Local application of periodontal ligament stromal cells promotes soft tissue regeneration

Human Periodontal Ligament Stem Cells (hPDLSCs) Spontaneously Differentiate into Myofibroblasts to Repair Diabetic Wounds

Advanced glycation end product (AGE) accumulation due to diabetes causes vascular and neurological lesions, delaying healing. The use of stem cells could overcome these problems. Although many studies have shown the potential beneficial effects of stem cell therapies in the treatment of chronic and refractory skin ulcers, their delivery methods are still under investigation. Human periodontal ligament stem cells (hPDLSCs) can spontaneously differentiate into myofibroblasts in specific cultures; therefore, they have the potential to effectively treat diabetic wounds and may also have applications in the field of medical cosmetics. The myofibroblastic differentiation ability of hPDLSCs in the presence of AGEs was evaluated by the expression of α-SMA and COL1A1 using RT-qPCR and WB technology. Wound healing in diabetic mice, induced by streptozotocin (STZ) and assessed using H&E staining, Masson staining, and immunohistochemical (IHC) and immunofluorescence (IF) staining, was used to validate the effects of hPDLSCs. In the wound tissues, the expression of α-SMA, COL1A1, CD31, CD206, iNOS, and vimentin was detected. The findings indicated that in H-DMEM, the expression of COL1A1 exhibited a significant decrease, while α-SMA demonstrated an increase in P7 cells, ignoring the damage from AGEs (p < 0.05). In an STZ-induced diabetic C57BL/6J mice whole-skin defect model, the healing rate of the hPDLSCs treatment group was significantly higher than that in the models (on the 7th day, the rate was 65.247% vs. 48.938%, p < 0.05). hPDLSCs have been shown to spontaneously differentiate into myofibroblasts in H-DMEM and resist damage from AGEs in both in vivo and in vitro models, suggesting their potential in the field of cosmetic dermatology.

Comparative analysis of proliferative and multilineage differentiation potential of human periodontal ligament stem cells from maxillary and mandibular molars

BACKGROUND

Clinical experience indicates that wounds in alveolar bone and periodontal tissue heal faster and more efficiently in the maxilla compared with the mandible. Since stem cells are known to have a decisive influence on wound healing and tissue regeneration, the aim of this study was to determine whether differences in proliferation and differentiation of periodontal ligament stem cells (PDLSC) from upper (u-PDLSC) and lower jaw (l-PDLSC) contribute to the enhanced wound healing in the maxilla.

METHODS

u-PDLSC and l-PDLSC from the same donor were harvested from the periodontal ligament of extracted human maxillary and mandibular third molars. Cell differentiation potential was assessed by analyzing stem cell markers, proliferation rate, and multilineage differentiation among each other and bone marrow-derived mesenchymal stem cells (MSC). Successful differentiation of PDLSC and MSC toward osteoblasts, adipocytes, and chondrocytes was analyzed via reverse transcriptase-quantitative polymerase chain reaction and histochemical staining (Alizarin Red, Oil Red O, Toluidine Blue).

RESULTS

u-PDLSC and l-PDLSC expressed the MSC-markers CD73+ , CD90+ , and CD105+ and lacked expression of CD34- and CD45- . Proliferation was significantly higher in u-PDLSC than in l-PDLSC, regardless of the culture conditions. Osteogenic (ALP, RunX2, and osteocalcin) and chondrogenic (SOX9 and ACAN) related gene expression as well as staining intensities were significantly higher in u-PDLSC than in l-PDLSC. No difference in adipogenic differentiation was observed.

CONCLUSION

u-PDLSC showed a significantly higher proliferative and differentiation potential than l-PDLSC, offering a possible cell-based explanation for the differences in periodontal wound healing efficacy between maxilla and mandible.

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.

2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside promotes the effects of dental pulp stem cells on rebuilding periodontal tissues in experimental periodontal defects

BACKGROUND

This study aimed to investigate the regenerative effects of 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside (THSG)-treated human dental pulp stem cells (DPSC) on the healing of experimental periodontal defects in rats.

