Effects of enamel matrix derivative on the proliferation and osteogenic differentiation of human gingival mesenchymal stem cells

CHIR99021-Treated Osteocytes with Wnt Activation in 3D-Printed Module Form an Osteogenic Microenvironment for Enhanced Osteogenesis and Vasculogenesis

Finding a bone implant that has high bioactivity that can safely drive stem cell differentiation and simulate a real in vivo microenvironment is a challenge for bone tissue engineering. Osteocytes significantly regulate bone cell fate, and Wnt-activated osteocytes can reversely regulate bone formation by regulating bone anabolism, which may improve the biological activity of bone implants. To achieve a safe application, we used the Wnt agonist CHIR99021 (C91) to treat MLO-Y4 for 24 h, in a co-culture with ST2 for 3 days after withdrawal. We found that the expression of Runx2 and Osx increased, promoted osteogenic differentiation, and inhibited adipogenic differentiation in the ST2 cells, and these effects were eliminated by the triptonide. Therefore, we hypothesized that C91-treated osteocytes form an osteogenic microenvironment (COOME). Subsequently, we constructed a bio-instructive 3D printing system to verify the function of COOME in 3D modules that mimic the in vivo environment. Within PCI3D, COOME increased the survival and proliferation rates to as high as 92% after 7 days and promoted ST2 cell differentiation and mineralization. Simultaneously, we found that the COOME-conditioned medium also had the same effects. Therefore, COOME promotes ST2 cell osteogenic differentiation both directly and indirectly. It also promotes HUVEC migration and tube formation, which can be explained by the high expression of Vegf. Altogether, these results indicate that COOME, combined with our independently developed 3D printing system, can overcome the poor cell survival and bioactivity of orthopedic implants and provide a new method for clinical bone defect repair.

Effects of CEM cement and emdogain on proliferation and differentiation of human stem cells from the apical papilla: a comparative in vitro study

OBJECTIVES

This study compared the effects of calcium-enriched mixture (CEM) cement, Emdogain (EMD), and their combination (CEM/Emdogain) on the differentiation and proliferation of stem cells from the apical papilla (SCAPs).

METHODS

In this in vitro, experimental study, SCAPs were isolated from two sound immature impacted third molars and cultured. After ensuring their stemness by detecting cell surface markers they were exposed to CEM cement, Emdogain, and CEM cement coated with Emdogain for 24 and 72 h. The control cells did not undergo any intervention. Cell viability [by methyl thiazolyl tetrazolium (MTT) assay], expression of odontogenic differentiation genes [by quantitative reverse-transcription polymerase chain reaction (qRT-PCR)], and alkaline phosphatase (ALP) activity (by ALP staining kit) were evaluated. Data were analyzed by one-way ANOVA, t-test, and Mann-Whitney test (α = 0.05).

RESULTS

Cell viability in the CEM cement and CEM/Emdogain groups decreased compared with the control group at 72 h (P < 0.05). Expression of dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), bone sialoprotein (BSP) genes, and ALP activity significantly increased in all three experimental groups compared with the control group at both 24 and 72 h. This increase was substantially more significant in CEM/Emdogain group (P > 0.05). The number of mineralized nodules significantly increased in all groups at 72 h, with a higher rate in the CEM/Emdogain group.

CONCLUSION

All biomaterials increased the differentiation of SCAPs, expression of odontogenic differentiation genes, and ALP activity, but CEM/Emdogain was considerably more effective for this purpose.

Efficacy of biologics for alveolar ridge preservation/reconstruction and implant site development: An American Academy of Periodontology best evidence systematic review

BACKGROUND

The use of biologics may be indicated for alveolar ridge preservation (ARP) and reconstruction (ARR), and implant site development (ISD). The present systematic review aimed to analyze the effect of autologous blood-derived products (ABPs), enamel matrix derivative (EMD), recombinant human platelet-derived growth factor-BB (rhPDGF-BB), and recombinant human bone morphogenetic protein-2 (rhBMP-2), on the outcomes of ARP/ARR and ISD therapy (i.e., alveolar ridge augmentation [ARA] and maxillary sinus floor augmentation [MSFA]).

METHODS

An electronic search for eligible articles published from January 2000 to October 2021 was conducted. Randomized clinical trials evaluating the efficacy of ABPs, EMD, rhBMP-2, and rhPDGF-BB for ARP/ARR and ISD were included according to pre-established eligibility criteria. Data on linear and volumetric dimensional changes, histomorphometric findings, and a variety of secondary outcomes (i.e., clinical, implant-related, digital imaging, safety, and patient-reported outcome measures [PROMs]) were extracted and critically analyzed. Risk of bias assessment of the selected investigations was also conducted.

RESULTS

A total of 39 articles were included and analyzed qualitatively. Due to the high level of heterogeneity across studies, quantitative analyses were not feasible. Most studies in the topic of ARP/ARR revealed that the use of biologics rendered similar results compared with conventional protocols. However, when juxtaposed to unassisted healing or socket filling using collagen sponges, the application of biologics did contribute to attenuate post-extraction alveolar ridge atrophy in most investigations. Additionally, histomorphometric outcomes were positively influenced by the application of biologics. The use of biologics in ARA interventions did not yield superior clinical or radiographic outcomes compared with control therapies. Nevertheless, ABPs enhanced new bone formation and reduced the likelihood of early wound dehiscence. The use of biologics in MSFA interventions did not translate into superior clinical or radiographic outcomes. It was observed, though, that the use of some biologics may promote bone formation during earlier stages of healing. Only four clinical investigations evaluated PROMs and reported a modest beneficial impact of the use of biologics on pain and swelling. No severe adverse events in association with the use of the biologics evaluated in this systematic review were noted.

