Periodontal tissue engineering by growth factors

Dual delivery of rhPDGF-BB and bone marrow mesenchymal stromal cells expressing the BMP2 gene enhance bone formation in a critical-sized defect model

Bone tissue healing is a dynamic, orchestrated process that relies on multiple growth factors and cell types. Platelet-derived growth factor-BB (PDGF-BB) is released from platelets at wound sites and induces cellular migration and proliferation necessary for bone regeneration in the early healing process. Bone morphogenetic protein-2 (BMP-2), the most potent osteogenic differentiation inducer, directs new bone formation at the sites of bone defects. This study evaluated a combinatorial treatment protocol of PDGF-BB and BMP-2 on bone healing in a critical-sized defect model. To mimic the bone tissue healing process, a dual delivery approach was designed to deliver the rhPDGF-BB protein transiently during the early healing phase, whereas BMP-2 was supplied by rat bone marrow stromal cells (BMSCs) transfected with an adenoviral vector containing the BMP2 gene (AdBMP2) for prolonged release throughout the healing process. In in vitro experiments, the dual delivery of rhPDGF-BB and BMP2 significantly enhanced cell proliferation. However, the osteogenic differentiation of BMSCs was significantly suppressed even though the amount of BMP-2 secreted by the AdBMP2-transfected BMSCs was not significantly affected by the rhPDGF-BB treatment. In addition, dual delivery inhibited the mRNA expression of BMP receptor type II and Noggin in BMSCs. In in vivo experiments, critical-sized calvarial defects in rats showed enhanced bone regeneration by dual delivery of autologous AdBMP2-transfected BMSCs and rhPDGF-BB in both the amount of new bone formed and the bone mineral density. These enhancements in bone regeneration were greater than those observed in the group treated with AdBMP2-transfected BMSCs alone. In conclusion, the dual delivery of rhPDGF-BB and AdBMP2-transfected BMSCs improved the quality of the regenerated bone, possibly due to the modulation of PDGF-BB on BMP-2-induced osteogenesis.

Percutaneous injection of augment injectable bone graft (rhPDGF-BB and β-tricalcium phosphate [β-TCP]/bovine type I collagen matrix) increases vertebral bone mineral density in geriatric female baboons

BACKGROUND CONTEXT

Recombinant human platelet-derived growth factor-BB (rhPDGF-BB) homodimer is a chemotactic, mitogenic, and angiogenic factor expressed by platelets. This biological triad is profoundly important in the bone regenerative cascade. Therefore, the expectation was that rhPDGF-BB locally administered to designated lumbar vertebrae in a soluble Type I bovine collagen/β-tricalcium phosphate (β-TCP) injectable paste would have an osteoanabolic effect.

PURPOSE

The study objective focused on safety and efficacy of the rhPDGF-BB and soluble Type I bovine collagen/β-TCP to increase bone density when injected directly into specific lumbar vertebral bodies in elderly (17- to 18-year-old) female baboons.

STUDY DESIGN/SETTING

The study was designed to determine whether vertebral bone mineral density (BMD) in aged female baboons could be increased by locally administering recombinant rhPDGF-BB combined in a soluble Type I bovine collagen/β-TCP paste formulation.

METHODS

A total of six baboons were divided equally into two groups. Group 1 received 1.0 mg/mL rhPDGF-BB in 20 mM sodium acetate plus soluble Type I bovine collagen/β-TCP. Group 2 was treated with 20 mM sodium acetate plus soluble Type I bovine collagen/β-TCP. Baboons in each group also received a sham surgery. Surgery was conducted using a percutaneous, fluoroscopically guided approach, and quantitative computed tomography (qCT) and radiographs were done at dedicated time periods. The qCT was used to determine volumetric BMD (vBMD). At euthanasia (36-week posttreatment), lumbar vertebrae were recovered and analyzed by qCT scans and histology. Funds were received to support this work from BioMimetic Therapeutics, Inc. The device that is the subject of this manuscript is not Food Drug Administration approved for this indication and is not commercially available in the United States.

RESULTS

The qCT and histopathological data suggested that vBMD and bone morphology increased significantly in the lumbar vertebrae treated with the rhPDGF-BB-containing composition.

CONCLUSIONS

Bone mineral density and bone morphology quality of lumbar vertebrae in aged female baboons were improved by direct injection of rhPDGF-BB in a soluble Type I bovine collagen/β-TCP paste. Throughout the course of the study, there were neither local nor systemic adverse effects.

Bone morphogenetic protein-2-impregnated biomimetic scaffolds successfully induce bone healing in a marginal mandibular defect

OBJECTIVES/HYPOTHESIS

To test the osteoregenerative potential and dosing of bone morphogenetic protein-2 (BMP-2)-impregnated biomimetic scaffolds in a rat model of a mandibular defect.

STUDY DESIGN

Prospective study using an animal model.

METHODS

Varied doses of BMP-2 (0.5, 1, 0.5, 0.5 in microspheres, 5, and 15 μg) were absorbed onto a biomimetic scaffold. Scaffolds were then implanted into marginal mandibular defects in rats. Blank scaffolds and unfilled defects were used as negative controls. Two months postoperatively, bone healing was analyzed with microcomputerized tomography (microCT).

RESULTS

MicroCT analysis demonstrated that all doses of BMP-2 induced successful healing of marginal mandibular defects in a rat mandible. Increasing doses of BMP-2 on the scaffolds produced increased tissue healing, with 15 μg demonstrating significantly more healing than all other dosing (P < .01).

CONCLUSIONS

BMP-2-impregnated biomimetic scaffolds successfully induce bone healing in a marginal mandibular defect in the rat. Percentage healing of defect, percentage of bone within healed tissue, and total bone volume are all a function of BMP-2 dosing. There appears to be an optimal dose of 5 μg beyond which there is no increase in bone volume.

LEVEL OF EVIDENCE

NA.

Clinical Comparison of Autogenous Bone Graft with and without Plasma Rich in Growth Factors in the Treatment of Grade II Furcation Involvement of Mandibular Molars

Background and aims

Plasma rich in growth factors (PRGF) is a concentrated suspension of growth factors, which is used to promote periodontal tissue regeneration. The aim of this randomized, controlled, clinical trial was to evaluate of the treatment of grade II mandibular molar furcation involvement using autogenous bone graft with and without PRGF.

Materials and methods

In this double-blind clinical trial, thirty mandibular molars with grade II furcation involvement in 30 patients were selected. The test group received bone graft combined with PRGF, while the control group was treated with bone graft only. Clinical parameters included clinical probing depth (CPD), vertical clinical attachment level (V-CAL), horizontal clinical attachment level (H-CAL), location of gingival margin (LGM), surgically exposed horizontal probing depth of bony defect (E-HPD), vertical depth of bone crest (V-DBC), vertical depth of the base of bony defect (V-DBD), and length of the intrabony defect (LID). After six months, a re-entry surgery was performed. Data were analyzed by SPSS 14, using Kolmogorov, Mann-Whitney U, and paired t-test.

