Expression of growth-factor receptors in normal and regenerating human periodontal cells

Insights into the mechanisms of diabetic wounds: pathophysiology, molecular targets, and treatment strategies through conventional and alternative therapies

Diabetes mellitus is a prevalent cause of mortality worldwide and can lead to several secondary issues, including DWs, which are caused by hyperglycemia, diabetic neuropathy, anemia, and ischemia. Roughly 15% of diabetic patient's experience complications related to DWs, with 25% at risk of lower limb amputations. A conventional management protocol is currently used for treating diabetic foot syndrome, which involves therapy using various substances, such as bFGF, pDGF, VEGF, EGF, IGF-I, TGF-β, skin substitutes, cytokine stimulators, cytokine inhibitors, MMPs inhibitors, gene and stem cell therapies, ECM, and angiogenesis stimulators. The protocol also includes wound cleaning, laser therapy, antibiotics, skin substitutes, HOTC therapy, and removing dead tissue. It has been observed that treatment with numerous plants and their active constituents, including Globularia Arabica, Rhus coriaria L., Neolamarckia cadamba, Olea europaea, Salvia kronenburgii, Moringa oleifera, Syzygium aromaticum, Combretum molle, and Myrtus communis, has been found to promote wound healing, reduce inflammation, stimulate angiogenesis, and cytokines production, increase growth factors production, promote keratinocyte production, and encourage fibroblast proliferation. These therapies may also reduce the need for amputations. However, there is still limited information on how to prevent and manage DWs, and further research is needed to fully understand the role of alternative treatments in managing complications of DWs. The conventional management protocol for treating diabetic foot syndrome can be expensive and may cause adverse side effects. Alternative therapies, such as medicinal plants and green synthesis of nano-formulations, may provide efficient and affordable treatments for DWs.

Biological processes and factors involved in soft and hard tissue healing

Wound healing is a complex and iterative process involving myriad cellular and biologic processes that are highly regulated to allow satisfactory repair and regeneration of damaged tissues. This review is intended to be an introductory chapter in a volume focusing on the use of platelet concentrates for tissue regeneration. In order to fully appreciate the clinical utility of these preparations, a sound understanding of the processes and factors involved in soft and hard tissue healing. This encompasses an appreciation of the cellular and biological mediators of both soft and hard tissues in general as well as specific consideration of the periodontal tissues. In light of good advances in this basic knowledge, there have been improvements in clinical strategies and therapeutic management of wound repair and regeneration. The use of platelet concentrates for tissue regeneration offers one such strategy and is based on the principles of cellular and biologic principles of wound repair discussed in this review.

Effect of platelet-rich plasma on the attachment of periodontal ligament fibroblasts to the diseased root surface and the attendant collagen formation

OBJECTIVE

To investigate the effect of different concentrations of platelet-rich plasma (PRP) on collagen formation via periodontal ligament fibroblasts (PDLFs) on the surface of demineralised diseased tooth roots.

METHODS

Various PDLFs were grown from tissue explants, with the cells between the fifth and eighth passage in the culture used. Human whole blood obtained from healthy subjects was collected in tubes containing an anticoagulant (acid-citrate-dextrose) and centrifuged (1300 rpm for 10 min) before the supernatant PRP layer was removed. A second spin at (2000 rpm for 10 min) produced the PRP fraction. The effect of PRP of various concentrations on the attachment of PDLFs on the diseased root surface of human teeth demineralised with ethylenediaminetetraacetic acid (EDTA) and treated with the PRP was then investigated in terms of PRP collagen formation, with the formation observed using the Sirius red staining method.

RESULTS

The optical density values of the experimental groups were statistically significantly higher than those of the control groups (P < 0.05), while the Sirius red staining returned positive results for both the experimental group (A) and the control group (B). The images were analysed using a histogram, and a statistically significant difference was found (P < 0.05).

CONCLUSION

While PRP could promote the attachment and collagen formation of PDLFs on the diseased root surface of human teeth demineralised with EDTA and treated with PRP, the effect is potentially reduced when the dose exceeds 20%.

Periodontal Wound Healing and Regeneration: Insights for Engineering New Therapeutic Approaches

Periodontitis is a widespread inflammatory disease that leads to loss of the tooth supporting periodontal tissues. The few therapies available to regenerate periodontal tissues have high costs and inherent limitations, inspiring the development of new approaches. Studies have shown that periodontal tissues have an inherent capacity for regeneration, driven by multipotent cells residing in the periodontal ligament (PDL). The purpose of this review is to describe the current understanding of the mechanisms driving periodontal wound healing and regeneration that can inform the development of new treatment approaches. The biologic basis underlying established therapies such as guided tissue regeneration (GTR) and growth factor delivery are reviewed, along with examples of biomaterials that have been engineered to improve the effectiveness of these approaches. Emerging therapies such as those targeting Wnt signaling, periodontal cell delivery or recruitment, and tissue engineered scaffolds are described in the context of periodontal wound healing, using key in vivo studies to illustrate the impact these approaches can have on the formation of new cementum, alveolar bone, and PDL. Finally, design principles for engineering new therapies are suggested which build on current knowledge of periodontal wound healing and regeneration.

Platelet-derived growth factor-BB regenerates functional periodontal ligament in the tooth replantation

Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms. In PDGF-BB pretreated replanted teeth (PDGF-BB group), ankylosis was markedly reduced and functionally organized PDL collagen fibers were restored; the mechanical strength of the healing PDL was restored to an average of 76% of that in non-replanted normal teeth at 21 days. The numbers of PDGF-Rβ- and BrdU-positive cells in the periodontal tissues of the PDGF-BB group were greater than those of atelocollagen pretreated replanted teeth (AC group). Moreover, in the PDGF-BB group, the periodontal tissues had fewer osteocalcin-positive cells and decreased number of nuclear β-catenin-positive cells compared to those in the AC group. In vitro analyses showed that PDGF-BB increased the proliferation and migration of human periodontal fibroblasts. PDGF-BB downregulated mRNA expressions of RUNX2 and ALP, and inhibited upregulatory effects of Wnt3a on β-catenin, AXIN2, RUNX2, COL1A1, and ALP mRNA expressions. These findings indicate that in tooth replantation, topical PDGF-BB treatment enhances cell proliferation and migration, and inhibits canonical Wnt signaling activation in bone-tooth ankylosis, leading to occlusal loading of the PDL tissues and subsequent functional restoration of the healing PDL. This suggests a possible clinical application of PDGF-BB to reduce ankylosis after tooth replantation and promote proper regeneration of PDL.

Epidermal growth factor attenuates lingual papillae lesions in a rat model of sialoadenectomy

Salivary epidermal growth factor (EGF) plays an important role in the maintenance of the oral and gastro-esophageal mucosa. Sialoadenectomy delays healing of oral wounds and affects lingual papillae. In this work, we aimed to determine the effect of EGF deficiency induced by sialoadenectomy and evaluate the effect of exogenous EGF administration on the lingual papillae and taste buds in rats. Thirty male adult Wistar albino rats were equally divided into 3 groups; sham-operated control group, sialoadenectomy group and group of sialoadenectomy + EGF. EGF was given 8 weeks after sialoadenectomy in a dose of 1 μg /ml/day in drinking water for 2 weeks. The anterior two-thirds of the tongue was dissected and cut longitudinally into two halves; one half for light microscope and the other for electron microscope examinations. Saliva and blood were collected to determine salivary and plasma EGF. Our results revealed that sialoadenectomy significantly reduced plasma and saliva levels of EGF which resulted in severe disruption of the architecture of lingual papillae. These changes were effectively improved by the exogenous EGF administration. In conclusion, EGF supplementation reversed the effects of sialoadenectomy and restored almost normal architecture of lingual papillae and taste buds.