CONCLUSIONS

Outcomes of therapy after post-extraction ARP/ARR and ARA in edentulous ridges were comparable among different therapeutic modalities evaluated in this systematic review. Nevertheless, the use of biologics (i.e., PRF, EMD, rhPDGF-BB, and rhBMP-2) in combination with a bone graft material generally results into superior histomorphometric outcomes and faster wound healing compared with control groups.

Calcium Phosphate Nanoclusters for the Repair of Tooth Enamel Erosion

The artificial repair of tooth enamel is still an urgent requirement because it has a complicated and well-arranged structure. Herein, calcium phosphate nanoclusters (CaP NCs) were synthesized, via a facile approach, for application in the repair of tooth enamel erosion. Structural and optical characterizations validated the successful preparation of spherical CaP NCs, with an average size of 2.1 ± 0.11 nm. By evaporating the ethanol and triethylamine (TEA) solvents, pure CaP was produced, which was further used to repair the tooth enamel. Simulated caries lesions were achieved via phosphoric acid etching to cause damage to enamel rods. After repair, the damaged enamel rods were directly covered with CaP. According to microhardness testing, after repair with CaP NCs, the hardness value of the tooth enamel with acid etching increased to a similar level to that of normal tooth enamel. The results of the microhardness test indicated that CaP NCs revealed great potential for repairing tooth enamel erosion. Our work demonstrates a promising potential for treating the early stage of tooth erosion with CaP NCs. Based on these findings, we believe that stable CaP NCs can be employed as a precursor for the tunable, effective repair of tooth enamel in the near future.

Enamel Matrix Derivative Enhances the Odontoblastic Differentiation of Dental Pulp Stem Cells via Activating MAPK Signaling Pathways

The odontoblastic differentiation of dental pulp stem cells (DPSCs) contributes to pulp-dentin regeneration. Enamel matrix derivative (EMD) is considered to be a critical epithelial signal to induce cell differentiation during odontogenesis and has been widely applied to clinical periodontal tissue regeneration. The purpose of this study was to explore the effect of EMD on DPSCs proliferation and odontoblastic differentiation, as well as the underlying mechanisms. We conducted in vitro and in vivo researches to get a comprehensive understanding of EMD. In vitro phase: cell proliferation was assessed by a cell counting kit-8 (CCK-8) assay; then, alkaline phosphatase (ALP) activity and staining, alizarin red staining, real-time RT-PCR, and western blot analysis were conducted to determine the odontoblastic potential and involvement of MAPK signaling pathways. In vivo phase: after ensuring the biocompatibility of VitroGel 3D-RGD via scanning electron microscopy (SEM), the hydrogel mixture was subcutaneously injected into nude mice followed by histological and immunohistochemical analyses. The results revealed that EMD did not interfere with DPSCs proliferation but promoted the odontoblastic differentiation of DPSCs in vitro and in vivo. Furthermore, blocking the MAPK pathways suppressed the EMD-enhanced differentiation of DPSCs. Finally, VitroGel 3D-RGD could well support the proliferation, differentiation, and regeneration of DPSCs. Overall, this study demonstrates that EMD enhances the odontoblastic differentiation of DPSCs through triggering MAPK signaling pathways. The findings provide a new insight into the mechanism by which EMD affects DPSCs differentiation and proposes EMD as a promising candidate for future stem cell therapy in endodontics.

Effect of biodentine coated with emdogain on proliferation and differentiation of human stem cells from the apical papilla

BACKGROUND

This study assessed the effect of Biodentine coated with Emdogain (Biodentine/Emdogain) on proliferation and differentiation of human stem cells from the apical papilla (SCAPs). METHODS AND RESULTS: In this in vitro, experimental study, SCAPs were isolated from two immature impacted third molars and cultured. After ensuring the stemness of the cells by assessing the cell surface markers, they were exposed to Biodentine, Emdogain, and Biodentine/Emdogain for 24 and 72 h. The control cells did not receive any intervention. Cell viability was evaluated by the methyl thiazolyl tetrazolium assay. Expression of odontogenic differentiation genes was analyzed by the quantitative reverse transcription polymerase chain reaction. Alkaline phosphatase (ALP) activity was quantified by the respective kit. Data were analyzed by one-way ANOVA, t-test, and Mann-Whitney test (α = 0.05). Cell viability did not change after 24 h of exposure to biomaterials. At 72 h, the viability of the cells exposed to Biodentine and Biodentine/Emdogain decreased compared with the control group. The expression of dentin sialophosphoprotein, dentin matrix protein 1, and bone sialoprotein genes, and ALP activity significantly increased in all three experimental groups, compared with the control group at both 24 and 72 h; this increase was significantly greater in Biodentine/Emdogain group. The number of mineralized nodules significantly increased in all groups after 72 h with a greater rate in Biodentine/Emdogain group.

CONCLUSIONS

All biomaterials increased the differentiation of SCAPs, expression of odontogenic genes, and ALP activity, but Biodentine/Emdogain was significantly more effective for this purpose.

