Fibre guiding scaffolds for periodontal tissue engineering

The periodontium is a highly hierarchically organized organ composed of gingiva, alveolar bone, periodontal ligament and cementum. Periodontitis leads to the destruction of hard and soft tissues ultimately leading to a loss of the teeth supporting apparatus. Current treatments are capable of limiting the disease progression; however, true regeneration, characterized by perpendicularly oriented periodontal ligament fibre attachment to cementum on the root surface remains challenging. Tissue engineering approaches have been developed to enhance regeneration via micro-engineered topographical features, purposely designed to guide the insertion of the regenerated ligament to the root surface. This review reports on the recent advancements in scaffold manufacturing methodologies for generating fibre guiding properties and provides a critical insight in the current limitations of these techniques for the formation of functional periodontal attachment.     

Platelet-derived growth factor (PDGF) gene delivery for application in periodontal tissue engineering.

BACKGROUND: A challenge in the reconstruction of periodontal structures is the targeted delivery of growth-promoting molecules to the tooth root surface. Polypeptide growth factors such as platelet-derived growth factor (PDGF) stimulate both cementogenesis and osteogenesis. Recent advances in gene therapy offer the advantage of delivering recombinant proteins to tissues for extended periods of time in vivo. METHODS: Recombinant adenoviral vectors encoding for the PDGF-A gene were constructed to allow delivery of PDGF transgenes to cells. The recombinant adenoviruses were assembled using the viral backbone of Ad2/CMV/EGFP and replacing GFP (reporter gene encoding green fluorescent protein driven by the cytomegalovirus promoter [CMV] within adenovirus type 2) with the PDGF-A gene. Root lining cells (cloned cementoblasts) were transduced with Ad2/PDGF-A and evaluated for gene expression, DNA synthesis, and cell proliferation. PDGF-inducible genes, c-myc and osteopontin, were also evaluated following gene delivery of Ad2/PDGF-A. RESULTS: The results revealed high level transduction of cementoblasts by gene transfer for 7 days as evidenced by flow cytometry and Northern blotting. Cementoblast DNA synthesis and subsequent proliferation were stimulated by Ad2/PDGF-A at levels equal to or greater than continuous rhPDGF-AA application. Strong message for the PDGF-A gene and protein as evidenced by Northern blotting and immunocytochemistry was noted. Furthermore, the potent induction of c-myc and osteopontin mRNA was found after PDGF gene delivery to cementoblasts. CONCLUSIONS: These findings demonstrate that gene delivery of platelet-derived growth factor stimulates cementoblast activity that is sustained above that of rhPDGF-AA application. The use of gene therapy as a mode of growth factor delivery offers a novel approach to periodontal tissue engineering.     

牙周组织工程研究新进展

牙周炎是累及4种牙周支持组织的炎症性、破坏性疾病,现在包括GTR手术等传统的牙周治疗手段通常不能实现已破坏的牙周组织完全再生。近年来,大量的促进牙周再生方面的研究集中在牙周组织工程方面。本文就牙周组织工程的研究现状做一综述。     

牙周组织工程研究进展

牙周骨移植、引导组织再生 ( guidedtissueregeneration ,GTR)为牙周病治疗和牙周缺损修复带来新的希望 ,但在恢复牙周组织的生理结构和功能上还远未达到所期望的目标。组织工程学是近年来发展起来的一门新兴边缘学科 ,其基本方法是将体外培养的高浓度、功能相关的活细胞种植于具有良好生物相容性和生物降解性的细胞外基质材料上 ,经过一段时间的培养 ,将这种细胞与生物材料复合体植入机体病损部位以形成新的具有其原来特殊功能和形态的相应组织和器官 ,达到修复创伤和重建功能的目的。将组织工程技术引入牙周组织再生治疗 ,为牙周病的治…     

