Current concepts in periodontal bioengineering

Combined Effects of Fibroblast Growth Factor-2 and Carbonate Apatite Granules on Periodontal Healing: An In Vivo and In Vitro Study

The aim of this study was to investigate in vivo and in vitro the effectiveness of the use of fibroblast growth factor (FGF)-2 with carbonate apatite (CO3Ap) on periodontal healing. Periodontal defects created in the maxillary first molars in rats were treated with FGF-2, CO3Ap, FGF-2 + CO3Ap or left unfilled. Healing was evaluated using microcomputed tomography, histological, and immunohistochemical analyses. In vitro experiments were performed to assess cellular behaviors and the expression of osteoblastic differentiation markers in MC3T3-E1 cells. At 4 weeks, the bone volume fraction in the FGF-2 + CO3Ap group was significantly greater than that in the CO3Ap group, but there was no significant difference from the FGF-2 group. The FGF-2 + CO3Ap group demonstrated greater new bone compared with the FGF-2 or CO3Ap group. The FGF-2 + CO3Ap group showed greater levels of osteocalcin-positive cells compared with the CO3Ap group, but there was no significant difference from the FGF-2 group. In vitro, the FGF-2 + CO3Ap group exhibited a greater extent of cell attachment and more elongated cells compared with the CO3Ap group. Compared with the CO3Ap group, the FGF-2 + CO3Ap group showed significantly higher viability/proliferation, but the expressions of Runx2 and Sp7 were reduced. The results indicated that the use of FGF-2 with CO3Ap enhanced healing in the periodontal defects. FGF-2 promoted cell attachment to and proliferation on CO3Ap and regulated osteoblastic differentiation, thereby contributing to novel bone formation.

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.

Histological evaluation of nonsurgical periodontal treatment with and without the use of sodium hypochlorite / amino acids and cross-linked hyaluronic acid gels in dogs

OBJECTIVES

To evaluate periodontal wound healing following scaling and root planing (SRP) in conjunction with the application of sodium hypochlorite/amino acids and cross-linked hyaluronic acid (xHyA) gels in dogs.

MATERIALS AND METHODS

In four beagle dogs, 2-wall intrabony defects were created and metal strips were placed around the teeth. Clinical parameters were measured 4 weeks after plaque accumulation. The experimental root surfaces were subjected to SRP with either the subgingival application of a sodium hypochlorite/amino acid gel and a xHyA gel (test group) or SRP alone (control group) using a split-mouth design. Clinical parameters were re-evaluated at 6 weeks. The animals were sacrificed at 8 weeks for histological analysis.

RESULTS

The test group showed significant improvements in all clinical parameters compared to the control group. Histologically, the test group exhibited statistically significantly greater new bone formation [i.e., length of newly formed bone, new bone area] compared with the control group (p < 0.05). Furthermore, statistically significantly greater formation of new attachment [i.e., linear length of new cementum adjacently to newly formed bone with inserting collagen fibers] and new cementum was detected in the test group compared with the control group at 8 weeks (p < 0.05 and p < 0.01, respectively).

CONCLUSION

The adjunctive subgingival application of sodium hypochlorite/amino acid and xHyA gels to SRP offers an innovative novel approach to enhance periodontal wound healing/regeneration.

CLINICAL RELEVANCE

The present findings have for the first-time shown histologic evidence for periodontal regeneration in support of this novel treatment modality.

Impact of local drug delivery and natural agents as new target strategies against periodontitis: new challenges for personalized therapeutic approach

Periodontitis is a persistent inflammation of the soft tissue around the teeth that affects 60% of the population in the globe. The self-maintenance of the inflammatory process can cause periodontal damage from the alveolar bone resorption to tooth loss in order to contrast the effects of periodontitis, the main therapy used is scaling and root planing (SRP). At the same time, studying the physiopathology of periodontitis has shown the possibility of using a local drug delivery system as an adjunctive therapy. Using local drug delivery devices in conjunction with SRP therapy for periodontitis is a potential tool since it increases drug efficacy and minimizes negative effects by managing drug release. This review emphasized how the use of local drug delivery agents and natural agents could be promising adjuvants for the treatment of periodontitis patients affected or not by cardiovascular disease, diabetes, and other system problems. Moreover, the review evidences the current issues and new ideas that can inspire potential later study for both basic research and clinical practice for a tailored approach.

Guided Tissue and Bone Regeneration Membranes: A Review of Biomaterials and Techniques for Periodontal Treatments

This comprehensive review provides an in-depth analysis of the use of biomaterials in the processes of guided tissue and bone regeneration, and their indispensable role in dental therapeutic interventions. These interventions serve the critical function of restoring both structural integrity and functionality to the dentition that has been lost or damaged. The basis for this review is laid through the exploration of various relevant scientific databases such as Scopus, PubMed, Web of science and MEDLINE. From a meticulous selection, relevant literature was chosen. This review commences by examining the different types of membranes used in guided bone regeneration procedures and the spectrum of biomaterials employed in these operations. It then explores the manufacturing technologies for the scaffold, delving into their significant impact on tissue and bone regenerations. At the core of this review is the method of guided bone regeneration, which is a crucial technique for counteracting bone loss induced by tooth extraction or periodontal disease. The discussion advances by underscoring the latest innovations and strategies in the field of tissue regeneration. One key observation is the critical role that membranes play in guided reconstruction; they serve as a barrier, preventing the entry of non-ossifying cells, thereby promoting the successful growth and regeneration of bone and tissue. By reviewing the existing literature on biomaterials, membranes, and scaffold manufacturing technologies, this paper illustrates the vast potential for innovation and growth within the field of dental therapeutic interventions, particularly in guided tissue and bone regeneration.

Biomechanical Modulation of Dental Pulp Stem Cell (DPSC) Properties for Soft Tissue Engineering

Dental pulp regeneration strategies frequently result in hard tissue formation and pulp obliteration. The aim of this study was to investigate whether dental pulp stem cells (DPSCs) can be directed toward soft tissue differentiation by extracellular elasticity. STRO-1-positive human dental pulp cells were magnetically enriched and cultured on substrates with elasticities of 1.5, 15, and 28 kPa. The morphology of DPSCs was assessed visually. Proteins relevant in mechanobiology ACTB, ITGB1, FAK, p-FAK, TALIN, VINCULIN, PAXILLIN, ERK 1/2, and p-ERK 1/2 were detected by immunofluorescence imaging. Transcription of the pulp marker genes BMP2, BMP4, MMP2, MMP3, MMP13, FN1, and IGF2 as well as the cytokines ANGPT1, VEGF, CCL2, TGFB1, IL2, ANG, and CSF1 was determined using qPCR. A low stiffness, i.e., 1.5 kPa, resulted in a soft tissue-like phenotype and gene expression, whereas DPSCs on 28 kPa substrates exhibited a differentiation signature resembling hard tissues with a low cytokine expression. Conversely, the highest cytokine expression was observed in cells cultured on intermediate elasticity, i.e., 15 kPa, substrates possibly allowing the cells to act as “trophic mediators”. Our observations highlight the impact of biophysical cues for DPSC fate and enable the design of scaffold materials for clinical pulp regeneration that prevent hard tissue formation.

