[Show abstract][Hide abstract] ABSTRACT: Transcription factors have been implicated in regulating the differentiation of odontoblasts from dental pulp stem cells/progenitors (DPSCs/progenitors), but their regulatory network is not completely understood.Result: New transcription factors that control the odontoblast differentiation of human DPSCs/progenitors were analyzed using a microarray. The result revealed bobby sox homolog (BBX) to be expressed most strongly during odontoblast differentiation. Validation using RT-PCR also revealed the strong expression of BBX during the odontoblast differentiation of DPSCs/progenitors. BBX expression was also detected in adult molar odontoblasts and other tissues, including the heart, kidney, testis, and bone marrow. To understand the role of BBX in odontoblast differentiation, BBX variant 1 and 2 cDNA were cloned and overexpressed in DPSCs/progenitors. The results showed that the overexpression of BBX cDNA in DPSCs/progenitors induced substantial mineralization and expression of the odontoblast marker genes, such as ALP, OPN, BSP, DMP1, and DSPP. The knockdown of BBX using shRNA, however, did not affect mineralization, but the expression of ALP and DSPP was decreased substantially. Meanwhile overexpression or knockdown of BBX did not modulate proliferation of DPSCs/progenitors.
Cell communication and signaling : CCS. 05/2014; 12(1):35.
[Show abstract][Hide abstract] ABSTRACT: Teraspanin transmembrane protein, Perp (P53 apoptosis effector related to PMP22), which is found in the plasma membrane as a component of the desmosome, is reported to be involved in the morphogenesis of the epithelium and the enamel formation of the incisor. However, its expression pattern and signaling regulation during molar development have not been elucidated in detail. We have examined the precise expression patterns of Perp in developing lower molars and employed the knock-down of Perp by antisense oligodeoxynucleotide treatment during in vitro organ cultivation at embryonic day 13 to define the precise developmental function of Perp. Perp was expressed mainly in the dental lamina and stellate reticulum regions at the bud and cap stages. After Perp knock-down, the tooth germ showed disruption of the dental lamina and stellate reticulum with altered apoptosis and proliferation. The changed expression levels of related signaling molecules from the enamel knot and desmosome were evaluated by real-time quantitative polymerase chain reaction. A renal capsule transplantation method was employed to examine the effects of Perp knock-down on molar crown development. Ultrastructural observations revealed that enamel was deposited more densely in an irregular pattern in the cusp region, and that dentin was hypo-mineralized after Perp knock-down at the cap stage. Thus, Perp might play important roles in the formation and integration of stellate reticulum, dental lamina structure and enamel formation through signaling interactions with the enamel knot and desmosome-related signaling molecules at the cap stage of lower molar development.
Cell and Tissue Research 05/2014; · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives
This study contributes three well-documented cases of multiple simple bone cysts (SBCs) of the jaws and reviews previously published cases.
A comprehensive literature search of multiple SBCs was conducted using PubMed database. Synonyms of SBC were used as search key words in combination with “mandible or jaw”, “bilateral, multiple, multifocal, atypical, and unusual”.
A total of 34 cases of multiple SBCs (including 2 asynchronous cases) were identified, including the three new cases reported here. Multiple SBCs primarily occurred in the second decade (52.9 %) and bilaterally in the posterior mandible. Lesions showed female predominance (1.8:1) and were frequently accompanied by bony expansion (44.1 %) and a multilocular radiolucent appearance (20.6 %). Recurrence was reported in 3 patients (mean age: 39.3 years old).
Knowledge of the clinical and radiographic features of multiple SBCs is important in the diagnosis and management of this entity.
[Show abstract][Hide abstract] ABSTRACT: Human amniotic fluid stem (hAFS) cells have been shown to differentiate into multiple lineages, including myoblasts. However, molecular mechanisms underlying the myogenic differentiation of hAFS cells and their regenerative potential for muscle injury remain to be elucidated.
In order to induce myogenic differentiation of hAFS cells, lentiviruses for MYOD were constructed and transduced into hAFS cells. Formation of myotube-like cells was analyzed by immunocytochemistry, and expression of molecular markers for myoblasts was analyzed by reverse transcription polymerase chain reaction and Western blotting. For in vivo muscle regeneration, MYOD transduced human AFS cells were injected into left tibialis anterior (TA) muscles injured with cardiotoxin, and muscle regeneration was analyzed using hematoxilin and eosin, immunocytochemistry, and formation of neuro-muscular junction.