Results

After 6 months, both treatment methods led to significant improvement in V-CAL and H-CAL and significant decreases in CPD, E-HPD, V-DBD and LID; there was no significant difference in LGM and V-DBC in any of the treated groups compared to the baseline values. Also, none of the parameters showed significant differences between the study groups.

Conclusion

Although autogenous bone grafts, with or without PRGF, were successful in treating grade II furcation involvement, no differences between the study groups were observed.

Use of plasma rich in growth factor for schneiderian membrane management during maxillary sinus augmentation procedure

The aim of this pilot study was to present a novel technique for the management of the Schneiderian membrane during maxillary sinus lift surgery using plasma rich in growth factors (PRGF). Eight maxillary sinuses were augmented in 8 patients. Two small perforations of the Schneiderian membrane occurred during the lifting procedure, which were solved using the PRGF clot before grafting the site with PRGF and anorganic bovine bone. With the exception of 1 patient who experienced pain following an acute sinus infection after 3 days of uneventful healing, the patients' postoperative quality of life was generally good. The most common complication (50% of cases) was hematoma, which disappeared after 1 week. Despite the limitations of this study concerning the sample size and the study design, the use of PRGF may be helpful in reducing complications following sinus lift surgery. More well-designed studies, with larger sample size, are needed to validate this protocol.

Tissue engineering: A new vista in periodontal regeneration

Tissue engineering is a highly promising field of reconstructive biology that draws on recent advances in medicine, surgery, molecular and cellular biology, polymer chemistry, and physiology. The objective of using tissue engineering as therapeutic application has been to harness its ability to exploit selected and primed cells together with an appropriate mix of regulatory factors, to allow growth and specialization of cells and matrix. The authors reviewed controlled clinical trials which also included histological studies that evaluated the potential of tissue engineering as a clinical tool in regeneration. PubMed/MEDLINE databases were searched for studies up to and including June 2010 to identify appropriate articles. A comprehensive search was designed, and the articles were independently screened for eligibility. Articles with authentic controls and proper randomization and pertaining specifically to their role in periodontal regeneration were included. Studies demonstrated that the periodontal regeneration with the use of combination of tissue engineered products with an osteoconductive matrix improve the beneficial effect of these materials by accelerating cellular in growth and revascularization of the wound site. Studies have suggested the use of rh Platelet-derived growth factor + beta tricalcium phosphate for regeneration of the periodontal attachment apparatus in combination with collagen membranes as an acceptable alternative to connective tissue graft for covering gingival recession defects. The studies concluded that growth factors promote true regeneration of the periodontal attachment apparatus and the use of combination protein therapeutics which is commercially available can provide more predictable, faster, less invasive, less traumatic, and efficient outcome for the patient.

Bone repair cells for craniofacial regeneration

Reconstruction of complex craniofacial deformities is a clinical challenge in situations of injury, congenital defects or disease. The use of cell-based therapies represents one of the most advanced methods for enhancing the regenerative response for craniofacial wound healing. Both somatic and stem cells have been adopted in the treatment of complex osseous defects and advances have been made in finding the most adequate scaffold for the delivery of cell therapies in human regenerative medicine. As an example of such approaches for clinical application for craniofacial regeneration, Ixmyelocel-T or bone repair cells are a source of bone marrow derived stem and progenitor cells. They are produced through the use of single pass perfusion bioreactors for CD90+ mesenchymal stem cells and CD14+ monocyte/macrophage progenitor cells. The application of ixmyelocel-T has shown potential in the regeneration of muscular, vascular, nervous and osseous tissue. The purpose of this manuscript is to highlight cell therapies used to repair bony and soft tissue defects in the oral and craniofacial complex. The field at this point remains at an early stage, however this review will provide insights into the progress being made using cell therapies for eventual development into clinical practice.

Calcium phosphate composite layers for surface-mediated gene transfer

In this review, the surface-mediated gene transfer system using calcium phosphate composite layers is described. Calcium phosphate ceramics are osteoconductive bioceramics used typically in orthopedic and dental applications. Additionally, calcium phosphate particles precipitated by a liquid-phase process have long been used as a safe and biocompatible transfection reagent in molecular biology. Recently, calcium phosphate composite layers immobilizing DNA were fabricated on the surfaces of base materials through a biomimetic process using supersaturated solutions. These composite layers possess useful characteristics of both osteoconductive bioceramics and transfection reagents; they thus provide a biocompatible surface to support cell adhesion and growth, and can stimulate the cell effectively via surface-mediated gene transfer. By modifying the fabrication conditions, physicochemical and biological properties of the composite layers can be varied. With such an approach, these composite layers can be designed to have improved affinity for cells and to exhibit increased gene transfer efficiency over that of conventional lipid transfection reagents. The composite layers with the increased gene transfer efficiency induced specific cell differentiation and tissue regeneration in vivo. These composite layers, given their good biocompatibility and the potential to control cell behavior on their surfaces, have great potential in tissue engineering applications.

Periodontal regeneration employing gingival margin-derived stem/progenitor cells: an animal study

AIM

This study investigated the periodontal regenerative potential of gingival margin-derived multipotent postnatal stem/progenitor cells.

MATERIAL AND METHODS

Periodontal defects were induced at six sites in eight miniature pigs in the premolar/molar area (-4 weeks). Autologous cells isolated from the gingival margin were magnetically sorted using STRO-1 antibodies and characterized flow cytometrically for the expression of CD14, CD31, CD34, CD45, CD117 and STRO-1 surface markers. Colony formation and multilineage differentiation potential were tested. The cells were expanded and loaded on deproteinized bovine cancellous bone (DBCB) and Collagen scaffolds. Within every miniature pig, six periodontal defects were randomly treated with loaded-DBCB (test group 1), unloaded-DBCB (control group 1), loaded-Collagen scaffolds (test group 2), unloaded-Collagen scaffolds (control group 1), scaling and root planing (negative control 1) or left untreated (negative control 2). Differences in clinical attachment level (ΔCAL), probing depth (ΔPD), gingival recession (ΔGR) and radiographic defect volume (ΔRDV) between baseline and 12 weeks, as well as histological attachment level (HAL), junctional epithelium length (JE) and connective tissue adhesion (CTA) after 12 weeks were evaluated.

RESULTS

Isolated cells showed stem/progenitor cell characteristics. Cell-loaded scaffolds showed higher ΔCAL, ΔPD, ΔGR, HAL and lower JE and CTA compared with unloaded scaffolds and negative controls. The sort of scaffold had no significant influence on the measured outcomes.