METHODS

The maxillary first molars of 30 male Sprague-Dawley rats were extracted, and after healing, bilateral periodontal defects were surgically created mesially in second molars. The defects were treated with Matrigel (as control), DPSC, or DPSC + THSG. After 2 weeks, the healed defects were evaluated using microcomputed tomography and through histological and immunohistochemical analyses.

RESULTS

In the microcomputed tomography analysis, more new bone formation in the DPSC and DPSC + THSG groups was observed compared with the control group. The periodontal bone supporting ratio in site with DPSC + THSG was significantly higher than that in DPSC. Histologically, an enhanced new bone formation and more significant periodontal attachment were observed in the DPSC + THSG group. The expression levels of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), and osteopontin (OPN) in the DPSC + THSG group were significantly greater than those in other groups.

CONCLUSIONS

THSG-revolutionized DPSCs significantly shortened the regenerative period of periodontal defects by enhancing the cell recruitment and possibly the angiogenesis in rat models, which illustrate the critical implications for a clinical application and provide a novel tactic for periodontitis treatment.

Topical phenytoin effects on palatal wound healing

BACKGROUND

The clinical benefits of autogenous soft tissue grafts are countered by donor site morbidity. The aim of this prospective split-mouth clinical trial is to assess clinical, histological and patient outcomes following topical phenytoin (PHT) treatment of experimental palatal wounds.

METHODS

Systemically healthy adults were recruited. One 6 mm diameter wound (posterior) and one 4 mm diameter wound (anterior), each 1-1.5 mm deep, were created on both sides of the palate. Wounds on one randomly chosen side received 10% phenytoin USP and contralateral wounds received carrier alone. Biopsies were harvested from anterior wounds (Day 1 or Day 5) and were routinely processed for histology. Posterior wounds were left undisturbed to clinically evaluate healing (using photographs and Healing Score Index) on Days 1, 5, 14, and 21. Questionnaires were used to assess patient-centered outcomes. Data analysis was performed using generalized logistic and generalized linear mixed models.

RESULTS

Twenty participants completed all visits. 30% of participants reported more pain on control side than the PHT side at Day 1 (P = 0.014). PHT treated sites were more likely to not exhibit swelling (OR = 9.35; P = 0.009) and to not experience pain on palpation (OR = 6.278; P = 0.007). PHT significantly and time-dependently affected granulation tissue appearance (P = 0.004). Histologically, there were no significant differences between control and PHT, at any time point (P ≥ 0.853).

CONCLUSIONS

The results of the present study, the first one to report on topical PHT as palatal wound treatment, suggest that PHT application on palatal wounds could result in improved healing outcomes.

Biofunctionalized Scaffold in Bone Tissue Repair

Bone tissue engineering is based on bone grafting to repair bone defects. Bone graft substitutes can contribute to the addition of mesenchymal stem cells (MSCs) in order to enhance the rate and the quality of defect regeneration. The stem cell secretome contains many growth factors and chemokines, which could affect cellular characteristics and behavior. Conditioned medium (CM) could be used in tissue regeneration avoiding several problems linked to the direct use of MSCs. In this study, we investigated the effect of human periodontal ligament stem cells (hPDLSCs) and their CM on bone regeneration using a commercially available membrane scaffold Evolution (EVO) implanted in rat calvarias. EVO alone or EVO + hPDLSCs with or without CM were implanted in Wistar male rats subjected to calvarial defects. The in vivo results revealed that EVO membrane enriched with hPDLSCs and CM showed a better osteogenic ability to repair the calvarial defect. These results were confirmed by acquired micro-computed tomography (CT) images and the increased osteopontin levels. Moreover, RT-PCR in vitro revealed the upregulation of three genes (Collagen (COL)5A1, COL16A1 and transforming growth factor (TGF)β1) and the down regulation of 26 genes involved in bone regeneration. These results suggest a promising potential application of CM from hPDLSCs and scaffolds for bone defect restoration and in particular for calvarial repair in case of trauma.