MYOD expression in hAFS cells successfully induced differentiation into multinucleated myotube-like cells. Consistently, significant expression of myogenic marker genes, such as MYOG, DES, DMD, and MYH, was induced by MYOD. Analysis of pre-myogenic factors showed that expression of PAX3, MEOX1, and EYA2 was significantly increased by MYOD. MYOD was phosphorylated and localized in the nucleus. These results suggest that in hAFS cells, MYOD is phosphorylated and localized in the nucleus, thus inducing expression of myogenic factors, resulting in myogenic differentiation of hAFS cells. To test regenerative potential of MYOD-transduced hAFS cells, we transplanted them into injured muscles of immunodeficient BALB/cSlc-nu mice. The results showed a substantial increase in the volume of TA muscle injected with MYOD-hAFS cells. In addition, TA muscle tissue injected with MYOD-hAFS cells has more neuro-muscular junction, indicating functional restoration of muscle injury by hAFS cells expressing by MYOD.
Collectively, our data suggest that transduction of hAFS cells with MYOD lentiviruses induces skeletal myogenic differentiation in vitro and morphological and functional regeneration of injured muscle in vivo.
[Show abstract][Hide abstract] ABSTRACT: A 10-year-old boy presented with a swelling on the right side of the jaw. He had undergone excision of the lesion about 10 months ago at a private dental clinic and the swelling began to regrow 4 months after surgery. A panoramic radiograph revealed 4 sclerotic round masses with radiolucent rims surrounded by sclerosis of the right posterior mandible. Computed tomography scan showed 4 round bony masses centered on the buccal cortex and bone marrow space, sclerosis of the adjacent bone and periosteal reaction. He underwent a marginal resection under general anesthesia and the final histopathological report confirmed the diagnosis of osteoid osteoma. Postoperative course was uneventful, and there was no evidence of recurrence at the 5.5-year follow-up. In the review of the literature, 20 osteoid ostemas were found in the jaw and to the best of our knowledge, the present case is the only one showing multifocal nidi.
[Show abstract][Hide abstract] ABSTRACT: Adult human dental pulp stem cells (hDPSCs) are a unique population of precursor cells those are isolated from postnatal dental pulp and have the ability to differentiate into a variety of cell types utilized for the formation of a reparative dentin-like complex. Using LC-MS/MS proteomics approaches, we identified the proteins secreted from the differentiating hDPSCs in mineralization media. Lysyl oxidase-like 2 (LOXL2) was identified as a protein that was down-regulated in the hDPSCs that differentiate into odontoblast-like cells. The role of LOXL2 has not been studied in dental pulp stem cells. LOXL2 mRNA levels were reduced in differentiating hDPSCs, whereas the levels of other LOX family members including LOX, LOXL1, LOXL3, and LOXL4, are increased. The protein expression and secretion levels of LOXL2 were also decreased during odontogenic differentiation. Recombinant LOXL2 protein treatment to hDPSCs resulted in a dose-dependent decrease in the early differentiation and the mineralization accompanying with the lower levels of odontogenic markers such as DSPP, DMP-1 and ALP. These results suggest that LOXL2 has a negative effect on the differentiation of hDPSCs and blocking LOXL2 can promote the hDPSC differentiation to odontoblasts.
[Show abstract][Hide abstract] ABSTRACT: An ideal scaffold for bone tissue regeneration should be dissolved at the same rate of host bone growth into the defect. Therefore, to produce such a scaffold, it is necessary to obtain a standard healing rate of bone defects. In this study, we compared healing rate of bone defects in calvarial and long bones, which have differential developmental and regenerative mechanisms. In the calvaria and tibia, 3 mm defects were made, and healing was analyzed using microcomputed tomography (microCT) and histology up to six weeks. MicroCT analysis showed that in calvarial defects, an unhealed gap remained until six weeks, whereas tibial defects had healed after three weeks. H&E and Trichrome staining consistently showed that calvarial defects were not completely healed by six weeks, however, a tibial defect started to heal from three weeks. Results of histomorphometric analysis showed that 60% of calvarial defects had healed at six weeks after surgery, whereas 80% of tibial defects showed regeneration at three weeks. Cartilage formation was detected only in tibial defects, suggesting endochondral regeneration in long bone, but not in flat bone. Collectively, these results demonstrate that healing of a long bone defect is faster than that of flat bone by approximately two folds. Therefore, our data suggest that dissolution of scaffold should be optimized based on the type of bone defect.