Enamel matrix derivative (EMD) enhances the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs)

To investigate the EMD's capacity in BMSCs osteogenic differentiation. In vivo and in vitro, BMSCs were treated with EMD, scanning electron microscopy, and Alizarin Red staining were used to detect the changes in the osteogenic ability of BMSCs, and the proliferation ability of BMSCs was evaluated by CCK8. In addition, by adding xav939, a typical inhibitor of Wnt/β-catenin signaling pathway, the regulatory function of Wnt/β-catenin signaling was clarified. The results showed that EMD promote cell proliferation and 25 μg/ml EMD had the most significant effect. Cells inducing osteogenesis for 2 and 3 even 4 weeks, the cell staining is deeper in EMD treated group than that of the control (P < 0.05) by alizarin Red staining, suggesting more mineralization of BMSCs. In vivo implanting the titanium plate wrapped with 25 μg/ml EMD treated-BMSC film into nude mice for 8 weeks, more nodules were formed on the surface of the titanium plate than that the control (P < 0.05). HE showed that there is a little blue-violet immature bone-like tissue block. Besides, the expression of RUNX Family Transcription Factor 2 (Runx2), Osterix, Osteocalcin (OCN), collagen I (COLI), alkaline phosphatase (ALP) and β-catenin were inhibited in xav939 group (P < 0.05); Inversely, all were activated in EMD group (P < 0.05). In conclusion, EMD promoted the proliferation and osteogenic differentiation of BMSCs. EMD's function on BMSCs might be associated with the Wnt/β-catenin signaling pathway.

Cold Atmospheric Plasma Promotes Regeneration-Associated Cell Functions of Murine Cementoblasts In Vitro

The aim of the study was to examine the efficacy of cold atmospheric plasma (CAP) on the mineralization and cell proliferation of murine dental cementoblasts. Cells were treated with CAP and enamel matrix derivates (EMD). Gene expression of alkaline phosphatase (ALP), bone gamma-carboxyglutamate protein (BGLAP), periostin (POSTN), osteopontin (OPN), osterix (OSX), collagen type I alpha 1 chain (COL1A1), dentin matrix acidic phosphoprotein (DMP)1, RUNX family transcription factor (RUNX)2, and marker of proliferation Ki-67 (KI67) was quantified by real-time PCR. Protein expression was analyzed by immunocytochemistry and ELISA. ALP activity was determined by ALP assay. Von Kossa and alizarin red staining were used to display mineralization. Cell viability was analyzed by XTT assay, and morphological characterization was performed by DAPI/phalloidin staining. Cell migration was quantified with an established scratch assay. CAP and EMD upregulated both mRNA and protein synthesis of ALP, POSTN, and OPN. Additionally, DMP1 and COL1A1 were upregulated at both gene and protein levels. In addition to upregulated RUNX2 mRNA levels, treated cells mineralized more intensively. Moreover, CAP treatment resulted in an upregulation of KI67, higher cell viability, and improved cell migration. Our study shows that CAP appears to have stimulatory effects on regeneration-associated cell functions in cementoblasts.

2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside-stimulated dental pulp stem cells-derived conditioned medium enhances cell activity and anti-inflammation

Background/purpose

Dental pulp stem cells (DPSCs) contribute to the regeneration of various tissues and have superior proliferation, immune privilege, and anti-inflammation properties to other mesenchymal stem cells. 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) not only enhances the aforementioned properties of DPSCs but also promotes self-renewal and reprogramming-like ability. However, whether THSG enhances the aforementioned properties and abilities through direct or indirect interaction mechanisms remains unclear. To address this knowledge gap, we examined the effects of THSG-stimulated DPSC-derived conditioned medium (THSG-CM) on the activity and anti-inflammation properties of cells.

Materials and methods

DPSCs were treated with various concentrations of THSG to produce THSG-CM, which was then collected, analyzed, and lyophilized. A cytokine profiling antibody assay was used to compare protein components between THSG-treated and nontreated CM. Human skin fibroblasts (HSFs) and human gingival fibroblasts (HGFs) were used to investigate the effect of THSG-CM on cell proliferation, anti-inflammation, and wound healing abilities; for this investigation, MTS assay, quantitative real-time PCR analysis, and 2-well silicone inserts wound model were conducted.

Results

We observed that THSG enhanced the secretion of growth- and immune-associated proteins in THSG-CM and increased the proliferation of HSFs and HGFs. Furthermore, THSG-CM significantly attenuated lipopolysaccharide-stimulated mRNA levels of cytokines in both cells and improved wound healing abilities.

Conclusion

We conclude that THSG-CM had more beneficial effects on cell activity and anti-inflammation in the HSFs and HGFs than DPSC-derived CM. DPSC-derived CM can be developed into a cell-free regenerative strategy in the future, and its therapeutic efficacy may be improved by THSG-CM.

Stemness Potency of Human Gingival Cells-Application in Anticancer Therapies and Clinical Trials

Gingivae, as the part of periodontium, are involved in tooth support and possess the ability to heal rapidly, without scar formation. Recently, dental tissues have been identified as a potential source of mesenchymal stem cells (MSCs) and several populations of MSCs were isolated from the orofacial region, including gingival mesenchymal stem cells (GMSCs). GMSCs exhibit robust immunomodulatory and differentiation potential and are easily obtainable, which make them promising candidates for cellular therapies. Apart from being tested for application in immunologic- and inflammatory-related disorders and various tissue regeneration, GMSCs promise to be a valuable tool in cancer treatment, especially in tongue squamous cell carcinoma (TSCC) with the use of targeted therapy, since GMSCs are able to selectively migrate towards the cancerous cells both in vitro and in vivo. In addition to their ability to uptake and release anti-neoplastic drugs, GMSCs may be transduced with apoptosis-inducing factors and used for cancer growth inhibition. Moreover, GMSCs, as most mammalian cells, secrete exosomes, which are a subset of extracellular vesicles with a diameter of 40–160 nm, containing DNA, RNA, lipids, metabolites, and proteins. Such GMSCs-derived exosomes may be useful therapeutic tool in cell-free therapy, as well as their culture medium. GMSCs exhibit molecular and stem-cell properties that make them well suited in preclinical and clinical studies.