Stem cell-based tooth and periodontal regeneration

Currently regeneration of tooth and periodontal damage still remains great challenge. Stem cell-based tissue engineering raised novel therapeutic strategies for tooth and periodontal repair. Stem cells for tooth and periodontal regeneration include dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), stem cells from the dental apical papilla (SCAPs), and stem cells from human exfoliated deciduous teeth (SHEDs), dental follicle stem cells (DFSCs), dental epithelial stem cells (DESCs), bone marrow mesenchymal stem cells (BMMSCs), adipose-derived stem cells (ADSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). To date, substantial advances have been made in stem cell-based tooth and periodontal regeneration, including dentin-pulp, whole tooth, bioroot and periodontal regeneration. Translational investigations have been performed such as dental stem cell banking and clinical trials. In this review, we present strategies for stem cell-based tissue engineering for tooth and periodontal repair, and the translational studies.

Local Injection of Hyaluronic Acid Filler Improves Open Gingival Embrasure: Validation Through a Rat Model

BACKGROUND

The open gingival embrasure, the so-called black triangle, is one of the unsolved dilemmas in adult dentistry. Although various techniques have been introduced to improve black triangles, the lack of reproducible experimental models has prevented development of successful protocols to regenerate or to compensate loss of the interdental papilla. Therefore, the objective of this study is first to develop a reliable animal model of open gingival embrasure and then to validate a minimally invasive injection technique using hyaluronic acid (HA) filler to augment the interdental papilla.

METHODS

To reproduce open gingival embrasure in rats, rapid space opening was induced between the mandibular incisors by attachment of a compression spring. Loss of interdental papilla height was morphologically evaluated and calculated using standardized serial photographs, microcomputed tomography, and histologic sections. Afterward, HA fillers or phosphate-buffered saline (PBS) was locally injected, and changes in the interdental papilla were evaluated.

RESULTS

After 7 days of space opening, the margin of the interdental papilla between the mandibular incisors gradually became irregular and flat, indicating a condition similar to the open gingival embrasure (P <0.05). Local injection of HA filler induced an augmentation effect of the interdental papilla compared with injection of PBS (P <0.05). Interdental papilla became convex, and inner granules containing HA were detected within the submucosal layer after its injection.

CONCLUSIONS

Open gingival embrasure was reproduced reliably in vivo. Local injection of HA filler was validated as a meaningful minimally invasive procedure to improve open gingival embrasure.

Periodontal regeneration in swine after cell injection and cell sheet transplantation of human dental pulp stem cells following good manufacturing practice

Background

Periodontitis, one of the most prevalent infectious diseases in humans, results in the destruction of tooth-supporting tissues. The purpose of the present study is to evaluate the effect of cell injection and cell sheet transplantation on periodontal regeneration in a swine model.

Methods

In the present study, human dental pulp stem cells (hDPSCs) were transplanted into a swine model for periodontal regeneration. Twelve miniature pigs were used to generate periodontitis with bone defects of 5 mm in width, 7 mm in length, and 3 mm in depth. hDPSCs were obtained for bone regeneration using cell injection or cell sheet transplantation. After 12 weeks, clinical, radiological, and histological assessments of regenerated periodontal tissues were performed to compare periodontal regeneration treated with xenogeneic cell injection and cell sheet implantation.

Results

Our study showed that translating hDPSCs into this large animal model could significantly improve periodontal bone regeneration and soft tissue healing. After 12 weeks, both the hDPSC sheet treatment and hDPSC injection significantly improved periodontal tissue healing clinically in comparison with the control group. The volume of regenerative bone in the hDPSC sheet group (52.7 ± 4.1 mm³) was significantly larger than in the hDPSC injection group (32.4 ± 5.1 mm³) (P < 0.05). The percentage of bone in the periodontium in the hDPSC injection group was 12.8 ± 4.4 %, while it was 17.4 ± 5.3 % in the hDPSC sheet group (P < 0.05).

Conclusion

Both hDPSC injection and cell sheet transplantation significantly regenerated periodontal bone in swine. The hDPSC sheet had more bone regeneration capacity compared with hDPSC injection.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0362-8) contains supplementary material, which is available to authorized users.