Expression of gingival crevicular fluid markers during early and late healing of intrabony defects after surgical treatment: a systematic review

BACKGROUND

Surgical treatments such as guided tissue regeneration (GTR) and access flap surgery are widely employed for the treatment of intrabony defects. However, little is known regarding the postoperative expression of gingival crevicular fluid (GCF) markers.

OBJECTIVE

The aim of this systematic review was to compare the expression of GCF markers following treatment of periodontal intrabony defects with guided tissue regeneration or access surgery. The association of the markers' expression with the clinical outcome was also assessed.

METHODS

An electronic literature search was conducted in MEDLINE, EMBASE, OpenGrey, LILACS and Cochrane Library up to December 2018 complemented by a manual search. Human, prospective clinical studies were identified. The changes from baseline up to 30 days (early healing) and 3 months (late healing) were assessed.

RESULTS

A total of 164 publications were identified and reviewed for eligibility. Of these, 10 publications fulfilled the inclusion criteria. The included studies evaluated 15 different GCF markers with a follow-up time between 21 and 360 days postoperatively. PDGF, VEGF and TIMP-1 changes were often investigated in the included studies; however, contrasting results were reported. Two studies agreed that both GTR and OFD lead to similar OPG level changes. TGF-β1 is increased early postoperatively, irrespective of the surgical technique employed.

CONCLUSION

There is limited evidence available on the expression of GCF markers after surgical interventions of intrabony periodontal defects. However, OPG and TGF-β1 tend to increase early post-operatively, irrespective of the surgical technique employed, irrespective of the surgical technique employed.

CLINICAL RELEVANCE

More well-designed, powered studies with sampling periods reflecting the regenerative process are needed, and future research should focus on employing standardised protocols for collecting, storing and analysing GCF markers.

Mechanistic insight into diabetic wounds: Pathogenesis, molecular targets and treatment strategies to pace wound healing

Wound management in diabetic patient is of an extreme clinical and social concern. The delayed and impaired healing makes it more critical for research focus. The research on impaired healing process is proceeding hastily evident by new therapeutic approaches other than conventional such as single growth factor, dual growth factor, skin substitutes, cytokine stimulators, cytokine inhibitors, matrix metalloproteinase inhibitors, gene and stem cell therapy, extracellular matrix and angiogenesis stimulators. Although numerous studies are available that support delayed wound healing in diabetes but detailed mechanistic insight including factors involved and their role still needs to be revealed. This review mainly focuses on the molecular cascades of cytokines (with growth factors) and erstwhile factors responsible for delayed wound healing, molecular targets and recent advancements in complete healing and its cure. Present article briefed recent pioneering information on possible molecular targets and treatment strategies including clinical trials to clinicians and researchers working in similar area.

Gelatin nonwovens-based epithelial morphogenesis involves a signaling axis comprising EGF-receptor, MAP kinases ERK 1/2, and β1 integrin

In biomaterials research, biomechanics which support tissue regeneration steadily gains of importance. Hence, we have previously shown that gelatin-based electrospun nonwoven mats (NWMs) with a distinct modulus of elasticity (3.2 kPa) promotes epithelial morphogenesis. Since molecular mechanisms of this morphogenesis are still unknown, the present study aims at identifying molecules, involved herein. Epithelia established on the NMWs showed persistence of the activated state of the epidermal growth factor receptor (EGF-R), phosphorylated at the src-specific tyrosine 845 (EGF-R_T845 ) throughout the observation period of 10 days. To elucidate whether the observed morphogenesis mechanistically involves EGF-R signaling, we inhibited EGF-R, by employing the EGF-R_T845 specific inhibitor Gefitinib (IRESSA®). Gefitinib administration yielded a reduced expression of the β1 integrin subunit, a well-known cell-matrix interaction receptor, concomitant with downregulation of p42/44 ERK1/2 MAP-kinase activity. To elucidate whether the observed downregulation of β1 is EGF-R_T845 -dependent or emerging from ERK1/2 signaling, we exposed epithelia, grown on the NWMs, with the ERK1/2-directed inhibitor U0126. In the absence of Gefitinib, inhibition of p42/44 MAP-kinase activity resulted in decreased β1 integrin protein levels, thus indicating that β1 expression is dependent on ERK1/2 and not EGF-R_T845 . Our results showed the first time that an EGF-R-β1 integrin-signaling axis, including ERK1/2, promotes NWM-elasticity-based epithelial morphogenesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 663-677, 2019.

Porphyromonas gingivalis and its lipopolysaccharide differently modulate epidermal growth factor-dependent signaling in human gingival epithelial cells

Periodontitis is an inflammatory disease induced by pathogenic bacteria such as Porphyromonas gingivalis. Little is known about epidermal growth factor (EGF) signals in human gingival epithelial cells (HGEC), which are major targets of P. gingivalis, and how the expression of proteins participating in EGF signaling—that is, EGF-receptor (EGFR), suppressor of cytokine signaling-3 (SOCS-3), interferon regulatory factor-1 (IRF-1), and signal transducers and activators of transcription (STAT-3)—are modified. This study aimed to assess the effects of P. gingivalis and its purified lipopolysaccharide (LPS-Pg) on EGF signaling. HGEC were infected for 2 h in a dose-dependent manner with P. gingivalis and with heat-killed P. gingivalis, and activated for 2 and 24 h by 1 µg/mL of purified LPS-Pg. Quantitative reverse transcription polymerase chain reaction and Western blotting were performed to measure mRNA and protein levels for SOCS-3, IRF-1 EGF, EGFR, and STAT-3. The tyrosine-phosphorylation status of STAT-3 was also examined. The results showed that infection of HGEC cells with P. gingivalis, but not with heat-killed P. gingivalis, led to significant reductions in expression levels of mRNAs and proteins for SOCS-3, IRF-1, and EGFR, while LPS-Pg over time significantly increased the expression of these mRNAs and proteins. Tyrosine-phosphorylation of STAT-3 was significantly increased during infection with P. gingivalis and activation by LPS-Pg but not modified during infection with heat-killed P. gingivalis. This study highlights that P. gingivalis and its purified LPS differentially modulated the expression of proteins (SOCS-3, IRF-1, EGFR, and STAT-3) interfering with EGF signaling.

Evaluation of MicroRNA-146a and Its Targets in Gingival Tissues of Patients With Chronic Periodontitis

BACKGROUND

MicroRNAs (miRNAs) are a group of small non-coding RNAs that play an important role in the regulation of gene expression. miRNA-146a (miR-146a), a member of the miR-146 family, is involved in the control of inflammation. Periodontitis is a set of chronic inflammatory disorders of the tissues surrounding the teeth that lead to the breakdown of alveolar bone and tooth loss. In this study, expression levels of miR-146a and its targets, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, are evaluated in human patients with chronic periodontitis (CP).

METHODS

The study population consisted of 10 healthy controls and 20 individuals with CP. For each participant, clinical parameters including probing depth and clinical attachment level were measured, and a gingival tissue sample was collected. Levels of miR-146a, TNF-α, IL-1β, and IL-6 were quantified using real-time polymerase chain reaction.

