Oxya chinensis sinuosa (OC) Extracts Protects ARPE-19 Cells against Oxidative Stress via Activation of the Mitogen-Activated Protein Kinases (MAPKs)/ Nuclear Factor-κB (NF-κB) Pathway.

Oxya chinensis sinuosa (OC) is a well-known edible insect. Several researches on the health benefits of OC consumption have been performed to date; however, their effect on eye health remains largely unknown. This study aimed to assess the protective effects of OC extracts on the oxidative stress on the retinal pigment epithelium (RPE) cells. Oxidative damage has been identified as one of the key regulatory factors in age-related macular degeneration. H2O2-induced reactive oxygen species (ROS) production, a well-known oxidative stress factor, can cause cell death in retinal pigment epithelia cells. In this study, we found that three OC extracts effectively prevented H2O2-induced ROS production and subsequent death of ARPE-19 cells in a dose-dependent manner. In addition, the OC extracts inhibited the phosphorylation of mitogen-activated protein kinases including p38, JNK, and ERK. The OC extracts restored IκBα degradation induced by H2O2, indicating that OC extracts suppressed the activation of nuclear factor-κB. Furthermore, the three OC extracts were shown to have antioxidant effects by up-regulating the intracellular expression of key antioxidant proteins such as SOD, NQO, and HO-1. Here we demonstrated the antioxidant and anti-apoptotic effects of the OC extracts on ARPE-19, indicating their potential role in improving eye health. These results suggest that three OC extracts plays a critical role in oxidative stress-induced cell death protects in ARPE-19 cells.

Protaetia brevitarsis seulensis larvae ethanol extract inhibits RANKL-stimulated osteoclastogenesis and ameliorates bone loss in ovariectomized mice.

Modulation of osteoclast formation could be a therapeutic target for inhibiting pathological bone destruction. The receptor activator of nuclear factor (NF)-κB ligand (RANKL) is known to be an essential factor in osteoclast differentiation and activation inducers. However, whether Protaetia brevitarsis seulensis (P. brevitarsis) larvae-a traditional animal-derived medicine used in many Asian countries-can inhibit RANKL-induced osteoclast formation and prevent ovariectomy (OVX)-induced bone loss has not been evaluated. Here, we aimed to investigate the anti-osteoporotic effects of P. brevitarsis larvae ethanol extract (PBE) in RANKL-stimulated RAW264.7 cells and OVX mice. In vitro, PBE (0.1, 0.5, 1, and 2 mg/mL) decreased RANKL­induced tartrate-resistant acid phosphatase (TRAP) activity and expression of osteoclastogenesis-associated genes and proteins. Furthermore, PBE (0.1, 0.5, 1, and 2 mg/mL) significantly inhibited the phosphorylation of p38 and NF-κB. Female C3H/HeN mice were divided into five groups (n = 5 per group), namely, sham-operated, OVX, OVX+PBEL (100 mg/kg, oral gavage), OVX+PBEH (200 mg/kg, oral gavage), and OVX+estradiol (0.03 µg/day, subcutaneous injection). High doses of PBE significantly increased femoral bone mineral density (BMD) and bone volume/tissue volume (BV/TV), whereas femoral bone surface/bone volume (BS/BV) and osteoclastogenesis-associated protein expression decreased compared to those in the OVX group. Moreover, PBE (200 mg/kg) significantly increased estradiol and procollagen type I N-terminal propeptide and decreased N-terminal telopeptide of type I collagen and C-terminal telopeptide of type I collagen compared to those in the OVX group. Our results suggest that PBE can be an effective therapeutic candidate for preventing or treating postmenopausal osteoporosis.

The optimal scaffold for silk sericin-based bone graft: collagen versus gelatin.