Fetal ovine model for in-situ esophagus tissue engineering. 01/2013; 10(6). · 3.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: Bisphosphonate-related jaw necrosis (BRONJ) associated with dental implants is a rare but continuously reported complication. To verify clinical and pathological characteristics of BRONJ around dental implants, the present study analyzed clinical, radiographic and histopathological findings of these lesions. PATIENTS AND METHODS: Nineteen patients were diagnosed with osteonecrosis of the jaw associated with dental implants and treated at our institute from 2008 to 2011. The patients' medical history, demographic features, radiographic, and histopathological findings along with information on bisphosphonates (BP) administration were analyzed. RESULTS: The majority of BRONJ patients associated with dental implants used oral BP for osteoporosis. The patients were divided into two groups: BP initiation before (n = 16) and after (n = 3) implant surgery. Only three patients (15.8%) could be regarded as "implant surgery-triggered" BRONJ. Many patients (n = 9) showed successful osteointegration after fixture installation to an average of 35 months (11-82 months) until the development of osteonecrosis. The histological features of the lesion showed that the necrotic bone with empty lacunae was infiltrated by inflammatory cells and bacterial colonies. Viable osteocytes were also observed in some areas of the bony specimens. Three types of bone destruction pattern were observed: (i) complete necrosis of the bone around the implant (frozen type), (ii) extensive osteolysis around the implant with or without sequestra (osteolytic type), and (iii) sequestration of bone with an implant maintaining direct implant-bone contact (en block sequestration type). These findings could be existed at the same lesions depending on the degree of local bone destruction and the severity of the infection. CONCLUSION: These results and those of others suggested that already osseointegrated dental implants can also cause the osteonecrosis around the implant after BP administration. En block sequestration of bone with implant might be one of the characteristics of implant-related BRONJ, which is different from peri-implantitis-induced bone destruction. The possible role of microcracks in this type of bone destruction needs to be examined further.
Clinical Oral Implants Research 12/2012; · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Communication between osteoblasts and endothelial cells is essential for bone fracture repair, but the molecular identities of such communicating factors are not well defined. Here we identify DJ-1 as a novel mediator of the cross-talk between osteoblasts and endothelial cells through an unbiased screening of molecules secreted from human mesenchymal stem cells during osteogenesis. We show that DJ-1 stimulates the differentiation of human mesenchymal stem cells to osteoblasts and that DJ-1 induces angiogenesis in endothelial cells through activation of fibroblast growth factor receptor-1 signalling. In a rodent model of bone fracture repair, extracellular application of DJ-1 enhances bone regeneration in vivo by stimulating the formation of blood vessels and new bones. Both these effects are blocked by antagonizing fibroblast growth factor receptor-1 signalling. These findings uncover previously undefined extracellular roles of DJ-1 to promote angiogenesis and osteogenesis, suggesting DJ-1 may have therapeutic potential to stimulate bone regeneration.
[Show abstract][Hide abstract] ABSTRACT: Stem cell maintenance requires a specific microenvironment. Hematopoietic stem cells (HSCs) are mainly maintained by the endosteal osteoblast (OB) niche, which provides a quiescent HSC microenvironment, and the vascular niche, which regulates the proliferation, differentiation, and mobilization of HSCs. The systemic administration of FGF2 failed to induce normal hematopoiesis in bone marrow (BM) by reducing SDF-1, an important factor for hematopoiesis. Interestingly, SDF-1 levels were decreased in the OBs, but increased in vascular endothelial C166 cells when FGF2 was administered. We hypothesized that FGF2 induces changes in HSC migration from BM; therefore, we investigated FGF2-induced factors of HSC migration by a microarray chip. We searched the genes that were decreased in primary OBs, but increased in C166 cells upon FGF2 treatment. We confirmed selected genes that function in the extracellular region and identified the CXCR2-related chemokine candidate LIX/Cxcl5. A chemotaxis assay showed that CXCL5 induced the migration of HSCs (CD34(-/low)LSK). Our data suggest that the differential regulation of the chemokine CXCL5 between OBs and endothelial cells upon FGF2 treatment is involved in HSC mobilization from the OB niche or BM to peripheral blood.
Stem cells and development 07/2012; · 4.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to supplement the current ameloblastoma database by reporting the clinicopathologic features of ameloblastoma from Asia and North America.