RESULTS

Levels of miR-146a were significantly higher in patients with CP (P <0.001). There was a positive correlation between levels of miR-146a and clinical parameters (P <0.05). Elevated miR-146a was accompanied by a significant reduction in TNF-α and IL-6 (P <0.001).

CONCLUSIONS

Patients with CP had higher levels of miR-146a than healthy individuals, accompanied by reduced levels of TNF-α and IL-6. A positive relationship between miR-146a levels and clinical parameters suggests a pathophysiologic role of miR-146a in CP.

Resolvin D1 protects periodontal ligament

Resolution agonists are endogenous mediators that drive inflammation to homeostasis. We earlier demonstrated in vivo activity of resolvins and lipoxins on regenerative periodontal wound healing. The goal of this study was to determine the impact of resolvin D1 (RvD1) on the function of human periodontal ligament (PDL) fibroblasts, which are critical for wound healing during regeneration of the soft and hard tissues around teeth. Primary cells were cultured from biopsies obtained from three individuals free of periodontal diseases. Peripheral blood mononuclear cells were isolated by density gradient centrifugation from whole blood of healthy volunteers. PGE2, leukotriene B4 (LTB4), and lipoxin A4 (LXA4) in culture supernatants were measured by ELISA. The direct impact of RvD1 on PDL fibroblast proliferation was measured and wound closure was analyzed in vitro using a fibroblast culture "scratch assay." PDL fibroblast function in response to RvD1 was further characterized by basic FGF production by ELISA. IL-1β and TNF-α enhanced the production of PGE2. Treatment of PDL cells and monocytes with 0.1-10 ng/ml RvD1 (0.27-27 M) reduced cytokine induced production of PGE2 and upregulated LXA4 production by both PDL cells and monocytes. RvD1 significantly enhanced PDL fibroblast proliferation and wound closure as well as basic FGF release. The results demonstrate that anti-inflammatory and proresolution actions of RvD1 with upregulation of arachidonic acid-derived endogenous resolution pathways (LXA4) and suggest resolution pathway synergy establishing a novel mechanism for the proresolution activity of the ω-3 docosahexaenoic acid-derived resolution agonist RvD1.

Differential effects of growth factors and cytokines on the synthesis of SPARC, DNA, fibronectin and alkaline phosphatase activity in human periodontal ligament cells

Growth factors and cytokines play an important role in tissue development and repair. However, it remains unknown how they act on proliferation and differentiation of periodontal ligament cells. In this study, we investigated the effects of several growth factors and cytokines on the synthesis of DNA, alkaline phosphatase (ALPase), fibronectin, and secreted protein acidic and rich in cysteine (SPARC) in human periodontal ligament (HPL) cells. Transforming growth factor-beta (TGF-beta) increased the synthesis of DNA, fibronectin and SPARC, whereas it decreased ALPase activity. Basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) and tumor necrosis factor-alpha (TNF-alpha) decreased SPARC and ALPase levels, whereas these peptides increased DNA synthesis and did not affect fibronectin synthesis. Epidermal growth factor (EGF) up-regulated the synthesis of DNA and fibronectin and inhibited SPARC and ALPase levels. Interleukin-1beta (IL-1beta) decreased the synthesis of DNA, ALPase, fibronectin and SPARC. These findings demonstrate that TGF-beta, bFGF, EGF, PDGF, TNF-alpha and IL-1beta have characteristically different patterns of action on DNA, SPARC, fibronectin and ALPase synthesis by HPL cells. The differences in regulation of function of periodontal ligament cells by these peptides may be involved in the regeneration and repair of periodontal tissue.

Prospective potency of TGF-β1 on maintenance and regeneration of periodontal tissue

Periodontal ligament (PDL) tissue, central in the periodontium, plays crucial roles in sustaining tooth in the bone socket. Irreparable damages of this tissue provoke tooth loss, causing a decreased quality of life. The question arises as to how PDL tissue is maintained or how the lost PDL tissue can be regenerated. Stem cells included in PDL tissue (PDLSCs) are widely accepted to have the potential to maintain or regenerate the periodontium, but PDLSCs are very few in number. In recent studies, undifferentiated clonal human PDL cell lines were developed to elucidate the applicable potentials of PDLSCs for the periodontal regenerative medicine based on cell-based tissue engineering. In addition, it has been suggested that transforming growth factor-beta 1 is an eligible factor for the maintenance and regeneration of PDL tissue.

Inactivation of epidermal growth factor by Porphyromonas gingivalis as a potential mechanism for periodontal tissue damage

Porphyromonas gingivalis is a Gram-negative bacterium associated with the development of periodontitis. The evolutionary success of this pathogen results directly from the presence of numerous virulence factors, including peptidylarginine deiminase (PPAD), an enzyme that converts arginine to citrulline in proteins and peptides. Such posttranslational modification is thought to affect the function of many different signaling molecules. Taking into account the importance of tissue remodeling and repair mechanisms for periodontal homeostasis, which are orchestrated by ligands of the epidermal growth factor receptor (EGFR), we investigated the ability of PPAD to distort cross talk between the epithelium and the epidermal growth factor (EGF) signaling pathway. We found that EGF preincubation with purified recombinant PPAD, or a wild-type strain of P. gingivalis, but not with a PPAD-deficient isogenic mutant, efficiently hindered the ability of the growth factor to stimulate epidermal cell proliferation and migration. In addition, PPAD abrogated EGFR-EGF interaction-dependent stimulation of expression of suppressor of cytokine signaling 3 and interferon regulatory factor 1. Biochemical analysis clearly showed that the PPAD-exerted effects on EGF activities were solely due to deimination of the C-terminal arginine. Interestingly, citrullination of two internal Arg residues with human endogenous peptidylarginine deiminases did not alter EFG function, arguing that the C-terminal arginine is essential for EGF biological activity. Cumulatively, these data suggest that the PPAD-activity-abrogating EGF function in gingival pockets may at least partially contribute to tissue damage and delayed healing within P. gingivalis-infected periodontia.

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.

Significance of the platelet-derived growth factor in periodontal tissue regeneration

AIM

The aim was to review the significance of the platelet derived growth factor (PGDF) in periodontal tissue regeneration.

METHODS AND RESULTS

Databases were searched using the following terms in different combinations: "growth factors", "guided bone regeneration", "guided tissue regeneration", "periodontal", "platelet rich plasma" and "platelet derived growth factor". Titles and abstracts of articles obtained using the above-described criteria were then screened by the authors and checked for agreement. The next step was to hand-search the reference lists of original and review studies that were found to be relevant in the previous step. PDGF has a stimulatory effect on the DNA replication and chemotaxis of osteoblasts, fibroblasts, leukocytes, monocytes, neutrophils periodontal and alveolar bone cells. Proliferation of mesenchymal stem cells is also promoted by supplement treatment with PDGF. PDGF in combination with other growth factors enhances periodontal tissue repair.

CONCLUSIONS

The PDGF plays a significant role in periodontal bone and tissue regeneration.

Periodontal nitric oxide pathway alteration due to precompetition anxiety in handball players

BACKGROUND

Psychologic and physical stress is known to be related with periodontal disorders. The objective of this study is to investigate salivary and gingival crevicular fluid (GCF) nitric oxide (NO) metabolism and its association with the periodontal reaction to precompetition anxiety in competitive athletes.

