Fibroblast growth factor‐2 regulates expression of osteopontin in periodontal ligament cells

Surgical Periodontal Therapy with Recombinant Human Fibroblast Growth Factor-2 in Treatment of Chronic Periodontitis: A Case Report with 2-year Follow-up

We report a case of generalized chronic periodontitis requiring periodontal regenerative therapy. The patient was a 53-year-old woman who presented with the chief complaint of gingival swelling. An initial examination revealed 31.5% of sites with a probing depth of ≥4 mm and 46.3% with bleeding on probing. Radiographic examination showed vertical bone resorption in tooth #33. Horizontal adsorption was also observed in other areas. Based on a clinical diagnosis of severe generalized chronic periodontitis, initial periodontal therapy consisting of plaque control, scaling and root planing, occlusal adjustment, caries treatment, and splint placement was performed. After re-evaluation, surgical periodontal treatment was performed at selected sites. Periodontal regeneration therapy with recombinant human fibroblast growth factor (rhFGF)-2 was performed at #33. Two other sites (#14, 15), which had residual periodontal pockets, were treated by open-flap debridement. After re-evaluation, the patient was placed on a maintenance program. Periodontal regenerative therapy with rhFGF-2 resulted in an improvement in angular bone resorption, which has been properly maintained for 2 years. Continued care is needed to maintain stable periodontal conditions.

The Role of Type 2 Fibroblast Growth Factor in Periodontal Therapy

The prevalence of periodontitis is around 20-50% in the global population. If it is not treated, it can cause tooth loss. Periodontal treatment aims at preserving the patient's teeth from various damages, including infection control and restoring lost periodontal tissue. The periodontium has great biological regenerative potential, and several biomaterials can be used to improve the outcome of periodontal treatment. To achieve the goal of periodontal tissue regeneration, numerous studies have used fibroblast growth factor 2 (FGF2) to stimulate the regeneration of both the soft tissue and bone. FGF2 induced a significant increment in the percentage of bone fill, bone mineral levels of the defect sites, length of the regenerated periodontal ligament, angiogenesis, connective tissue formation on the root surface, formation of dense fibers bound to the alveolar bone and newly synthesized cementum in teeth. This review will open further avenues to better understand the FGF2 therapy for periodontal regeneration.

Role of hyaluronan in regulating self-renewal and osteogenic differentiation of mesenchymal stromal cells and pre-osteoblasts

Objectives

The aim of the study was to investigate the impact of two hyaluronan (HA) formulations on the osteogenic potential of osteoblast precursors.

Materials and methods

Proliferation rates of HA-treated mesenchymal stromal ST2 and pre-osteoblastic MC3T3-E1 cells were determined by 5-bromo-20-deoxyuridine (BrdU) assay. Expression of genes encoding osteogenic differentiation markers, critical growth, and stemness factors as well as activation of downstream signaling pathways in the HA-treated cells were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunoblot techniques.

Results

The investigated HAs strongly stimulated the growth of the osteoprogenitor lines and enhanced the expression of genes encoding bone matrix proteins. However, expression of late osteogenic differentiation markers was significantly inhibited, accompanied by decreased bone morphogenetic protein (BMP) signaling. The expression of genes encoding transforming growth factor-β1 (TGF-β1) and fibroblast growth factor-1 (FGF-1) as well as the phosphorylation of the downstream signaling molecules Smad2 and Erk1/2 were enhanced upon HA treatment. We observed significant upregulation of the transcription factor Sox2 and its direct transcription targets and critical stemness genes, Yap1 and Bmi1, in HA-treated cells. Moreover, prominent targets of the canonical Wnt signaling pathway showed reduced expression, whereas inhibitors of the pathway were considerably upregulated. We detected decrease of active β-catenin levels in HA-treated cells due to β-catenin being phosphorylated and, thus, targeted for degradation.

Conclusions

HA strongly induces the growth of osteoprogenitors and maintains their stemness, thus potentially regulating the balance between self-renewal and differentiation during bone regeneration following reconstructive oral surgeries.

Clinical relevance

Addition of HA to deficient bone or bony defects during implant or reconstructive periodontal surgeries may be a viable approach for expanding adult stem cells without losing their replicative and differentiation capabilities.

Electronic supplementary material

The online version of this article (10.1007/s00784-020-03259-8) contains supplementary material, which is available to authorized users.