Comparative evaluation of low-level laser therapy on proliferation of long-term cryopreserved human dental pulp cells isolated from deciduous and permanent teeth

The aim of the current study was to evaluate the proliferative effect of low-level laser therapy on long-term cryopreserved dental pulp stem cells (DPSC_S) and stem cells from human exfoliated deciduous teeth (SHED_S). The DPSC_S and SHED_S were divided into 2 main groups according to gallium aluminum arsenide (GaAIAs) diode laser irradiation densities as 5 J/cm² and 7 J/cm². Each main group was further divided into 4 groups according to laser irradiation periods as 0, 24, 48, 72 h groups. During the incubation periods, cells received laser irradiation in every 24 h according to their groups and were put into incubator after irradiation. Cell groups that were not subjected to laser irradiation were served as control groups. Viabilities of cells were determined via MTT assay at the end of all incubation periods, and data were statistically analyzed. Laser irradiation demonstrated significant effects on proliferation rate of DPSCs and SHEDs in comparison with control. Intragroup comparison data of DPSC_S revealed that repetitive laser irradiation for long term (72 h) increased the cellular viability significantly in comparison with all other treatment groups; however, no significant differences were found when energy densities were compared within each time interval, except for 48 h group at which irradiation with 7 J/cm² provided significantly higher cell viability rates of SHED_S. DPSCs showed significantly higher cellular viability than SHEDs only for the 7 J/cm² energy density in 72 h. Longer term (72 h) repetitive laser irradiation with energy densities of 5 and 7 J/cm² (wavelength of 980 nm) may be recommended to induce the proliferative effect on long-term cryopreserved DPSC_S and SHED_S.

Fibroblast growth factor-4 maintains cellular viability while enhancing osteogenic differentiation of stem cell spheroids in part by regulating RUNX2 and BGLAP expression

Fibroblast growth factors (FGFs) are growth factors that were initially identified as proteins that stimulate fibroblast proliferation. The aim of the present study was to examine the effects of FGF-4 on the morphology, cellular viability and osteogenic differentiation of stem cell spheroids. Stem cell spheroids were generated using concave microwells in the presence of FGF-4 at concentrations of 0, 50, 100 and 200 ng/ml. Cellular viability was qualitatively assessed by a fluorometric live/dead assay using a microscope and quantitatively determined by using Cell Counting Kit-8. Furthermore, alkaline phosphatase activity and calcium deposition were determined to assess osteogenic differentiation. Reverse transcription-quantitative PCR (RT-qPCR) was performed to evaluate the mRNA expression levels of Runt-related transcription factor 2 (RUNX2) and bone γ-carboxyglutamate protein (BGLAP). Spheroidal shapes were achieved in the microwells on day 1 and a significant increase in the spheroid diameter was observed in the 200 ng/ml FGF-4 group compared with the control group on day 1 (P<0.05). The results regarding viability using Cell Counting Kit-8 in the presence of FGF-4 at 50, 100 and 200 ng/ml at day 1 were 98.0±2.5, 106.2±17.6 and 99.5±6.0%, respectively, when normalized to the control group (P>0.05). Furthermore, the alkaline phosphatase activity was significantly elevated in the 200 ng/ml group, when compared with the control group. The RT-qPCR results demonstrated that the mRNA expression levels of RUNX2 and BGLAP were significantly increased at 200 ng/ml. Therefore, the present results suggested that the application of FGF-4 maintained cellular viability while enhancing the osteogenic differentiation of stem cell spheroids, at least partially by regulating RUNX2 and BGLAP expression levels.

Therapeutic Functions of Stem Cells from Oral Cavity: An Update

Adult stem cells have been developed as therapeutics for tissue regeneration and immune regulation due to their self-renewing, differentiating, and paracrine functions. Recently, a variety of adult stem cells from the oral cavity have been discovered, and these dental stem cells mostly exhibit the characteristics of mesenchymal stem cells (MSCs). Dental MSCs can be applied for the replacement of dental and oral tissues against various tissue-damaging conditions including dental caries, periodontitis, and oral cancers, as well as for systemic regulation of excessive inflammation in immune disorders, such as autoimmune diseases and hypersensitivity. Therefore, in this review, we summarized and updated the types of dental stem cells and their functions to exert therapeutic efficacy against diseases.

Effect of Flap Design for Enamel Matrix Derivative Application in Intraosseous Defects

Objective:

To systematically review the literature addressing the focused question: What is the effectiveness of different surgical and nonsurgical procedures combined with enamel matrix derivative (EMD) on clinical, radiographic, and patient-centered outcomes in intraosseous defects?

Methods:

Electronic (Medline, Scopus, and Cochrane databases) and hand literature searches were performed for studies including at least 1 treatment arm where EMD had been applied according to 1 of the following procedures: modified Widman flap; papilla preservation variants (PPVs), including papilla preservation technique, modified papilla preservation technique, and simplified papilla preservation technique; minimally invasive variants, including minimally invasive surgical approach and minimally invasive surgical technique; single-flap variants (SFVs), including single-flap approach and modified minimally invasive surgical technique; or nonsurgical application (flapless approach). Data from 42 selected articles were used to perform a network meta-analysis, and a hierarchy of surgical and nonsurgical applications of EMD was built separately for EMD and EMD + graft based on 6- to 12-mo clinical and radiographic outcomes.

