Application of autologous periosteal cells for the regeneration of class III furcation defects in Beagle dogs

Evaluation of hyaluronic acid gel with or without acellular dermal matrix allograft in the treatment of class II furcation defects in dogs: A histologic and histomorphometric study

Aim

To evaluate the histologic and histomorphometric effects of hyaluronic acid (HA) gel with or without acellular dermal matrix allograft (ADMA) on periodontal regeneration in Class II furcation defects in dogs.

Materials and methods

Class II furcation defects were surgically created in the mandibular first and second premolars bilaterally in eight beagle dogs. The Class II furcation defects were assigned randomly, using the split-mouth design, into the test and control sides. The teeth on the test sides were equally and randomly divided into the HA/ADMA group (n = 8) treated with 0.8% HA gel followed by ADMA, and the HA-only group (n = 8) treated with 0.8% HA only. The furcation defects of the control sides (n = 16) were subjected to open flap debridement (OFD group). The animals were euthanized for histologic and histomorphometric analyses after one month (n = 4) and three months (n = 4).

Results

At one month, the newly formed bone area (NFBA) was larger in the HA/ADMA (6.23 ± 1.41 mm2) and HA-only (5.90 ± 1.43 mm2) groups than in the OFD group (2.42 ± 1.62 mm2) (p < 0.05). The newly formed cementum (NFAC) and periodontal ligament (NFPL) were similar in the HA/ADMA and HA-only groups but significantly lesser in the OFD group (p < 0.05.) At three months, the NFBA, NFAC, and NFPL were greater in the HA/ADMA group than in the HA-only group (p < 0.05). New regenerative tissue was significantly greater in both the test groups than in the OFD group (p < 0.05), while epithelial downgrowth predominated the healing in the latter.

Conclusions

These results suggest that HA with ADMA positively affects the periodontal regeneration and wound healing in Class II furcation defects.

Cross-linked hyaluronic acid gel with or without a collagen matrix in the treatment of class III furcation defects: A histologic and histomorphometric study in dogs

AIM

To histologically evaluate the effects of cross-linked hyaluronic acid (xHyA) with or without a collagen matrix (CM) on periodontal wound healing/regeneration in class III furcation defects in dogs.

MATERIALS AND METHODS

Class III furcation defects were surgically created in the mandibular premolars in six beagle dogs. The defects were randomly treated as follows: open flap debridement (OFD) + CM (CM), OFD + xHyA (xHyA), OFD + xHyA + CM (xHyA/CM) and OFD alone (OFD). At 10 weeks, the animals were euthanized for histological evaluation.

RESULTS

The newly formed bone areas in the xHyA (4.04 ± 1.51 mm² ) and xHyA/CM (4.32 ± 1.14 mm² ) groups were larger than those in the OFD (3.25 ± 0.81 mm² ) and CM (3.31 ± 2.26 mm² ) groups. The xHyA (6.25 ± 1.45 mm) and xHyA/CM (6.40 ± 1.35 mm) groups yielded statistically significantly (p < .05) greater formation of new connective tissue attachment (i.e., new cementum, with inserting connective tissue fibres) compared with the OFD (1.47 ± 0.85 mm) group. No significant differences were observed in any of the histomorphometric parameters between the xHyA and xHyA/CM groups. Complete furcation closure was not observed in any of the four treatment modalities.

CONCLUSIONS

Within their limits, the present results suggest that the use of xHyA with or without CM positively influences periodontal wound healing in surgically created, acute-type class III furcation defects.

Stem Cell Transplantation and Cell-Free Treatment for Periodontal Regeneration

Increasing attention has been paid to cell-based medicines. Many in vivo and in vitro studies have demonstrated the efficacy of stem cell transplantation for the regeneration of periodontal tissues over the past 20 years. Although positive evidence has accumulated regarding periodontal regeneration using stem cells, the exact mechanism of tissue regeneration is still largely unknown. This review outlines the practicality and emerging problems of stem cell transplantation therapy for periodontal regeneration. In addition, possible solutions to these problems and cell-free treatment are discussed.