BACKGROUND: Silk sericin is an active ingredient in bone grafts. However, the optimal scaffold for silk sericin has yet to be identified. METHOD: A critical-sized bone defect model in rat calvaria was used to evaluate bone regeneration. Silk sericin from Yeonnokjam, Bombyx mori, was incorporated into gelatin (group G, n = 6) and collagen (group C, n = 6). Bone regeneration was evaluated using micro-computed tomography (mCT) and histology. RESULTS: Group C showed a larger bone volume than group G in the mCT analysis (P = 0.001). Histological analysis showed a larger area of bony defects in group G than in group C. The bone regeneration area in group C was significantly larger than that in group G (P = 0.003). CONCLUSION: Compared with gelatin, collagen shows better bone regeneration in silk sericin-based bone grafts.

Effect of Extraction Ingredients on the Conformation and Stability of Silk Sericin (SS).

Silk sericin (SS) has different physicochemical properties depending on the extraction technique. In this study, SS was isolated in the presence of ingredients, including 5 to 10% ethanol (EtOH) and 5 to 10% glycine. Furthermore, temperature conditions of 80 °C, 100 °C, and 120 °C were used for 1, 3, and 5 h to evaluate the extraction rates. The extraction, gelation, structural, and cytotoxicity properties of SS extracted under different conditions were investigated. Extraction at 100 °C and 120 °C were found to have the highest SS yield, with 80 °C being the lowest. SS isolated at 100 °C and 120 °C for 1 and 3 h in water, and EtOH gelled at 4 °C in 2 to 3 days and 37 °C in 40 min. Glycine SS extracts were obtained at 100 °C and 120 °C for 1 h, gelled at 4 °C for 20 days and 37 °C for 16 h. SS was observed at 80 °C, with no gelation occurring. Glycine SS extracts obtained for 3, and 5 h at 120 °C showed no gelation. Circular dichroism (CD) results show glycine in SS induces α-helix and random coil structure. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and fast performance liquid chromatography (FPLC) were used to quantify the molecular weight distribution at 63 and 70 kDa, respectively. The MMT assay (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) revealed no cytotoxicity in macrophage RAW 264.7 cells treated with this method SS; these findings present the significance and possibility of using selected extraction ingredients in SS that allow for the application of native SS at an initial extraction viscosity.

Competitive Hybridization of a Microarray Identifies CMKLR1 as an Up-Regulated Gene in Human Bone Marrow-Derived Mesenchymal Stem Cells Compared to Human Embryonic Fibroblasts.

Mesenchymal stem cells (MSCs) have been widely applied to the regeneration of damaged tissue and the modulation of immune response. The purity of MSC preparation and the delivery of MSCs to a target region are critical factors for success in therapeutic application. In order to define the molecular identity of an MSC, the gene expression pattern of a human bone marrow-derived mesenchymal stem cell (hBMSC) was compared with that of a human embryonic fibroblast (hEF) by competitive hybridization of a microarray. A total of 270 and 173 genes were two-fold up- and down-regulated with FDR < 0.05 in the hBMSC compared to the hEF, respectively. The overexpressed genes in the hBMSC over the hEF, including transcription factors, were enriched for biological processes such as axial pattern formation, face morphogenesis and skeletal system development, which could be expected from the differentiation potential of MSCs. CD70 and CD339 were identified as additional CD markers that were up-regulated in the hBMSC over the hEF. The differential expression of CD70 and CD339 might be exploited to distinguish hEF and hBMSC. CMKLR1, a chemokine receptor, was up-regulated in the hBMSC compared to the hEF. RARRES2, a CMKLR1 ligand, stimulated specific migration of the hBMSC, but not of the hEF. RARRES2 manifested as ~two-fold less effective than SDF-1α in the directional migration of the hBMSC. The expression of CMKLR1 was decreased upon the osteoblastic differentiation of the hBMSC. However, the RARRES2-loaded 10% HA-silk scaffold did not recruit endogenous cells to the scaffold in vivo. The RARRES2−CMKLR1 axis could be employed in recruiting systemically delivered or endogenous MSCs to a specific target lesion.