Results:

Among surgical approaches, EMD was associated with best regenerative outcomes when applied through SFVs, with a mean clinical attachment level gain of 3.93 mm and a reduction in the intrabony component of the defect of 3.35 mm. For EMD + graft, limited differences in regenerative outcomes were observed among surgical procedures. PPVs were associated with the highest residual probing depth for EMD (4.08 mm) and EMD + graft (4.32 mm).

Conclusions:

In the treatment of periodontal intraosseous defects, 1) SFVs appear to optimize the regenerative outcomes of EMD; 2) substantial regenerative outcomes can be obtained with SFVs and conservative double flaps (i.e., PPVs and minimally invasive variants) when EMD is combined with a graft; and 3) residual probing depth was higher following PPVs for EMD and EMD + graft.

Knowledge Transfer Statement:

The results of the present systematic review and meta-analysis can be used by clinicians to identify the most effective surgical or nonsurgical procedure to treat an intraosseous defect with EMD or EMD + graft. The main findings indicate that when EMD application is indicated, surgical access based on a single flap seems the most appropriate to optimize clinical outcomes. The application of EMD + graft can be effectively combined with single flaps and conservative double flaps.

The Potential of Different Origin Stem Cells in Modulating Oral Bone Regeneration Processes

Tissue engineering has gained much momentum since the implementation of stem cell isolation and manipulation for regenerative purposes. Despite significant technical improvements, researchers still have to decide which strategy (which type of stem cell) is the most suitable for their specific purpose. Therefore, this short review discusses the advantages and disadvantages of the three main categories of stem cells: embryonic stem cells, mesenchymal stem cells and induced pluripotent stem cells in the context of bone regeneration for dentistry-associated conditions. Importantly, when deciding upon the right strategy, the selection needs to be made in concordance with the morbidity and the life-threatening level of the condition in discussion. Therefore, even when a specific type of stem cell holds several advantages over others, their availability, invasiveness of the collection method and ethical standards become deciding parameters.

Split-mouth evaluation of connective tissue graft with or without enamel matrix derivative for the treatment of isolated gingival recession defects in dogs

OBJECTIVES

The potential additive effect of an enamel matrix derivative (EMD) to a subepithelial connective tissue graft (CTG) for recession coverage is still controversially discussed. Therefore, the aim of this study was to histologically evaluate the healing of gingival recessions treated with coronally advanced flap (CAF) and CTG with or without EMD in dogs.

MATERIALS AND METHODS

Gingival recession defects (5 mm wide and 7 mm deep) were surgically created on the labial side of bilateral maxillary canines in 7 dogs. After 8 weeks of plaque accumulation and subsequent 2 weeks of chemical plaque control, the 14 chronic defects were randomized to receive either CAF with CTG (CAF/CTG) or CAF with CTG and EMD (CAF/CTG/EMD). The animals were sacrificed 10 weeks after reconstructive surgery for histologic evaluation.

RESULTS

Treatment with CAF/CTG/EMD demonstrated statistically significantly better results in terms of probing pocket depth reduction (P < 0.05) and clinical attachment level gain (P < 0.001). The length of the epithelium was statistically significantly shorter in the CAF/CTG/EMD group than in the CAF/CTG group (1.00 ± 0.75 mm vs. 2.38 ± 1.48 mm, respectively, P < 0.01). Cementum formation was statistically significantly greater in the CAF/CTG/EMD group than following treatment with the CAF/CTG group (3.20 ± 0.89 mm vs. 1.88 ± 1.58 mm, respectively, P < 0.01). The CAF/CTG/EMD group showed statistically significantly greater complete periodontal regeneration (i.e., new cementum, new periodontal ligament, and new bone) than treatment with CAF/CTG (0.54 ± 0.73 mm vs. 0.07 ± 0.27 mm, respectively, P < 0.05).

CONCLUSION

Within their limits, the present findings indicate that the additional use of EMD in conjunction with CAF + CTG favors periodontal regeneration in gingival recession defects.

CLINICAL RELEVANCE

The present findings support the use of EMD combined with CTG and CAF for promoting periodontal regeneration in isolated gingival recession defects.

A comprehensive study on donor-matched comparisons of three types of mesenchymal stem cells-containing cells from human dental tissue

BACKGROUND AND OBJECTIVE

Mesenchymal stem cells (MSCs) have been widely used in tissue engineering, such as for regenerating the supporting structures of teeth destroyed by periodontal diseases. In recent decades, dental tissue-derived MSCs have drawn much attention owing to their accessibility, plasticity and applicability. Dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs) and gingival MSCs (GMSCs) are the most readily available MSCs among all types of dental MSCs. The purpose of this study was to comprehensively compare the characteristics of MSCs from dental pulp (DP), periodontal ligament (PDL) and gingiva (G) in vitro and thus provide insight into optimizing the performance of cells and seed cell selection strategies for tissue regeneration.

MATERIALS AND METHODS

In this study, patient-matched (n = 5) cells derived from DP, PDL and G which, respectively, contained DPSCs, PDLSCs and GMSCs were evaluated using multiple methods in terms of their proliferation, senescence, apoptosis, multilineage differentiation and stemness maintenance after long-term passage.