Impact of the source and serial passaging of goat mesenchymal stem cells on osteogenic differentiation potential: implications for bone tissue engineering

BACKGROUND

Adult mesenchymal stem cells (MSCs) can be conveniently sampled from bone marrow, peripheral blood, muscle, adipose and connective tissue, harvested from various species, including, rodents, dogs, cats, horses, sheep, goats and human beings. The MSCs isolated from adult tissues vary in their morphological and functional properties. These variations are further complicated when cells are expanded by passaging in culture. These differences and changes in MSCs must be considered prior to their application in the clinic or in a basic research study. Goats are commonly used as animal models for bone tissue engineering to test the potential of stem cells for bone regeneration. As a result, goat MSCs isolated from bone marrow or adipose tissue should be evaluated using in vitro assays, prior to their application in a tissue engineering project.

RESULTS

In this study, we compared the stem cell properties of MSCs isolated from goat bone marrow and adipose tissue. We used quantitative and qualitative assays with a focus on osteogenesis, including, colony forming unit, rate of cell proliferation, tri-lineage differentiation and expression profiling of key signal transduction proteins to compare MSCs from low and high passages. Primary cultures generated from each source displayed the stem cell characteristics, with variations in their osteogenic potentials. Most importantly, low passaged bone marrow MSCs displayed a significantly higher and superior osteogenic potential, and hence, will be the preferred choice for bone tissue engineering in future in vivo experiments. In the bone marrow MSCs, this process is potentially mediated by the p38 MAPK pathway. On the other hand, osteogenic differentiation in the adipose tissue MSCs may involve the p44/42 MAPK pathway.

CONCLUSIONS

Based on these data, we can conclude that bone marrow and fat-derived MSCs undergo osteogenesis via two distinct signaling pathways. Even though the bone marrow MSCs are the preferred source for bone tissue engineering, the adipose tissue MSCs are an attractive alternative source and undergo osteo-differentiation differently from the bone marrow MSCs and hence, might require a cell-based enhancer/inducer to improve their osteogenic regenerative capacity.

Matricellular proteins as regulators of cancer metastasis to bone

Metastasis is the major cause of death in cancer patients, and a frequent site of metastasis for many cancers is the bone marrow. Therefore, understanding the mechanisms underlying the metastatic process is necessary for future prevention and treatment. The tumor microenvironment is now known to play a role in the metastatic cascade, both at the primary tumor and in metastatic sites, and includes both cellular and non-cellular components. The extracellular matrix (ECM) provides structural support and signaling cues to cells. One particular group of molecules associated with the ECM, known as matricellular proteins, modulate multiple aspects of tumor biology, including growth, migration, invasion, angiogenesis and metastasis. These proteins are also important for normal function in the bone by regulating bone formation and bone resorption. Recent studies have described a link between some of these proteins and metastasis of various tumors to the bone. The aim of this review is to summarize what is currently known about matricellular protein influence on bone metastasis. Particular attention to the contribution of both tumor cells and non-malignant cells in the bone has been given.

Characterization of human periodontal ligament cells cultured on three-dimensional biphasic calcium phosphate scaffolds in the presence and absence of L-ascorbic acid, dexamethasone and β-glycerophosphate in vitro

The aim of this study was to evaluate the effect of porous biphasic calcium phosphate (BCP) scaffolds on the proliferation and osteoblastic differentiation of human periodontal ligament cells (hPDLCs) in the presence and absence of osteogenic inducer (L-ascorbic acid, dexamethasone and β-glycerophosphate). The cell growth within the scaffolds in the absence of osteogenic inducers was studied by cell counting kit-8 (CCK-8) assay and scanning electron microscopy (SEM). Alkaline phosphatase (ALP) activity and osteoblastic differentiation markers of hPDLCs in BCP scaffolds were examined in the presence and absence of osteogenic inducers. The cell number of hPDLCs in the BCP scaffolds was less than that of hPDLCs cultured in microplates (control). SEM images showed that cells successfully adhered to the BCP scaffolds and spread amongst the pores; they also produced abundant extracellular cell matrix. In the presence and absence of osteogenic inducers, the ALP activity of hPDLCs within BCP scaffolds was suppressed in varying degrees at all time-points. In the absence of osteogenic inducers, hPDLCs in BCP scaffolds express significant higher levels of osteopontin (OPN) mRNA than the control, and there were no significant differences for Runx2 and osteocalcin (OCN) mRNA levels compared with those cultured in microplates. In the presence of osteogenic inducers, Runx2 expression levels were significantly higher than those in control. OPN and OCN mRNA levels were downregulated slightly. Three-dimensional porous BCP scaffolds are able to stimulate the osteoblastic differentiation of hPDLCs in the presence and absence of osteogenic inducer and may be capable of supporting hPDLC-mediated bone formation.