A Review of Tissue Engineering for Periodontal Tissue Regeneration

Periodontal disease is one of the most common diagnoses in small animal veterinary medicine. This infectious disease of the periodontium is characterized by the inflammation and destruction of the supporting structures of teeth, including periodontal ligament, cementum, and alveolar bone. Traditional periodontal repair techniques make use of open flap debridement, application of graft materials, and membranes to prevent epithelial downgrowth and formation of a long junctional epithelium, which inhibits regeneration and true healing. These techniques have variable efficacy and are made more challenging in veterinary patients due to the cost of treatment for clients, need for anesthesia for surgery and reevaluation, and difficulty in performing necessary diligent home care to maintain oral health. Tissue engineering focuses on methods to regenerate the periodontal apparatus and not simply to repair the tissue, with the possibility of restoring normal physiological functions and health to a previously diseased site. This paper examines tissue engineering applications in periodontal disease by discussing experimental studies that focus on dogs and other animal species where it could potentially be applied in veterinary medicine. The main areas of focus of tissue engineering are discussed, including scaffolds, signaling molecules, stem cells, and gene therapy. To date, although outcomes can still be unpredictable, tissue engineering has been proven to successfully regenerate lost periodontal tissues and this new possibility for treating veterinary patients is discussed.

Efficacy of biocompatible trilayers nanofibrous scaffold with/without allogeneic adipose-derived stem cells on class II furcation defects of dogs' model

OBJECTIVE

This study aimed to evaluate the regenerative capacity of a newly-developed polycaprolactone (PCL)-based nanofibrous composite scaffold either alone or in combination with adipose-derived mesenchymal stem cells (ADSCs) as a treatment modality for class II furcation defects.

MATERIALS AND METHODS

After ADSCs isolation and scaffold characterization, the mandibular premolars of adult male mongrel dogs were selected and randomly assigned into three equal groups. In group I, class II furcation defects were surgically induced to the inter-radicular bone. While class II furcation defects of group II were induced as in group I. In addition, the defects were filled with the prefabricated scaffold. Moreover, class II furcation defects of group III were induced as in group II and instead the defects were filled with the prefabricated scaffold seeded with ADSCs. The dogs were sacrificed at 30 days or at 60 days. Periodontal wound healing/regeneration was evaluated by radiological examination using cone beam computed tomography and histologically using ordinary, histochemical, and immunohistochemical staining.

RESULTS

In the two examination periods, group II defects compared to group I, and group III compared to the other groups showed a decrease in defect dimensions radiographically. Histologically, histochemically, and immunohistochemically, they significantly demonstrated better periodontal wound healing/regeneration, predominant collagen type I of newly formed bone and periodontal ligament with a significant increase in the immunoreactivity of vascular endothelial growth factor and osteopontin.

CONCLUSIONS

The newly fabricated nanofibrous scaffold has enhanced periodontal wound healing/regeneration of class II furcation defects with further enhancement achieved when ADSCs seeded onto the scaffold before implantation.

CLINICAL RELEVANCE

The implementation of our newly-developed PCL-based nanofibrous composite scaffolds in class II furcation defect either alone or in conjunction with ADSCs can be considered as a suitable treatment modality to allow periodontal tissues regeneration.

Tooth transplantation with a β-tricalcium phosphate scaffold accelerates bone formation and periodontal tissue regeneration

OBJECTIVES

Although tooth transplantation is a useful treatment option as a substitute for a missing tooth, transplantation to a narrow alveolar ridge is not feasible. In this study, we tested a tissue engineering approach simultaneously with tooth transplantation using a scaffold or a combination with cells to accelerate bone formation and periodontal tissue regeneration.

