaffold was produced from a natural collagen matrix - purified porcine acellular dermal matrix (PADM), which was then treated with hydroxyapatite (HA) through a biomimetic chemical process to obtain hydroxyapatite-porcine acellular dermal matrix (HA-PADM) scaffold. The hPDL cells were cultured with HA-PADM scaffolds for 1, 3, 6, 14, and 28 days. The cell viability assay, scanning electron microscopy (SEM), hematoxylin and eosin (H&E) staining, immunohistochemistry, and confocal microscopy were employed in different time points to evaluate the biocompatibility of the scaffolds with hPDL cells.

RESULTS

The cell viability assay (WST-1 test) verified cell proliferation on the HA-PADM scaffolds. The SEM study showed unique morphology of hPDL cells, which attach and spread on the surface of the scaffolds. The H&E staining, immunohistochemistry, and confocal microscopy demonstrated that hPDL cells were able to grow into the HA-PADM scaffolds and maintain viability after prolonged culture.

CONCLUSIONS

This study proved that HA-PADM scaffold is -biocompatible for hPDL cells. The cells were able to proliferate and migrate into the scaffold. These observations suggest that HA-PADM is a potential cell carrier for periodontal tissue regeneration.

Tissue engineering bone-ligament complexes using fiber-guiding scaffolds

Regeneration of bone-ligament complexes destroyed due to disease or injury is a clinical challenge due to complex topologies and tissue integration required for functional restoration. Attempts to reconstruct soft-hard tissue interfaces have met with limited clinical success. In this investigation, we manufactured biomimetic fiber-guiding scaffolds using solid free-form fabrication methods that custom fit complex anatomical defects to guide functionally-oriented ligamentous fibers in vivo. Compared to traditional, amorphous or random-porous polymeric scaffolds, the use of perpendicularly oriented micro-channels provides better guidance for cellular processes anchoring ligaments between two distinct mineralized structures. These structures withstood biomechanical loading to restore large osseous defects. Cell transplantation using hybrid scaffolding constructs with guidance channels resulted in predictable oriented fiber architecture, greater control of tissue infiltration, and better organization of ligament interface than random scaffold architectures. These findings demonstrate that fiber-guiding scaffolds drive neogenesis of triphasic bone-ligament integration for a variety of clinical scenarios.