METHODS

A total of 18 elite male handball players participated in this study. The anxiety level of participants was determined by using a competitive state anxiety inventory-2 (CSAI-2). Periodontal clinical measurements, saliva, and GCF samples were obtained before the application of the CSAI-2 during the half-season break and just before the league championship match. NO-level, arginase, and NO synthase (NOS) activities were analyzed in saliva samples; NO and basic fibroblast growth factor (FGF-b) levels were analyzed in GCF samples.

RESULTS

The CSAI-2 was significantly different between the two evaluation time points. GCF NO and FGF-b levels increased before the championship match, whereas saliva levels did not change. The plaque index and gingival index (GI) increased at the evaluation just before the championship match. The difference in the GI was statistically significant.

CONCLUSION

The competitive stress of athletes may lead to a gingival/periodontal disturbance accompanied by an altered NO metabolism in saliva and GCF.

Interactions of enamel matrix derivative and biomechanical loading in periodontal regenerative healing

BACKGROUND

Although enamel matrix derivative (EMD) has been shown to promote periodontal regeneration, it is unknown whether the actions of EMD are modulated by occlusal loading. This in vitro study was performed to investigate whether biomechanical forces regulate the response of periodontal ligament (PDL) cells to EMD.

METHODS

Human PDL cells were treated with EMD in the presence and absence of cyclic tensile strain (CTS) of various magnitudes for ≤ 14 days. Synthesis of transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), growth factor receptors, collagen, and runt-related transcription factor 2- (RUNX2), cell numbers and adhesion, wound fill rate, and calcium accumulation were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, a wound healing assay, and alizarine red S staining.

RESULTS

Wound fill rate, cell numbers and adhesion, and expression of TGF-β1, VEGF, collagen, and RUNX2 were significantly increased by EMD. In the presence of CTS, the EMD-induced effects were significantly reduced. The inhibition of the EMD-upregulated VEGF expression by CTS was blocked by a specific inhibitor of nuclear factor-kappa B signaling. Moreover, CTS downregulated receptors for growth factors involved in the actions of EMD. CTS also antagonized significantly the EMD-induced calcium deposition.

CONCLUSIONS

These in vitro findings suggest that the beneficial actions of EMD on PDL cell functions critical for periodontal regeneration are jeopardized by biomechanical loading. Clinical studies should clarify whether protection of teeth against occlusal forces in the early healing stage may positively affect the outcome of regenerative therapy with EMD.

Regulation of human adipose-derived stromal cell osteogenic differentiation by insulin-like growth factor-1 and platelet-derived growth factor-alpha

BACKGROUND

Human adipose-derived stromal cells possess a great potential for tissue engineering purposes. The authors' laboratory is interested in harnessing human adipose-derived stromal cells for skeletal tissue regeneration and identifying those factors that enhance human adipose-derived stromal cell osteogenic differentiation. The authors hypothesized that insulin-like growth factor (IGF) and platelet-derived growth factor (PDGF) would stimulate human adipose-derived stromal cell osteogenesis and that IGF would stimulate adipogenesis.

METHODS

Adipose-derived stromal cells were harvested from human lipoaspirate. Previously, a microarray analysis examined gene expression throughout osteogenic differentiation. In a candidate fashion, the authors added recombinant IGF-1 and PDGF-alpha individually and in combination. Osteogenesis and adipogenesis were assessed by alkaline phosphatase, alizarin red, and oil red O staining, and quantitative real-time polymerase chain reaction (RUNX2, ALP, OCN, IGF1, PPARG, LPL, AP2, and GCP1). Finally, intersection between IGF and PDGF signaling pathways was evaluated.

RESULTS

IGF-1 was observed to increase osteogenic differentiation by all markers (p < 0.01). However, PDGF-alpha when added alone primarily did not affect osteogenic markers. PDGF-alpha positively regulated transcription of IGF1. Addition of PDGF-alpha in combination with or before IGF-1 enhanced osteogenesis more than either alone. IGF-1 increased whereas PDGF-alpha diminished human adipose-derived stromal cell adipogenesis.

CONCLUSIONS

IGF signaling significantly increased osteogenesis in human adipose-derived stromal cells and may be used for tissue-engineering purposes. The combination of PDGF and IGF may be more beneficial than either alone in driving adipose-derived stromal cell osteogenesis. Future in vivo applications will focus on the combination of adipose-derived stromal cells, biomimetic scaffolds, and recombinant IGF.

Toward delivery of multiple growth factors in tissue engineering

Inspired by physiological events that accompany the "wound healing cascade", the concept of developing a tissue either in vitro or in vivo has led to the integration of a wide variety of growth factors (GFs) in tissue engineering strategies in an effort to mimic the natural microenvironments of tissue formation and repair. Localised delivery of exogenous GFs is believed to be therapeutically effective for replication of cellular components involved in tissue development and the healing process, thus making them important factors for tissue regeneration. However, any treatment aiming to mimic the critical aspects of the natural biological process should not be limited to the provision of a single GF, but rather should release multiple therapeutic agents at an optimised ratio, each at a physiological dose, in a specific spatiotemporal pattern. Despite several obstacles, delivery of more than one GF at rates mimicking an in vivo situation has promising potential for the clinical management of severely diseased tissues. This article summarises the concept of and early approaches toward the delivery of dual or multiple GFs, as well as current efforts to develop sophisticated delivery platforms for this ambitious purpose, with an emphasis on the application of biomaterials-based deployment technologies that allow for controlled spatial presentation and release kinetics of key biological cues. Additionally, the use of platelet-rich plasma or gene therapy is addressed as alternative, easy, cost-effective and controllable strategies for the release of high concentrations of multiple endogenous GFs, followed by an update of the current progress and future directions of research utilising release technologies in tissue engineering and regenerative medicine.

Periodontal regeneration: focus on growth and differentiation factors

Several growth and differentiation factors have shown potential as therapeutic agents to support periodontal wound healing/regeneration, although optimal dosage, release kinetics, and suitable delivery systems are still unknown. Experimental variables, including delivery systems, dose, and the common use of poorly characterized preclinical models, make it difficult to discern the genuine efficacy of each of these factors. Only a few growth and differentiation factors have reached clinical evaluation. It appears that well-defined discriminating preclinical models followed by well-designed clinical trials are needed to further investigate the true potential of these and other candidate factors. Thus, current research is focused on finding relevant growth and differentiation factors, optimal dosages, and the best approaches for delivery to develop clinically meaningful therapies in patient-centered settings.

Platelet-derived growth factor-B gene delivery sustains gingival fibroblast signal transduction

BACKGROUND AND OBJECTIVE

Platelet-derived growth factor-BB is a potent mediator of tooth-supporting periodontal tissue repair and regeneration. A limitation of the effects of topical platelet-derived growth factor-BB application is its short half-life in vivo. Gene therapy has shown strong promise for the long-term delivery of platelet-derived growth factor in both skin ulcer healing and periodontal tissue engineering. However, little is known regarding the extended effects of platelet-derived growth factor-B on cell signaling via gene delivery, especially at the level of phosphorylation of intracellular kinases. This study sought to evaluate the effect of gene transfer by Ad-PDGF-B on human gingival fibroblasts (HGFs) and the subsequent regulation of genes and cell-surface proteins associated with cellular signaling.