RESULTS

Mesenchymal stem cells-containing cells from G (MSCs/GCs) showed superior proliferation capability, whereas patient-matched MSCs-containing cells from PDL (MSCs/PDLCs) exhibited excellent osteogenic and adipogenic differentiation ability; MSCs-containing cells from DP (MSCs/DPCs) achieved mediocre results in both aspects. In addition, MSCs/GCs were the least susceptible to senescence, while MSCs/PDLCs were the most prone to ageing. Furthermore, the biological properties of these three types of cells were all affected after long-term in vitro culture.

CONCLUSION

These three types of dental MSCs showed different biological characteristics. MSCs/PDLCs are the best candidate cells for bone regeneration, but the application of MSCs/PDLCs might be limited to certain number of passages. Improving the differentiation of MSCs/GCs remains the key issue regarding their application in tissue engineering.

Stem cell-like populations and immunoregulatory molecules in periodontal granulation tissue

BACKGROUND AND OBJECTIVES

Determine the presence of mesenchymal stem cells (MSCs) in healthy periodontal tissue and periodontal granulation tissue (GT) and explore associations between immuno-regulatory molecules and selected subgingival microorganisms.

MATERIAL AND METHODS

Mesenchymal stem cells were isolated, propagated and characterised by flow cytometry from a region of healthy gingival tissue and inflamed GT of 10 systemically healthy non-smokers with chronic periodontitis. Tissue levels of immunoregulatory molecules were determined by qPCR and Gingival Crevicular Fluid (GCF) levels by ELISA. Subgingival plaque levels of periodontal pathogens were determined by qPCR RESULTS: Cells with MSC-properties were isolated from both inflamed GT and healthy gingival (G) tissue. A pro-inflammatory process predominated in GT which was partly reflected in GCF and putative periodontal pathogens were higher at diseased sites. However, there was no significant difference in surface levels of mesenchymal (CD90, CD73, CD146, CD271, STRO-1), endothelial (CD105, CD106), hematopoietic (CD34, CD45) and embryonic (SSEA-4) stem cell markers between MSCs isolated from GT and G tissue.

CONCLUSION

Periodontal lesions, albeit inflamed, retain healing potential as inferred by the presence of MSC-like cells with similar immunophenotypic characteristics to those found in healthy periodontal tissue. Therefore, there might be merits for healing in preserving sufficient GT in-situ during periodontal surgery.

Bone marrow-derived mesenchymal stem cells ameliorate parotid injury in ovariectomized rats

BACKGROUND AIMS

Parotid hypofunction causes life-disrupting effects, and there are no effective medications for xerostomia. We hypothesized that mesenchymal stem cells (MSCs) have repairing effects on parotid glands of ovariectomized (OVX) rats.

METHODS

Forty-five adult female rats were divided into three equal groups: group I (Control group), group II (OVX-group) and group III (OVX rats that received MSCs at 4 and 8 weeks post-ovariectomy). At 12 weeks post-ovariectomy, histological (Masson's trichrome and periodic acid-Schiff with alcian blue stains), immunohistochemical (caspase-3 and CD44) and morphometric studies and salivary flow rate and saliva pH determination were carried out.

RESULTS

Histologically, the OVX group displayed numerous irregular vacuolated acini, thickened septa with marked cellular infiltration and vascular congestion. Degenerated organelles and few or irregular secretory granules with a different density were observed. Caspase-3-positive cells were highly expressed. MSC-treated glands exhibited a considerable degree of preservation of glandular architecture with numerous CD44-expressing and few caspase-3-expressing cells. Significant decrease of the salivary flow rate in the OVX group was detected, which reverted to normal levels in group III.

CONCLUSIONS

MSCs ameliorated the damaging effects of ovariectomy on the parotid glands.

In vitro models for evaluation of periodontal wound healing/regeneration

Periodontal wound healing and regeneration are highly complex processes, involving cells, matrices, molecules and genes that must be properly choreographed and orchestrated. As we attempt to understand and influence these clinical entities, we need experimental models to mimic the various aspects of human wound healing and regeneration. In vivo animal models that simulate clinical situations of humans can be costly and cumbersome. In vitro models have been devised to dissect wound healing/regeneration processes into discrete, analyzable steps. For soft tissue (e.g. gingival) healing, in vitro models range from simple culture of cells grown in monolayers and exposed to biological modulators or physical effectors and materials, to models in which cells are 'injured' by scraping and subsequently the 'wound' is filled with new or migrating cells, to three-dimensional models of epithelial-mesenchymal recombination or tissue explants. The cells employed are gingival keratinocytes, fibroblasts or endothelial cells, and their proliferation, migration, attachment, differentiation, survival, gene expression, matrix production or capillary formation are measured. Studies of periodontal regeneration also include periodontal ligament fibroblasts or progenitors, osteoblasts or osteoprogenitors, and cementoblasts. Regeneration models measure cellular proliferation, attachment and migration, as well as gene expression, transfer and differentiation into a mineralizing phenotype and biomineralization. Only by integrating data from models on all levels (i.e. a single cell to the whole organism) can various critical aspects of periodontal wound healing/regeneration be fully evaluated.

Mesenchymal Stem Cells Improve Healing of Diabetic Foot Ulcer

Mesenchymal stem cells (MSCs), an ideal cell source for regenerative therapy with no ethical issues, play an important role in diabetic foot ulcer (DFU). Growing evidence has demonstrated that MSCs transplantation can accelerate wound closure, ameliorate clinical parameters, and avoid amputation. In this review, we clarify the mechanism of preclinical studies, as well as safety and efficacy of clinical trials in the treatment of DFU. Bone marrow-derived mesenchymal stem cells (BM-MSCs), compared with MSCs derived from other tissues, may be a suitable cell type that can provide easy, effective, and cost-efficient transplantation to treat DFU and protect patients from amputation.