Clinical and patient-reported outcomes of tissue engineering strategies for periodontal and peri-implant reconstruction

Scientific advancements in biomaterials, cellular therapies, and growth factors have brought new therapeutic options for periodontal and peri-implant reconstructive procedures. These tissue engineering strategies involve the enrichment of scaffolds with living cells or signaling molecules and aim at mimicking the cascades of wound healing events and the clinical outcomes of conventional autogenous grafts, without the need for donor tissue. Several tissue engineering strategies have been explored over the years for a variety of clinical scenarios, including periodontal regeneration, treatment of gingival recessions/mucogingival conditions, alveolar ridge preservation, bone augmentation procedures, sinus floor elevation, and peri-implant bone regeneration therapies. The goal of this article was to review the tissue engineering strategies that have been performed for periodontal and peri-implant reconstruction and implant site development, and to evaluate their safety, invasiveness, efficacy, and patient-reported outcomes. A detailed systematic search was conducted to identify eligible randomized controlled trials reporting the outcomes of tissue engineering strategies utilized for the aforementioned indications. A total of 128 trials were ultimately included in this review for a detailed qualitative analysis. Commonly performed tissue engineering strategies involved scaffolds enriched with mesenchymal or somatic cells (cell-based tissue engineering strategies), or more often scaffolds loaded with signaling molecules/growth factors (signaling molecule-based tissue engineering strategies). These approaches were found to be safe when utilized for periodontal and peri-implant reconstruction therapies and implant site development. Tissue engineering strategies demonstrated either similar or superior clinical outcomes than conventional approaches for the treatment of infrabony and furcation defects, alveolar ridge preservation, and sinus floor augmentation. Tissue engineering strategies can promote higher root coverage, keratinized tissue width, and gingival thickness gain than scaffolds alone can, and they can often obtain similar mean root coverage compared with autogenous grafts. There is some evidence suggesting that tissue engineering strategies can have a positive effect on patient morbidity, their preference, esthetics, and quality of life when utilized for the treatment of mucogingival deformities. Similarly, tissue engineering strategies can reduce the invasiveness and complications of autogenous graft-based staged bone augmentation. More studies incorporating patient-reported outcomes are needed to understand the cost-benefits of tissue engineering strategies compared with traditional treatments.

TNFα, IL-6, miR-103a-3p, miR-423-5p, miR-23a-3p, miR-15a-5p and miR-223-3p in the crevicular fluid of periodontopathic patients correlate with each other and at different stages of the disease

Periodontitis is one of the main frequent intraoral diseases. Pathogenesis triggers are the immune responses with pro-inflammatory cytokines production and non-coding RNAs expression. The purpose of the present study was to evaluate the involvement of selected miRNAs in various stages of periodontitis and their relationship with the levels of inflammatory mediators in gingival crevicular fluid (GCF). For this study, 36 subjects (21 with periodontal disease, 15 healthy controls) were selected with an age mean of 59.1 ± 3.7 years. Clinical parameters included plaque index, gingival index, sulcus bleeding index, pocket depth, and clinical attachment level. The GCF samples were taken using capillary paper. The levels of miRNAs in GCF were estimated using a Real-Time PCR and TNFα and IL-6 levels were assessed by enzyme-linked immunosorbent assay (ELISA). The results indicated that the miRNA-103a-3p, miRNA-23a-3p, miRNA-15a-5p, and miRNA-223-3p were significantly upregulated with respect to healthy controls. Significant differences were observed for miRNA-23a-3p, miRNA-103a-3p and miRNA-423-5p levels in accord with the disease stages. Inflammatory mediators evaluated in GCF correlate well with the clinical parameters and the severity of the periodontal disease. miRNAs can represent biomarkers of disease stage and can be investigated as a possible therapeutic target, as well as levels of TNFα and IL-6 may drive the disease progression by acting as prognostic markers.

Recent advances in GTR scaffolds

Periodontitis is a serious chronic inflammatory condition that can cause periodontal tissue deterioration and, eventually, tooth loss. Periodontal regenerative therapy using membranes and bone grafting materials, as well as flap debridement and/or flap curettage, have all been used with varying degrees of clinical effectiveness. Current resorbable and non-resorbable membranes serve as a physical barrier, preventing connective and epithelial tissue down growth into the defect and promoting periodontal tissue regeneration. The "perfect" membrane for use in periodontal regenerative therapy has yet to be created, as these conventional membranes have several structural, mechanical, and bio-functional constraints. We hypothesised in this narrative review that the next-generation of guided tissue and guided bone regeneration (GTR/GBR) membranes for periodontal tissue engineering will be a graded-biomaterials that closely mimics the extracellular matrix.

Therapeutic and Metagenomic Potential of the Biomolecular Therapies against Periodontitis and the Oral Microbiome: Current Evidence and Future Perspectives

The principles of periodontal therapy are based on the control of microbial pathogens and host factors that contribute to biofilm dysbiosis, with the aim of modulating the progression of periodontitis and periodontal tissue destruction. It is currently known how differently each individual responds to periodontal treatment, depending on both the bacterial subtypes that make up the dysbiotic biofilm and interindividual variations in the host inflammatory response. This has allowed the current variety of approaches for the management of periodontitis to be updated by defining the goals of target strategies, which consist of reducing the periodontopathogenic microbial flora and/or modulating the host-mediated response. Therefore, this review aims to update the current variety of approaches for the management of periodontitis based on recent target therapies. Recently, encouraging results have been obtained from several studies exploring the effects of some targeted therapies in the medium- and long-term. Among the most promising target therapies analyzed and explored in this review include: cell-based periodontal regeneration, mediators against bone resorption, emdogain (EMD), platelet-rich plasma, and growth factors. The reviewed evidence supports the hypothesis that the therapeutic combination of epigenetic modifications of periodontal tissues, interacting with the dysbiotic biofilm, is a key step in significantly reducing the development and progression of disease in periodontal patients and improving the therapeutic response of periodontal patients. However, although studies indicate promising results, these need to be further expanded and studied to truly realize the benefits that targeted therapies could bring in the treatment of periodontitis.

Layered scaffolds in periodontal regeneration

Periodontitis is a common inflammatory disease in dentistry that may lead to tooth loss and aesthetic problems. Periodontal tissue has a sophisticated architecture including four sections of alveolar bone, cementum, gingiva, and periodontal ligament fiber; all these four can be damaged during periodontitis. Thus, for whole periodontal regeneration, it is important to form both hard and soft tissue structures simultaneously on the tooth root surface without forming junctional epithelium and ankylosis. This condition makes the treatment of the periodontium a challenging process. Various regenerative methods including Guided Bone/Tissue Regeneration (GBR/GTR) using various membranes have been developed. Although using such GBR/GTR membranes was successful for partial periodontal treatment, they cannot be used for the regeneration of complete periodontium. For this purpose, multilayered scaffolds are now being developed. Such scaffolds may include various biomaterials, stem cells, and growth factors in a multiphasic configuration in which each layer is designed to regenerate specific section of the periodontium. This article provides a comprehensive review of the multilayered scaffolds for periodontal regeneration based on natural or synthetic polymers, and their combinations with other biomaterials and bioactive molecules. After highlighting the challenges related to multilayered scaffolds preparation, features of suitable scaffolds for periodontal regeneration are discussed.