Gene therapy of bone morphogenetic protein for periodontal tissue engineering

BACKGROUND: The reconstruction of lost periodontal support including bone, ligament, and cementum is a major goal of therapy. Bone morphogenetic proteins (BMPs) have shown much potential in the regeneration of the periodontium. Limitations of BMP administration to periodontal lesions include need for high-dose bolus delivery, BMP transient biological activity, and low bioavailability of factors at the wound site. Gene transfer offers promise as an alternative treatment strategy to deliver BMPs to periodontal tissues. METHODS: This study utilized ex vivo BMP-7 gene transfer to stimulate tissue engineering of alveolar bone wounds. Syngeneic dermal fibroblasts (SDFs) were transduced ex vivo with adenoviruses encoding either green fluorescent protein (Ad-GFP or control virus), BMP-7 (Ad-BMP-7), or an antagonist of BMP bioactivity, noggin (Ad-noggin). Transduced cells were seeded onto gelatin carriers and then transplanted to large mandibular alveolar bone defects in a rat wound repair model. RESULTS: Ad-noggin treatment tended to inhibit osteogenesis as compared to the control-treated and Ad-BMP-7-treated specimens. The osseous lesions treated by Ad-BMP-7 gene delivery demonstrated rapid chrondrogenesis, with subsequent osteogenesis, cementogenesis and predictable bridging of the periodontal bone defects. CONCLUSION: These results demonstrate the first successful evidence of periodontal tissue engineering using ex vivo gene transfer of BMPs and offers a new approach for repairing periodontal defects.     

组织工程细胞片在牙周组织再生中的作用

牙周组织工程系指将在体外以理想的种子细胞和细胞外基质构建的具有生命活性的复合体植入牙周缺损部位,对牙周缺损部位进行结构功能性重建。组织工程细胞膜片构建主要有温敏培养皿、刮取法、胶原凝胶法、磁力组织工程法、表面粗糙颗粒单分子层法和聚合电解质等。牙周组织工程细胞片主要有牙周膜干细胞和骨髓间充质干细胞片,分别将其与不同的载体叠加并植入动物体内,可发现细胞外基质和纤维黏附,牙骨质样组织和牙周组织再生。将人牙周膜成纤维细胞和人脐静脉内皮细胞、人真皮成纤维细胞和人脐静脉内皮细胞共培养,所形成的细胞片可生成类似原生血管的管状结构。目前的组织工程细胞片的生物力学性能较差,与传统支架结合仍然存在着材料降解引起的组织纤维化和免疫排斥等问题,组织工程细胞片在牙周组织工程应用中具有较大应用前景;但是,要实现牙周组织的完全再生,其技术有待进一步的研究。本文就细胞片的构建、不同的牙周组织工程细胞片、细胞片工程面临的问题等研究进展作一综述。     

脱乙酰壳多糖支架在牙周组织工程中的应用

脱乙酰壳多糖生物材料尽管具有良好的生物相容性,但其作为牙周组织工程支架材料时也有自身的局限和不足。本文就牙周组织工程、脱乙酰壳多糖、脱乙酰壳多糖牙周组织工程支架等研究进展作一综述。     

组织工程牙周膜细胞片的体内实验研究

目的:探索一种形成组织工程牙周膜的新方法并建立动物模型,为牙周组织工程奠定基础。方法:原代分离培养人牙周膜细胞,部分细胞复合明胶海绵设为对照组;另一部分细胞经特殊条件连续培养成细胞膜片设为实验组。2组实验结果择优复合支架材料后植入裸鼠皮下,4周后取材行组织病理检测。结果:经特殊条件连续培养的牙周膜细胞层叠交错相连形成具有良好的机械加工性能的生物膜片,该膜片经裸鼠体内培养形成牙周膜样组织,并在近羟基磷灰石支架侧有矿化的牙骨质样结构生成。结论:该方法制备的牙周膜细胞片在牙周组织工程具有良好的应用前景。     

Application of eGFP to label human periodontal ligament stem cells in periodontal tissue engineering

ObjectivesTo establish human periodontal ligament stem cells (hPDLSC) with high and stable expression of enhanced green fluorescent protein (eGFP) and to obtain an ideal vector expression system that suitable for gene therapy in periodontal tissue engineering.MethodshPDLSCs were transfected with eGFP for 48 h via different MOI (25, 50, 100, 200 and 400) by lentiviral vector, the transfection efficiency was evaluated by fluorescent microscopy and flow cytometry, and transfected hPDLSCs proliferation was evaluated by MTT. Pluripotent, differentiation capacity and ALP expression status were determined further. Osteoblast-associated genes expressions for osteogenesis were evaluated by quantitative-PCR. In addition, rat molar periodontal fenestration defect model was used for evaluating periodontal tissue engineering.ResultsThe transfection efficiency after 48 h were 44.7%, 60.9%, 71.7%, 85.8%, and 86.9% respectively. There was no significant effect of transfection (at different MOI levels of 25, 50, 100, and 200) on the proliferation of hPDLSCs (designated as eGFP-hPDLSCs) compared with hPDLSCs (P > 0.05). However, proliferation of eGFP hPDLSCs at MOI 400 became slower (P < 0.05). Both eGFP hPDLSCs and hPDLSCs were able to differentiate into osteocytes and adipocytes under certain conditioned media. At 7 days, expression levels of COL-1, RUNX2 in hPDLSCS were higher than those in eGFP hPDLSCs (P < 0.05); expression levels of ALP and OPN in eGFP hPDLSCs were similar to those in hPDLSCs (P > 0.05). Newly regenerated bone formation was observed in the defect model used.ConclusionsAmong the transfection conditions, 48 h transfection at MOI 200 is optimal for labelling hPDLSCs with eGFP in a lentiviral vector. There is no change in capability of the eGFP hPDLSCs osteogenesis. The lentiviral vector with eGFP is an appropriate expression vector system and hPDLSCs are ideal seeding cells for gene therapy in periodontal tissue engineering.     