Effect of low-level laser irradiation on proliferation of human dental mesenchymal stem cells; a systemic review

CONTEXT

Identification of factors that enhance the proliferation of human dental mesenchymal stem cells (DMSCs) is vital to facilitate tissue regeneration. The role of low-level laser irradiation (LLLI) on proliferation of human DMSCs has not been well established.

OBJECTIVE

To assess the effect of LLLI on proliferation of human DMSCs when applied in-vitro.

DATA SOURCES

Electronic search of literature was conducted (2000-2016) on PubMed, Web of Science, and Scopus databases. Search terms included low-level light therapy, low-level laser irradiation, low-level light irradiation, LLLT, humans, adolescent, adult, cells, cultured, periodontal ligament, dental pulp, stem cells, dental pulp stem cells, mesenchymal stem cells, periodontal ligament stem cell, deciduous teeth, cell proliferation, adult stem cells, radiation, and proliferation.

RESULTS

The literature search identified 165 studies with 6 being eligible for inclusion; all used diode lasers; 5 studies used InGaAIP diode lasers; 4 used 660nm, and the other two applied 810nm or 980nm wavelength LLLI. The distance between the DMSCs and the laser spot ranged between 0.5mm to 2mm. The time intervals of cell proliferation analysis ranged from 0h to 7days after LLLI. After 660nm LLLI, an increase in the DMSC's proliferation was reported [DMSCs extracted from dental pulp of deciduous teeth (two irradiations, 3J/cm(2), 20mW was more effective than 40mW), adult teeth (two irradiations, 0.5 and 1.0J/cm(2), 30mW), and from adult periodontal ligament (two irradiations, 1.0J/cm(2) was more effective than 0.5J/cm(2), 30mW)]. Similarly, an increase in the proliferation of DMSCs extracted from dental pulp of adult teeth was reported after 810nm LLLI (7 irradiations in 7days, 0.1 and 0.2J/cm(2), 60mW) or 980nm LLLI (single irradiation, 3J/cm(2), 100mW). However, 660nm LLLI in one study did not increase the proliferation of DMSCs (single irradiation, energy densities of 0.05, 0.30, 7, and 42J/cm(2), 28mW).

CONCLUSION

There is limited evidence that in-vitro LLLI (660/810/980nm, with energy densities of 0.1-3J/cm(2)) increases the proliferation of DMSCs. Considering the limited evidence and their method heterogeneity it is difficult to reach a firm conclusion. Further research is necessary to identify the optimal characteristics of the LLLI setting (wave length, energy density, power output, frequency/duration of irradiations, distance between the cells and the laser spot/probe) to increase proliferation of DMSCs, and assess its impact on replicative senescence, as well as determine feasibility of the use in the clinical setting.

Therapeutic effects of human gingiva-derived mesenchymal stromal cells on murine contact hypersensitivity via prostaglandin E2-EP3 signaling

BACKGROUND

The immunomodulatory and anti-inflammatory functions of human gingiva-derived mesenchymal stromal cells (GMSCs) have been demonstrated in contact hypersensitivity (CHS) models; however, their therapeutic effect during the late phase of CHS has been poor.

METHODS

The murine CHS model was induced by applying oxazolone to the ears of mice. Mesenchymal stromal cells were applied via two methods (intravenous or local injection) at three time points: 1 day before sensitization, 1 day before challenge, or 1 h after challenge. Prostaglandin E2 (PGE2) and sulprostone were administered subcutaneously 1 h after challenge.

RESULTS

The application of GMSCs, bone marrow mesenchymal stem cells, and adipose-derived stem cells all effectively suppressed CHS; however, GMSC treatment exhibited the greatest efficacy. Local injection of GMSCs led to a more marked attenuation of CHS compared with intravenous injection, especially during the late phase of CHS, and this manifested as decreased infiltration of inflammatory cells, suppression of the levels of various proinflammatory cytokines, reconstruction of the disrupted Th1/Th2 balance, and upregulation of regulatory T cells in the allergen contact areas. Pretreatment with indomethacin significantly abrogated the GMSC-mediated immunosuppressive effects, while PGE2 application reversed the effects of indomethacin pretreatment of GMSCs. Moreover, GMSC administration promoted the expression of EP3, a prostaglandin E receptor, and the application of sulprostone, an agonist of EP3, significantly attenuated CHS to a similar degree as that of GMSC administration.

CONCLUSIONS

GMSCs have reproducible and powerful immunomodulatory functions. Local injection of GMSCs is the superior mode for therapeutic application. PGE2-EP3 signaling plays an important role in the immunomodulatory functions of GMSCs in murine CHS.

Effectiveness of enamel matrix derivative on the clinical and microbiological outcomes following surgical regenerative treatment of peri-implantitis. A randomized controlled trial

OBJECTIVE

This randomized clinical trial aimed at comparing radiological, clinical and microbial effects of surgical treatment of peri-implantitis alone or in combination with enamel matrix derivative (EMD).

METHODS

Twenty-six subjects were treated with open flap debridement and decontamination of the implant surfaces with gauze and saline preceding adjunctive EMD or no EMD. Bone level (BL) change was primary outcome and secondary outcomes were changes in pocket depth (PD), plaque, pus, bleeding and the microbiota of the peri-implant biofilm analyzed by the Human Oral Microbe Identification Microarray over a time period of 12 months.