Association of SRXN1 Receptor Gene Polymorphism with Susceptibility to Periodontitis

Background

Emerging evidence suggests that oxidative stress forms a key component in the etiopathogenesis of periodontitis. Literature evidence have shown potential antioxidants responsible for combating the pro-oxidants which stress the periodontium, but the peroxiredoxin-sulfiredoxin system is explored very minimally in periodontal disease. Thus, the present study was aimed to evaluate the genetic association of SRXN1 receptor gene polymorphism (rs6053666).

Materials and Methods

A total of 100 subjects were recruited for this study, which included 50 Periodontitis patients (Stage II and above based on the criteria of American Association of Periodontology-2018) and 50 periodontally healthy or mild gingivitis. Genomic DNA was extracted from the whole blood collected from the subjects. DNA was amplified using specific primers flanking the BtgI region of the SRXN1 receptor gene. The amplicon was further subjected to genotyping using restriction fragment length using BtgI enzyme. The genotype obtained based on the restriction fragment length polymorphism pattern was recorded and used for statistical analysis. The distribution of genotypes and allele frequencies in the periodontitis and control groups were compared using the Chi-square test. The risk associated with individual alleles or genotypes was calculated as the odds ratio with 95% confidence intervals. Statistical significance in all tests was determined at P < 0.05.

Results

The genotype frequency and distributions of SRXN1 receptor BtgI polymorphism did not differ significantly at ꭕ2df (P = 0.557). Our study results showed that homozygous and heterozygous mutant genotypes had no significant difference (CC vs. CT + TT) between the periodontitis patients and control group with a P = 0.4266. The detected frequency of CT (38% vs. 34%) and TT (42% vs. 52%) genotype showed no significant difference between control and test group. There was no significant difference in C allele (39% vs. 31%) and T allele (61% vs. 69%) between the test and control group.

Conclusion

The present study denotes that SRXN1 receptor gene polymorphism is not associated with periodontitis in the study group analyzed.

An Up-To-Date Overview of Dental Tissue Regeneration Using Dental Origin Mesenchymal Stem Cells: Challenges and Road Ahead

Stem cells (SCs) research has experienced exponential growth in recent years. SC-based treatments can enhance the lives of people suffering from cardiac ischemia, Alzheimer’s disease, and regenerative drug conditions, like bone or loss of teeth. Numerous kinds of progenitor/SCs have been hypothesized to depend on their potential to regain and/or heal wounded tissue and partly recover organ function. Growing data suggest that SCs (SCs) are concentrated in functions and that particular tissues have more SCs. Dental tissues, in particular, are considered a significant cause of mesenchymal stem cells (MSCs) cells appropriate for tissue regeneration uses. Tissue regeneration and SCs biology have particular attention in dentistry because they may give a novel method for creating clinical material and/or tissue redevelopment. Dental pulp, dental papilla, periodontal ligament, and dental follicle contain mesenchymal SCs. Such SCs, which must be identified and cultivated in specific tissue culture environments, may be used in tissue engineering applications such as tooth tissue, nerve regeneration, and bone redevelopment. A new cause of SCs, induced pluripotent SCs, was successfully made from human somatic cells, enabling the generation of the patient and disease-specific SCs. The dental SC’s (DSCs) multipotency, rapid proliferation rate, and accessibility make it an ideal basis of MSC for tissue redevelopment. This article discusses current advances in tooth SC investigation and its possible application in tissue redevelopment.

Transplantation of Mature Adipocyte-Derived Dedifferentiated Fat Cells Facilitates Periodontal Tissue Regeneration of Class II Furcation Defects in Miniature Pigs

Adipose tissue is composed mostly of adipocytes that are in contact with capillaries. By using a ceiling culture method based on buoyancy, lipid-free fibroblast-like cells, also known as dedifferentiated fat (DFAT) cells, can be separated from mature adipocytes with a large single lipid droplet. DFAT cells can re-establish their active proliferation ability and transdifferentiate into various cell types under appropriate culture conditions. Herein, we sought to compare the regenerative potential of collagen matrix alone (control) with autologous DFAT cell-loaded collagen matrix transplantation in adult miniature pigs (microminipigs; MMPs). We established and transplanted DFAT cells into inflammation-inducing periodontal class II furcation defects. At 12 weeks after cell transplantation, a marked attachment gain was observed based on the clinical parameters of probing depth (PD) and clinical attachment level (CAL). Additionally, micro computed tomography (CT) revealed hard tissue formation in furcation defects of the second premolar. The cemento-enamel junction and alveolar bone crest distance was significantly shorter following transplantation. Moreover, newly formed cellular cementum, well-oriented periodontal ligament-like fibers, and alveolar bone formation were observed via histological analysis. No teratomas were found in the internal organs of recipient MMPs. Taken together, these findings suggest that DFAT cells can safely enhance periodontal tissue regeneration.

Mesenchymal Stromal/Stem Cells-Derived Exosomes as an Antimicrobial Weapon for Orodental Infections

The oral cavity as the second most various microbial community in the body contains a broad spectrum of microorganisms which are known as the oral microbiome. The oral microbiome includes different types of microbes such as bacteria, fungi, viruses, and protozoa. Numerous factors can affect the equilibrium of the oral microbiome community which can eventually lead to orodental infectious diseases. Periodontitis, dental caries, oral leukoplakia, oral squamous cell carcinoma are some multifactorial infectious diseases in the oral cavity. In defending against infection, the immune system has an essential role. Depending on the speed and specificity of the reaction, immunity is divided into two different types which are named the innate and the adaptive responses but also there is much interaction between them. In these responses, different types of immune cells are present and recent evidence demonstrates that these cell types both within the innate and adaptive immune systems are capable of secreting some extracellular vesicles named exosomes which are involved in the response to infection. Exosomes are 30-150 nm lipid bilayer vesicles that consist of variant molecules, including proteins, lipids, and genetic materials and they have been associated with cell-to-cell communications. However, some kinds of exosomes can be effective on the pathogenicity of various microorganisms and promoting infections, and some other ones have antimicrobial and anti-infective functions in microbial diseases. These discrepancies in performance are due to the origin of the exosome. Exosomes can modulate the innate and specific immune responses of host cells by participating in antigen presentation for activation of immune cells and stimulating the release of inflammatory factors and the expression of immune molecules. Also, mesenchymal stromal/stem cells (MSCs)-derived exosomes participate in immunomodulation by different mechanisms. Ease of expansion and immunotherapeutic capabilities of MSCs, develop their applications in hundreds of clinical trials. Recently, it has been shown that cell-free therapies, like exosome therapies, by having more advantages than previous treatment methods are emerging as a promising strategy for the treatment of several diseases, in particular inflammatory conditions. In orodental infectious disease, exosomes can also play an important role by modulating immunoinflammatory responses. Therefore, MSCs-derived exosomes may have potential therapeutic effects to be a choice for controlling and treatment of orodental infectious diseases.

