The use of biologic mediators and tissue engineering in dentistry

Therapeutics of stem cells in periodontal regeneration

The structure and composition of the periodontium are affected in many acquired and heritable diseases, and the most significant among these is periodontal disease. Periodontal regeneration is considered to be organically promising but clinically capricious. The principal requirements for tissue engineering are the incorporation of appropriate numbers of responsive progenitor cells and the presence of bioactive levels of regulatory signals within an appropriate extracellular matrix or carrier construct. Stem cell therapy is a treatment that uses stem cells, or cells that come from stem cells, to replace or to repair a patient's cells or tissues that are damaged. And, recent progress in stem cell research and in tissue engineering promises novel prospects for tissue regeneration in dental practice in the future, with regeneration of a functional and living tooth as one of the most promising therapeutic strategies for the replacement of a diseased or damaged tooth.

Effects of concomitant use of fibroblast growth factor (FGF)-2 with beta-tricalcium phosphate (β-TCP) on the beagle dog 1-wall periodontal defect model

The effects of concomitant use of fibroblast growth factor-2 (FGF-2) and beta-tricalcium phosphate (β-TCP) on periodontal regeneration were investigated in the beagle dog 1-wall periodontal defect model. One-wall periodontal defects were created in the mesial portion of both sides of the mandibular first molars, and 0.3% FGF-2 plus β-TCP or β-TCP alone was administered. Radiographic evaluation was performed at 0, 3, and 6 weeks. At 6 weeks, the periodontium with the defect site was removed and histologically analyzed. Radiographic findings showed that co-administration of FGF-2 significantly increased bone mineral contents of the defect sites compared with β-TCP alone. Histologic analysis revealed that the length of the regenerated periodontal ligament, the cementum, distance to the junctional epithelium, new bone height, and area of newly formed bone were significantly increased in the FGF-2 group. No abnormal inflammatory response or ankylosis was observed in either group. These findings indicate the efficacy of concomitant use of FGF-2 and β-TCP as an osteoconductive material for periodontal regeneration following severe destruction by progressive periodontitis.

FGF-2 stimulates periodontal regeneration: results of a multi-center randomized clinical trial

The efficacy of the local application of recombinant human fibroblast growth factor-2 (FGF-2) in periodontal regeneration has been investigated. In this study, a randomized, double-blind, placebo-controlled clinical trial was conducted in 253 adult patients with periodontitis. Modified Widman periodontal surgery was performed, during which 200 µL of the investigational formulation containing 0% (vehicle alone), 0.2%, 0.3%, or 0.4% FGF-2 was administered to 2- or 3-walled vertical bone defects. Each dose of FGF-2 showed significant superiority over vehicle alone (p < 0.01) for the percentage of bone fill at 36 wks after administration, and the percentage peaked in the 0.3% FGF-2 group. No significant differences among groups were observed in clinical attachment regained, scoring approximately 2 mm. No clinical safety problems, including an abnormal increase in alveolar bone or ankylosis, were identified. These results strongly suggest that topical application of FGF-2 can be efficacious in the regeneration of human periodontal tissue that has been destroyed by periodontitis.

Culture and characterization of mesenchymal stem cells from human gingival tissue

BACKGROUND

Tissue engineering using mesenchymal stem cells (MSCs) is a recent therapeutic modality that has several advantages. MSCs have high proliferation potential and may be manipulated to permit differentiation before being transplanted, suggesting they may be an ideal candidate for regenerative procedures. Precise identification of cells capable of regenerating the periodontium is valuable because no predictable regeneration procedure has yet been described. The purpose of this study is to determine the presence of MSCs in human gingival connective tissue and their morphologic and functional characteristics.

METHODS

Gingival connective tissue samples were obtained from five healthy students. The samples were deepithelialized, leaving only connective tissue. The explants were minced and cultured on tissue culture dishes for 3 to 4 weeks, after which cells were characterized by flow cytometry. Differentiation into osteogenic, chondrogenic, and adipogenic lineages was induced and evaluated by culture staining. An immunoregulation assay was also performed.