PLAP-1/Asporin Regulates TLR2- and TLR4-induced Inflammatory Responses

Periodontal ligament-associated protein 1 (PLAP-1)/asporin is an extracellular matrix protein preferentially expressed in periodontal ligaments. PLAP-1/asporin inhibits the cytodifferentiation and mineralization of periodontal ligament cells and has important roles in the maintenance of periodontal tissue homeostasis. However, the involvement of PLAP-1/asporin in inflammatory responses during periodontitis is poorly understood. This study hypothesized that PLAP-1/asporin might affect the pathogenesis of periodontitis by regulating periodontopathic bacteria-induced inflammatory responses. Proinflammatory cytokine expression induced by Toll-like receptor 2 (TLR2) and TLR4 was significantly downregulated when PLAP-1/asporin was overexpressed in periodontal ligament cells. Similarly, recombinant PLAP-1/asporin inhibited TLR2- and TLR4-induced proinflammatory cytokine expression in macrophages. We also confirmed that NF-κB activity induced by TLR2 and TLR4 signaling was suppressed by the addition of recombinant PLAP-1/asporin. Furthermore, IκB kinase α degradation induced by TLR4 was reduced by PLAP-1/asporin. Immunoprecipitation assays demonstrated the binding abilities of PLAP-1/asporin to both TLR2 and TLR4. Taken together, PLAP-1/asporin negatively regulates TLR2- and TLR4-induced inflammatory responses through direct molecular interactions. These findings indicate that PLAP-1/asporin has a defensive role in periodontitis lesions by suppressing pathophysiologic TLR signaling and that the modulating effects of PLAP-1/asporin might be useful for periodontal treatments.

Time-lapse Raman imaging of osteoblast differentiation

Osteoblastic mineralization occurs during the early stages of bone formation. During this mineralization, hydroxyapatite (HA), a major component of bone, is synthesized, generating hard tissue. Many of the mechanisms driving biomineralization remain unclear because the traditional biochemical assays used to investigate them are destructive techniques incompatible with viable cells. To determine the temporal changes in mineralization-related biomolecules at mineralization spots, we performed time-lapse Raman imaging of mouse osteoblasts at a subcellular resolution throughout the mineralization process. Raman imaging enabled us to analyze the dynamics of the related biomolecules at mineralization spots throughout the entire process of mineralization. Here, we stimulated KUSA-A1 cells to differentiate into osteoblasts and conducted time-lapse Raman imaging on them every 4 hours for 24 hours, beginning 5 days after the stimulation. The HA and cytochrome c Raman bands were used as markers for osteoblastic mineralization and apoptosis. From the Raman images successfully acquired throughout the mineralization process, we found that β-carotene acts as a biomarker that indicates the initiation of osteoblastic mineralization. A fluctuation of cytochrome c concentration, which indicates cell apoptosis, was also observed during mineralization. We expect time-lapse Raman imaging to help us to further elucidate osteoblastic mineralization mechanisms that have previously been unobservable.

Tissue engineering for bone regeneration and osseointegration in the oral cavity

OBJECTIVE

The focus of this review is to summarize recent advances on regenerative technologies (scaffolding matrices, cell/gene therapy and biologic drug delivery) to promote reconstruction of tooth and dental implant-associated bone defects.

METHODS

An overview of scaffolds developed for application in bone regeneration is presented with an emphasis on identifying the primary criteria required for optimized scaffold design for the purpose of regenerating physiologically functional osseous tissues. Growth factors and other biologics with clinical potential for osteogenesis are examined, with a comprehensive assessment of pre-clinical and clinical studies. Potential novel improvements to current matrix-based delivery platforms for increased control of growth factor spatiotemporal release kinetics are highlighting including recent advancements in stem cell and gene therapy.

RESULTS

An analysis of existing scaffold materials, their strategic design for tissue regeneration, and use of growth factors for improved bone formation in oral regenerative therapies results in the identification of current limitations and required improvements to continue moving the field of bone tissue engineering forward into the clinical arena.