Effect of rhBMP-2 applied with a 3D-printed titanium implant on new bone formation in rabbit calvarium

OBJECTIVE

This study sought to compare the biocompatibility of a three-dimensional (3D)-printed titanium implant with a conventional machined titanium product, as well as the effect of such implant applied with recombinant human Bone Morphogenetic Protein Type 2 (rhBMP-2) for guided bone regeneration.

METHODOLOGY

Disk-shaped titanium specimens fabricated either by the conventional machining technique or by the 3D-printing technique were compared by MC3T3-E1 cells cytotoxicity assay. New bone formation was evaluated using a rapid prototype titanium cap applied to the calvaria of 10 rabbits, which were divided into two groups: one including an atelopeptide collagen plug on one side of the cap (group I) and the other including a plug with rhBMP-2 on the other side (group II). At six and 12 weeks after euthanasia, rabbits calvaria underwent morphometric analysis through radiological and histological examination.

RESULTS

Through the cytotoxicity assay, we identified a significantly higher number of MC3T3-E1 cells in the 3D-printed specimen when compared to the machined specimen after 48 hours of culture. Moreover, morphometric analysis indicated significantly greater bone formation at week 12 on the side where rhBMP-2 was applied when evaluating the upper portion immediately below the cap.

CONCLUSION

The results suggest that 3D-printed titanium implant applied with rhBMP-2 enables new bone formation.

Effect of interleukin-1β on bone morphogenetic protein-9-induced osteoblastic differentiation of human periodontal ligament fibroblasts

Bone morphogenetic protein-9 (BMP-9) has been shown to potently induce osteoblastic differentiation of periodontal ligament fibroblasts (PDLFs) and may be a candidate therapeutic agent for periodontal tissue healing/regeneration, but the effect of the inflammatory environment of periodontitis on such approaches is unclear. We investigated whether interleukin-1β (IL-1β) affected BMP-9-mediated osteoblastic differentiation of human (h) PDLFs. IL-1β suppressed BMP-9-induced osteogenic differentiation of hPDLFs, as evidenced by reduced alkaline phosphatase (ALP) activity and mineralization, and the downregulated expression of BMP-9-mediated bone-related genes, RUNX2, SP7, IBSP, and SPP1. In hPDLFs, with or without BMP-9, IL-1β increased the protein expression of activin A, a BMP-9 antagonist, and decreased follistatin protein, an antagonist of activin A. Similarly, IL-1β upregulated the expression of the activin A gene and downregulated that of the follistatin gene. Notably, follistatin re-established BMP-9-induced ALP activity suppressed by IL-1β. Activin A inhibited the expression of BMP-9-responsive genes and BMP-9-induced ALP activity, while follistatin re-established them. Finally, extracellular signal-regulated kinase 1/2 (ERK1/2), p38, and nuclear factor-kappa B (NF-κB) inhibition significantly blocked IL-1β-induced activin A gene expression. Our data indicate that IL-1β inhibits BMP-9-induced osteoblastic differentiation of hPDLFs, possibly by promoting activin A production via the ERK1/2, p38, and NF-κB pathways.

Local drug delivery systems as therapeutic strategies against periodontitis: A systematic review

Periodontitis is a chronic inflammation of the soft tissue surrounding and supporting the teeth, which causes periodontal structural damage, alveolar bone resorption, and even tooth loss. Its prevalence is very high, with nearly 60% of the global population affected. Hence, periodontitis is an important public health concern, and the development of effective healing treatments for oral diseases is a major target of the health sciences. Currently, the application of local drug delivery systems (LDDS) as an adjunctive therapy to scaling and root planning (SRP) in periodontitis is a promising strategy, giving higher efficacy and fewer side effects by controlling drug release. The cornerstone of successful periodontitis therapy is to select an appropriate bioactive agent and route of administration. In this context, this review highlights applications of LDDS with different properties in the treatment of periodontitis with or without systemic diseases, in order to reveal existing challenges and future research directions.

Treatment of Chronic Periodontitis with Recombinant Human Fibroblast Growth Factor-2 and Deproteinized Bovine Bone Mineral in Wide Intrabony Defects:12-month Follow-up Case Series

Clinical use of 0.3% recombinant human fibroblast growth factor (rhFGF)-2 for periodontal regeneration received formal approval in Japan in 2016. The combination of growth factor and bone graft material is used to enhance periodontal healing in regenerative therapy. The exact effects of combination therapy on periodontal healing remain unknown, however. Here, we report three cases of chronic periodontitis treated with the combination of rhFGF-2 and deproteinized bovine bone mineral (DBBM). Following initial periodontal therapy, periodontal regenerative therapy using rhFGF-2 in combination with DBBM was performed to treat wide intrabony defects. Periodontal parameters and radiographic bone fill were reevaluated at 3 months, 6 months, and 1 year postoperatively. Oral health-related quality of life (OHRQL) was assessed as a patient-reported measure of outcome. At 1 year postoperatively, probing pocket depth and clinical attachment level showed a significant improvement in comparison with at baseline. An improvement was also noted in radiographic evidence of bone fill and total OHRQL scores. Combination therapy yielded clinically favorable results in the present cases.

RhPDGF – Basic Characteristics and Potential Application in the Oral Surgery – An Overview

Growth factors (GFs) are bioactive molecules participating in organ development, tissue regeneration and repair. They are protein molecules with a relatively low molecular weight and are released by activated platelets. Platelet-derived growth factor (PDGF) is one of the GFs of highest amount in human platelets. It is known to stimulate cell proliferation and extracellular matrix synthesis, as well as angiogenesis in healthy tissues and neoplasms. However, most of the studies in the literature demonstrate the influence of PDGF on tissue regeneration without revealing its intimate mechanisms of action on different cell types. In the current review we emphasis on the effects of PDGF in order to stimulate various biological processes in wide number of pre-clinical and clinical studies.

New biodegradable nanoparticles-in-nanofibers based membranes for guided periodontal tissue and bone regeneration with enhanced antibacterial activity

Introduction

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are commonly used surgical procedures for the repair of damaged periodontal tissues. These procedures include the use of a membrane as barrier to prevent soft tissue ingrowth and to create space for slowly regenerating periodontium and bone. Recent approaches involve the use of membranes/scaffolds based on resorbable materials. These materials provide the advantage of dissolving by time without the need of surgical intervention to remove the scaffolds.

Objectives

This study aimed at preparing a new series of nanofibrous scaffolds for GTR/GBR applications with enhanced mechanical properties, cell adhesion, biocompatibility and antibacterial properties.

Methods

Electrospun nanofibrous scaffolds based on polylactic acid/cellulose acetate (PLA/CA) or poly(caprolactone) (PCL) polymers were prepared and characterized. Different concentrations of green-synthesized silver nanoparticles, AgNPs (1-2% w/v) and hydroxyapatite nanoparticles, HANPs (10-20% w/v) were incorporated into the scaffolds to enhance the antibacterial and bone regeneration activity.

Results

In-vitro studies showed that addition of HANPs improved the cell viability by around 50% for both types of nanofibrous scaffolds. The tensile properties were also improved through addition of 10% HANPs but deteriorated upon increasing the concentration to 20%. AgNPs significantly improved the antibacterial activity with 40 mm inhibition zone after 32 days. Additionally, the nanofibrous scaffolds showed a desirable degradation profile with losing around 40-70% of its mass in 8 weeks.