MATERIALS AND METHODS

Bone marrow mononuclear cells (BM-MNCs) were harvested from C57BL/6J mice. The upper first or the second molar of 3-week-old C57BL/6J mice and a β-tricalcium phosphate (β-TCP) scaffold were transplanted with BM-MNCs (MNC group) or without BM-MNCs (β-TCP group) into the thigh muscle of syngeneic mice. The tooth alone was also transplanted (control group). After 4 weeks, the transplants were harvested and analyzed.

RESULTS

Bone volume was significantly larger in the MNC and the β-TCP groups than that in the control group, and the newly formed bone was observed on the lateral wall of the root. Compared with the control group, the MNC group showed a larger trabecular thickness and fractal dimension.

CONCLUSION

This study showed accelerated bone formation and periodontal tissue regeneration when tooth transplantation was performed with a β-TCP scaffold. BM-MNCs may accelerate bone maturation, while the effect on bone formation was limited.

Characteristic comparison between canine and human dental mesenchymal stem cells for periodontal regeneration research in preclinical animal studies

The effectiveness of stem cell-based periodontal tissue engineering need to be assessed by preclinical animal studies. Dog models are widely used animal models; however, there are not sufficient data on characterization of canine dental mesenchymal stem cells. Therefore, we aimed to compare the characteristics among canine and human periodontal ligament stem cells and canine and human dental pulp stem cells. Canine periodontal ligament stem cells and dental pulp stem cells showed significantly weaker clonogenic capability, and proliferation and migration capacity, and they displayed lower positive rates for CD90, CD73, CD105, and STRO-1. All of these canine and human cells showed multilineage differentiation potential. After osteogenic induction, the expression of alkaline phosphatase was obviously upregulated in human dental mesenchymal stem cells, but it was not upregulated in canine dental pulp stem cells. Other osteogenic genes, such as runt-related transcription factor 2 and bone morphogenetic protein 2, were upregulated in all induced canine and human cells, but their upregulation occurred later in canine cells. These results confirmed the stem cell properties of canine mesenchymal stem cells, but also suggested that more attention should be paid to the choice of appropriate research approaches, osteogenic gene markers, and time points for the utilization of canine dental mesenchymal stem cells due to their distinct characteristics.

Periodontal regenerative medicine using mesenchymal stem cells and biomaterials: A systematic review of pre-clinical studies

The aim of the systematic review was to analyze the use of mesenchymal stem cells (MSC) and biomaterial for periodontal regeneration from preclinical animal models and human. Electronic databases were searched and additional hand-search in leading journals was performed. The research strategy was achieved according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The including criteria were as follows: MSC, biomaterial, in vivo studies, with histologic and radiologic analysis and written in English. The risk of bias was assessed for individual studies. A total of 50 articles were selected and investigated in the systematic review. These results indicate that MSC and scaffold provide beneficial effects on periodontal regeneration, with no adverse effects of such interventions. Future studies need to identify the suitable association of MSC and biomaterial and to characterize the type of new cementum and the organization of the periodontal ligament fiber regeneration.

Histologic evidence of periodontal regeneration in furcation defects: a systematic review

OBJECTIVE

To systematically review the available histologic evidence on periodontal regeneration in class II and III furcations in animals and humans.

MATERIALS AND METHODS

A protocol including all aspects of a systematic review methodology was developed including definition of the focused question, defined search strategy, study inclusion criteria, determination of outcome measures, screening methods, data extraction and analysis, and data synthesis. The focused question was defined as follows: "What is the regenerative effect obtained by using or not several biomaterials as adjuncts to open flap surgery in the treatment of periodontal furcation defects as evaluated in animal and human histological studies?"

SEARCH STRATEGY

Using the MEDLINE database, the literature was searched for articles published up to and including September 2018: combinations of several search terms were applied to identify appropriate studies. Reference lists of review articles and of the included articles in the present review were screened. A hand search of the most important dental journals was also performed.