SIGNIFICANCE

Development of optimized scaffolding matrices for the predictable regeneration of structurally and physiologically functional osseous tissues is still an elusive goal. The introduction of growth factor biologics and cells has the potential to improve the biomimetic properties and regenerative potential of scaffold-based delivery platforms for next-generation patient-specific treatments with greater clinical outcome predictability.

Porphyromonas gingivalis GroEL induces osteoclastogenesis of periodontal ligament cells and enhances alveolar bone resorption in rats

Porphyromonas gingivalis is a major periodontal pathogen that contains a variety of virulence factors. The antibody titer to P. gingivalis GroEL, a homologue of HSP60, is significantly higher in periodontitis patients than in healthy control subjects, suggesting that P. gingivalis GroEL is a potential stimulator of periodontal disease. However, the specific role of GroEL in periodontal disease remains unclear. Here, we investigated the effect of P. gingivalis GroEL on human periodontal ligament (PDL) cells in vitro, as well as its effect on alveolar bone resorption in rats in vivo. First, we found that stimulation of PDL cells with recombinant GroEL increased the secretion of the bone resorption-associated cytokines interleukin (IL)-6 and IL-8, potentially via NF-κB activation. Furthermore, GroEL could effectively stimulate PDL cell migration, possibly through activation of integrin α1 and α2 mRNA expression as well as cytoskeletal reorganization. Additionally, GroEL may be involved in osteoclastogenesis via receptor activator of nuclear factor κ-B ligand (RANKL) activation and alkaline phosphatase (ALP) mRNA inhibition in PDL cells. Finally, we inoculated GroEL into rat gingiva, and the results of microcomputed tomography (micro-CT) and histomorphometric assays indicated that the administration of GroEL significantly increased inflammation and bone loss. In conclusion, P. gingivalis GroEL may act as a potent virulence factor, contributing to osteoclastogenesis of PDL cells and resulting in periodontal disease with alveolar bone resorption.

An insight into the possibilities of fibroblast growth factor in periodontal regeneration

Periodontitis is caused by bacterial biofilms and is modulated by a variety of risk factors. The periodontal ligament comprises heterogeneous cell populations which are lost in the disease process. A variety of regenerative therapies, such as bone grafts, guided tissue regeneration treatment, application of enamel matrix derivative, have been introduced, with some success in periodontal tissue regeneration. Topical application of recombinant cytokines is now one of the most effective methods to stimulate stem cells. Researchers are now exploring the potential applications and uses of fibroblast growth factor in periodontal regeneration.

Cooperative effects of FGF-2 and VEGF-A in periodontal ligament cells

We previously demonstrated that topical application of fibroblast growth factor (FGF)-2 enhanced periodontal tissue regeneration. Although angiogenesis is a crucial event for tissue regeneration, the mechanism(s) by which topically applied FGF-2 induces angiogenesis in periodontal tissues has not been fully clarified. In this study, we investigated whether FGF-2 could induce vascular endothelial growth factor (VEGF)-A expression in periodontal ligament (PDL) cells and whether cell-to-cell interactions between PDL cells and endothelial cells could stimulate angiogenesis. FGF-2 induced VEGF-A secretion from MPDL22 cells (mouse periodontal ligament cell line) in a dose-dependent manner. Transwell and wound-healing assays revealed that co-stimulation with FGF-2 plus VEGF-A synergistically stimulated the migration of MPDL22 cells. Interestingly, co-culture of MPDL22 cells with bEnd5 cells (mouse endothelial cell line) also stimulated VEGF-A production from MPDL22 cells and tube formation by bEnd5 cells. Furthermore, time-lapse analysis revealed that MPDL22 cells migrated close to the tube-forming bEnd5 cells, mimicking pericytes. Thus, FGF-2 induces VEGF-A expression in PDL cells and induces angiogenesis in combination with VEGF-A. Cell-to-cell interactions with PDL cells also facilitate angiogenesis.

Protein and peptide-based therapeutics in periodontal regeneration

Protein and peptide-based therapeutics provide a unique strategy for controlling highly specific and complex biologic actions that cannot be accomplished by simple devices or chemical compounds. This article reviews some of the key characteristics and summarizes the clinical effectiveness of protein and peptide-based therapeutics targeting periodontal regeneration.

EVIDENCE ACQUISITION

A literature search was conducted of randomized clinical trials and systematic reviews evaluating protein and peptide-based therapeutics for the regeneration of periodontal tissues of at least 6 months duration. Data sources included PubMed and Embase electronic databases, hand-searched journals, and the ClinicalTrials.gov registry.