Conclusions

The obtained results show that the developed nanofibrous membranes are promising scaffolds for both GTR and GBR applications.

The use of plasma rich in growth factors (PRGF) in guided tissue regeneration and guided bone regeneration. A review of histological, immunohistochemical, histomorphometrical, radiological and clinical results in humans

BACKGROUND

Modern surgeries have advanced toward personalized minimal-invasive treatments with a high rate of clinical healing that facilitates the regeneration of tissues. One of the leading approaches to deliver endogenous plasma- and platelet-derived growth factors is the plasma rich in growth factors (PRGF). This narrative review determines the effects of using PRGF in different oral surgical procedures including alveolar ridge augmentation, socket preservation, sinus floor augmentation and periodontal regeneration.

METHODS

For this narrative review, a literature search was conducted using PubMed and Researchgate. A combination of the following text words was used to maximize search specificity and sensitivity: "platelet-rich plasma", "PRP", "PRGF", "Platelet-rich growth factor", "socket preservation", "Extraction", "infra-bony pockets", "sinus floor augmentation", "randomized clinical controlled trials", "Alveolar osteitis", "Periodontal regeneration", "guided bone regeneration", "guided tissue regeneration".

RESULTS

Investigations have generally agreed that PRGF can promote and accelerate the healing process. PRGF optimizes the patient's quality of life by reducing pain, swelling and inflammation rate and also accelerates regeneration of soft tissue and bone tissue regeneration as well.

CONCLUSIONS

There is increasing evidence to support the use of PRGF in oral surgical procedures in order to improve the healing processes of the oral soft and hard tissues.

Thyroxine-loaded chitosan/carboxymethyl cellulose/hydroxyapatite hydrogels enhance angiogenesis in in-ovo experiments

Angiogenesis is one of the most important processes in repair and regeneration of many tissues and organs. Blood vessel formation also play a major role in repair of dental tissue(s) after ailments like periodontitis. Here we report the preparation of chitosan/carboxymethyl cellulose/hydroxyapatite based hydrogels, loaded with variable concentrations of thyroxin i.e., 0.1 μg/ml, 0.5 μg/ml and 1 μg/ml. Scanning electron microcopy images (SEM) showed all hydrogels were found to be porous and solution absorption study exhibited high swelling potential in aqueous media. FTIR spectra confirmed that the used materials did not change their chemical identity in synthesized hydrogels. The synthesized hydrogels demonstrated good bending, folding, rolling and stretching abilities. The hydrogels were tested in chick chorioallantoic membrane (CAM) assay to investigate their angiogenic potential. Hydrogel containing 0.1 μg/ml of thyroxine showed maximum neovascularization. For cytotoxicity analyses, preosteoblast cells (MC3T3-E1) were seeded on these hydrogels and materials were found to be non-toxic. These hydrogels with pro-angiogenic activity possess great potential to be used for periodontal regeneration.

Gene Delivery Therapeutics in the Treatment of Periodontitis and Peri-Implantitis: A State of the Art Review

BACKGROUND

Periodontal disease is a chronic inflammatory condition that affects supporting tissues around teeth, resulting in periodontal tissue breakdown. If left untreated, periodontal disease could have serious consequences; this condition is in fact considered as the primary cause of tooth loss. Being highly prevalent among adults, periodontal disease treatment is receiving increased attention from researchers and clinicians. When this condition occurs around dental implants, the disease is termed peri-implantitis. Periodontal regeneration aims at restoring the destroyed attachment apparatus, in order to improve tooth stability and thus reduce disease progression and subsequent periodontal tissue breakdown. Although many biomaterials have been developed to promote periodontal regeneration, they still have their own set of disadvantages. As a result, regenerative medicine has been employed in the periodontal field, not only to overcome the drawbacks of the conventional biomaterials but also to ensure more predictable regenerative outcomes with minimal complications. Regenerative medicine is considered a part of the research field called tissue engineering/regenerative medicine (TE/RM), a translational field combining cell therapy, biomaterial, biomedical engineering and genetics all with the aim to replace and restore tissues or organs to their normal function using in vitro models for in vivo regeneration. In a tissue, cells are responding to different micro-environmental cues and signaling molecules, these biological factors influence cell differentiation, migration and cell responses. A central part of TE/RM therapy is introducing drugs, genetic materials or proteins to induce specific cellular responses in the cells at the site of tissue repair in order to enhance and improve tissue regeneration. In this review, we present the state of art of gene therapy in the applications of periodontal tissue and peri-implant regeneration.

PURPOSE

We aim herein to review the currently available methods for gene therapy, which include the utilization of viral/non-viral vectors and how they might serve as therapeutic potentials in regenerative medicine for periodontal and peri-implant tissues.

Enhancing cell seeding and osteogenesis of MSCs on 3D printed scaffolds through injectable BMP2 immobilized ECM-Mimetic gel

OBJECTIVE

Design of bioactive scaffolds with osteogenic capacity is a central challenge in cell-based patient-specific bone tissue engineering. Efficient and spatially uniform seeding of (stem) cells onto such constructs is vital to attain functional tissues. Herein we developed heparin functionalized collagen gels supported by 3D printed bioceramic scaffolds, as bone extracellular matrix (ECM)-mimetic matrices. These matrices were designed to enhance cell seeding efficiency of mesenchymal stem cells (MSCs) as well as improve their osteogenic differentiation through immobilized bone morphogenic protein 2 (BMP2) to be used for personalized bone regeneration.

METHODS

A 3D gel based on heparin-conjugated collagen matrix capable of immobilizing recombinant human bone morphogenic protein 2 (BMP2) was synthesized. Isolated dental pulp Mesenchymal stem cells (MSCs) were then encapsulated into the bone ECM microenvironment to efficiently and uniformly seed a bioactive ceramic-based scaffold fabricated using additive manufacturing technique. The designed 3D cell-laden constructs were comprehensively investigated trough in vitro assays and in vivo study.

RESULTS

In-depth rheological characterizations of heparin-conjugated collagen gel revealed that elasticity of the matrix is significantly improved compared with freely incorporated heparin. Investigation of the MSCs laden collagen-heparin hydrogels revealed their capability to provide spatiotemporal bioavailability of BMP2 while suppressing the matrix contraction over time. The in vivo histology and real-time polymerase chain reaction (qPCR) analysis showed that the designed construct supported the osteogenic differentiation of MSCs and induced the ectopic bone formation in rat model.

SIGNIFICANCE

The presented hybrid constructs combine bone ECM chemical cues with mechanical function providing an ideal 3D microenvironment for patient-specific bone tissue engineering and cell therapy applications. The implemented methodology in design of ECM-mimetic 3D matrix capable of immobilizing BMP2 to improve seeding efficiency of customized scaffolds can be exploited for other bioactive molecules.