4-Hexylresorcinol Treatment before Degumming Increases the ß-Sheet Structure of Silk Sericin and BMP-2 Expression in RAW264.7 Cells.

Silk sericin is a degumming product used by the silk industry. The degumming process can affect the protein structure and molecular weight of silk sericin. The present study examined how pretreatment with 4-hexylresorcinol (4HR) affects the biomedical properties of silk sericin. Before the degumming process, silkworm cocoons were treated with 4HR solution. The protein structure of the final degumming product was evaluated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy. Untreated silk sericin (S) and silk sericin pretreated with 4HR (S+4HR) were added to RAW264.7 cells, and the expression of BMP-2 was determined. The bone-regenerating capacity of S+4HR was evaluated using the critical-sized rat calvarial defect model. Compared with S, S+4HR showed an increase in ß-sheet structures. Administration of S+4HR to RAW264.7 cells increased expression of BMP-2, mainly via the TLR-mediated signaling pathway. Bone volume, as measured by micro-computerized tomography, was significantly greater in the S+4HR group than in the S, gelatin alone, and unfilled control groups (p < 0.05 each). Expression of BMP-2 and runx2 in tissue specimens was significantly higher following treatment with S+4HR than with S (p < 0.05). Taken together, these findings show that 4HR pretreatment before the degumming process increased the ß-sheet structure of silk sericin, as well as inducing BMP-2 expression and bone regeneration ability.

Silk sericin application increases bone morphogenic protein-2/4 expression via a toll-like receptor-mediated pathway.

Bone morphogenic protein-2/4 (BMP-2/4) is an osteoinductive protein that accelerates osteogenesis when administered to bony defects. Sericin is produced by silkworms, and has a biological activity that differs depending on the degumming method used. Our results indicated that the high molecular weight fraction of silk sericin (MW > 30 kDa) obtained via sonication had a more abundant ß-sheet structure than the low molecular weight fraction. Administration of the ß-sheet structure silk sericin increased BMP-2/4 expression in a dose-dependent manner in RAW264.7 cells and human monocytes. This sericin increased the expression levels of toll-like receptor (TLR)-2, TLR-3, and TLR-4 in RAW264.7 cells. Application of a TLR-2 antibody or TLR pathway blocker decreased BMP-2/4 expression following sericin administration. In the animal model, the bone volume and BMP-2/4 expression were higher in rats treated with a sericin-incorporated gelatin sponge than in rats treated with a gelatin sponge alone or a sponge-incorporated with denatured sericin. In conclusion, sericin with a more abundant ß-sheet structure increased BMP-2/4 expression and bone formation better than sericin with a less abundant ß-sheet structure.

Effects of Ultraviolet Light Irradiation on Silk Fibroin Films Prepared under Different Conditions.

Silk fibroin (SF)-based materials are exposed to both natural and artificial ultraviolet (UV) light during preparation or administration. However, the effects of UV irradiation on SF films prepared under different conditions have not yet been described in detail. In this study, four SF films with different molecular weight (MW) distribution were fabricated using SF solutions, which were prepared by dissolving degummed SF for 0.5-24 h. We observed UV (365 nm) irradiation on SF films induced the increase of yellowness and absorbance at 310 nm of SF films, indicating the formation of new photo-products and di-tyrosine bonds by photo-oxidation. Due to di-tyrosine cross-links between SF chains, UV-irradiated SF films were not fully dissociated in urea solution. In addition to formation of new products, UV reduced the crystallinity of SF films by breaking hydrogen bonds of ß-sheet conformation. Unlike the UV-induced decomposition of physical interactions, UV did not affect the covalent bonds (i.e., peptide bonds). Through these experiments, we could expect that SF with higher MW was more susceptible and SF with lower MW was more resistant to UV-induced photo-oxidation and photo-degradation. These results provide useful information about UV-induced aging of SF-based materials under natural sunlight and UV irradiating conditions.

Bone regeneration is associated with the concentration of tumour necrosis factor-α induced by sericin released from a silk mat.