Biopsy records of the participating institutes were reviewed for lesions diagnosed as ameloblastoma during the years 1993 to 2009. Slides were reclassified according to the World Health Organization Classification of Odontogenic Tumors in 2005. Clinical information and radiographic features were collected and analyzed.
The mean age of the patients ± SD was 38.27 ± 17.78 years; 662 patients (51.36%) were men. Mandible (84.26%) outnumbered maxilla and other locations combined in all countries. The number of multilocular radiolucencies (43.40%) was comparable with that of unilocular radiolucencies (42.04%). Follicular pattern was the most common histopathologic pattern (27.70%), followed by plexiform (21.10%) and unicystic pattern (20.71%), respectively.
The clinicopathologic features of ameloblastomas in the present study show some similarities with previous studies; however, minor differences exist.
[Show abstract][Hide abstract] ABSTRACT: Living dental pulp tissue exposed to the oral environment should be protected with an appropriate pulp capping material to support the dentinogenesis potential of the pulp cells. Mineral trioxide aggregate (MTA) is the material of choice for the treatment of pulp. However, due to cytotoxicity during the initial setting phase of MTA, a new material is required that can act as a barrier to direct contact but facilitate the favorable effect of MTA. This study examined the feasibility of using electrospun poly(ε-caprolactone) fiber (PCL-F) meshes in the MTA-based pulp capping procedures. An experimental pulp capping was performed on the premolars of beagle dogs, and the efficacy of the PCL-F meshes was evaluated after 8 weeks. PCL-F/MTA formed a dentin bridge that was approximately fourfold thicker than that formed by the MTA. Columnar polarized odontoblast-like cells with long processes and tubular dentin-like matrices were observed beneath the dentin bridge in the PCL-F/MTA. The cells were also intensely immunostained for dentin sialoprotein. In cell cultures, PCL-F/MTA reduced cell death to ~8% of that in the MTA group. The proliferation of the cells cultured on PCL-F/MTA was much greater than that of cells cultured on MTA. Furthermore, PCL-F/MTA promoted the differentiation of MDPC23 cells to odontoblast-like cells and biomineralization, as confirmed by the expression of alkaline phosphatase and dentin sialophosphoprotein, and by the deposition of calcium. Based on these histologic findings and the cell responses observed in this study, PCL-F may be used efficiently in the MTA-based dental pulp therapy.
[Show abstract][Hide abstract] ABSTRACT: Calcium phosphate ceramics have been widely used as scaffolds for bone regeneration. Here, to improve the osteogenic potential of hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) and to apply the bioactive peptide in situ, matrix extracellular phosphoglycoprotein (MEPE) peptide, which has been shown to stimulate osteoblast differentiation, was covalently and directionally immobilized on HA/β-TCP particles. The free-hydroxyl groups on the surface of the HA/β-TCP particles were sequentially conjugated with APTES, PEG-(SS)(2), and the synthetic MEPE peptide. Using FTIR and XPS, immobilization of the MEPE peptide on the HA/β-TCP was confirmed. Implantation of the MEPE peptide-immobilized HA/β-TCP into calvarial defect and subsequent analyses using a micro CT and histology showed significant bone regeneration and increased bone area (9.89-fold) as compared to that of unmodified HA/β-TCP. Moreover, tartrate-resistant acid phosphatase-positive osteoclasts were observed in regenerated bone by the MEPE peptide-immobilized HA/β-TCP, indicating that the bones newly formed by the MEPE peptide-immobilized HA/β-TCP are actively remodeled by osteoclasts. Therefore, our data demonstrate that MEPE peptide immobilization onto the HA/β-TCP surface stimulates bone regeneration associated with physiological bone remodeling.
Journal of Biomedical Materials Research Part B Applied Biomaterials 04/2012; 100(3):841-9. · 2.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tooth development is regulated by the complex interplay of various regulatory molecules. To identify new regulatory genes released from the dental epithelium, gene expression profiling of dental epithelium was analysed.
ICR mouse dental epithelia were isolated from the initiation (E10.5) and bell (E16.5) stages, and microarray analysis was performed using Affymetrix GeneChip(®). Microarray data were validated using reverse transcriptase polymerase chain reaction (RT-PCR), and gene ontology and signalling network were analysed.