CONCLUSION

Gingival margin-derived stem/progenitor cells show significant periodontal regenerative potential.

Advanced reconstructive technologies for periodontal tissue repair

Reconstructive therapies to promote the regeneration of lost periodontal support have been investigated through both preclinical and clinical studies. Advanced regenerative technologies using new barrier-membrane techniques, cell-growth-stimulating proteins or gene-delivery applications have entered the clinical arena. Wound-healing approaches using growth factors to target the restoration of tooth-supporting bone, periodontal ligament and cementum are shown to significantly advance the field of periodontal-regenerative medicine. Topical delivery of growth factors, such as platelet-derived growth factor, fibroblast growth factor or bone morphogenetic proteins, to periodontal wounds has demonstrated promising results. Future directions in the delivery of growth factors or other signaling models involve the development of innovative scaffolding matrices, cell therapy and gene transfer, and these issues are discussed in this paper.

Postextraction osteotome sinus floor elevation technique using plasma-rich growth factors

PURPOSE

To evaluate a modified osteotome sinus floor elevation technique with immediate postextraction implant placement and the adjunct of a platelet-derived fibrin plug for the rehabilitation of maxillary premolar sites.

MATERIAL AND METHODS

Fifteen patients with nonrestorable fractured endodontically treated maxillary premolars were consecutively enrolled in the study. After extraction, the membrane was gradually elevated using osteotomes, with the interposition of a fibrin clot. Subsequently, an implant embedded with plasma very rich in growth factors was inserted.

RESULTS

No implant failed after a mean follow-up of 35 months. The average membrane lift was 2.9 ± 0.8 mm. After 1 year of loading, marginal bone loss averaged 0.36 ± 0.19 mm. No postoperative symptoms were reported. All patients reported full satisfaction for mastication function, phonetics, and aesthetics.

CONCLUSIONS

The present technique represents a viable option for the rehabilitation of fresh postextraction maxillary premolar sockets.

Effect of platelet concentrate on quality of life after periradicular surgery: a randomized clinical study

INTRODUCTION

Control of postoperative discomfort might enhance the patient's quality of life and treatment acceptance. The aim of the present randomized single-blind study was to evaluate whether the use of platelet concentrate during endodontic surgery might have a favorable impact on pain and other factors related to patient's quality of life during the first week after surgery.

METHODS

Eighteen patients with periapical lesion were treated with modern endodontic surgical procedure (control group). In another 18 patients, in adjunct to surgical procedure, platelet concentrate was applied on the root end in liquid form, within the bone defect in clot form, and over the suture in liquid form (test group). All patients completed a questionnaire for evaluation of main symptoms and daily activities during the first week after surgery. The outcomes of the questionnaires of the 2 groups were statistically compared.

RESULTS

The test group showed significantly less pain and swelling, fewer analgesics taken, and improved functional activities as compared with the control group.

CONCLUSIONS

The adjunct of platelet concentrate to the endodontic surgical procedure produced significant beneficial effect to patients' quality of life during the early postoperative stage.

Treatment of through-and-through bone lesion using autologous growth factors and xenogeneic bone graft: a case report

BACKGROUND

This pilot case study aimed at evaluating the possibility of achieving optimal hard and soft tissue regeneration using plasma rich in growth factors (PRGF) and anorganic bovine bone (ABB) for the surgical treatment of a large through-and-through periapical bone lesion.

CASE REPORT

Maxillary incisors of a patient with through-and-through periapical lesion of endodontic origin were treated using modern endodontic surgical technique with the adjunct of PRGF. The PRGF clot was positioned over the palatal side of the lesion while the remaining bone defect was grafted with PRGF and ABB. A collagen membrane embedded with plasma very rich in growth factors covered the graft. Post-operative pain and swelling were negligible, and soft tissue healing was very fast. One-year clinical and radiographic outcome showed complete healing and functionality.

DISCUSSION

The addition of PRGF to ABB could improve the regenerative process, reducing postoperative symptoms and resulting in a fast and predictable hard and soft tissue healing.

Insulin-like growth factor 1 enhances the proliferation and osteogenic differentiation of human periodontal ligament stem cells via ERK and JNK MAPK pathways

Insulin-like growth factor 1 (IGF-1) is a potent mitogenic protein which can enhance the osteogenic differentiation of periodontal ligament (PDL) fibroblasts. However, it remains unclear whether IGF-1 can stimulate the osteogenic differentiation and osteogenesis of human periodontal ligament stem cells (PDLSCs). In this study, STRO-1(+) PDLSCs were isolated from human PDL tissues, treated with IGF-1, and their osteogenic capacity was investigated in vitro and in vivo. Dimethyl-thiazol-diphenyl tetrazolium bromide assay and flow cytometry results demonstrated that 10-200 ng/mL IGF-1 can stimulate the proliferation ability of PDLSCs and 100 ng/mL is the optimal concentration. Exogenous IGF-1 can modify the ultrastructure, enhance the alkaline phosphatase activity, the mineralization ability of PDLSCs, and increase the expression of osteogenic markers (runt-related transcription factor 2, osterix, and osteocalcin) at mRNA and protein levels. In vivo transplantation illustrated that IGF-1 treated implants generated more mineralized tissues, and presented stronger expression of RUNX2, OSX, and OCN than control group. Moreover, the expression of phosphor-ERK and phosphor-JNK in these stem cells was upregulated by IGF-1, indicating that MAPK signaling pathway was activated during the osteogenic differentiation of PDLSCs mediated by IGF-1. Together, the results showed that IGF-1 can promote the osteogenic differentiation and osteogenesis of STRO-1(+) PDLSCs via ERK and JNK MAPK pathway, suggesting that IGF-1 is a potent agent for stem cell-based periodontal tissue regeneration.

Effects of the immobilization of heparin and rhPDGF-BB to titanium surfaces for the enhancement of osteoblastic functions and anti-inflammation

PURPOSE

This study was to investigate the effects of recombinant human platelet-derived growth factor (rhPDGF-BB) and heparin to titanium surfaces for enhancement of osteoblastic functions and inhibition of inflammation activity.

MATERIALS AND METHODS

The anodized titanium discs, not coated with any material, were used as a control group. In heparinized- Ti group, dopamine was anchored to the surface of Ti substrates, and coated with heparin. In PDGF-Ti group, rhPDGF-BB was immobilized onto heparinized Ti surface. The surface morphologies were investigated by the scanning electron microscope in each group. The release kinetics of rhPDGF-BB were analyzed, and cytotoxicity tests for each group were conducted. The biocompatibilities were characterized by measuring cell proliferation, alkaline phosphatase activity, and calcium deposition using MG-63 cells. Statistical comparisons were carried out by one-way ANOVA tests. Differences were considered statistically significant at ^*P<.05 and ^**P<.001.