CRITERIA FOR STUDY SELECTION AND INCLUSION

Only articles published in English describing animal and human histological studies evaluating the effect of surgical treatment, with or without the adjunctive use of potentially regenerative materials (i.e., barrier membranes, grafting materials, growth factors/proteins, and combinations thereof) for the treatment of periodontal furcation defects were considered. Only studies reporting a minimum of 8 weeks healing following reconstructive surgery were included. The primary outcome variable was formation of periodontal supporting tissues [e.g., periodontal ligament, root cementum, and alveolar bone, given as linear measurements (in mm) or as a percentage of the instrumented root length (%)] following surgical treatment with or without regenerative materials, as determined histologically/histomorphometrically. Healing type and defect resolution (i.e., complete regeneration, long junctional epithelium, connective tissue attachment, connective tissue adhesion, or osseous repair) were also recorded.

RESULTS

In animals, periodontal regeneration was reported in class II and III defects with open flap debridement alone or combined with various types of bone grafts/bone substitues, biological factors, guided tissue regeneration, and different combinations thereof. The use of biological factors and combination approaches provided the best outcomes for class II defects whereas in class III defects, the combination approaches seem to offer the highest regenerative outcomes. In human class II furcations, the best outcomes were obtained with DFDBA combined with rhPDGF-BB and with GTR. In class III furcations, evidence from two case reports indicated very limited to no periodontal regeneration.

CONCLUSIONS

Within their limits, the present results suggest that (a) in animals, complete periodontal regeneration has been demonstrated in class II and class III furcation defects, and (b) in humans, the evidence for substantial periodontal regeneration is limited to class II furcations.

CLINICAL RELEVANCE

At present, regenerative periodontal surgery represents a valuable treatment option only for human class II furcation defects but not for class III furcations.

Cementum regeneration using stem cells in the dog model: A systematic review

OBJECTIVE

Restoring lost tissues of the periodontium, such as cementum, is essential in reducing the risk of tooth loss due to periodontitis and/or severe root resorption. Stem cell therapy is a regenerative strategy in cementum regeneration. This systematic review aimed to analyze the effect of various stem cells and their transplantation method on cementum regeneration in the dog model.

METHODS

Electronic databases were searched, in addition to performing hand searches and a gray literature search. Titles and abstracts were searched according to the inclusion criteria and full texts were selected to be included in this systematic review. Data was extracted from each article and risk of bias was assessed for individual studies.

RESULTS

Most studies reported that the treatment using a variety of stem cells resulted in significantly greater cementum regeneration.

CONCLUSIONS

Because of variations in additional factors included in each study and varied risk of bias among those studies, the effect of each type of stem cell on cementum regeneration in dogs is difficult to clarify. Additional information needs to be obtained from each study in order to further analyze the individual effect of stem cells on cementum regeneration in dogs.

Use of Autologous Stem Cells for the Regeneration of Periodontal Defects in Animal Studies: a Systematic Review and Meta-Analysis

OBJECTIVES

To overview preclinical animal trials and quantify the effect size that stem cell therapy has on the regeneration of periodontal tissue complex.

MATERIAL AND METHODS

A systematic MEDLINE (PubMed) online library search was conducted for preclinical animal studies in vivo , using autologous periodontal ligament, dental pulp, cementum, alveolar periosteal, gingival margin or adipose stem cell types for periodontal tissue complex regeneration purposes. Studies had to be published between 2007.09.01 and 2017.09.01 in the English language.

RESULTS

Online library search yielded 2099 results. After the title, abstract and full-text screening ten studies fit inclusion criteria and were pooled into meta-analysis. Overall the stem cell regenerative therapy had a statistically significant positive influence on the periodontal tissue regeneration when compared to the control groups. The biggest influence was made to the regeneration of cementum (standardised mean difference [SMD] 2.25 [95% confidence interval (CI) = 1.31 to 3.2]) while the smallest influence was made to the alveolar bone (SMD 1.47 [95% CI = 0.7 to 2.25]) the effect size for periodontal ligament regeneration was (SMD 1.8 [95% CI = 1 to 2.59]). Subgroup analysis showed statistically significant (P < 0.05) differences between different cell types in the alveolar bone and cementum regeneration groups and in alveolar bone group in relation to scaffold materials.