EVIDENCE SYNTHESIS

Commercially marketed protein and peptide-based therapeutics for periodontal regeneration provide gains in clinical attachment level and bone formation that are comparable or superior to other regenerative approaches. Results from several clinical trials indicate that protein and peptide-based therapies can accelerate repair and regeneration when compared with other treatments and that improvements in clinical parameters continue beyond 12 months. Protein and peptide-based therapies also exhibit the capacity to increase the predictability of treatment outcomes.

CONCLUSIONS

Clinical and histologic studies support the effectiveness of protein- and peptide-based therapeutics for periodontal regeneration. Emerging evidence suggests that the delivery devices/scaffolds play a critical role in determining the effectiveness of this class of therapeutics.

Engineering three-dimensional constructs of the periodontal ligament in hyaluronan-gelatin hydrogel films and a mechanically active environment

BACKGROUND AND OBJECTIVE

Periodontal ligament (PDL) cells in stationary two-dimensional culture systems are in a double default state. Our aim therefore was to engineer and characterize three-dimensional constructs, by seeding PDL cells into hyaluronan-gelatin hydrogel films (80-100 μm) in a format capable of being mechanically deformed.

MATERIAL AND METHODS

Human PDL constructs were cultured with and without connective tissue growth factor (CTGF) and fibroblast growth factor (FGF)-2 in (i) stationary cultures, and (ii) mechanically active cultures subjected to cyclic strains of 12% at 0.2 Hz each min, 6 h/d, in a Flexercell FX-4000 Strain Unit. The following parameters were measured: cell number and viability by laser scanning confocal microscopy; cell proliferation with the MTS assay; the expression of a panel of 18 genes using real-time RT-PCR; matrix metalloproteinases (MMPs) 1-3, TIMP-1, CTGF and FGF-2 protein levels in supernatants from mechanically activated cultures with Enzyme-linked immunosorbent assays. Constructs from stationary cultures were also examined by scanning electron microscopy and immunostained for actin and vinculin.

RESULTS

Although initially randomly distributed, the cells became organized into a bilayer by day 7; apoptotic cells remained constant at approximately 5% of the total. CTGF/FGF-2 stimulated cell proliferation in stationary cultures, but relative quantity values suggested modest effects on gene expression. Two transcription factors (RUNX2 and PPARG), two collagens (COL1A1, COL3A1), four MMPs (MMP-1-3, TIMP-1), TGFB1, RANKL, OPG and P4HB were detected by gel electrophoresis and Ct values < 35. In mechanically active cultures, with the exception of P4HB, TGFB1 and RANKL, each was upregulated at some point in the time scale, as was the synthesis of MMPs and TIMP-1. SOX9, MYOD, SP7, BMP2, BGLAP or COL2A1 were not detected in either stationary or mechanically active cultures.

CONCLUSION

Three-dimensional tissue constructs provide additional complexity to monolayer culture systems, and suggest some of the assumptions regarding cell growth, differentiation and matrix turnover based on two-dimensional cultures may not apply to cells in three-dimensional matrices. Primarily developed as a transitional in vitro model for studying cell-cell and cell-matrix interactions in tooth support, the system is also suitable for investigating the pathogenesis of periodontal diseases, and importantly from the clinical point of view, in a mechanically active environment.

Effect of basic fibroblast growth factor (FGF-2) in combination with beta tricalcium phosphate on root coverage in dog

OBJECTIVE

In root coverage treatment, periodontal regeneration in gingival recession-type defects is an important challenge for the periodontist. The aim of this study was to histometrically investigate the effect of combined use of basic fibroblast growth factor (FGF-2) and beta tricalcium phosphate (β-TCP) on root coverage in dogs.

MATERIALS AND METHODS

Sixteen adult beagle dogs were used. Buccal gingival recession defects were surgically created bilaterally in the maxillary canines. The defects in each animal were randomly assigned to: (1) an FGF-2 alone (control) group or (2) FGF-2/β-TCP (experimental) group. At 2, 4 or 8 weeks following surgery, specimens were obtained and subjected to microscopic examination and histometric assessment.