RESULTS

The combination of rhPDGF-BB and heparin stimulated alkaline phosphatase activity and OCN mRNA expression in osteoblastic cells (^*P<.05 and ^**P<.001). MG-63 cells grown on PDGF-Ti had significantly higher amounts of calcium deposition than those grown on anodized Ti (^**P<.001). Heparinized Ti was more anti-inflammatory compared to anodized Ti, when exposed to lipopolysaccharide using the transcript levels of TNF-α and IL-6 of proinflammatory cytokine (^*P<.05 and ^**P<.001).

CONCLUSION

The result of this study demonstrated that the incorporation of rhPDGF-BB and heparin onto Ti surface enhanced osteoblastic functions and inhibited inflammation.

Is autologous platelet concentrate beneficial for post-extraction socket healing? A systematic review

The aim of this systematic review was to assess if the use of autologous platelet concentrates may be beneficial to the healing of extraction sockets. Medline, Embase and Cochrane Central Register of Controlled Trials were searched using a combination of specific search terms. Hand searching of the relevant journals and of the bibliographies of reviews was also performed. Prospective comparative studies evaluating the effect of a platelet concentrate on fresh extraction sockets were included. Outcome variables related to hard and soft tissue healing, aesthetics and postoperative discomfort were considered. A methodological study quality assessment was made. The initial search yielded 425 articles, eight were finally included. 207 tooth extractions (104 tests and 103 controls) in 115 patients were evaluated. The articles provided a broad range of variable outcomes to assess the regenerative potential of platelet concentrate and its possible benefits to the treatment. Favourable effects on hard and soft tissue healing and postoperative discomfort reduction were often reported. A large heterogeneity was found regarding study design, sample size, surgical techniques and methods for preparing platelet concentrates. Standardization of experimental design is needed in order to detect the true effect of platelet concentrates in regenerative procedures of extraction sockets.

Effect of coating Straumann Bone Ceramic with Emdogain on mesenchymal stromal cell hard tissue formation

Periodontal tissue engineering requires a suitable biocompatible scaffold, cells with regenerative capacity, and instructional molecules. In this study, we investigated the capacity of Straumann Bone Ceramic coated with Straumann Emdogain, a clinical preparation of enamel matrix protein (EMP), to aid in hard tissue formation by post-natal mesenchymal stromal cells (MSCs) including bone marrow stromal cells (BMSCs) and periodontal ligament fibroblasts (PDLFs). MSCs were isolated and ex vivo-expanded from human bone marrow and periodontal ligament and, in culture, allowed to attach to Bone Ceramic in the presence or absence of Emdogain. Gene expression of bone-related proteins was investigated by real time RT-PCR for 72 h, and ectopic bone formation was assessed histologically in subcutaneous implants of Bone Ceramic containing MSCs with or without Emdogain in NOD/SCID mice. Alkaline phosphatase activity was also assessed in vitro, in the presence or absence of Emdogain. Collagen-I mRNA was up-regulated in both MSC populations over the 72-h time course with Emdogain. Expression of BMP-2 and the osteogenic transcription factor Cbfa-1 showed early stimulation in both MSC types after 24 h. In contrast, expression of BMP-4 was consistently down-regulated in both MSC types with Emdogain. Up-regulation of osteopontin and periostin mRNA was restricted to BMSCs, while higher levels of bone sialoprotein-II were observed in PDLFs with Emdogain. Furthermore, alkaline phosphatase activity levels were reduced in both BMSCs and PDLFs in the presence of Emdogain. Very little evidence was found for ectopic bone formation following subcutaneous implantation of MSCs with Emdogain-coated or -uncoated Bone Ceramic in NOD/SCID mice. The early up-regulation of several important bone-related genes suggests that Emdogain may have a significant stimulatory effect in the commitment of mesenchymal cells to osteogenic differentiation in vitro. While Emdogain inhibited AP activity and appeared not to induce ectopic bone formation, longer-term studies are required to determine whether it promotes the final stages of osteoblast formation and mineralization at gene and protein levels. While used in clinical applications, whether Emdogain and other commercial preparations of EMPs truly possess the capacity to induce the regeneration of bone or other components of the periodontium remains to be established.

Effect of autologous growth factors in maxillary sinus augmentation: a systematic review

PURPOSE

The aim of the present study was to systematically evaluate the effect of autogenous platelet concentrates on the clinical and histomorphometric outcomes of maxillary sinus augmentation.

MATERIALS AND METHODS

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched using a combination of specific search terms. Furthermore, a hand searching of the relevant journals and of the bibliographies of reviews was performed. Prospective comparative clinical studies were included. Implant survival and histomorphometric outcomes were evaluated.

RESULTS

Twelve studies were included. Four hundred forty-five sinus floor augmentation procedures were considered. No difference in implant survival was reported between test and control groups. Six studies reported a beneficial effect of platelet concentrates based on histomorphometric outcomes, while another six studies found no significant effect. A large heterogeneity was found regarding study design, surgical techniques, graft materials, clinical and histomorphometric outcome variables, and methods for preparing platelet concentrates. Favorable effects on soft tissue healing and postoperative discomfort reduction were often reported but not quantified.

CONCLUSIONS

A clear advantage of platelet concentrates could not be evidenced. Standardization in the experimental design is needed in order to detect the true effect of platelet concentrates in maxillary sinus augmentation procedure, especially regarding postoperative quality of life.

Is platelet concentrate advantageous for the surgical treatment of periodontal diseases? A systematic review and meta-analysis

BACKGROUND

The aim of the present review is to systematically evaluate the effects of autogenous platelet concentrates on clinical outcomes of the surgical treatment of periodontal diseases.

METHODS

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched using a combination of specific search terms. Furthermore, a hand search of relevant journals and bibliographies of reviews was performed. Only randomized clinical trials were included. For periodontal intrabony defects, the primary outcome variable was the clinical attachment level. For gingival recession, outcome variables were root coverage and keratinized tissue increase. Data were adjusted for baseline values. The methodologic quality of the included studies was assessed. The results of studies in which the only difference between test and control groups was the adjunct of platelet concentrates were aggregated using a meta-analysis. For intrabony defects, the influences of guided tissue regeneration (GTR) and study type (split-mouth versus parallel studies) were also evaluated.

RESULTS

The initial search yielded 424 studies. Of the 29 eligible studies, 24 studies were included. There were 16 studies on the treatment of periodontal intrabony defects, all of which used platelet-rich plasma (PRP); six studies on gingival recession treatment; and two studies on the treatment of furcation defects. A significant positive effect of the adjunct of PRP was found for intrabony defects. Such an effect was magnified in studies in which GTR was not used, whereas in studies using GTR, the use of PRP had no adjunctive effect. No effect of the study type was found. No significant effect of platelet concentrates was found for gingival recession treatment in which only studies with a follow-up ≤6 months displayed positive results. No significant benefit of PRP could be demonstrated for furcation treatment.