RESULTS

The results show that gingival tissue cells fulfill the minimal criteria proposed by the International Society for Cellular Therapy to be defined as MSCs. Cell characterization was consistently positive for CD90, CD105, CD73, CD44, and CD13 markers and negative for hematopoietic markers CD34, CD38, CD45, and CD54. We observed differentiation in positive staining of adipogenic, chondrogenic, and osteogenic lineages. Furthermore, gingival cells showed immunomodulative capacity.

CONCLUSION

Gingival connective tissue could be a reservoir of MSCs that could be used in regenerative procedures based on tissue engineering.

Dental follicle cells combined with beta-tricalcium phosphate ceramic: a novel available therapeutic strategy to restore periodontal defects

Tissue-engineering strategies to restore the periodontal defects are being developed. It will result in the periodontal formation and growing new function tissue rather than new replacement of periodontium. Although a number of procedures have been investigated in an attempt to regenerate lost periodontal tissue, none has yet led to new cementum formation, remodeling of the periodontal ligament, and new bone formation in clinic. Dental follicle cells (DFCs), as a progenitor cell of periodontal ligament cell and stem cell, have more potential abilities than PDL-cell in formation of periodontal tissue. More researches focus on the inductive environments, such as bone morphogenetic protein-2 (BMP-2), dexamethasone, and transfer growth factor, and scaffold. We hypotheses that DFCs from Beagle's dog are isolated, induced by BMP-2, basic-fibroblast growth factor and dexamethasone, and seeded by beta-tricalcium phosphate ceramic (beta-TCP), then the complex was auto-implanted into the periodontal defects in the same Beagle's dog to observe the regeneration of periodontal tissue in vivo. The study will explore the feasibility and application of restore of periodontal defects by DFCs-beta-TCP complex. We believe it is especially helpful to future clinical study and application.

Periodontal tissue engineering and regeneration: current approaches and expanding opportunities

The management of periodontal tissue defects that result from periodontitis represents a medical and socioeconomic challenge. Concerted efforts have been and still are being made to accelerate and augment periodontal tissue and bone regeneration, including a range of regenerative surgical procedures, the development of a variety of grafting materials, and the use of recombinant growth factors. More recently, tissue-engineering strategies, including new cell- and/or matrix-based dimensions, are also being developed, analyzed, and employed for periodontal regenerative therapies. Tissue engineering in periodontology applies the principles of engineering and life sciences toward the development of biological techniques that can restore lost alveolar bone, periodontal ligament, and root cementum. It is based on an understanding of the role of periodontal formation and aims to grow new functional tissues rather than to build new replacements of periodontium. Although tissue engineering has merged to create more opportunities for predictable and optimal periodontal tissue regeneration, the technique and design for preclinical and clinical studies remain in their early stages. To date, the reconstruction of small- to moderate-sized periodontal bone defects using engineered cell-scaffold constructs is technically feasible, and some of the currently developed concepts may represent alternatives for certain ideal clinical scenarios. However, the predictable reconstruction of the normal structure and functionality of a tooth-supporting apparatus remains challenging. This review summarizes current regenerative procedures for periodontal healing and regeneration and explores their progress and difficulties in clinical practice, with particular emphasis placed upon current challenges and future possibilities associated with tissue-engineering strategies in periodontal regenerative medicine.

Periodontal regeneration

The ultimate goal of periodontal therapy is the regeneration of the tissues destroyed as a result of periodontal disease. Currently, two clinical techniques, based on the principles of "guided tissue regeneration" (GTR) or utilization of the biologically active agent "enamel matrix derivative" (EMD), can be used for the regeneration of intrabony and Class II mandibular furcation periodontal defects. In cases where additional support and space-making requirements are necessary, both of these procedures can be combined with a bone replacement graft. There is no evidence that the combined use of GTR and EMD results in superior clinical results compared to the use of each material in isolation. Great variability in clinical outcomes has been reported in relation to the use of both EMD and GTR, and these procedures can be generally considered to be unpredictable. Careful case selection and treatment planning, including consideration of patient, tooth, site and surgical factors, is required in order to optimize the outcomes of treatment. There are limited data available for the clinical effectiveness of other biologically active molecules, such as growth factors and platelet concentrates, and although promising results have been reported, further clinical trials are required in order to confirm their effectiveness. Current active areas of research are centred on tissue engineering and gene therapy strategies which may result in more predictable regenerative outcomes in the future.