Effects of the combination of bone morphogenetic protein-2 and nano-hydroxyapatite on the osseointegration of dental implants

Objectives@#This study aimed to investigate the in vitro osteoinductivity of the combination of bone morphogenetic protein-2 (BMP-2) and nanohydroxyapatite (nHAp) and the in vivo effects of implants coated with nHAp/BMP-2. @*Materials and Methods@#To evaluate the in vitro efficacy of nHAp/BMP-2 on bone formation, bone marrow-derived mesenchymal stem cells (BMMSCs) were seeded onto titanium disks coated with collagen (Col), ColHAp, or ColHAp/BMP-2. Protein levels were determined by a biochemical assay and reverse transcriptase-polymerase chain reaction. Stem cell differentiation was analyzed by flow cytometry. For in vivo studies with mice,Col, ColHAp, and ColHAp/BMP-2 were injected in subcutaneous pockets. Titanium implants or implants coated with ColHAp/BMP-2 were placed bilaterally on rabbit tibias and evaluated for 4 weeks. @*Results@#In the in vitro study, BM-MSCs on ColHAp/BMP-2 showed reduced levels of CD73, CD90, and CD105 and increased levels of glycos-aminoglycan, osteopontin, and alkaline phosphatase activity. After 4 weeks, the ColHAp/BMP-2 implant showed greater bone formation than the control (P=0.07), while no differences were observed in bone implant contact and removal torque. @*Conclusion@#These results suggest that a combination of BMP-2 and an nHAp carrier would activate osseointegration on dental implant surfaces.

Pigmentation Effect of Rice Bran Extract in Hair Follicle-Like Tissue and Organ Culture Models

BACKGROUND@#Melanogenesis is a biological process resulting in the production of melanin pigment, which plays an important role in the prevention of sun-induced skin injury and determines the hair and skin color. Melanin has the ability to block ultraviolet radiation and scavenge free oxygen radicals, thus protecting the skin from their harmful effects. Agents that increase melanin synthesis in melanocytes may reduce the risk of photodamage and skin cancer. Hence, various approaches have been proposed to increase the synthesis of melanin. @*METHODS@#The current study aimed to develop a three-dimensional hair follicle-like tissue (HFLT) model with human dermal papilla, melanocytes, and outer root sheaths cells. This model showed enhanced melanogenesis-related protein expression after rice bran ash extract (RBE) treatment. Next, we investigated the melanogenic effect of RBE in the HFLT and compared the results to those of hair follicle (HF) organ culture model. @*RESULTS@#RBE was found to significantly increase the expression of microphthalmia-associated transcription factor, a key transcription factor involved in melanin production, in both HFLT and organ culture models. Results showed that melanogenesis-related protein expression levels were higher in the RBE group compared to those in the control group. Similar results were obtained by immunohistochemistry. @*CONCLUSION@#Our data suggested that RBE promotes melanin biosynthesis. Taken together, this simple in vitro HFLT model system has the potential to provide significant insights into the underlying molecular mechanisms of HF melanogenesis, and hence can be used for controlled evaluation of the efficacy of new materials for melanogenesis.

Pigmentation Effect of Rice Bran Extract in Hair Follicle-Like Tissue and Organ Culture Models

BACKGROUND@#Melanogenesis is a biological process resulting in the production of melanin pigment, which plays an important role in the prevention of sun-induced skin injury and determines the hair and skin color. Melanin has the ability to block ultraviolet radiation and scavenge free oxygen radicals, thus protecting the skin from their harmful effects. Agents that increase melanin synthesis in melanocytes may reduce the risk of photodamage and skin cancer. Hence, various approaches have been proposed to increase the synthesis of melanin. @*METHODS@#The current study aimed to develop a three-dimensional hair follicle-like tissue (HFLT) model with human dermal papilla, melanocytes, and outer root sheaths cells. This model showed enhanced melanogenesis-related protein expression after rice bran ash extract (RBE) treatment. Next, we investigated the melanogenic effect of RBE in the HFLT and compared the results to those of hair follicle (HF) organ culture model. @*RESULTS@#RBE was found to significantly increase the expression of microphthalmia-associated transcription factor, a key transcription factor involved in melanin production, in both HFLT and organ culture models. Results showed that melanogenesis-related protein expression levels were higher in the RBE group compared to those in the control group. Similar results were obtained by immunohistochemistry. @*CONCLUSION@#Our data suggested that RBE promotes melanin biosynthesis. Taken together, this simple in vitro HFLT model system has the potential to provide significant insights into the underlying molecular mechanisms of HF melanogenesis, and hence can be used for controlled evaluation of the efficacy of new materials for melanogenesis.