CONCLUSIONS

PRP may exert a positive adjunctive effect when used in combination with graft materials, but not with GTR, for the treatment of intrabony defects. No significant benefit of platelet concentrates was found for the treatment of gingival recession.

Significant type I and type III collagen production from human periodontal ligament fibroblasts in 3D peptide scaffolds without extra growth factors

We here report the development of two peptide scaffolds designed for periodontal ligament fibroblasts. The scaffolds consist of one of the pure self-assembling peptide scaffolds RADA16 through direct coupling to short biologically active motifs. The motifs are 2-unit RGD binding sequence PRG (PRGDSGYRGDS) and laminin cell adhesion motif PDS (PDSGR). RGD and laminin have been previously shown to promote specific biological activities including periodontal ligament fibroblasts adhesion, proliferation and protein production. Compared to the pure RADA16 peptide scaffold, we here show that these designer peptide scaffolds significantly promote human periodontal ligament fibroblasts to proliferate and migrate into the scaffolds (for approximately 300 microm/two weeks). Moreover these peptide scaffolds significantly stimulated periodontal ligament fibroblasts to produce extracellular matrix proteins without using extra additional growth factors. Immunofluorescent images clearly demonstrated that the peptide scaffolds were almost completely covered with type I and type III collagens which were main protein components of periodontal ligament. Our results suggest that these designer self-assembling peptide nanofiber scaffolds may be useful for promoting wound healing and especially periodontal ligament tissue regeneration.

Development and validation of a multiplex bead assay for measuring growth mediators in wound fluid

Large amounts of biological samples are usually required to measure multiple components by the enzyme-linked immunosorbant assay. However, the amounts of many tissue extracts and fluids, including gingival crevicular fluid (GCF), are generally extremely small. The aim of this study was, therefore, to develop and validate a novel multiplex bead assay (MBA) to simultaneously measure a profile of healing-related mediators in the GCF of treated periodontal wounds. An MBA was developed and validated by assessment of assay selectivity, recovery, precision and sensitivity, using eight recombinant human growth mediators as assay standards. GCF samples were collected on paper strips from healing wound (test) and healthy unaffected (control) sites of 15 patients with periodontitis, seven days post-periodontal surgery. Each GCF sample was eluted and the levels of the mediators measured using the MBA and antibody pairs specific for angiopoietin-1, vascular endothelial growth-factor, bone morphogenetic protein-2, osteoprotegerin, tissue inhibitor of metalloprotease-1 (TIMP-1), basic fibroblast growth-factor, keratinocyte growth-factor, and platelet derived growth-factor. Less than 1.8% of cross-reactivity was observed between antibodies and the eight different analytes, for which the recovery was more than 85%. Mean intra- and inter-assay precision were within the acceptance criteria of 20% and 25%, respectively. Detection of all mediators was highly sensitive (<or=70 ng/L) except for TIMP-1 (215 ng/L). Angiogenic factors were the most highly secreted in the GCF seven days post-surgery. This new MBA can simultaneously measure small amounts of eight different growth mediators in the GCF of healing periodontal wounds. It might also be a valuable tool for evaluating the components of wound fluids as a prognostic indicator of the success of therapeutic intervention.

Immediate implant placement into fresh extraction sites with chronic periapical pathologic features combined with plasma rich in growth factors: preliminary results of single-cohort study

PURPOSE

The purpose of this prospective study was to evaluate the clinical outcome of implants immediately placed into fresh extraction sockets of teeth affected by chronic periapical pathologic findings, using plasma rich in growth factors (PRGFs) as an adjunct during the surgical procedure.

MATERIALS AND METHODS

A total of 30 partially edentulous patients with teeth requiring extraction and chronic periapical lesions were included in the present study. A total of 61 transmucosal implants were installed immediately after extraction and careful debridement combined with PRGF placement into the socket. Before insertion, the implant surface was bioactivated by humidification with liquid PRGFs. The prosthetic phase occurred 3 to 4 months after surgery. The implant success and survival and radiographic bone loss were evaluated after 1 year of function. Patient satisfaction for mastication function, phonetics, and esthetics was assessed using a questionnaire.

RESULTS

Of the 61 implants, 1 had failed 2 months after insertion because of infection. No additional complications were recorded. The overall implant success and survival rate was 98.4% at 1 year of function. The mean follow-up was 18.5 months (range 10 to 21). All prostheses were successful. The peri-implant bone loss after 1 year averaged 0.41 +/- 0.22 mm. All patients reported full satisfaction for mastication function, phonetics, and esthetics.

CONCLUSIONS

The use of PRGFs combined with an immediate implant placement procedure can be considered a safe, effective, and predictable treatment option for the rehabilitation of fresh postextraction infected sockets.

Increased osteoblast functions in the presence of BMP-7 short peptides for nanostructured biomaterial applications

To improve bone regeneration around orthopedic biomaterials, researchers have attempted to combine growth factors on and in implants. Equally as exciting, greater bone growth has been demonstrated around nanoscaled materials (like helical rosette nanotubes or nanocrystalline hydroxyapatite) that mimic the geometry of the natural components of bone. To combine these two approaches, in this in vitro study, the ability of three short peptides [labeled for convenience: a or SNVILKKYRN, b or KPSSAPTQLN, and c or KAISVLYFDDS chosen from the larger bone morphogenetic protein-7 (BMP-7)] to promote osteoblast (bone-forming cells) functions were determined. Shorter peptides of BMP-7 are required for growth factor incorporation into nanoscale biomaterials because their sizes are in the nanometer regime. Results showed that of all the peptides, peptide b and the peptide combination a,b, enhanced osteoblast density the most after 5 days when compared with the controls (no growth factors). Furthermore, osteoblasts cultured with peptide b had a larger and more spread morphology than did controls. In addition, peptide c and its combinations (a, c; b, c; and a, b, c) increased osteoblast calcium deposition after 14 and 21 days compared with the controls. Since these peptides are much smaller than BMP-7, the results of this study provided information that peptides can be easily chemically functionalized onto nanoscaled biomaterials to improve bone growth. Thus, the present study elucidated that shorter peptides in BMP-7 was found to be more appropriate for inclusion in and on nanomaterials to promote osteoblast proliferation (peptide b and the peptide combination a,b) and osteoblast deposition of calcium-containing mineral (peptide c and the peptide combinations a,c; b,c; and a, b, c).