Past, Present, and Future of Regeneration Therapy in Oral and Periodontal Tissue: A Review

Chronic periodontitis is the most common disease which induces oral tissue destruction. The goal of periodontal treatment is to reduce inflammation and regenerate the defects. As the structure of periodontium is composed of four types of different tissue (cementum, alveolar bone periodontal ligament, and gingiva), the regeneration should allow different cell proliferation in the separated spaces. Guided tissue regeneration (GTR) and guided bone regeneration (GBR) were introduced to prevent epithelial growth into the alveolar bone space. In the past, non-absorbable membranes with basic functions such as space maintenance were used with bone graft materials. Due to several limitations of the non-absorbable membranes, membranes of the second and third generation equipped with controlled absorbability, and a functional layer releasing growth factors or antimicrobials were introduced. Moreover, tissue engineering using biomaterials enabled faster and more stable tissue regeneration. The scaffold with three-dimensional structures manufactured by computer-aided design and manufacturing (CAD/CAM) showed high biocompatibility, and promoted cell infiltration and revascularization. In the future, using the cell sheath, pre-vascularizing and bioprinting techniques will be applied to the membrane to mimic the original tissue itself. The aim of the review was not only to understand the past and the present trends of GTR and GBR, but also to be used as a guide for a proper future of regeneration therapy in the oral region.

Synergistic effect of hyperbaric oxygen therapy with PTH [1-34] on calvarial bone graft in irradiated rat

OBJECTIVE

To determine the synergistic effect of parathyroid hormone (PTH) [1-34] in combination with hyperbaric oxygen (HBO) on bone graft in a rat calvarial bone defect model under impaired osteogenic conditions.

MATERIALS AND METHODS

Twenty-four rats were divided into three groups. Localized radiation with a single 12 Gy dose was administered to the calvaria. Four weeks after radiation, calvarial circular defects were created in the parietal bones. All defects were filled with biphasic calcium phosphate. After the bone graft, PTH [1-34] was injected subcutaneously, and HBO was administered. At 6 weeks after the bone graft, the rats were sacrificed, and specimens were harvested.

RESULTS

Histomorphometric evaluation showed that the percentage of new bone area was higher in the PTH and PTH/HBO groups than in the control group. The percent residual material area was decreased in the PTH/HBO group compared with the control group. The percentage blood vessel number was highest in the PTH group. Micro-CT evaluation showed that the new bone volume was highest in the PTH/HBO group. The residual material volume was lowest in the PTH/HBO group.

CONCLUSION

Within the limitations of this study, our data indicate that PTH combined with HBO may reverse radiation-induced impairment of bone healing.

Biomaterials, Current Strategies, and Novel Nano-Technological Approaches for Periodontal Regeneration

Periodontal diseases involve injuries to the supporting structures of the tooth and, if left untreated, can lead to the loss of the tooth. Regenerative periodontal therapies aim, ideally, at healing all the damaged periodontal tissues and represent a significant clinical and societal challenge for the current ageing population. This review provides a picture of the currently-used biomaterials for periodontal regeneration, including natural and synthetic polymers, bioceramics (e.g., calcium phosphates and bioactive glasses), and composites. Bioactive materials aim at promoting the regeneration of new healthy tissue. Polymers are often used as barrier materials in guided tissue regeneration strategies and are suitable both to exclude epithelial down-growth and to allow periodontal ligament and alveolar bone cells to repopulate the defect. The problems related to the barrier postoperative collapse can be solved by using a combination of polymeric membranes and grafting materials. Advantages and drawbacks associated with the incorporation of growth factors and nanomaterials in periodontal scaffolds are also discussed, along with the development of multifunctional and multilayer implants. Tissue-engineering strategies based on functionally-graded scaffolds are expected to play an ever-increasing role in the management of periodontal defects.

Fabrication, modeling and optimization of lyophilized advanced platelet rich fibrin in combination with collagen-chitosan as a guided bone regeneration membrane

In this study, lyophilized advanced platelet rich fibrin (A-PRF) was used in combination with collagen-chitosan membrane for the first time to combine advantages of both collagen and A-PRF membranes. Response surface methodology (RSM) was used to design the experimental condition and to correlate the effects of parameters, including chitosan/collagen (chit/col) weight ratio and A-PRF concentration on Young's modulus, mesenchymal stem cell (MSCs) viability and degradation rate of the membranes. Results showed that Young's modulus of the membranes was intensified by increasing chit/col weight ratio and decreasing A-PRF concentration from 3 to 8 MPa. Cell viability of MSCs was improved by both increasing chit/col weight ratio and A-PRF concentration. Moreover, as chit/col weight ratio increased from 0 to 4 and A-PRF concentration decreased from 5 to 0, degradation rate of the membranes decreased from 90 to 20% after four weeks incubation. Finally, based on Design Expert Software calculation for minimizing the degradation rate and maximizing both Young's modulus and cell viability, the values of chit/col weight ratio and A-PRF concentration were suggested to be 4 and 0.58 mg/ml, respectively. Alkaline phosphatase (ALP) activity analysis showed that the addition of A-PRF caused higher osteogenic differentiation.

Comparison of the effects of recombinant human bone morphogenetic protein-2 and -9 on bone formation in rat calvarial critical-size defects

OBJECTIVES

Among bone morphogenetic protein (BMP) family members, BMP-2 and BMP-9 have demonstrated potent osteoinductive potential. However, in vivo differences in their potential for bone regeneration remain unclear. The present study aimed to compare the effects of recombinant human (rh) BMP-2 and rhBMP-9 on bone formation in rat calvarial critical-size defects (CSD).

MATERIALS AND METHODS

Twenty-eight Wistar rats surgically received two calvarial defects bilaterally in each parietal bone. Defects (n = 56) were allocated into four groups: absorbable collagen sponge (ACS) alone, rhBMP-2 with ACS (rhBMP-2/ACS), rhBMP-9/ACS, or sham surgery (control), on the condition that the treatments of rhBMP-2/ACS and rhBMP-9/ACS, or the same treatments were not included in the same animal. Animals were sacrificed at 2 and 8 weeks post-surgery. The calvarial defects were analyzed for bone volume (BV) by micro-computed tomography and for percentages of defect closure (DC/DL), newly formed bone area (NBA/TA), bone marrow area (BMA/NBA), adipose tissue area (ATA/NBA), central bone height (CBH), and marginal bone height (MBH) by histomorphometric analysis.

RESULTS

The BV in the rhBMP-2/ACS group (5.44 ± 3.65 mm³, n = 7) was greater than the other groups at 2 weeks post-surgery, and the rhBMP-2/ACS and rhBMP-9/ACS groups (18.17 ± 2.51 and 16.30 ± 2.46 mm³, n = 7, respectively) demonstrated significantly greater amounts of BV compared with the control and ACS groups (6.02 ± 2.90 and 9.30 ± 2.75 mm³, n = 7, respectively) at 8 weeks post-surgery. The rhBMP-2/ACS and rhBMP-9/ACS groups significantly induced new bone formation compared to the control and ACS groups at 8 weeks post-surgery. However, there were no statistically significant differences found between the rhBMP-2/ACS and rhBMP-9/ACS groups in any of the histomorphometric parameters. The ATA/NBA in the rhBMP-2/ACS group (9.24 ± 3.72%, n = 7) was the highest among the treatment groups at 8 weeks post-surgery.

CONCLUSIONS

Within the limits of this study, it can be concluded that rhBMP-2/ACS induced a slight early increase in new bone formation at 2 weeks and that rhBMP-9/ACS provided comparable new bone formation to rhBMP-2/ACS with less adipose tissues after a healing period of 8 weeks in rat CSD.