Pigmentation Effect of Electromagnetic Fields at Various Intensities to Melanocytes

Melanogenesis is the biological process that results in the synthesis of skin pigment of melanin and it has various functions in living systems and is synthesized by the melanosome within the melanocytes. A variety of physical treatments are used to promote melanin production in the melanocytes for pigmentation control. The purpose of this study was to evaluate the intensity-dependent effect of extremely low-frequency electromagnetic fields (ELF-EMFs) on melanogenesis by melanocytes in vitro. Melanocytes were exposed to ELF-EMFs at a frequency of 50 Hz and at intensities in the range of 0.5–20 G over 4 days. The results of lactate dehydrogenase assay showed that there were no significant differences between cells exposed to 0.5 G or 2 G groups and the controls. The melanin contents increased 1.2–1.5-fold in cells exposed to ELF-EMFs and tyrosinase activity increased 1.3-fold in cells exposed to ELF-EMFs, relative to the controls. Also, exposure to ELF-EMFs was associated with activation in cyclic-AMP response element binding protein and microphthalmia-associated transcription factor (MITF) was up-regulated. Up-regulation of MITF induces the expression of melanogenesis-related markers, such as tyrosinase, tyrosinase-related protein (TRP)-1, TRP-2. In conclusion, the present study showed that the exposure to ELF-EMFs at low intensities can stimulate melanogenesis in melanocyte, and these results may be used to a therapeutic devices for inducing repigmentation in vitiligo patients.

Enhancement of Osseointegration of Artificial Ligament by Nano-Hydroxyapatite and Bone Morphogenic Protein-2 into the Rabbit Femur

The MTT assay showed that the cell proliferation on hydroxyapatite (HAp) and HAp/bone morphogenic protein (BMP) coated group was better than the control and BMP coated groups at 5 days. And after 7 days of culture, the mRNA expression levels of type I collagen, osteonectin, osteopontin, bonesialoprotein, BMP-2, alkaline phosphatase (ALP) and Runx-2 in the HAp/BMP coated group were significantly higher than the other groups. Also, in this group showed the most significant induction of osteogenic gene expression compared to mesenchymal stem cells (MSCs) grown on the other groups. In addition, the cells in the HAp/BMP coated group delivered higher levels of ALP than the other three groups. Also, silk scaffolds were implanted as artificial ligaments in knees of rabbits, and they were harvested 1 and 3 months after implantation. On gross examination, HE staining showed that new bone tissue formation was more observed in the HAp/BMP coated group 3 weeks postoperatively. And masson staining showed that in the HAp/BMP coated group, the silk fibers were encircled by osteoblast, chondrocyte, and collagen. Furthermore, the analysis showed that the width of the graft-bone interface in the HAp and HAp/BMP coated group was narrower than that in the other two groups 3 weeks postoperatively. So, it is concluded that BMP incorporated HAp coated silk scaffold can be enhanced osseointegration and osteogenesis in bone tunnel. As a result, these experimental designs have been demonstrated to be effective in the acceleration of graft-to-bone healing by increasing new bone or fibrocartilage formation at the interface between graft and bone.

Periodontal regeneration with nano-hyroxyapatite-coated silk scaffolds in dogs

PURPOSE: In this study, we investigated the effect of silk scaffolds on one-wall periodontal intrabony defects. We conjugated nano-hydroxyapatite (nHA) onto a silk scaffold and then seeded periodontal ligament cells (PDLCs) or dental pulp cells (DPCs) onto the scaffold. METHODS: Five dogs were used in this study. Bilateral 4 mmx2 mm (depthxmesiodistal width), one-wall intrabony periodontal defects were surgically created on the distal side of the mandibular second premolar and the mesial side of the mandibular fourth premolar. In each dog, four of the defects were separately and randomly assigned to the following groups: the PDLC-cultured scaffold transplantation group (PDLC group), the DPC-cultured scaffold transplantation group (DPC group), the normal saline-soaked scaffold transplantation group, and the control group. The animals were euthanized following an 8-week healing interval for clinical, scanning electron microscopy (SEM), and histologic evaluations. RESULTS: There was no sign of inflammation or other clinical signs of postoperative complications. The examination of cell-seeded constructs by SEM provided visual confirmation of the favorable characteristics of nHA-coated silk scaffolds for tissue engineering. The scaffolds exhibited a firm connective porous structure in cross section, and after PDLCs and DPCs were seeded onto the scaffolds and cultured for 3 weeks, the attachment of well-spread cells and the formation of extracellular matrix (ECM) were observed. The histologic analysis revealed that a well-maintained grafted volume was present at all experimental sites for 8 weeks. Small amounts of inflammatory cells were seen within the scaffolds. The PDLC and DPC groups did not have remarkably different histologic appearances. CONCLUSIONS: These observations indicate that nHA-coated silk scaffolds can be considered to be potentially useful biomaterials for periodontal regeneration.