Neural crest lineage segregation: a blueprint for periodontal regeneration

During the recent decade, the periodontal attachment apparatus has become one of the premier areas of the body for the development of novel tissue-engineering strategies. In the present review, we describe a developmental biology approach to characterize current concepts in periodontal regeneration and to discuss strategies for future applications in periodontal therapies. To decipher the developmental make-up of the periodontal region, we have followed the path of the migratory neural crest, since it gives rise to periodontal progenitor tissues, which in turn are subjected to the influence of diverse craniofacial extracellular matrices and peptide growth factors. Based on this developmental perspective, we have conducted a systematic analysis of the factors, progenitor cells, and matrices used in current periodontal tissue-engineering approaches. We propose that the developmental history of a tissue is a highly instructive design template for the discovery of novel bioengineering tools and approaches.

Effects of core binding factor alpha1 or bone morphogenic protein-2 overexpression on osteoblast/cementoblast-related gene expressions in NIH3T3 mouse cells and dental follicle cells

OBJECTIVES

Bone morphogenic protein-2 (BMP-2) has long been used to promote bone and periodontal regeneration, while core binding factor alpha1 (CBFA1) plays important roles in both osteogenic differentiation and tooth morphogenesis. The aim of this study was to evaluate the effects of CBFA1 or BMP-2 overexpression on osteoblast/cementoblast-related gene expressions in NIH3T3 cells and dental follicle cells (DFCs).

MATERIALS AND METHODS

CBFA1 or BMP-2 overexpression in NIH3T3 and DFCs was achieved by infection with retroviral vectors containing CBFA1 or BMP-2 cDNA. Cells stably integrated with CBFA1 or BMP-2 cDNA were selected with G418 for 14 days. Western blotting, real-time reverse transcriptase-polymerase chain reaction, and in vitro mineralization assay were performed to evaluate effects of CBFA1 or BMP-2 overexpression in cells undergoing osteoblast/cementoblast differentiation.

RESULTS

Our results demonstrated that osteoblast/cementoblast-related gene expression levels in CBFA1-overexpressing NIH3T3 cells were higher than those in BMP-2-overexpressing cells. More mineral nodules were observed in CBFA1-overexpressing NIH3T3 cells than in BMP-2-overexpressing cells. CBFA1 overexpression in DFCs also increased osteoblast/cementoblast-related gene expression and promoted mineral nodule formation. However, no significant changes in gene expression levels nor mineral nodule formation were found in BMP-2-overexpressing DFCs when compared with empty vector transduced DFCs.

CONCLUSIONS

CBFA1 overexpression up-regulated expression levels of osteoblast/cementoblast-related genes and enhanced in vitro osteogenic differentiation more efficiently than BMP-2 in both NIH3T3 cells and DFCs.

Tissue engineering: state of the art in oral rehabilitation

More than 85% of the global population requires repair or replacement of a craniofacial structure. These defects range from simple tooth decay to radical oncologic craniofacial resection. Regeneration of oral and craniofacial tissues presents a formidable challenge that requires synthesis of basic science, clinical science and engineering technology. Identification of appropriate scaffolds, cell sources and spatial and temporal signals (the tissue engineering triad) is necessary to optimize development of a single tissue, hybrid organ or interface. Furthermore, combining the understanding of the interactions between molecules of the extracellular matrix and attached cells with an understanding of the gene expression needed to induce differentiation and tissue growth will provide the design basis for translating basic science into rationally developed components of this tissue engineering triad. Dental tissue engineers are interested in regeneration of teeth, oral mucosa, salivary glands, bone and periodontium. Many of these oral structures are hybrid tissues. For example, engineering the periodontium requires growth of alveolar bone, cementum and the periodontal ligament. Recapitulation of biological development of hybrid tissues and interfaces presents a challenge that exceeds that of engineering just a single tissue. Advances made in dental interface engineering will allow these tissues to serve as model systems for engineering other tissues or organs of the body. This review will begin by covering basic tissue engineering principles and strategic design of functional biomaterials. We will then explore the impact of biomaterials design on the status of craniofacial tissue engineering and current challenges and opportunities in dental tissue engineering.

Assessment of the potential of growth factors for localized alveolar ridge augmentation: a systematic review

OBJECTIVE

To systematically assess the literature regarding the clinical, histological, and radiographic outcome of bone morphogenetic proteins (BMP-2, BMP-7), growth/differentiation factor-5 (GDF-5), platelet-derived growth factor (PDGF), and parathyroid hormone (PTH) for localized alveolar ridge augmentation.

MATERIAL AND METHODS

Five separate Medline searches were performed in duplicate for human and animal studies, respectively. The primary outcome of the included studies was bone regeneration of localized alveolar ridge defects or craniofacial defects.

RESULTS

In six human studies, BMP-2 affected local bone augmentation with increasing volume for higher doses. A majority (43 of 45) of animal studies using BMP-2 showed a positive effect in favour of the growth factor (GF). In six of eight studies, a positive effect was associated with the use of BMP-7. Only one animal study was included for GDF-5 revealing statistically significantly higher bone volume. Regarding PDGF, statistically significantly higher bone volume was observed in five of 10 included studies. Four animal studies using PTH revealed statistically significantly more bone regeneration compared with controls.

CONCLUSIONS

Differing levels and quantity of evidence were noted to be available for the GFs evaluated, revealing that BMP-2, BMP-7, GDF-5, PDGF, and PTH may stimulate local bone augmentation to various degrees. Human data for the potential of rhBMP-2 are supportive.

Occlusal stimuli influence on the expression of IGF-1 and the IGF-1 receptor in the rat periodontal ligament

OBJECTIVE

To test the hypothesis that hypofunction/recovered occlusal function has no effect on the changes in insulin-like growth factor-1 (IGF-1) and IGF-1 receptor expressions and cell proliferation of periodontal ligament (PDL) cells.

MATERIALS AND METHODS

To produce occlusal hypofunction, the appliances were attached to the rats' maxillary and mandibular incisors. Subsequently, occlusal contact of the molar area was thoroughly recovered by removal of the appliances.

RESULTS

In periodontal sections, localization of IGF-1, the IGF-1 receptor, and proliferating cell nuclear antigen (PCNA) immunoreactive cells was significantly more expressed in the control group compared with the hypofunctional group (P < .01). In addition, after the recovery of the occlusion, IGF-1, IGF-1 receptor, and PCNA were detected significantly much more than in the hypofunction group (P < .01).

CONCLUSION

The hypothesis was rejected. This study suggests that occlusal stimuli induce cell proliferation of PDL cells by increasing IGF-1 and IGF-1 receptor expression.