MATERIAL AND METHODS

HGFs from human subjects were treated by adenoviral PDGF-B, PDGF-1308 (a dominant negative mutant of PDGF) and recombinant human platelet-derived growth factor-BB, and then incubated in serum-free conditions for various time points and harvested at 1, 6, 12, 24, 48, 72 and 96 h. Exogenous PDGF-B was measured by RT-PCR and Western blot. Cell proliferation was evaluated by [methyl-3H]thymidine incorporation assay. We used proteomic arrays to explore phosphorylation patterns of 23 different intracellular kinases after PDGF-B gene transfer. The expression of alpha and beta PDGFR and Akt were measured by Western blot analysis.

RESULTS

Sustained in vitro expression of PDGF-B in HGFs by Ad-PDGF-B transduction was seen at both the mRNA and protein levels. Compared to rhPDGF-BB and Ad-PDGF-1308, Ad-PDGF-B maintained cell growth in serum-free conditions, with robust increases in DNA synthesis. Gene delivery of PDGF-B also prolonged downregulation of the growth arrest specific gene (gas) PDGF alpha R. Of the 23 intracellular kinases that we tested in proteomic arrays, Akt revealed the most notable long-term cell signaling effect as a result of the over-expression of Ad-PDGF-B, compared with pulse recombinant human platelet-derived growth factor BB. Prolonged Akt phosphorylation was induced by treatment with Ad-PDGF-B, for at least up to 96 h.

CONCLUSION

These findings further demonstrate that gene delivery of PDGF-B displays sustained signal transduction effects in human gingival fibroblasts that are higher than those conveyed by treatment with recombinant human platelet-derived growth factor-BB protein. These data on platelet-derived growth factor gene delivery contribute to an improved understanding of these pathways that are likely to play a role in the control of clinical outcomes of periodontal regenerative therapy.

Matrices and scaffolds for drug delivery in dental, oral and craniofacial tissue engineering

Current treatments for diseases and trauma of dental, oral and craniofacial (DOC) structures rely on durable materials such as amalgam and synthetic materials, or autologous tissue grafts. A paradigm shift has taken place to utilize tissue engineering and drug delivery approaches towards the regeneration of these structures. Several prototypes of DOC structures have been regenerated such as temporomandibular joint (TMJ) condyle, cranial sutures, tooth structures and periodontium components. However, many challenges remain when taking in consideration the high demand for esthetics of DOC structures, the complex environment and yet minimal scar formation in the oral cavity, and the need for accommodating multiple tissue phenotypes. This review highlights recent advances in the regeneration of DOC structures, including the tooth, periodontium, TMJ, cranial sutures and implant dentistry, with specific emphasis on controlled release of signaling cues for stem cells, biomaterial matrices and scaffolds, and integrated tissue engineering approaches.

Role of growth factors on periodontal repair

Regeneration of periodontal structures lost during periodontal diseases constitutes a complex biological process regulated among others by interactions between cells and growth factors. Growth factors are biologically active polypeptides affecting the proliferation, chemotaxis and differentiation of cells from epithelium, bone and connective tissue. They express their action by binding to specific cell-surface receptors present on various target cells including osteoblasts, cementoblasts and periodontal ligament fibroblasts. The observation that growth factors participate in all cell functions led to exogenous application during periodontal tissue repair aiming to their use as an alternative therapeutic approach to periodontal therapy. Cell types and cultures conditions, dose, carrier materials, application requirements are of critical importance in the outcome of periodontal repair. The purpose of this article is to review the literature with respect to the biological actions of PDGF, TGF, FGF, IGF and EGF on periodontal cells and tissues, which are involved in periodontal regeneration.

Effect of rhPDGF-BB delivery on mediators of periodontal wound repair

Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of tooth-supporting structures. This investigation examined the effect of the local delivery of PDGF-BB when combined with reconstructive periodontal surgery on local wound fluid (WF) levels of PDGF-AB, vascular endothelial growth factor (VEGF), and bone collagen telopeptide (ICTP) in humans with advanced periodontitis. Sixteen patients exhibiting localized periodontal osseous defects were randomized to one of three groups (beta-TCP carrier alone, beta-TCP + 0.3 mg/mL of recombinant human PDGF-BB [rhPDGF-BB], or beta-TCP + 1.0 mg/mL of rhPDGF-BB) and monitored for 6 months. WF was harvested and analyzed for PDGF-AB, VEGF, and ICTP WF levels. Teeth contralateral to the target lesions served as controls. Increased levels of VEGF in the WF was observed for all surgical treatment groups with the 1.0 mg/mL rhPDGF-BB group showing the most pronounced difference at 3 weeks in the AUC analysis versus control (p < 0.0001). PDGF-AB WF levels were increased for the carrier alone group compared to both rhPDGFBB groups. Low-dose rhPDGF-BB application elicited increases in ICTP at days 3-5 in the wound healing process, suggesting a promotion of bone turnover at early stages of the repair process (p < 0.02). These results demonstrate contrasting inducible expression patterns of PDGF-AB, VEGF, and ICTP during periodontal wound healing in humans.

Gene therapeutics for periodontal regenerative medicine

There has been significant advancement in the field of periodontal tissue engineering over the past decade for the repair of tooth-supporting structures. Although encouraging results for periodontal tissue regeneration have been found in numerous clinical investigations using recombinant growth factors, limitations exist with topical protein delivery. Newer approaches seek to develop methodologies that optimize growth factor targeting to maximize the therapeutic outcome of periodontal regenerative procedures. Genetic approaches in periodontal tissue engineering show early progress in achieving delivery of growth factor genes, such as platelet-derived growth factor or bone morphogenetic protein, to periodontal lesions. Ongoing investigations in ex vivo and in vivo gene transfer to periodontia seek to examine the extent of the potential effects in stimulating periodontal tissue engineering.

Platelet-derived growth factor (PDGF) isoform and PDGF receptor expression in drug-induced gingival overgrowth and hereditary gingival fibrosis

OBJECTIVE

To investigate possible associations between platelet-derived growth factor (PDGF), PDGF receptor expression and macrophages in drug-induced and hereditary gingival overgrowth.

MATERIALS AND METHODS

Tissues from patients with drug-induced gingival overgrowth (DIGO) (n = 10) and hereditary gingival fibrosis (n = 10) were studied and compared with 'control' gingiva (n = 10). Expression of PDGF and its alpha and beta receptors was investigated immunohistochemically and by RT-PCR. Macrophages were identified by immunostaining for CD68.

RESULTS

PDGF isoforms and receptors were detected in most cells within all specimens. There were no differences in the numbers of macrophages, or fibroblasts expressing PDGF or receptors, between groups. The level of PDGF expression by fibroblasts, determined by absorbance measurements, was similar between groups for PDGF A. Significantly lower levels of total PDGF and the receptors were detected in drug-induced overgrowth compared to those in hereditary fibrosis (P < 0.004) and control specimens (P < 0.034). All specimens expressed mRNA for PDGF A, PDGF B and alpha and beta receptors.

CONCLUSIONS

These data do not support a pivotal role for macrophage-derived PDGF B in the pathogenesis of DIGO. They suggest that fibroblasts in drug-induced lesions have a lowered capacity to produce, and respond to, PDGF, a property not shared by fibroblasts associated with hereditary fibrosis.