CONCLUSIONS

Stem cell therapy has a positive impact on periodontal tissue complex regeneration. Such therapy has the biggest influence on cementum regeneration meanwhile alveolar bone regeneration is influenced by the least amount. However more and less diverse preclinical studies are needed to have a greater statistical power in future meta-analyses.

Periodontal wound healing following reciprocal autologous root transplantation in class III furcation defects

Purpose

Furcation involvement in the molars is difficult to treat, and has been recognized as a risk factor for tooth loss. Although periodontal regenerative therapies, including guided tissue regeneration and various types of bone grafts, have been applied to furcation defects, the effects of these treatments are limited, especially in large class III furcation defects. The purpose of this pilot study was to investigate the effect of reciprocal autologous root transplantation on periodontal wound healing and regeneration in class III furcation defects in dogs.

Methods

Furcation defects (7 mm wide and 6 mm high) were surgically created after root separation of the unilateral third and fourth premolars in 4 dogs. Eight furcation defects were randomized to receive either reciprocal autologous root transplantation (test) or no further treatment (control). In the test group, the mesial and distal roots were transplanted into the distal and mesial extraction sockets, respectively. The animals were sacrificed 10 weeks after surgery for histologic evaluation.

Results

The healing pattern in the control group was characterized by extensive collapse of the flap and limited periodontal regeneration. New bone formation in the test group (3.56±0.57 mm) was significantly greater than in the control group (0.62±0.21 mm). Dense collagen fibers inserting into the residual cementum on the transplanted root surfaces were observed in the test group. Slight ankylosis was observed in 2 of the 4 specimens in the test group on the mesiodistal sides where the root-planed surfaces faced the existing bone. Root resorption (RR) was detected in both the control and test groups.

Conclusions

Within the limits of this study, it can be concluded that reciprocal autologous root transplantation was effective for bone regeneration in class III furcation defects in dogs. However, further studies are required to standardize the approach in order to prevent unwanted RR prior to clinical application.

Leptin Overexpression in Bone Marrow Stromal Cells Promotes Periodontal Regeneration in a Rat Model of Osteoporosis

BACKGROUND

Osteoporosis is associated with widespread periodontitis and impaired periodontal healing. However, there is a lack of information about the outcomes of regenerative approaches under the influence of osteoporosis. This study investigates the effect of leptin (LEP) overexpression on the regenerative potential of bone marrow stromal cells (BMSCs) in an osteoporotic rat periodontal fenestration defect model.

METHODS

Rat BMSCs were transfected with adenoviruses harboring the human (h)LEP gene. Cell proliferation and osteogenic differentiation were evaluated. A β-tricalcium phosphate scaffold seeded with transfected cells was implanted into nude mice to investigate ectopic osteogenesis and into an osteoporotic rat defect to study periodontal regeneration. Regenerated periodontal and bone-like tissues were analyzed by histologic methods.

RESULTS

hLEP overexpression induced osteogenic differentiation of BMSCs as evidenced by the upregulation of osteogenesis-related genes such as Runt-related transcription factor 2, alkaline phosphatase (ALP), and collagen Type I, as well as increased ALP activity and enhanced mineralization. Mice implanted with hLEP-BMSC-containing scaffolds showed more extensive formation of bone-like tissue than those in other groups. Periodontal defects were also filled to a greater degree when treated with hLEP-BMSCs and contained cementum and a well-organized periodontal ligament after 10 and 28 days.

CONCLUSION

hLEP overexpression in BMSCs can stimulate periodontal regeneration in osteoporotic conditions and might be a promising strategy for periodontal regeneration in patients with osteoporosis.