Detection signals more than 300 and changes more than two folds were considered as positive signals and were further analysed. Expressions of 193 genes in the E10.5 epithelium and 582 genes in the E16.5 epithelium were significantly increased. Validation of the selected genes using RT-PCR showed a well correlation with microarray data. Subsequent signalling network analysis revealed that at E10.5 and 16.5, nine genes such as histones, signalling molecules and transcription factors were closely related with neighbouring molecules. Moreover, gene ontology analysis showed that seven growth factors/receptors or secreted proteins were highly expressed at E10.5, including the platelet-derived growth factor, C polypeptide (Pdgfc), insulin-like growth factor binding protein 2 (Igfbp2) and Igfbp5. At E16.5, nine growth factors/receptors or secreted proteins, including Igfbp3, Igfbp10/Cyr61 and heparin-binding EGF-like growth factor (Hbegf) were highly expressed.
These data suggest that the regulatory genes newly identified in this study may play significant roles in tooth development.
Archives of oral biology 03/2012; 57(8):1100-7. · 1.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The molecular mechanisms for epithelial differentiation have been studied by observing skin development in embryogenesis, but the early signaling modulations involved in tongue epithelial differentiation are not completely understood. Based on the gene expression patterns of the Fgf signaling molecules and previous results from Fgf10 and Fgfr2b knockout mice, it was hypothesized that there would be fundamental signaling interactions through the epithelial Fgfr2b and its mesenchymal ligand Fgf10 to regulate tongue epithelium differentiation. To elucidate these reciprocal interactions in tongue epithelial differentiation, this study employed an in vitro tongue organ culture system with antisense-oligodeoxynucleotides (AS-ODNs) and recombinant protein-soaked bead implantation for the loss-of-function and gain-of-function studies. Functional analysis of Fgf signaling revealed precise reciprocal interactions, which showed that mesenchymal Fgf10 rather than Fgf7 modulates tongue epithelial differentiation via Fgfr2b in a temporal- and spatial-specific manner.
Cell and Tissue Research 07/2011; 345(2):265-73. · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to evaluate the amount of bone formation under a sinus membrane tented with implants and filled with venous blood as a graft material.
Fourteen patients (17 sinus augmentations) were consecutively treated with sinus floor elevation via the lateral window approach. The lateral bony window was created using a piezoelectric saw, and the sinus membrane was elevated to make a new compartment. After resorbable blast media-surfaced dental implants were placed simultaneously, the collected peripheral venous blood was applied to support the sinus membrane over the implant apex, and the bony portion of the lateral window was repositioned to seal the lateral window. In 6 cases, samples were taken for biopsy at the time of second stage surgery.
An average of 6.8 months after the sinus augmentation, new bone consolidation in the maxillary sinus was observed by radiographic and histologic evaluation. Vital bone formation was 38.70% according to the histomorphometric data. Of the 31 implants placed, 2 failed. The overall implant survival rate was 93.5%. All failures occurred when implants were placed into the extraction socket and were associated with poor initial stability.
This study suggests that simultaneous placement of dental implants and injection of peripheral venous blood as a graft material appears to be a safe alternative procedure for maxillary sinus augmentation.
Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 06/2011; 69(9):2357-67. · 1.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present study, we prepared a composite scaffold of demineralized dentin particles (DDPs) with poly(lactic co-glycolic acid) (PLGA) to investigate cranial bone regeneration. We first determined protein and elemental contents in DDPs demineralized with ethylenediamine-tetraacetic acid (EDTA) and guanidine-hydrochloride (Guanidine-HCl) in order to obtain DDPs with high protein contents which might stimulate osteogenesis. Compared to Guanidine-HCl, DDPs obtained with EDTA showed smooth surface morphologies, increased net protein contents and elements per unit weight, and retained the spectral intensity of NH2 bonding. The treatment of DDPs obtained with EDTA to dental pulp stem cells (DPSCs) and bone marrow stromal cells (BMSCs) supported cell growth, and, in combination with osteogenic (OS) medium, enhanced alkaline phosphatase activity and mineral deposition at the range of 1~10 μg DDP/cm2 in vitro. To manipulate DDPs as a sheet form of scaffolds, composite scaffolds containing 1, 3, 5 and 10 wt% of DDPs with PLGA were prepared with a salt leaching method. In vitro analysis showed that PLGA composite scaffolds containing 1 and 3 wt% DDPs enhanced cell adhesion and expression of osteogenic marker genes. In animal model with calvarial defects, the PLGA composite scaffold containing 3 wt% DDPs seeded with DPSCs showed enhanced calvarial bone regeneration. Therefore, we suggest that DDPs prepared with EDTA and the composite scaffolds with PLGA could be a useful material for cranial bone regeneration.