To understand the osteogenic effect of the middle layer of the silk cocoon, sericin was examined for its cellular effects associated with tumor necrosis factor-α (TNF-α) signaling in this study. The fragmented sericin proteins in the silk mat were evaluated for the TNF-α expression level in murine macrophages. The concentration of protein released from silk mats was higher in the outermost and the innermost layers than in the middle layers, and the protein released from the silk mat was identified as sericin. The level of TNF-α in murine macrophages was dependent on the applied concentration of sericin, and the expression of genes associated with osteogenesis in osteoblast-like cells was dependent on the applied concentration of TNF-α. In animal experiments, silk mats from the middle layers led to a higher regenerated bone volume than silk mats from the innermost layer or the outermost layer. If TNF-α protein was incorporated into the silk mats from the middle layers, bone regeneration was suppressed compared with unloaded silk mats from the middle layers. Accordingly, silk mats from the silk cocoon can be considered to be a fragmented sericin-secreting carrier, and the level of sericin secretion is associated with TNF-α induction and bone regeneration.

Silk Fibroin-Alginate-Hydroxyapatite Composite Particles in Bone Tissue Engineering Applications In Vivo.

The aim of this study was to evaluate the in vivo bone regeneration capability of alginate (AL), AL/hydroxyapatite (HA), and AL/HA/silk fibroin (SF) composites. Forty Sprague Dawley rats were used for the animal experiments. Central calvarial bone (diameter: 8.0 mm) defects were grafted with AL, AL/HA, or AL/HA/SF. New bone formation was evaluated by histomorphometric analysis. To demonstrate the immunocompatibility of each group, the level of tumor necrosis factor (TNF)-α expression was studied by immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) at eight weeks post implantation. Additionally, osteogenic markers, such as fibroblast growth factor (FGF)-23, osteoprotegerin (OPG), and Runt-related transcription factor (Runx2) were evaluated by qPCR or IHC at eight weeks post implantation. The AL/HA/SF group showed significantly higher new bone formation than did the control group (p = 0.044) and the AL group (p = 0.035) at four weeks post implantation. Additionally, the AL/HA/SF group showed lower relative TNF-α mRNA levels and higher FGF-23 mRNA levels than the other groups did at eight weeks post implantation. IHC results demonstrated that the AL/HA/SF group had lower TNF-α expression and higher OPG and Runx2 expression at eight weeks post implantation. Additionally, no evidence of the inflammatory reaction or giant cell formation was observed around the residual graft material. We concluded that the AL/HA/SF composite could be effective as a scaffold for bone tissue engineering.

Accelerated biodegradation of silk sutures through matrix metalloproteinase activation by incorporating 4-hexylresorcinol.

Silk suture material is primarily composed of silk fibroin and regarded as a non-resorbable material. It is slowly degraded by proteolysis when it is implanted into the body. 4-Hexylresorcinol (4HR) is a well-known antiseptic. In this study, the biodegradability of 4HR-incorporated silk sutures were compared to that of untreated silk sutures and polyglactin 910 sutures, a commercially available resorbable suture. 4HR-incorporated silk sutures exhibited anti-microbial properties. Matrix metalloproteinase (MMP) can digest a wide spectrum of proteins. 4HR increased MMP-2, -3, and -9 expression in RAW264.7 cells. MMP-2, -3, and -9 were able to digest not only silk fibroin but also silk sutures. Consequently, 59.5% of the 4HR-incorporated silk suture material remained at 11 weeks after grafting, which was similar to that of polyglactin 910 degradation (56.4% remained). The residual amount of bare silk suture material at 11 weeks after grafting was 91.5%. The expression levels of MMP-2, -3 and -9 were high in the 4HR-incorporated silk suture-implanted site 12 weeks after implantation. In conclusion, 4HR-treated silk sutures exhibited anti-microbial properties and a similar level of bio-degradation to polyglactin 910 sutures and induced higher expression of MMP-2, -3, and -9 in macrophages.