Transforming growth factor-beta stimulates Interleukin-11 production by human periodontal ligament and gingival fibroblasts

BACKGROUND

Transforming growth factor (TGF)-beta is a potent multifunctional polypeptide, abundant in the bone matrix. Interleukin (IL)-11 is a pleiotropic cytokine with effects on multiple cell types. The present study was performed to evaluate the regulatory effects of TGF-beta on IL-11 production by human periodontal ligament cells (PDL) and human gingival fibroblasts (HGF).

MATERIAL AND METHODS

The expression of TGF-beta receptor in PDL and HGF were observed using flow cytometry. PDL and HGF were stimulated with TGF-beta with or without protein kinase C (PKC) inhibitors and activator. IL-11, bone morphogenetic protein-2 (BMP-2) and TGF-beta mRNA expression was quantified by real-time polymerase chain reaction (PCR). IL-11 production was measured using enzyme-linked immunosorbent assay.

RESULTS

PDL and HGF expressed both TGF-beta receptor I and TGF-beta receptor II on the cell surfaces. IL-11 mRNA expression and IL-11 production were augmented by TGF-beta in both PDL and HGF, with higher values in PDL. PKC inhibitors partially suppressed TGF-beta-induced IL-11 production in PDL and HGF, whereas activator enhanced it. TGF-beta mRNA and BMP-2 mRNA expression were up-regulated by TGF-beta in PDL.

CONCLUSION

These results suggest that PDL produce IL-11 in response to TGF-beta.

Differential effects of PDGF-BB on matrix metalloproteases and cytokine release in fibroblasts of Type 2 diabetic patients and normal controls in vitro

AIMS/HYPOTHESIS

The complex process of wound healing is regulated by various growth factors. The systemic character of diabetes mellitus favors the chronification of diabetic wounds. In this study, the in vitro effects of platelet-derived growth factor (PDGF)-BB on the expression of cytokines and matrix metalloproteases (MMPs) in fibroblasts of Type 2 diabetic patients and healthy controls were investigated.

METHODS

We studied six Type 2 diabetic patients (mean Hba1(c)=7.5%) and six healthy controls. For proliferation studies, cultivated fibroblasts, prepared from biopsies taken from the thigh, were stimulated with different concentrations of PDGF. After 48 h, the expression of MMPs and cytokines was measured. We analysed the mRNA expression by RT-PCR (TaqMan), tissue protein levels by zymography, and cell supernatant levels by ELISA.

RESULTS

Levels of MMP-mRNA were elevated in diabetic fibroblasts compared with healthy controls. At baseline, MMP-2 protein levels were significantly increased in the fibroblast of diabetic patients (P=.019). For MMP-9, a trend towards higher levels (P=.3) was found. After incubation with PDGF, a significant reduction of MMP-9 (P=.01) and MMP-13 (P=.04) was found. Analysis of cytokine release in cell culture supernatant showed elevated levels of interleukin (IL)-8 at baseline conditions. MMP-1 and MMP-2 levels in the supernatant were concentration-dependently reduced.

CONCLUSIONS

This study, for the first time, demonstrates elevated MMPs in cultivated fibroblasts (derived from intact skin and not from an open wound) of diabetic patients compared with healthy controls under in vitro conditions. Therefore, our data support the hypothesis of alterations of wound healing in diabetic patients on the cellular level, reflecting the systemic character of the disease.

Effect of rhPDGF-BB on bone turnover during periodontal repair

PURPOSE

Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of periodontia. Pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) is a well-known biomarker of bone turnover, and as such is a potential indicator of osseous metabolic activity. The objective of this study was to evaluate the release of the ICTP into the periodontal wound fluid (WF) following periodontal reconstructive surgery using local delivery of highly purified recombinant human PDGF (rhPDGF)-BB.

METHODS

Forty-seven human subjects at five treatment centres possessing chronic severe periodontal disease were monitored longitudinally for 24 weeks following PDGF regenerative surgical treatment. Severe periodontal osseous defects were divided into one of three groups and treated at the time of surgery with either: beta-tricalcium phosphate (TCP) osteoconductive scaffold alone (active control), beta-TCP+0.3 mg/ml of rhPDGF-BB, or beta-TCP+1.0 mg/ml of rhPDGF-BB. WF was harvested and analysed for local ICTP levels by radioimmunoassay. Statistical analysis was performed using analysis of variance and an area under the curve analysis (AUC).

RESULTS

The 0.3 and 1.0 mg/ml PDGF-BB treatment groups demonstrated increases in the amount of ICTP released locally for up to 6 weeks. There were statistically significant differences at the week 6 time point between beta-TCP carrier alone group versus 0.3 mg/ml PDGF-BB group (p<0.05) and between beta-TCP alone versus the 1.0 mg/ml PDGF-BB-treated lesions (p<0.03). The AUC analysis revealed no statistical differences amongst groups.

CONCLUSION

This study corroborates the release of ICTP as a measure of active bone turnover following local delivery of PDGF-BB to periodontal osseous defects. The amount of ICTP released from the WF revealed an early increase for all treatment groups. Data from this study suggests that when PDGF-BB is delivered to promote periodontal tissue engineering of tooth-supporting osseous defects, there is a direct effect on ICTP released from the wound.

Insulin-like growth factor-I attenuates the inhibitory effect of type I collagen through β1 integrin receptor

Extracellular matrix and growth factors are the crucial factors that regulate healing and regenerating processes in human periodontal ligament cells. The purpose of this study was to examine the effects of type I collagen and insulin-like growth factor-I (IGF-I) on osteopontin (OPN) expression. The data showed that OPN expression was significantly decreased when cells were cultured on collagen-coated plates. Addition of IGF-I obviously induced OPN expression only in a collagen-coated condition, suggesting an attenuating effect of IGF-I on the decrease of OPN expression. Cells treated with a combination of inhibitory antibody to beta1 integrin and IGF-I showed the same level of OPN expression as those treated with either inhibitory antibody to beta1 integrin or IGF-I alone. These results indicate that IGF-I counteracts with the inhibitory signal from type I collagen through beta1 integrin receptor.

Dexamethasone and basic-fibroblast growth factor regulate markers of mineralization in cementoblasts in vitro

BACKGROUND

The aim of this study was to determine the effects of basic-fibroblast growth factor (b-FGF) and/or dexamethasone (Dex) on cementoblasts in vitro.

METHODS

Murine cementoblasts were treated as follows: 1) 5% FBS (fetal bovine serum) + ascorbic acid (AA, 50 microg/ml, control); 2) 5% FBS + Dex (10(7)M) + AA; 3) 5% FBS + b-FGF (50 ng/ml)+AA; or 4) 5% FBS + Dex (10(7) M) + b-FGF (50 ng/ml)+AA and then evaluated by Northern analysis for changes in specific genes and by von Kossa stain for changes in mineral nodule formation.

RESULTS

Mitotic activity: b-FGF stimulated DNA synthesis significantly versus negative control. Gene expression: osteocalcin (OCN): Dex or b-FGF or the combination resulted in a decrease in expression versus control. Bone sialoprotein (BSP): Dex increased expression of BSP mRNA levels, b-FGF decreased transcript for BSP at 6 and 24 hours. Long-term (8 days) Dex, b-FGF, or Dex plus b-FGF caused a decrease in BSP expression versus control; osteopontin (OPN): both Dex and b-FGF increased transcripts for OPN seen by 6 hours, with a greater increase noted with b-FGF versus Dex. No apparent additive effect of Dex with b-FGF was noted; matrix gamma-carboxyglutamic acid protein (MGP): b-FGF induced transcripts for MGP and addition of Dex increased this effect, while Dex alone had no effect on expression. Biomineralization: Dex increased cementoblast- mediated biomineralization, while b-FGF blocked this activity, and addition of Dex to b-FGF did not alter FGF associated inhibition.