RESULTS

Inhibition of epithelial down-growth was observed in both groups. At week 2, in the newly formed connective tissue at the coronal portion, the FGF-2/β-TCP group showed significantly greater numbers of proliferating cell nuclear antigen-positive cells than the FGF-2 group (55.8 ± 4.8 vs 12.0 ± 1.4, p < 0.01). In the FGF-2/β-TCP group, new attachment was observed at 8 weeks and the extent of new bone and cementum formation was significantly greater in the FGF-2/β-TCP group than that in the FGF-2 alone group. In both groups, the dentin surface beneath the new cementum presented minor irregularities, but no replacement resorption was observed.

CONCLUSIONS

FGF-2 used in combination with β-TCP enhances formation of new bone and cementum without significant root resorption in root coverage in this dog model. This combination warrants further investigation in periodontal regeneration in root coverage treatment.

Effect of basic fibroblast growth factor on root resorption after delayed autotransplantation of tooth in dogs

OBJECTIVES

The aim of this study was to investigate the effect of basic fibroblast growth factor (FGF-2) on root resorption after delayed autotransplantation in dogs.

STUDY DESIGN

Mandibular second and third premolars of beagle dogs were extracted to create sites for autotransplantation. After 2 months, in the experimental sites the first and fourth mandibular premolars were extracted and air dried before autotransplantation with the application of recombinant FGF-2; the control sites received teeth without FGF-2. At 2, 4, or 8 weeks after surgery, the animals were killed and specimens collected and processed for histologic examination.

RESULTS

Autotransplantation with FGF-2 yielded formation of new periodontal ligament-like tissues with inserting collagen fibers, associated cementum, and bone. The occurrence of replacement resorption in the FGF-2 treated group was significantly lower than in the control group (P < .01).

CONCLUSIONS

It was demonstrated that topical application of FGF-2 reduced the occurrence of ankylosis and root resorption after delayed autotransplantation in this experimental model.

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

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

Nuclear isoforms of fibroblast growth factor 2 are novel inducers of hypophosphatemia via modulation of FGF23 and KLOTHO

FGF2 transgenic mice were developed in which type I collagen regulatory sequences drive the nuclear high molecular weight FGF2 isoforms in osteoblasts (TgHMW). The phenotype of TgHMW mice included dwarfism, decreased bone mineral density (BMD), osteomalacia, and decreased serum phosphate (P(i)). When TgHMW mice were fed a high P(i) diet, BMD was increased, and dwarfism was partially reversed. The TgHMW phenotype was similar to mice overexpressing FGF23. Serum FGF23 was increased in TgHMW mice. Fgf23 mRNA in bones and fibroblast growth factor receptors 1c and 3c and Klotho mRNAs in kidneys were increased in TgHMW mice, whereas the renal Na(+)/P(i) co-transporter Npt2a mRNA was decreased. Immunohistochemistry and Western blot analyses of TgHMW kidneys showed increased KLOTHO and decreased NPT2a protein. The results suggest that overexpression of HMW FGF2 increases FGF23/FGFR/KLOTHO signaling to down-regulate NPT2a, causing P(i) wasting, osteomalacia, and decreased BMD. We assessed whether HMW FGF2 expression was altered in the Hyp mouse, a mouse homolog of the human disease X-linked hypophosphatemic rickets/osteomalacia. Fgf2 mRNA was increased in bones, and Western blots showed increased FGF2 protein in nuclear fractions from osteoblasts of Hyp mice. In addition, immunohistochemistry demonstrated co-localization of FGF23 and HMW FGF2 protein in osteoblasts and osteocytes from Hyp mice. This study reveals a novel mechanism of regulation of the FGF23-P(i) homeostatic axis.

Activation of RhoA and FAK induces ERK-mediated osteopontin expression in mechanical force-subjected periodontal ligament fibroblasts