Comparison of Bio-degradation for Ridge Preservation Using Silk Fibroin-based Grafts and a Collagen Plug.

A material for ridge preservation should have dimensional stability to resist bio-degradation. This study was designed to compare bio-degradation of ridge preservation materials. Collagen plug was used as a positive control. Untreated, ethanol-treated, and 4-hexylresorcinol (4HR)-treated silk plugs were used for the experimental group. Each material underwent a scanning electron microscopic exam and a Fourier transform infrared (FT-IR) spectroscopic exam. Bio-degradation was evaluated by analyzing cylindrical bony defects in rabbit tibias. There were no prominent differences in microstructure among the silk plug groups. FT-IR exam demonstrated that the ethanol- and 4HR-treated silk plug groups had enhanced ß-sheet structure. All silk plug groups exhibited significantly higher residual graft than the collagen plug group 4 weeks postoperative (p < 0.05). In conclusion, silk fibroin-based ridge preservation material was less bio-degradable than a collagen plug until at least 4 weeks after grafting.

Comparison of unprocessed silk cocoon and silk cocoon middle layer membranes for guided bone regeneration.

BACKGROUND: Silk cocoon is composed of multiple layers. The natural silk cocoon containing all layers was cut as a rectangular shape as defined as total group. The inner and outermost layers were removed from the total group and the remained mat was defined as the middle group. The objectives of this study was to compare the total group with the middle group as a barrier membrane for the guided bone regeneration. METHODS: The effects of these materials on the cellular proliferation and alkaline phosphatase (ALP) expression of MG63 cells were explored. For comparing bone regeneration ability, bilateral bone defects were created in calvarial areas in ten adult New Zealand white rabbits. The defects were covered with silk membranes of the middle group, with silk membrane of the total group used as the control on the contralateral side. The defects were allowed to heal for 4 and 8 weeks. Micro-computerized tomography (µCT) and histological examination were performed. RESULTS: The middle group exhibited a higher MTT value 48 and 72 h after treatment compared to the total group. ALP expression was also higher in the middle group. The results of µCT and histologic examination showed that new bone formation was significantly higher in the middle group compared to the total group 8 weeks postoperatively (P < 0.05). CONCLUSIONS: In conclusion, the middle layer of the silk cocoon supports guided bone regeneration better than unprocessed silk cocoon.

Uncommon presentation of potential medication-related osteonecrosis of the jaw.

BACKGROUND: This article presents a patient with potential atypical medication-related osteonecrosis of the jaw and reviews related literatures. CASE PRESENTATION: A 52-year-old male showed pain in the left buccal area and had numbness on the left lower lip area. He received medications having anti-angiogenic effect for 4 years. He did not receive irradiation of the jaw regions. In histological view, most of the adipocytes were destroyed and disappeared in the scanty vascular marrow tissue, resulting in the replacement of the fatty necrosis with variable sized vacuolated empty spaces. In the immunohistochemistry analysis, the infiltrated macrophages into the marrow stromal tissue were strongly positive for lysozymes. These findings demonstrate that the presented osteonecrosis underwent a chronic and persistent granulomatous inflammatory reaction. CONCLUSIONS: We conclude that the present case might have been caused by anti-angiogenic drug abuse, affecting the reduction of the mandibular marrow vascularity and subsequently inducing fatty necrosis and an extensive osteolytic change of the mandible.

Novel fabrication of fluorescent silk utilized in biotechnological and medical applications.

Silk fibroin (SF) is a natural polymer widely used and studied for diverse applications in the biomedical field. Recently, genetically modified silks, particularly fluorescent SF fibers, were reported to have been produced from transgenic silkworms. However, they are currently limited to textile manufacturing. To expand the use of transgenic silkworms for biomedical applications, a solution form of fluorescent SF needed to be developed. Here, we describe a novel method of preparing a fluorescent SF solution and demonstrate long-term fluorescent function up to one year after subcutaneous insertion. We also show that fluorescent SF labeled p53 antibodies clearly identify HeLa cells, indicating the applicability of fluorescent SF to cancer detection and bio-imaging. Furthermore, we demonstrate the intraoperative use of fluorescent SF in an animal model to detect a small esophageal perforation (0.5 mm). This study suggests how fluorescent SF biomaterials can be applied in biotechnology and clinical medicine.