Regeneration of periodontal ligament and cementum by BMP-applied tissue engineering

Previously, we demonstrated that the inductive properties of bone morphogenetic protein (BMP) highly depend on the nature of the carrier material used for implantation. In this paper, we show that administration of BMP incorporated in a fibrous collagen membrane can help to regenerate periodontal ligament and cementum both in cat canines and in monkey molars. The partially purified bovine BMP was combined with one or two layers of a fibrous collagen membrane. Although the single layer approach showed partial regeneration of periodontal defects, it also quite often led to ankylosis. The double layer technique in artificially prepared class III furcation defects in monkey molars gave favorable results. After 12 wk, not only the alveolar process but also the periodontal ligament and cementum had regenerated along the entire treated dentin surface. Collagen fibers were arranged more or less perpendicular to the surface of the new cementum. Ankylosis was not seen. It is concluded that the double-layer approach is superior to the single-layer technique in regenerating cementum.     

Tissue engineering for periodontal regeneration

As a result of periodontal regeneration research, a series of clinical techniques have emerged that permit tissue engineering to be performed for more efficient regeneration and repair of periodontal defects and improved implant site development. Historically, periodontal regeneration research has focused on a quest for "magic filler" material. This search has led to the development of techniques utilizing autologous bone and bone marrow, allografts, xenografts, and various man-made bone substitutes. Though these techniques have had limited success, the desire for a more effective regenerative approach has resulted in the development of tissue engineering techniques. Tissue engineering is a relatively new field of reconstructive biology which utilizes mechanical, cellular, or biologic mediators to facilitate reconstruction/regeneration of a particular tissue. In periodontology, the concept of tissue engineering had its beginnings with guided tissue regeneration, a mechanical approach utilizing nonresorbable membranes to obtain regeneration in defects. In dental implantology, guided bone regeneration membranes +/- mechanical support are used for bone augmentation of proposed implant placement sites. With the availability of partially purified protein mixture from developing teeth and growth factors from recombinant technology, a new era of tissue engineering whereby biologic mediators can be used for periodontal regeneration. The advantage of recombinant growth factors is this tissue engineering device is consistent in its regenerative capacity, and variations in regenerative response are due to individual healing response and/or poor surgical techniques. In this article, the authors review how tissue engineering has advanced and discuss its impact on the clinical management of both periodontal and osseous defects in preparation for implant placement. An understanding of these new tissue engineering techniques is essential for comprehending today's ever-expanding oral plastic surgery procedures.     

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

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

应用组织工程技术修复牙周组织缺损的研究进展

牙周病可造成牙槽骨吸收、牙齿脱落。组织工程技术在牙周组织再生治疗中的应用,为牙周病的治疗及牙周缺损的修复提供了新的技术手段。本文就近年来牙周组织再生治疗中关于生物材料、生长因子、细胞治疗和基因治疗等组织工程技术的研究及应用进展作一综述。     

脂肪干细胞在牙周组织工程学中的应用前景

脂肪干细胞（adipose tissue-derived stem cells，ADSCs），是一种新的组织工程的干细胞来源。本文阐述了脂肪组织干细胞优势，并对脂肪干细胞的培养与鉴定以及成骨分化潜能，在牙周组织工程学中的潜在应用前景作一综述。     

脂肪干细胞在牙周组织工程学中的的应用前景

脂肪干细胞(adipose tissue-derived stem cells,ADSCs),是一种新的组织工程的干细胞来源.本文阐述了脂肪组织干细胞优势,并对脂肪干细胞的培养与鉴定以及成骨分化潜能,在牙周组织工程学中的潜在应用前景作一综述.