Cell-Based Approaches in Periodontal Regeneration: A Systematic Review and Meta-Analysis of Periodontal Defect Models in Animal Experimental Work

Various cell types have been assessed for experimental periodontal tissue regeneration in a variety of animal models. Nonetheless, the efficacy of cell-based approaches for periodontal regeneration is still controversial. Therefore, the purpose of this study was to systematically review cell-based approaches for periodontal regeneration in animal studies including a meta-analysis to obtain more clarity on their efficacy. The results of this systematic review and meta-analysis revealed that cell-based approaches have a favorable effect on periodontal tissue regeneration, as displayed by the positive effect of cell-based approaches on new bone, cementum, and periodontal ligament (PDL) formation in periodontal defects. Moreover, subgroup analysis showed a favorable effect on PDL formation by PDL-derived cells, but not by bone marrow mesenchymal stem cells (BMSCs). However, meta-analysis did not show any statistically significant differences in effect between PDL-derived cells and BMSCs. These results provide important information for the implementation of cell-based approaches in clinical practice as a routine treatment for periodontal regeneration in the future.

Increased osteogenesis in osteoporotic bone marrow stromal cells by overexpression of leptin

Osteoporosis leads to increased bone fractures and net bone loss, in part because of the dysfunction of bone marrow stromal cells (BMSCs). Leptin is an adipokine that plays important roles in many biological processes, including the regulation of the actions of mesenchymal stem cells. Our aim is to investigate the osteogenic effects of leptin in osteoporotic BMSCs in vitro and in vivo. The leptin gene was transferred into BMSCs isolated from osteoporotic rats by using recombinant adenoviruses. Once the gene and protein expression of leptin had been confirmed, MTT assays were performed; leptin overexpression was confirmed not to affect the viability of osteoporotic BMSCs. However, alkaline phosphatase (ALP) activity measurements, Alizarin red staining and analyses by quantitative real-time reverse transcription with the polymerase chain reaction revealed that leptin upregulated ALP activity, mineral deposition and the mRNA levels of runt-related transcription factor 2, ALP and collagen type І. Lastly, the effects of leptin on osteogenic differentiation were assessed in vivo. Cells transfected with leptin exhibited increased osteogenic differentiation and enhanced formation of bone-like structures. This study thus reveals, for the first time, that the overexpression of leptin in osteoporotic BMSCs (1) enhances their capacity to differentiate into osteoblasts and to form bone-like tissue and (2) might be a useful skeletal regenerative therapy in osteoporotic patients.

Concise review: mesenchymal stromal cells used for periodontal regeneration: a systematic review

Periodontitis is a chronic infectious disease of the soft and hard tissues supporting the teeth. Recent advances in regenerative medicine and stem cell biology have paved the way for periodontal tissue engineering. Mesenchymal stromal cells (MSCs) delivered in situ to periodontal defects may exert their effects at multiple levels, including neovascularization, immunomodulation, and tissue regeneration. This systematic review had two goals: (a) to objectively quantify key elements for efficacy and safety of MSCs used for periodontal regeneration and (b) to identify patterns in the existing literature to explain differences between studies and suggest recommendations for future research. This systematic review provided good evidence of the capacity of MSCs to regenerate periodontal tissues in animals; however, experimentally generated defects used in animal studies do not sufficiently mimic the pathophysiology of periodontitis in humans. Moreover, the safety of such interventions in humans still needs to be studied. There were marked differences between experimental and control groups that may be influenced by characteristics that are crucial to address before translation to human clinical trials. We suggest that the appropriate combination of cell source, carrier type, and biomolecules, as well as the inclusion of critical path issues for a given clinical case, should be further explored and refined before transitioning to clinical trials. Future studies should investigate periodontal regenerative procedures in animal models, including rodents, in which the defects generated are designed to more accurately reflect the inflammatory status of the host and the shift in their pathogenic microflora.