Early effect of Botox-A injection into the masseter muscle of rats: functional and histological evaluation.

BACKGROUND: The purpose of this study was to evaluate the change of food intake after different dosages of botulinum toxin A (BTX) injection in the animal model. Additionally, the dimensional and histological change at 14 days after BTX injection was also evaluated. METHODS: The comparative study was performed using the BTX injection model in rats (n = 5 for each group). Group 1 was the saline-injected group. Group 2 was the 5-unit BTX-injection group to each masseter muscle. Group 3 was the 10-unit BTX-injection group to each masseter muscle. Food intake rates and body weight were checked daily before and after BTX injection until 10 days. All animals were sacrificed at 14 days after BTX injection, and the specimens underwent hematoxylin and eosin stain and immunohistochemical staining for myosin type II (MYH2). RESULTS: The recovery of food intake in groups 2 and 3 decreased significantly compared with group 1 from day 2 to day 7 and day 9 after injection (p < 0.05). The BTX-treated masseter muscles were significantly smaller than those in group 1 (p = 0.015). The immunohistochemical findings demonstrated that the expression of MYH2 was significantly higher in group 3 compared to groups 1 and 2 (p < 0.001). CONCLUSIONS: BTX injection to the masseter muscle in rats demonstrated short food-intake-rate reduction with recovery until 10 days after injection. The thickness of the masseter muscle and MYH2 expression were significantly changed according to the injected dose of BTX.

Comparison of silkworm-cocoon-derived silk membranes of two different thicknesses for guided bone regeneration.

The objective of this study was to compare the effectiveness of silk membranes (SMs) of different thicknesses for guided bone regeneration. Two kinds of SMs were prepared (SM1: 0.01 mm thickness, SM2: 0.5 mm thickness). Before use in animal experiments, scanning electron microscope images were taken to examine the gross morphology of each membrane. Ten New Zealand white rabbits were used for this study. Bilateral round-shaped defects were created in the parietal bone (diameter: 8.0 mm) and each defect was covered with SM1 or SM2. Animals were killed at 4 weeks and 8 weeks. Bone regeneration was analyzed in each specimen by micro-computed tomography (µ-CT) and histological analysis. In the µ-CT analysis, the average amount of newly formed bone in the SM2 group was greater than that in the SM1 group. There was a significant difference at 4 weeks after surgery (P = 0.004). In the histological analysis, the amount of formed lamellar bone was much greater in the SM2 group than in the SM1 group at 8 weeks after surgery (P = 0.021). In conclusion, the thick SM was much more effective for bone regeneration of bone defects than the thin SM.

The effects of tetracycline-loaded silk fibroin membrane on proliferation and osteogenic potential of mesenchymal stem cells.