CLINICAL RELEVANCE

RhBMP-9/ACS treatment provided new bone formation with less adipose tissues compared with rhBMP-2/ACS.

Electrospun polyurethane nanofiber scaffolds with ciprofloxacin oligomer versus free ciprofloxacin: Effect on drug release and cell attachment

An electrospun degradable polycarbonate urethane (PCNU) nanofiber scaffold loaded with antibiotic was investigated in terms of antibacterial efficacy and cell compatibility for potential use in gingival tissue engineering. Antimicrobial oligomer (AO), a compound which consists of two molecules of ciprofloxacin (CF) covalently bound via hydrolysable linkages to triethylene glycol (TEG), was incorporated via a one-step blend electrospinning process using a single solvent system at 7 and 15% w/w equivalent CF with respect to the PCNU. The oligomeric form of the drug was used to overcome the challenge of drug aggregation and burst release when antibiotics are incorporated as free drug. Electrospinning parameters were optimized to obtain scaffolds with similar alignment and fiber diameter to non-drug loaded fibers. AO that diffused from the fibers was hydrolysed to release CF slowly and in a linear manner over the duration of the study, whereas scaffolds with CF at the same concentration but in free form showed a burst release within 1h with no further release throughout the study duration. Human gingival fibroblast (HGF) adhesion and spreading was dependent on the concentration and form the CF was loaded (AO vs. free CF), which was attributed in part to differences in scaffold surface chemistry. Surface segregation of AO was quantified using surface-resolved X-ray photoelectron spectroscopy (XPS). These findings are encouraging and support further investigation for the use of AO as a means of attenuating the rapid release of drug loaded into nanofibers. The study also demonstrates through quantitative measures that drug additives have the potential to surface-locate without phase separating from the fibers, leading to fast dissolution and differential fibroblast cell attachment.

From restoration to regeneration: periodontal aging and opportunities for therapeutic intervention

With the march of time our bodies start to wear out: eyesight fades, skin loses its elasticity, teeth and bones become more brittle and injuries heal more slowly. These universal features of aging can be traced back to our stem cells. Aging has a profound effect on stem cells: DNA mutations naturally accumulate over time and our bodies have evolved highly specialized mechanisms to remove these damaged cells. Whilst obviously beneficial, this repair mechanism also reduces the pool of available stem cells and this, in turn, has a dramatic effect on tissue homeostasis and on our rate of healing. Simply put: fewer stem cells means a decline in tissue function and slower healing. Despite this seemingly intractable situation, research over the past decade now demonstrates that some of the effects of aging are reversible. Nobel prize-winning research demonstrates that old cells can become young again, and lessons learned from these experiments-in-a-dish are now being translated into human therapies. Scientists and clinicians around the world are identifying and characterizing methods to activate stem cells to reinvigorate the body's natural regenerative process. If this research in dental regenerative medicine pans out, the end result will be tissue homeostasis and healing back to the levels we appreciated when we were young.

Recent advancements in regenerative dentistry: A review

Although human mouth benefits from remarkable mechanical properties, it is very susceptible to traumatic damages, exposure to microbial attacks, and congenital maladies. Since the human dentition plays a crucial role in mastication, phonation and esthetics, finding promising and more efficient strategies to reestablish its functionality in the event of disruption has been important. Dating back to antiquity, conventional dentistry has been offering evacuation, restoration, and replacement of the diseased dental tissue. However, due to the limited ability and short lifespan of traditional restorative solutions, scientists have taken advantage of current advancements in medicine to create better solutions for the oral health field and have coined it "regenerative dentistry." This new field takes advantage of the recent innovations in stem cell research, cellular and molecular biology, tissue engineering, and materials science etc. In this review, the recently known resources and approaches used for regeneration of dental and oral tissues were evaluated using the databases of Scopus and Web of Science. Scientists have used a wide range of biomaterials and scaffolds (artificial and natural), genes (with viral and non-viral vectors), stem cells (isolated from deciduous teeth, dental pulp, periodontal ligament, adipose tissue, salivary glands, and dental follicle) and growth factors (used for stimulating cell differentiation) in order to apply tissue engineering approaches to dentistry. Although they have been successful in preclinical and clinical partial regeneration of dental tissues, whole-tooth engineering still seems to be far-fetched, unless certain shortcomings are addressed.

Emerging regenerative approaches for periodontal reconstruction: a systematic review from the AAP Regeneration Workshop

More than 30 years have passed since the first successful application of regenerative therapy for treatment of periodontal diseases. Despite being feasible, periodontal regeneration still faces numerous challenges, and complete restoration of structure and function of the diseased periodontium is often considered an unpredictable task. This review highlights developing basic science and technologies for potential application to achieve reconstruction of the periodontium. A comprehensive search of the electronic bibliographic database PubMed was conducted to identify different emerging therapeutic approaches reported to influence either biologic pathways and/or tissues involved in periodontal regeneration. Each citation was assessed based on its abstract, and the full text of potentially eligible reports was retrieved. Based on the review of the full papers, their suitability for inclusion in this report was determined. In principle, only reports from scientifically well-designed studies that presented preclinical in vivo (animal studies) or clinical (human studies) evidence for successful periodontal regeneration were included. Hence, in vitro studies, namely those conducted in laboratories without any live animals, were excluded. In case of especially recent and relevant reviews with a narrow focus on specific regenerative approaches, they were identified as such, and thereby the option of referring to them to summarize the status of a specific approach, in addition to or instead of listing each separately, was preserved. Admittedly, the presence of subjectivity in the selection of studies to include in this overview cannot be excluded. However, it is believed that the contemporary approaches described in this review collectively represent the current efforts that have reported preclinical or clinical methods to successfully enhance regeneration of the periodontium. Today's challenges facing periodontal regenerative therapy continue to stimulate important research and clinical development, which, in turn, shapes the current concept of periodontal tissue engineering. Emerging technologies--such as stem cell therapy, bone anabolic agents, genetic approaches, and nanomaterials--also offer unique opportunities to enhance the predictability of current regenerative surgical approaches and inspire development of novel treatment strategies.

Recombinant human bone morphogenetic protein-9 potently induces osteogenic differentiation of human periodontal ligament fibroblasts

To accomplish effective periodontal regeneration for periodontal defects, several regenerative methods using growth and differentiation factors, including bone morphogenetic proteins (BMPs), have been developed. Bone morphogenetic protein-9 exhibits the most potent osteogenic activity of this growth factor family. However, it is unclear whether exogenous BMP-9 can induce osteogenic differentiation in human periodontal ligament (PDL) fibroblasts. Here, we examined the effects of recombinant human (rh) BMP-9 on osteoblastic differentiation in human PDL fibroblasts in vitro, compared with rhBMP-2. Recombinant human BMP-9 potently induced alkaline phosphatase (ALP) activity, mineralization, and increased expression of runt-related transcription factor-2/core binding factor alpha 1 (RUNX2/CBFA1), osterix, inhibitor of DNA binding/differentiation-1 (ID1), osteopontin, and bone sialoprotein genes, compared with rhBMP-2. The levels of rhBMP-9-induced osterix and ALP mRNA were significantly reduced in activin receptor-like kinase-1 and -2 small interfering RNA (siRNA)-transfected human PDL fibroblasts. Recombinant human BMP-9-induced ALP activity was not inhibited by noggin, in contrast to rhBMP-2 induced ALP activity, which was. Phosphorylation of SMAD1/5/8 in human PDL fibroblasts was induced by addition of rhBMP-9. Recombinant human BMP-9-induced ALP activity was suppressed by SB203580, SP600125, and U0126, which are inhibitors of p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase 1/2 (ERK1/2), respectively. Our data suggest that rhBMP-9 is a potent inducer of the differentiation of human PDL fibroblasts into osteoblast-like cells and that this may be mediated by the SMAD and mitogen-activated protein kinase (p38, ERK1/2, and JNK) pathways.