Analysis of a rapid, simple, and inexpensive technique used to obtain platelet-rich plasma for use in clinical practice

The use of platelet-rich plasma (PRP) has become more generally accepted, and implant dentists are using PRP more frequently to promote the healing of oral surgical and/or periodontal wounds. Critical elements of PRP are thought to be growth factors contained within the concentrated platelets. These growth factors are known to promote soft-tissue healing, angiogenesis and osteogenesis. We present a rapid, simple, and inexpensive methodology for preparing PRP using the Cliniseal centrifuge method. This study demonstrates that platelets are concentrated approximately 6-fold without altering platelet morphology. Further we demonstrate that key growth factors, platelet-derived growth factor BB (PDGF-BB), transforming growth factor B (TGF-B1), vasculature endothelial growth factor (VEGF), and epidermal growth factor (EGF) are present in comparable or higher concentrations than those reported with the use of other techniques. Prolonged bench set time (>3 hours) after centrifugation resulted in decreased concentration of TGF-B1 but not decreased concentration of PDGF-BB, VEGF, or EGF. This study confirms the molecular aspects of PRP obtained using this inexpensive and efficient methodology.

Preparation of highly concentrated and white cell-poor platelet-rich plasma by plateletpheresis

BACKGROUND AND OBJECTIVES

Contaminating white blood cells (WBC) contribute remarkably to the overall growth factor content of locally applicable platelet-rich plasma (PRP) or platelet (PLT) gel and change the relative proportions of the contained growth factors.

MATERIALS AND METHODS

To study the independent effects of locally applicated highly concentrated PLTs, the development of preparations is needed that contain large amounts of PLTs and no or at least very few leucocytes. Therefore, 20 plateletpheresis procedures were performed in voluntary blood donors to get highly concentrated and extremely WBC-poor plateletpheresis concentrates. The degree of spontaneous PLT activation, the PLT aggregation response to agonists and the level of the growth factor TGF-beta1 (transforming growth factor beta1) were measured immediately after the donation and 1 day later.

RESULTS

The concentrates contained 1.96 +/- 0.36 x 10e11 PLTs per unit in 55.2 +/- 7.9 ml, respectively. In comparison to the donors' blood, the PLT-enrichment factor was 15.3 +/- 5.4. At the same time, the concentrates contained extremely low residual numbers of WBCs (0.8 +/- 3.3 x 10e3/ml). The concentration of the growth factor TGF-beta1 was 743.2 +/- 243.9 ng/ml. On day 1, the PLT concentration and the TGF-beta1 content of the PLT concentrates had not decreased.

CONCLUSIONS

In summary, plateletpheresis is suited to provide PRP products with higher concentrations of human platelets and platelet-derived growth factors than previously reported PRP preparation methods but with extremely low numbers of contaminating leucocytes.

Recombinant human platelet-derived growth factor: biology and clinical applications

The abilities of bone to remodel, fractures to repair, and bone grafts to incorporate are all fundamental reflections of the bone remodeling cycle. This process is characterized by the recruitment and differentiation of osteoblastic and osteoclastic cell populations, whose cellular activities are coordinated and regulated by an elaborate system of growth factors and cytokines. One of the crucial biological factors responsible for reparative osseous activity is platelet-derived growth factor (PDGF). The potent stimulatory effects of PDGF as a chemoattractant and mitogen for mesenchymal cells (including osteogenic cells), along with its ability to promote angiogenesis, have been demonstrated in a variety of preclinical models predicting maxillofacial, spine and appendicular skeletal, and soft-tissue applications. The biological profile of PDGF, including its ability to recruit osteoprogenitor cells, makes it particularly suited to address the skeletal defects that are seen with comorbid conditions such as osteoporosis, diabetes, and the effects of smoking. The clinical success and safety that have been demonstrated with use of recombinant human PDGF (rhPDGF) in the repair of periodontal defects have led to U.S. Food and Drug Administration (FDA) approval of rhPDGF for this indication. Ongoing pilot and pivotal trials in the United States and internationally will continue to clarify the promising role of PDGF in the treatment of challenging skeletal disorders.

In Vitro Effects of Combined and Sequential Bone Morphogenetic Protein Administration

OBJECTIVE

To assess the effects of combined and sequential administration of bone morphogenetic protein 2 (BMP-2) and BMP-7 on osteoblastic differentiation compared with administration of single growth factors.

DESIGN

In vitro study of osseous differentiation in murine pluripotent cells using assays of extracellular matrix calcification, alkaline phosphatase activity, and expression of osseous markers. Mesenchymal cells were cultured with BMP-2, BMP-7, or a combination of these growth factors or were sequentially exposed to the growth factors.

RESULTS

Sequential administration of BMP-2 and BMP-7 resulted in increased extracellular matrix calcification and expression of osteocalcin, whereas all groups treated with BMP up-regulated expression of the osteoblastic transcription factor Runx2/cbfa1, type I collagen, and the inhibitory BMP second messenger Smad6. None of the experimental groups demonstrated increased expression of osteopontin or Smad1, and only cells treated with concurrent administration of BMP-2 and BMP-7 increased Smad5 expression. Alkaline phosphatase activity was increased from baseline only in cells treated with BMP-2 alone.

CONCLUSIONS

Culture with BMP-2 and BMP-7, their sequential administration, and their coadministration had variable effects on osseous differentiation in mesenchymal cells. These results demonstrate the need for increased understanding of the role of growth factors and their combinations in bone development and have important implications for the ongoing development of osteoinductive therapies.

Gene expression profiling of cells involved in periodontal regeneration

Understanding the molecular mechanisms involved in periodontal regeneration is important for the development of more predictable clinical techniques. This study aimed to identify these mechanisms by comparing the gene expression profiles of cells derived from regenerating defects with patient-matched periodontal ligament cells. Gene profiling was carried out via Affymetrix U133A arrays containing probes for 22,000 genes. Robust differences in gene expression were obtained by identifying genes that consistently changed by a minimum of 2-fold. Analysis of molecular function as designated by gene ontology (GO) identified differentially regulated mechanisms including protein metabolism, tyrosine kinase activity, and skeletal development. The differentially expressed genes could be broadly divided into the categories of protein biosynthesis and turnover, structural constituents of the cytoskeleton and extracellular matrix, and signal transduction. The differential expression of 4 genes (EGR-1, elastin, osteoprotegerin, and IGFBP3) was confirmed via real-time polymerase chain reaction (PCR). Further, the expression of another 2 differentially expressed transcripts, decorin and biglycan, was immunohistochemically confirmed in a periodontal wound healing model and the protein expression was consistent with the pattern of gene expression. This study gives insight into the molecular processes involved in periodontal regeneration and identifies cell markers that are characteristic of regenerating periodontal tissues.

Platelet-rich plasma: growth factors and pro- and anti-inflammatory properties

BACKGROUND

Platelet-rich plasma (PRP) promotes regeneration of bone, presumably through the action of concentrated growth factors. However, it is not clear how PRP affects the inflammatory response. The purpose of this study was to analyze the growth factors in PRP and to study the effects of PRP on monocyte cytokine release and lipoxin A(4) (LXA(4)) generation.