BACKGROUND: The main objective of this study was to investigate the effect of tetracycline-loaded silk fibroin membranes (TC-SFMs) on the proliferation and the osteogenic differentiation of human mesenchymal stem cells. MATERIALS AND METHODS: Four groups (0, 1, 5, and 10% concentration) of TC-SFMs were prepared for the experiments. We investigated cumulative tetracycline (TC) release profile for 7 d. Human gingiva-derived mesenchymal stem cells (GMSCs) were isolated from our previous study and seeded to the TC-SFMs. WST-8 assay (Cell Counting Kit-8; SigmaeAldrich Co, St. Louis, MO), staining of Phalloidin-FITC, and scanning electron microscope analyzed the cellular attachment and viability. Staining of Alizarin Red S (Sigma-Aldrich Co.) and osteogenic marker (osteocalcin) analyzed osteogenic differentiation. Additionally, quantitative polymerase chain reaction measured the expression of osteogenic lineage genes, including bone gamma-carboxyglutamic acid protein, bone sialoprotein, runt-related transcription factor 2, and collagen type I α1 according to TC concentration (0.05, 0.1, 0.25, and 0.5 mg/mL). RESULTS: The release of TC from TC-SFMs plateaued and neared completion in 24 h. Significantly higher viability was noted achieved in 1% and 5% TC-SFMs. The morphology of GMSCs on TC-SFMs at 0% and 1% concentration showed spindle shapes, but cells in 10% TC-SFMs appeared spheroid. During Alizarin Red S staining at 21 d of osteogenic differentiation, calcium and osteocalcin formation were significantly lower in the 10% TC-SFM group than in the 0, 1, and 5 groups. Compared with the control group, bone gamma-carboxyglutamic acid protein showed significantly low expression rate at TC concentration ≥0.05 mg/mL. Bone sialoprotein was low at TC concentration ≥0.1 mg/mL. Likewise, runt-related transcription factor 2 and collagen type I α1 were low at TC concentration of 0.5 mg/mL. CONCLUSIONS: Within the limits of this study, 1% and 5% TC-SFMs showed higher proliferation and osteogenic potential of GMSCs than 10% TC-SFM. Therefore, the use of 1% to 5% range of TC may be more suitable to silk fibroin membrane for stem cell tissue engineering.

Hydroxyapatite and silk combination-coated dental implants result in superior bone formation in the peri-implant area compared with hydroxyapatite and collagen combination-coated implants.

PURPOSE: The objective of this study was to compare bone formation after installation of uncoated (UC), hydroxyapatite-coated (HA), collagen plus HA-coated (CH), and silk plus HA-coated (SH) implants. MATERIALS AND METHODS: Implants in the UC group had acid-etched surfaces. Surface coating was applied using the aerosol deposition method. Cellular responses on the coated surfaces were examined with scanning electron microscopy. Cellular responses to the surfaces were studied with the corresponding coated discs and MG63 cells. Subsequently, 3-(4, 5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alkaline phosphatase (ALP) assays were performed. Peri-implant bone formation was evaluated with the rabbit tibia model. Twenty-four implants from each group were installed. The animals were sacrificed 6 weeks after implant installation. Peri-implant bone formation and implant-to-bone contact were measured in histologic sections. Significance of differences across groups was evaluated using analysis of variance. RESULTS: Scanning electron microscopic images showed that the CH and SH groups exhibited cells that appeared more spread out than those in the other groups. The SH group exhibited the highest value in the MTT assay. The CH group exhibited the highest level of ALP activity. Comparisons of these modifications with the acid-etched surfaces showed that the CH and SH groups displayed significantly greater peri-implant bone formation (P < .001). CONCLUSION: The SH group displayed significantly greater new bone formation and bone-to-implant contact than did the other groups.

Inhibition of foreign body giant cell formation by 4- hexylresorcinol through suppression of diacylglycerol kinase delta gene expression.

Grafted macromolecules often induce granuloma formation with foreign body giant cell (FBGC) infiltration, and this is the main reason for graft failure. Diacylglycerol kinase (DAGK) is an important intracellular mediator of FBGC formation in macrophages. In this study, 4-hexylresorcinol (4HR) inhibited DAGKδ in a macrophage cell line (RAW264.7 cells). As a result of DAGK-δ inhibition by 4HR, FBGC formation was significantly inhibited in RAW264.7 cells. Silk fibroin is a well-known natural macromolecule, and when it is grafted into bone defects, it results in granuloma formation with massive FBGC formation. 4HR-incorporating silk graft materials displayed significant reduction of granuloma formation and increases in the extent of new bone formation in a rabbit calvarial defect model. In conclusion, 4HR could inhibit foreign body reaction via a DAGK-mediated pathway.