The precise mechanism by which Rho kinase translates the mechanical signals into OPN up-regulation in force-exposed fibroblasts has not been elucidated. Human periodontal ligament fibroblasts (hPLFs) were exposed to mechanical force by centrifuging the culture plates at a magnitude of 50 g/cm(2) for 60 min. At various times of the force application, they were processed for analyzing cell viability, trypan blue exclusion, and OPN expression at protein and RNA levels. Cellular mechanism(s) of the force-induced OPN up-regulation was also examined using various kinase inhibitors or antisense oligonucleotides specific to mechanosensitive factors. Centrifugal force up-regulated OPN expression and induced a rapid and transient increase in the phosphorylation of focal adhesion kinase (FAK), extracellular signal-regulated kinase (ERK), and Elk1. Pharmacological blockade of RhoA/Rho-associated coiled coil-containing kinase (ROCK) signaling markedly reduced force-induced FAK and ERK1/2 phosphorylation. Transfecting hPLFs with FAK antisense oligonucleotide diminished ERK1/2 activation and force-induced OPN expression. Further, ERK inhibitor inhibited significantly OPN expression, Elk1 phosphorylation, and activator protein-1 (AP-1)-DNA binding activation, but not FAK phosphorylation, in the force-applied cells. These results demonstrate that FAK signaling plays critical roles in force-induced OPN expression in hPLFs through interaction with Rho/ROCK as upstream effectors and ERK-Elk1/ERK-c-Fos as downstream effectors.

Effect of combined application of bFGF and inorganic polyphosphate on bioactivities of osteoblasts and initial bone regeneration

Basic fibroblast growth factor (bFGF) and inorganic polyphosphate (poly(P)) have been recognized as therapeutic agents that enhance bone regeneration. It has also been shown that poly(P) may enhance the mitogenic activity of bFGF. The purpose of this study is to evaluate the combined effect of bFGF and poly(P) on bioactivities of osteoblasts and initial bone regeneration in vitro and in vivo. MC3T3-E1 cells were treated with bFGF, poly(P) or bFGF+poly(P), then subjected to cell proliferation assay, alkaline phosphatase (ALP) activity measurement, quantitative real-time reverse transcription-polymerase chain reaction and Alizarin S Red staining. In an in vivo study, bFGF-, poly(P)- and bFGF+poly(P)-modified interconnected porous hydroxyapatite (IPHA) complexes were fabricated, and placed into the femurs of rabbits to evaluate new bone formation histologically and histomorphometrically. The highest enhancement of cell proliferation were observed in those treated with bFGF+poly(P) on days 5 and 7. Cells treated with bFGF+poly(P) also exhibited increased ALP activity on days 5 and 10, up-regulated mRNA levels of osteocalcin and osteopontin, and enhanced calcification when compared to the non-treated cells. In vivo, the highest bone formation ratio was observed in bFGF+poly(P)-modified IPHA complexes. This study indicated that co-application of bFGF and poly(P) may provide enhanced bone formation by modulating cell proliferation and the mineralization process. It is anticipated that a combined application of bFGF and poly(P) can provide a novel method for bone regeneration in clinical use.

Periodontal tissue regeneration using fibroblast growth factor-2: randomized controlled phase II clinical trial

BACKGROUND

The options for medical use of signaling molecules as stimulators of tissue regeneration are currently limited. Preclinical evidence suggests that fibroblast growth factor (FGF)-2 can promote periodontal regeneration. This study aimed to clarify the activity of FGF-2 in stimulating regeneration of periodontal tissue lost by periodontitis and to evaluate the safety of such stimulation.

METHODOLOGY/PRINCIPAL FINDINGS

We used recombinant human FGF-2 with 3% hydroxypropylcellulose (HPC) as vehicle and conducted a randomized double-blinded controlled trial involving 13 facilities. Subjects comprised 74 patients displaying a 2- or 3-walled vertical bone defect as measured > or = 3 mm apical to the bone crest. Patients were randomly assigned to 4 groups: Group P, given HPC with no FGF-2; Group L, given HPC containing 0.03% FGF-2; Group M, given HPC containing 0.1% FGF-2; and Group H, given HPC containing 0.3% FGF-2. Each patient underwent flap operation during which we administered 200 microL of the appropriate investigational drug to the bone defect. Before and for 36 weeks following administration, patients underwent periodontal tissue inspections and standardized radiography of the region under investigation. As a result, a significant difference (p = 0.021) in rate of increase in alveolar bone height was identified between Group P (23.92%) and Group H (58.62%) at 36 weeks. The linear increase in alveolar bone height at 36 weeks in Group P and H was 0.95 mm and 1.85 mm, respectively (p = 0.132). No serious adverse events attributable to the investigational drug were identified.

CONCLUSIONS

Although no statistically significant differences were noted for gains in clinical attachment level and alveolar bone gain for FGF-2 groups versus Group P, the significant difference in rate of increase in alveolar bone height (p = 0.021) between Groups P and H at 36 weeks suggests that some efficacy could be expected from FGF-2 in stimulating regeneration of periodontal tissue in patients with periodontitis.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00514657.