Periodontal regeneration using periodontal ligament stem cell-transferred amnion

Periodontal disease is characterized by the destruction of tooth supporting tissues. Regeneration of periodontal tissues using ex vivo expanded cells has been introduced and studied, although appropriate methodology has not yet been established. We developed a novel cell transplant method for periodontal regeneration using periodontal ligament stem cell (PDLSC)-transferred amniotic membrane (PDLSC-amnion). The aim of this study was to investigate the regenerative potential of PDLSC-amnion in a rat periodontal defect model. Cultured PDLSCs were transferred onto amniotic membranes using a glass substrate treated with polyethylene glycol and photolithography. The properties of PDLSCs were investigated by flow cytometry and in vitro differentiation. PDLSC-amnion was transplanted into surgically created periodontal defects in rat maxillary molars. Periodontal regeneration was evaluated by microcomputed tomography (micro-CT) and histological analysis. PDLSCs showed mesenchymal stem cell-like characteristics such as cell surface marker expression (CD90, CD44, CD73, CD105, CD146, and STRO-1) and trilineage differentiation ability (i.e., into osteoblasts, adipocytes, and chondrocytes). PDLSC-amnion exhibited a single layer of PDLSCs on the amniotic membrane and stability of the sheet even with movement and deformation caused by surgical instruments. We observed that the PDLSC-amnion enhanced periodontal tissue regeneration as determined by micro-CT and histology by 4 weeks after transplantation. These data suggest that PDLSC-amnion has therapeutic potential as a novel cell-based regenerative periodontal therapy.

Stem cell-delivery therapeutics for periodontal tissue regeneration

Periodontitis, an inflammatory disease, is the most common cause of tooth loss in adults. Attempts to regenerate the complex system of tooth-supporting apparatus (i.e., the periodontal ligament, alveolar bone and root cementum) after loss/damage due to periodontitis have made some progress recently and provide a useful experimental model for the evaluation of future regenerative therapies. Concentrated efforts have now moved from the use of guided tissue/bone regeneration technology, a variety of growth factors and various bone grafts/substitutes toward the design and practice of endogenous regenerative technology by recruitment of host cells (cell homing) or stem cell-based therapeutics by transplantation of outside cells to enhance periodontal tissue regeneration and its biomechanical integration. This shift is driven by the general inability of conventional therapies to deliver satisfactory outcomes, particularly in cases where the disease has caused large tissue defects in the periodontium. Cell homing and cell transplantation are both scientifically meritorious approaches that show promise to completely and reliably reconstitute all tissue and connections damaged through periodontal disease, and hence research into both directions should continue. In view of periodontal regeneration by paradigms that unlock the body's innate regenerative potential has been reviewed elsewhere, this paper specifically explores and analyses the stem cell types and cell delivery strategies that have been or have the potential to be used as therapeutics in periodontal regenerative medicine, with particular emphasis placed on the efficacy and safety concerns of current stem cell-based periodontal therapies that may eventually enter into the clinic.

Comparison of different tissue-derived stem cell sheets for periodontal regeneration in a canine 1-wall defect model

Cytotherapeutic approaches have been investigated to overcome the limitations of existing procedures for periodontal regeneration. In this study, cell sheet transplantation was performed using three kinds of mesenchymal tissue (periodontal ligament, alveolar periosteum, and bone marrow)-derived cells to compare the differences between cell sources in a canine severe defect model (one-wall intrabony defect). Periodontal ligament cells (PDLCs), iliac bone marrow mesenchymal stromal cells (BMMSCs), and alveolar periosteal cells (APCs) were obtained from each dog; a total of four dogs were used. Three-layered cell sheets of each cell source supported with woven polyglycolic acid were autologously transplanted to the denuded root surface. One-wall intrabony defects were filled with a mixture of β-tricalcium phosphate (β-TCP) and collagen. Eight weeks after the transplantation, periodontal regeneration was significantly observed with both newly formed cementum and well-oriented PDL fibers more in the PDLC group than in the other groups. In addition, nerve filament was observed in the regenerated PDL tissue only in the PDLC group. The amount of alveolar bone regeneration was highest in the PDLC group, although it did not reach statistical significance among the groups. These results indicate that PDLC sheets combined with β-TCP/collagen scaffold serve as a promising tool for periodontal regeneration.