RESULTS

In multivariate modelling, increased marginal BL at implant site was significantly associated with EMD, the number of osseous walls in the peri-implant bone defect and a Gram+/aerobic microbial flora, whereas reduced BL was associated with a Gram-/anaerobic microbial flora and presence of bleeding and pus, with a cross-validated predictive capacity (Q(2) ) of 36.4%. Similar, but statistically non-significant, trends were seen for BL, PD, plaque, pus and bleeding in univariate analysis.

CONCLUSION

Adjunctive EMD to surgical treatment of peri-implantitis was associated with prevalence of Gram+/aerobic bacteria during the follow-up period and increased marginal BL 12 months after treatment.

Gingival Mesenchymal Stem/Progenitor Cells: A Unique Tissue Engineering Gem

The human gingiva, characterized by its outstanding scarless wound healing properties, is a unique tissue and a pivotal component of the periodontal apparatus, investing and surrounding the teeth in their sockets in the alveolar bone. In the last years gingival mesenchymal stem/progenitor cells (G-MSCs), with promising regenerative and immunomodulatory properties, have been isolated and characterized from the gingival lamina propria. These cells, in contrast to other mesenchymal stem/progenitor cell sources, are abundant, readily accessible, and easily obtainable via minimally invasive cell isolation techniques. The present review summarizes the current scientific evidence on G-MSCs' isolation, their characterization, the investigated subpopulations, the generated induced pluripotent stem cells- (iPSC-) like G-MSCs, their regenerative properties, and current approaches for G-MSCs' delivery. The review further demonstrates their immunomodulatory properties, the transplantation preconditioning attempts via multiple biomolecules to enhance their attributes, and the experimental therapeutic applications conducted to treat multiple diseases in experimental animal models in vivo. G-MSCs show remarkable tissue reparative/regenerative potential, noteworthy immunomodulatory properties, and primary experimental therapeutic applications of G-MSCs are very promising, pointing at future biologically based therapeutic techniques, being potentially superior to conventional clinical treatment modalities.

Biologic Agents for Periodontal Regeneration and Implant Site Development

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

Enamel matrix derivative improves gingival fibroblast cell behavior cultured on titanium surfaces

OBJECTIVE

Although an extensive amount of research has demonstrated the positive effects of an enamel matrix derivative (EMD) on soft tissue wound healing around intrabony defects, little information is available describing its effect on peri-implant soft tissues, an area that has recently gained tremendous awareness due to the increasing prevalence of peri-implantitis. The aim of the present study was to assess the role of EMD when gingival fibroblasts were cultured on titanium surface with different surface topographies.

METHODS

Human primary gingival fibroblasts were cultured on pickled (PT) and sand-blasted with large grit followed by acid etching (SLA) surfaces and assessed for cell adhesion at 2, 4, and 8 h, cell morphology at 2, 4, 8, and 24 h as well as cell proliferation at 1, 3, and 5 days post-seeding. Furthermore, genes encoding collagen 1a1, vascular endothelial growth factor-A (VEGF-A), and fibronectin were assessed by real-time PCR. Human gingival fibroblasts were also quantified for their ability to synthesize a collagen matrix on the various titanium surfaces with and without EMD by immunofluorescence staining.

RESULTS

The results from the present study demonstrate that EMD significantly increased cell spreading at 2, 4, 8, and 24 h on PT surfaces and 4, 8, and 24 h on SLA surfaces. Furthermore, proliferation at 5 days on PT surfaces and 3 and 5 days on SLA surfaces was also increased for groups containing EMD. Real-time PCR results demonstrated that the culture of gingival fibroblasts with EMD significantly increased extracellular matrix synthesis of collagen 1 as well as improved mRNA levels of VEGF-A and fibronectin. Collagen1 immuno-fluorescent staining revealed a significantly higher area of staining for cells seeded on PT + EMD at 7 and 14 days and 14 days for SLA + EMD when compared to control samples.

CONCLUSION

The results from the present study favor the use of EMD for colonization of gingival fibroblasts on titanium surfaces by increasing cell growth, spreading, and synthesis of an extracellular matrix. The improvements were primarily irrespective of surface topography. Future animal and human studies are necessary to fully characterize the beneficial effects of incorporating EMD during soft tissue regeneration of implant protocols.

CLINICAL RELEVANCE

The use of EMD may speed up the quality of soft tissue integration around dental implants by facilitating gingival cell attachment, proliferation, and matrix synthesis of collagen 1.

Stem cell therapy: A novel treatment approach for oral mucosal lesions

Stem cells have enormous potential to alleviate sufferings of many diseases that currently have no effective therapy. The research in this field is growing at an exponential rate. Stem cells are master cells that have specialized capability for self-renewal, potency and capability to differentiate to many cell types. At present, the adult mesenchymal stem cells are being used in the head and neck region for orofacial regeneration (including enamel, dentin, pulp and alveolar bone) in lieu of their proliferative and regenerative properties, their use in the treatment of oral mucosal lesions is still in budding stages. Moreover, there is scanty literature available regarding role of stem cell therapy in the treatment of commonly seen oral mucosal lesions like oral submucous fibrosis, oral lichen planus, oral ulcers and oral mucositis. The present review will focus on the current knowledge about the role of stem cell therapies in oral mucosal lesions and could facilitate new advancements in this area (articles were obtained from electronic media like PubMed, EBSCO, Cochrane and Medline etc., from year 2000 to 2014 to review the role of stem cell therapy in oral mucosal lesions).