CONCLUSION

Dex and FGF alone and in combination alter cementoblast behavior, but additional studies are required to determine whether these factors have beneficial effects at the clinical level.

Engineering of tooth-supporting structures by delivery of PDGF gene therapy vectors

Platelet-derived growth factor (PDGF) exerts potent effects on wound healing including the regeneration of tooth-supporting structures. Limitations of topical protein delivery to periodontal osseous defects include transient biological activity and the bioavailability of PDGF at the wound site. The objective of this investigation was to determine the feasibility of in vivo PDGF-B gene transfer to stimulate periodontal tissue regeneration in large tooth-associated alveolar bone defects in rats. Periodontal lesions (0.3 x 0.2 cm in size) were treated with a 2.6% collagen matrix alone or a matrix containing adenoviruses encoding luciferase (control), a dominant negative mutant of PDGF-A (PDGF-1308), or PDGF-B. Block biopsies were harvested at 3, 7, and 14 days post-gene delivery and descriptive histology and histomorphometric analyses were performed. The defects treated with Ad-PDGF-B demonstrated greater proliferating cell nuclear antigen positively stained cells and strong evidence of bone and cementum regeneration beyond that of Ad-luciferase and Ad-PDGF-1308 groups. Quantitative image analysis showed a nearly fourfold increase in bridging bone and sixfold increase in tooth-lining cemental repair in the Ad-PDGF-B-treated sites compared to lesions treated with Ad-luciferase or collagen matrix alone, which showed limited hard tissue neogenesis. In addition, the Xenogen In Vivo Imaging System revealed sustained and localized gene expression of the luciferase reporter at the periodontal lesions for up to 21 days after gene transfer. These results indicate that in vivo direct gene transfer of PDGF-B stimulates alveolar bone and cementum regeneration in large periodontal defects. Gene therapy utilizing PDGF-B may offer the potential for periodontal tissue engineering applications.

Cytokine and chemokine response of bone cells after dentin challenge in vitro

OBJECTIVE

The aim of this study was to characterize the effects of dentin extracts on cytokine, chemokine and nitric oxide (NO) production by primary rat bone cells.

STUDY DESIGN

Osteoblastic bone marrow cultures were exposed to particulate (D-part), non-particulate (D-n-part) and demineralized dentin extracts and evaluated for proliferative activity, cell morphology, alkaline phosphatase activity and bone-like nodule formation. Cytokine production was assessed by enzyme-linked immunosorbent assay and NO release by the Griess method.

RESULTS

The dentin extracts did not affect osteoblast numbering. Conversely, they up regulated in a dose-dependent manner the production by the osteoblasts of the pro-inflammatory interleukin-1beta (IL-1beta), tumor necrosis factor-alpha, IL-6, cytokine-induced neutrophil chemoattractant-1, and of the anti-inflammatory cytokine, IL-10. The NO production was stimulated only by D-n-part.

CONCLUSION

These results demonstrate that dentin induces the production of inflammatory cytokines by osteoblasts and suggest that pro-resorptive pathways might be stimulated when dentin molecules come into contact with bone cells during pathological processes associated with dentin and bone matrix dissolution.

Identification of epidermal growth factor receptor-derived peptides recognised by both cellular and humoral immune responses in HLA-A24+ non-small cell lung cancer patients

The epidermal growth factor receptor (EGFR) is one of the most appropriate target molecules for cancer therapy because of its high expression in epithelial cancers. A novel EGFR-tyrosine-kinase inhibitor, ZD1839, has been approved as a drug for non-small cell lung cancer (NSCLC), and many other agents are now being tested in clinical trials. Cytotoxic T lymphocyte (CTL)-directed epitope peptides could be another class of useful compounds in EGFR-targeted therapies. However, at present, there are no data on CTL-directed peptides of EGFR. Therefore, this study aimed to identify immunogenic EGFR-derived peptides in HLA-A24(+) NSCLC patients. We report in this study three such EGFR-derived peptides at positions 54-62, 124-132 and 800-809. These peptides were recognised by both cellular and humoral immune responses in most of the peripheral blood mononuclear cells (PBMCs) and sera from NSCLC patients that we tested. These results may provide a scientific basis for the development of EGFR-based immunotherapy.

Changes in transforming growth factor-beta1 in gingival crevicular fluid following periodontal surgery

OBJECTIVES

Growth factors play a major part in wound healing, including in the periodontium. However, the presence of growth factors in gingival crevicular fluid (GCF) in humans during periodontal wound healing has not yet been determined. Our hypothesis is that such factors are present in GCF and that changes in their levels might be of value as a prognostic marker of wound-healing activity and therapeutic progress following periodontal surgery. The aim of this study was therefore to measure transforming growth factor-beta1 (TGF-beta1) in GCF collected from sites that have undergone guided tissue regeneration (GTR) and conventional flap (CF) surgery and to compare these with GCF collected from unaffected healthy sites.

MATERIALS AND METHODS

GCF samples were collected, using filter paper strips, at baseline (pre-surgical) and then at intervals up to 26 weeks from 16 patients undergoing GTR and from 11 patients undergoing CF surgery. After elution and acid treatment, TGF-beta1 levels were measured by ELISA.

RESULTS

Treatment of periodontal defect sites significantly reduced the mean probing pocket depth (PPD) and improved the mean lifetime cumulative attachment loss (LCAL). Average GCF volumes also significantly increased at all sites at 2 weeks post-surgery and thereafter declined to baseline levels, except at the GTR test sites that were still elevated at 7 weeks. TGF-beta1 could be detected in almost all GCF samples, and 2 weeks after surgery, the average levels increased two-fold at the surgically treated but not at the control sites, which remained unchanged.

CONCLUSION

TGF-beta1 is readily detectable in GCF and increases transiently following periodontal surgery. This suggests that changes in the levels of this growth factor in GCF might be useful for monitoring the progress of periodontal repair and regeneration.

Identification of epidermal growth factor receptor-derived peptides immunogenic for HLA-A2(+) cancer patients

Epidermal growth factor receptor (EGFR) is one of the most appropriate target molecules for cancer therapy because of its relatively high expression in about one-third of all epithelial cancers in correlation with neoplasmic progression. With respect to EGFR-targeted therapies, antibodies and tyrosine-kinase inhibitors have been intensively studied, a novel EGFR-tyrosine-kinase inhibitor ZD1839 has been approved as an anticancer drug, and many other agents are now under clinical trial. In addition, cytotoxic T lymphocyte (CTL)-directed epitope peptides could be another class of compounds useful in EGFR-targeted therapies. However, there is presently no information on CTL-directed peptides of EGFR. Therefore, from the viewpoint of development of peptide-based cancer therapy, this study was intended to determine the EGFR-derived peptides recognised by both cellular and humoral immunities in HLA-A2(+) epithelial cancer patients. We herein report finding of two such types of EGFR-derived peptides at position 479-488 and 1138-1147, both of which were recognised by the majority of patients' sera (IgG), and also possessed the ability to induce HLA-A2-restricted peptide-specific CTLs against EGFR-positive tumour cells in peripheral blood mononuclear cells (PBMCs) of epithelial cancer patients. These results may provide a scientific basis for the development of EGFR-based immunotherapy for HLA-A2(+) cancer patients.