Characterization of human periodontal ligament cells cultured on three-dimensional biphasic calcium phosphate scaffolds in the presence and absence of L-ascorbic acid, dexamethasone and β-glycerophosphate in vitro

The aim of this study was to evaluate the effect of porous biphasic calcium phosphate (BCP) scaffolds on the proliferation and osteoblastic differentiation of human periodontal ligament cells (hPDLCs) in the presence and absence of osteogenic inducer (L-ascorbic acid, dexamethasone and β-glycerophosphate). The cell growth within the scaffolds in the absence of osteogenic inducers was studied by cell counting kit-8 (CCK-8) assay and scanning electron microscopy (SEM). Alkaline phosphatase (ALP) activity and osteoblastic differentiation markers of hPDLCs in BCP scaffolds were examined in the presence and absence of osteogenic inducers. The cell number of hPDLCs in the BCP scaffolds was less than that of hPDLCs cultured in microplates (control). SEM images showed that cells successfully adhered to the BCP scaffolds and spread amongst the pores; they also produced abundant extracellular cell matrix. In the presence and absence of osteogenic inducers, the ALP activity of hPDLCs within BCP scaffolds was suppressed in varying degrees at all time-points. In the absence of osteogenic inducers, hPDLCs in BCP scaffolds express significant higher levels of osteopontin (OPN) mRNA than the control, and there were no significant differences for Runx2 and osteocalcin (OCN) mRNA levels compared with those cultured in microplates. In the presence of osteogenic inducers, Runx2 expression levels were significantly higher than those in control. OPN and OCN mRNA levels were downregulated slightly. Three-dimensional porous BCP scaffolds are able to stimulate the osteoblastic differentiation of hPDLCs in the presence and absence of osteogenic inducer and may be capable of supporting hPDLC-mediated bone formation.

Stem cell origin differently affects bone tissue engineering strategies

Bone tissue engineering approaches are encouraging for the improvement of conventional bone grafting technique drawbacks. Thanks to their self-renewal and multi-lineage differentiation ability, stem cells are one of the major actors in tissue engineering approaches, and among these adult mesenchymal stem cells (MSCs) hold a great promise for regenerative medicine strategies. Bone marrow MSCs (BM-MSCs) are the first- identified and well-recognized stem cell population used in bone tissue engineering. Nevertheless, several factors hamper BM-MSC clinical application and subsequently, new stem cell sources have been investigated for these purposes. The fruitful selection and combination of tissue engineered scaffold, progenitor cells, and physiologic signaling molecules allowed the surgeon to reconstruct the missing natural tissue. On the basis of these considerations, we analyzed the capability of two different scaffolds, planned for osteochondral tissue regeneration, to modulate differentiation of adult stem cells of dissimilar local sources (i.e., periodontal ligament, maxillary periosteum) as well as adipose-derived stem cells (ASCs), in view of possible craniofacial tissue engineering strategies. We demonstrated that cells are differently committed toward the osteoblastic phenotype and therefore, taking into account their specific features, they could be intriguing cell sources in different stem cell-based bone/periodontal tissue regeneration approaches.

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.

Bone Replacement Materials and Techniques Used for Achieving Vertical Alveolar Bone Augmentation

Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used alone or in combination with natural or synthetic graft materials to achieve vertical alveolar bone augmentation. While continuously improving surgical techniques combined with the use of auto- or allografts provide the most predictable clinical outcomes, their success often depends on the status of recipient tissues. The morbidity associated with donor sites for auto-grafts makes these techniques less appealing to both patients and clinicians. New developments in material sciences offer a range of synthetic replacements for natural grafts to address the shortcoming of a second surgical site and relatively high resorption rates. This narrative review focuses on existing techniques, natural tissues and synthetic biomaterials commonly used to achieve vertical bone height gain in order to successfully restore edentulous ridges with implant-supported prostheses.

Tooth-derived stem cells: Update and perspectives

Tissue engineering is an emerging field of science that focuses on creating suitable conditions for the regeneration of tissues. The basic components for tissue engineering involve an interactive triad of scaffolds, signaling molecules, and cells. In this context, stem cells (SCs) present the characteristics of self-renewal and differentiation capacity, which make them promising candidates for tissue engineering. Although they present some common markers, such as cluster of differentiation (CD)105, CD146 and STRO-1, SCs derived from various tissues have different patterns in relation to proliferation, clonogenicity, and differentiation abilities in vitro and in vivo. Tooth-derived tissues have been proposed as an accessible source to obtain SCs with limited morbidity, and various tooth-derived SCs (TDSCs) have been isolated and characterized, such as dental pulp SCs, SCs from human exfoliated deciduous teeth, periodontal ligament SCs, dental follicle progenitor cells, SCs from apical papilla, and periodontal ligament of deciduous teeth SCs. However, heterogeneity among these populations has been observed, and the best method to select the most appropriate TDSCs for regeneration approaches has not yet been established. The objective of this review is to outline the current knowledge concerning the various types of TDSCs, and discuss the perspectives for their use in regenerative approaches.

Isolation, characterization and investigation of differentiation potential of human periodontal ligament cells and dental follicle progenitor cells and their response to BMP-7 in vitro

The aim of this study was to assess the factors, mechanisms and the differences between periodontal ligament (PDL) cells and denta l follicle (DF) progenitor cells towards the osteoblastic/cementoblastic differentiation and to investigate the effects of BMP-7 on developmental (DF) and mature tissue-derived (PDL) cells, respectively. Primary cell culture of PDL cells and DF progenitor cells was performed. Osteogenic differentiation was evaluated using von Kossa, Alizarin Red S and immuno-histo-chemistry staining of osteocalcin. Gene expression pattern was evaluated via real-time PCR. A series of CD surface marks were tested using flow cytometry and fluorescence-activated cell-sorting analysis was performed. Real-time RT-PCR demonstrated similar gene expression pattern of PDL cells and DF progenitor cells: the expression of OPN and OCN significantly was elevated when incubated with osteogenic components, Runx2 was unaffected, and Osteorix was hardly expressed whether in basic medium or induction medium. In addition, BMP-7 induced osteoblast/cementoblast differentiation of PDLSCs and DF progenitor cells in a dose- and time-dependent manner, as reflected by enhanced Runx2 and (OCN) mRNA transcript expression. BMP-7 triggers PDL cells and DF progenitor cells to differentiate towards an osteoblast/cementoblast phenotype.

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.