METHODS

PRP was prepared from healthy donors. Platelet-derived growth factor (PDGF)-AB, PDGF-BB, transforming growth factor-beta1, insulin-like growth factor-I, fibroblast growth factor-basic (FGF-b), epidermal growth factor (EGF), vascular endothelial growth factor, interleukin-12 (p40/70), and regulated on activation, normal T-cell expressed and secreted (RANTES) levels were evaluated by enzyme-linked immunosorbent assay and bead-based multiplexing. Peripheral blood monocytes were isolated and cultured with or without PRP. Cytokine, chemokine, and LXA(4) levels as well as monocyte chemotactic migration were analyzed.

RESULTS

Growth factors were increased significantly in PRP compared to whole blood (WB) and platelet-poor plasma. Monocyte chemotactic protein-1 (MCP-1) was suppressed significantly by PRP, whereas RANTES was increased significantly in monocyte cultures. LXA(4) levels were significantly higher in PRP compared to WB. PRP stimulated monocyte chemotaxis in a dose-dependent fashion, whereas RANTES, in part, was responsible for PRP-mediated monocyte migration.

CONCLUSIONS

PRP is a rich source of growth factors and promoted significant changes in monocyte-mediated proinflammatory cytokine/chemokine release. LXA(4) was increased in PRP, suggesting that PRP may suppress cytokine release, limit inflammation, and, thereby, promote tissue regeneration.

The use of autologous platelet-leukocyte gels to enhance the healing process in surgery, a review

BACKGROUND

The therapeutic use of autologously prepared, platelet-leukocyte-enriched gel (PLG) is a relatively new technology for the stimulation and acceleration of soft tissue and bone healing. The effectiveness of this procedure lies in the delivery of a wide range of platelet growth factors mimicking the physiologic wound healing and reparative tissue processes. Despite an increase in PLG applications, the structures and kinetics of this autogenously derived biologic material have not been observed.

METHODS

A review of the most recent literature was performed to evaluate the use of PLG in various surgical disciplines.

RESULTS

The review showed that the application of PLG has been extended to various surgical disciplines including orthopedics, cardiac surgery, plastic and maxillofacial surgery, and recently also endoscopic surgery.

CONCLUSION

This review demonstrates the usefulness of PLG in a wide range of clinical applications for improvement of healing after surgical procedures.

Reviewing the Structural Features of Autologous Platelet-Leukocyte Gel and Suggestions for Use in Surgery

The therapeutic use of autologously prepared platelet-leukocyte gel (PLG) is a relatively new technology which might stimulate and accelerate soft-tissue and bone healing. The effectiveness of this procedure lies in the exogenous delivery of a wide range of platelet growth factors, intentionally released from autologously prepared PLG. The rationale to employ this technique is to mimic physiological wound healing and reparative tissue processes. Despite an increase in clinical PLG applications, the structures and kinetics of this biological material have not been completely examined. Electron microscopic imaging was performed to evaluate platelet-leukocyte gel structures. Furthermore, directions for PLG application are presented, based on results from published articles in various surgical disciplines. In conclusion, PLG can be useful in a wide range of clinical applications to enhance healing following surgical procedures, since exogenous applied PLG releases instantly platelet growth factors, in the presence of leukocytic cells.

Three-Dimensional Culture of Human Periodontal Ligament Cells on Highly Porous Polyglycolic Acid Scaffolds in vitro

Periodontal tissue engineering represents a possible approach to regenerate the human periodontal ligament (PDL) around dental implants. The aim of this study was to observe the morphological and biological property of the human periodontal ligament cells that were three-dimensional (3D) cultured onto PGA scaffolds in vitro. The human periodontal ligament cells were seeded and cultured onto PGA 3D scaffolds, and then the cellular morphology and structure, adhesion and biocompatibility with scaffolds were evaluated by light microscope and scanning electronic microscope, and the cellular type I collagen synthesis was observed by method of immunohistochemical staining with anti-type I collagen antibody. The results indicated that the human periodontal ligament cells adhere to scaffolds well and exhibit the excellent matrix secretion ability under light microscope and scanning electronic microscope, type I collagen was expressed positively in cell-scaffolds complex by immunohistochemical staining. These results suggested that delivery of PDL Cells via non-woven PGA mesh may serve as a viable approach for promoting periodontal tissue regeneration and provides a possibility of PDL regeneration on dental implants.

Craniofacial tissue engineering by stem cells

Craniofacial tissue engineering promises the regeneration or de novo formation of dental, oral, and craniofacial structures lost to congenital anomalies, trauma, and diseases. Virtually all craniofacial structures are derivatives of mesenchymal cells. Mesenchymal stem cells are the offspring of mesenchymal cells following asymmetrical division, and reside in various craniofacial structures in the adult. Cells with characteristics of adult stem cells have been isolated from the dental pulp, the deciduous tooth, and the periodontium. Several craniofacial structures--such as the mandibular condyle, calvarial bone, cranial suture, and subcutaneous adipose tissue--have been engineered from mesenchymal stem cells, growth factor, and/or gene therapy approaches. As a departure from the reliance of current clinical practice on durable materials such as amalgam, composites, and metallic alloys, biological therapies utilize mesenchymal stem cells, delivered or internally recruited, to generate craniofacial structures in temporary scaffolding biomaterials. Craniofacial tissue engineering is likely to be realized in the foreseeable future, and represents an opportunity that dentistry cannot afford to miss.

Influence of modified extracellular matrices on TI6AL4V implants on binding and release of VEGF

Besides osteoconductive and osteoinductive signals, angiogenesis plays a crucial role in bone development and regeneration and consequently in the integration of implants. Therefore we investigated in this study the binding and release behaviour of vascular endothelial growth factor (VEGF) from Ti6Al4V surfaces coated with 3-dimensional collageneous matrices, some additionally modified with heparin. The heparin was incorporated using different methods: a) adsorptive immobilization b) crosslinking with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) or c) incorporating during self-assembly of fibrils followed by cross-linking. For unmodified samples, maximum VEGF adsorption was reached with 85 ng VEGF/cm(2). On all 3d-collagen coated surfaces studied (with or without heparin), no saturation could be observed in the range of 0-256 ng VEGF/cm(2).Improved release kinetics were observed for the modified coatings. The initial burst of VEGF within the first 24 h was diminished. From the third day of delivery heparinized matrices showed a higher release of VEGF than the pure collagen matrix and the unmodified reference surface, respectively. In vitro, the proliferation of human dermal microvascular endothelial cells was increased with released VEGF from all investigated samples compared to a VEGF-free control. After 7 days highest increases in cell numbers were observed with solutions from heparinized matrices. It is concluded that functionalization of Ti6Al4V surfaces with heparinized collageneous matrices and VEGF leads to advantageous properties concerning the impact on angiogenesis and thus may improve bone regeneration in the microenvironment of implants.