Platelet-derived growth factor gene delivery stimulates ex vivo gingival repair

Destruction of tooth support due to the chronic inflammatory disease periodontitis is a major cause of tooth loss. There are limitations with available treatment options to tissue engineer soft tissue periodontal defects. The exogenous application of growth factors (GFs) such as platelet-derived growth factor (PDGF) has shown promise to enhance oral and periodontal tissue regeneration. However, the topical administration of GFs has not led to clinically significant improvements in tissue regeneration because of problems in maintaining therapeutic protein levels at the defect site. The utilization of PDGF gene transfer may circumvent many of the limitations with protein delivery to soft tissue wounds. The objective of this study was to test the effect of PDGF-A and PDGF-B gene transfer to human gingival fibroblasts (HGFs) on ex vivo repair in three-dimensional collagen lattices. HGFs were transduced with adenovirus encoding PDGF-A and PDGF-B genes. Defect fill of bilayer collagen gels was measured by image analysis of cell repopulation into the gingival defects. The modulation of gene expression at the defect site and periphery was measured by RT-PCR during a 10-day time course after gene delivery. The results demonstrated that PDGF-B gene transfer stimulated potent (>4-fold) increases in cell repopulation and defect fill above that of PDGF-A and corresponding controls. PDGF-A and PDGF-B gene expression was maintained for at least 10 days. PDGF gene transfer upregulated the expression of phosphatidylinosital 3-kinase and integrin alpha5 subunit at 5 days after adenovirus transduction. These results suggest that PDGF gene transfer has potential for periodontal soft tissue-engineering applications.

Dentin matrix proteins and soluble factors: intrinsic regulatory signals for healing and resorption of dental and periodontal tissues?

Dentin contains numerous polypeptides and signaling molecules sequestered in a mineralized matrix. The exposure and release of these molecules occur as a consequence of injury to the pulp and periodontal ligament, which may result from luxation, orthodontic movement or infections of tooth and periodontal structures. When released at these sites, dentin constituents have the potential to act on different surrounding cells, including periodontal cells, osteoblasts, osteoclasts and inflammatory cells, and to affect the course of dental disease. Experimental studies have highlighted the interactions between dentin and cells from tooth and periodontal tissues and reveal dentin to be a cell adhesive, signaling and migratory stimulus for various mesenchymal and inflammatory cells. These results support the hypothesis that dentin molecules might function as regulatory signals for the healing and resorption of dental and periodontal tissues. Data from recent and classical investigations are summarized, many open questions are discussed, and current hypotheses concerning the mechanisms of tooth resorption and periodontal healing are outlined. Many questions regarding the importance of dentin as a source of multifunctional molecules remain unanswered and provide important directions for future studies.

Stimulation of growth factor synthesis in skin wounds using tissue extract (G-90) from the earthwormEissenia foetida

Growth factors are biologically-active mediators that bind to specific receptors on target cells and regulate genes involved in cell growth, wound healing and regeneration. In the case of wound healing, a proper wound dressing is needed to cover the wound area, protect the damaged tissue, and if possible to activate cell proliferation and stimulate the healing process. In this study we examined the efficacy of a glycolipoprotein tissue homogenate extract from Eisenia foetida (G-90) to activate signal transduction pathways, leading to wound healing. We measured the activation of EGF and FGF in healthy skin, in wounds with physiological healing and in wounds treated with G-90. The activation of EGF and FGF was measured during the first 24 h of wound healing under both physiological conditions and treatment with G-90. In both cases an increased concentration of EGF and FGF was observed 6 h after wounding. In comparison with healthy skin, the concentration of EGF increased 10-fold and FGF five-fold in wounds treated with G-90 (10 ng ml(-1)). Healing in physiological conditions resulted in a two-fold increase of EGF and 1.5-fold of FGF.

Role of Insulin-Like Growth Factor-1 Signaling in Dental Fibroblast Apoptosis

BACKGROUND

Studies have shown that periodontal ligament fibroblasts (PDLF) and gingival fibroblasts (GF) respond differently to growth factors in the repair and regeneration of periodontal tissues. The goal of this study was to determine the effects of insulin-like growth factor-1 (IGF-1) signaling on cell apoptosis in PDLF compared to GF.

METHODS

The levels of apoptosis were compared between cultured PDLF and GF by DNA fragmentation assay and trypan blue exclusion assay, either in the presence or absence of IGF-1. The transcript level of upstream signaling molecules, such as IGF binding protein-5 (IGFBP-5), IGF-1 receptor (IGF-1R), and phosphoinositide 3-kinase (PI3K), was studied using reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, the role of IGFBP-5 in IGF-1 signaling was verified by annexin-V staining using flow cytometric analysis.

RESULTS

IGF-1 significantly inhibited the level of DNA fragmentation and decreased trypan blue-positive cells in PDLF compared to GF during serum deprivation. The mRNA expression of IGFBP-5, IGF-1R, and PI3K was constitutively upregulated in PDLF compared to GF. In the presence of exogenous IGFBP-5, the annexin-V-positive cells were significantly decreased in GF after IGF-1 stimulation.

CONCLUSIONS

The present study provides evidence that IGF-1 reduces apoptosis in cultured PDLF compared to GF. Upregulation of IGF-1R and PI3K in PDLF further suggests the activation of IGF signaling in PDLF. In addition, the anti-apoptotic effect of IGF-1 may be facilitated by the upregulation of IGFBP-5 in PDLF.

Transforming growth factor-beta 1 expression in the peri-implant soft tissues of healthy and failing dental implants

BACKGROUND

Transforming growth factor-beta (TGF-beta) is composed of a family of multifunctional polypeptide growth factors involved in embryogenesis, inflammation, regulation of immune response, angiogenesis, wound healing, and extracellular matrix formation. TGF-beta1 is the most common isoform found in human tissues. A role of TGF-beta in the pathogenesis of periodontal disease has been suggested. The aim of the present study was a comparative immunohistochemical evaluation of TGF-beta1 in normal keratinized gingiva and in the peri-implant soft tissues surrounding failing non-submerged implants.

METHODS

Twenty patients participated in this study. Ten biopsies from healthy keratinized mucosa and 10 biopsies from peri-implant soft tissues surrounding failing implants were obtained (one biopsy per patient). The biopsies were obtained from different patients.

RESULTS

In 5 cases of healthy mucosa, the stromal cells were positive between 1 to 5. In 7 cases, the epithelial layers were positive, between 1 and 18 cells. The superficial epithelial layer was negative in all cases. In 9 cases, there was a positivity of the vascular component, between 2 and 16 vessels. In failing implants, the stromal cells were positive in 6 cases, between 1 and 4. In all cases, cells of the epithelial layers were positive, between 15 and 40. The vascular component was positive in all cases, between 12 and 30 vessels. The differences between TGF-beta1 expression in the epithelium around healthy and failing implants were statistically significant (P < 0.0001). The differences between TGF-beta1 expression in the blood vessels in the soft tissues around healthy and failing implants were also statistically significant (P < 0.0001). No statistically significant difference was observed between the 2 groups in the TGF-beta1 expression in the stromal cells (P = 0.88).

CONCLUSION

TGF-beta1 may be one of the most important factors in the regulation of the infiltrate, and in the production of tissue repair with a stimulation of fibroblasts and endothelial cells.