Tissue Engineering and Regenerative Medicine. 05/2011; 8(3):306-313.
[Show abstract][Hide abstract] ABSTRACT: Epithelial appendages on palatal rugae develop during mouse palatogenesis through epithelial thickening and pattern formation. Recently, the patterned formation of nine rugae was observed together with the specific expression patterns of Shh in rodents. However, no crucial evidence was found for a direct association between Shh expression and the distinct structural formation of rugae. In order to reveal possible relationships, we investigated the morphological changes of rugae and expression patterns of Shh directly by in vitro organ culture at embryonic day 13 (E13) for 2 days. To compare and examine the diverse growing aspects of the palate and rugae, we carefully observed the detailed morphogenesis, with cell proliferation of the rugae occurring between E13 and E14.5. After 2 days of cultivation at E13, DiI micro-injections revealed that the middle part of the palate, adjacent to the upper molar-forming region, contributed to the formation of the subsequent structure of rugae by extensive cell rearrangement and proliferation within the epithelium in the preferred anteroposterior direction. The results also defined the intimate relationship between Shh expression and rugae formation.
Cell and Tissue Research 03/2011; 344(2):271-7. · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: While the soluble proteins of human teeth consist of various extracellular matrix and bioactive proteins, they have not yet been characterized fully. Moreover, the role they play in tooth regeneration is not clear. Analysis of the soluble proteins in human teeth by liquid chromatography-mass spectrometry revealed 147 different ethylenediaminetetraacetic acid-soluble tooth proteins (ESTPs). Of these, 29 had not been shown previously to be present in human teeth. To determine their effect on the in vitro responses of dental pulp stem cells (DPSCs), DPSCs were cultured in ESTP-coated culture plates and three-dimensional scaffolds. The ESTPs significantly enhanced DPSC odontoblast differentiation and mineralization in vitro, but had only partial effect on bone marrow stem cells or adipose tissue stem cells. To test the effect of ESTPs on in vivo dentin and tooth formation, mouse embryonic tooth-forming primordia and xenogenic murine apical bud epithelium/human DPSC composites were treated with ESTPs before implantation under the renal capsule of ICR mice. ESTP treatment promoted the formation of morphologically normal teeth by the tooth-forming primordium regions and enhanced the development of a regular and large dentin structure by the composites. These observations suggest that human ESTPs contain dentinogenic proteins and can promote dentin and tooth formation.
Tissue Engineering Part A 01/2011; 17(1-2):181-91. · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Synchrotron X-ray bioimaging was successfully carried out to observe bone regeneration by a novel artificial bone substitute of bioactive MegaGen Synthetic Bone (MGSB) and hyaluronate (HA) hydrogels. A biphasic calcium phosphate of MGSB was prepared by chemical precipitation method, with a porous spherical morphology. On the basis of the fact that HA plays important roles in bone regeneration and promotes the differentiation, vascularization, and migration of stem cells, HA-cystamine (CYS) hydrogels with cleavable disulfide linkages were prepared to supply HA continuously for effective bone regeneration by their controlled degradation in vivo. Among seven different samples using Bio-OSS®, MGSB, and/or several kinds of HA hydrogels, MGSB/HA-CYS hydrogels resulted in the most significant bone regeneration in the calvarial critical bone defect of New Zealand white rabbits. Histological and histomorphometric analyses revealed that the bone regeneration by MGSB/HA-CYS hydrogels was as high as 43%, occupying 71% of the bone defect area with MGSB in the form of a calvarial bone plate in 4 weeks. After that, MGSB was bioabsorbed and replaced gradually with regenerated bones as observed in 8 weeks. Synchrotron X-ray imaging clearly confirmed the effective bone regeneration by MGSB/HA-CYS hydrogels, showing three-dimensional micron-scale morphologies of regenerated bones interconnected with MGSB. In addition, sequential nondestructive synchrotron X-ray tomographic analysis results from anterior to posterior of the samples were well matched with the histomorphometric analysis results. The clinically feasible artificial bone substitutes of MGSB/HA-CYS hydrogels will be investigated further for various bone tissue engineering applications using the synchrotron X-ray bioimaging systems.
Tissue Engineering Part C Methods 10/2010; 16(5):1059-68. · 4.64 Impact Factor