Restoration of mandibular bone defects with demineralized bone matrix combined with three-dimensional cultured bone marrow-derived mesenchymal stem cells in minipig models.

Mandibular defects, caused by congenital, pathological or iatrogenic insults, can significantly affect patient quality of life. The reconstruction of mandible has recently gained the interest of clinical and tissue engineering researchers. The purpose of this study was to evaluate the effectiveness of three-dimensional (3-D) cultured autologous grafts prepared using bone marrow-derived mesenchymal stem cells (BMSCs) combined with demineralized bone matrix (DBM) scaffolds for the restoration of mandibular defects. Cylindrical defects were created in the mandibular body of minipigs and filled with 3D-cultured BMSCs/DBM autografts, 2D-cultured BMSCs/DBM autografts, DBM material (without cells), or were left unfilled (blank). Using computed tomographic (CT) imaging and histological staining, we found that treatment of mandibular defects using 3-D cultured BMSCs/DBM autografts offered improvements in bone formation over both 2-D cultured autografts and cell-free DBM scaffolds. We found increased osteoid formation in 3D and 2D cultures, with more osteogenic cells present in the 3D constructs. We suggest that 3-D cultured homograft BMSCs combined with DBM scaffolds represents a new strategy for bone reconstruction, with potential future clinical applicability.

Differences in the structure and osteogenesis capacity of the periosteum from different parts of minipig mandibles.

PURPOSE: To compare the structural and cellular differences of the periosteum from different parts of the mandible in minipigs by use of histologic and immunohistochemical methods to confirm the areas in which periosteal osteogenesis in situ can be used to treat mandible defects. MATERIALS AND METHODS: Three minipigs were killed, and the left mandible of each was retrieved with the periosteum remaining and then fixed, decalcified, and embedded. The specimens were cut from the buccal and lingual sides of the ramus, angle, and body of the mandible and the mentum. Sections were stained with hematoxylin-eosin and antibodies for Stro-1 (stem cell marker) and vWF (endothelial cell marker). For each periosteal area, the thickness and number of positive cells for each antibody were measured and analyzed. RESULTS: The mentum and mandibular angle periostea were thicker than those of the body and ramus. In addition, there were more blood vessels in the periostea of the mentum and mandibular body than the angle and ramus. There were more Stro-1-positive cells in the ramus periosteum than the mentum, body, and angle of the mandibles. CONCLUSIONS: The structure and cell populations of the periosteum appear to be site specific. Therefore we suggest periosteal osteogenesis in situ to treat mentum and mandibular body defects. The periosteum should be preserved as much as possible to guarantee a good healing process.

Collagen/nano-sized ß-tricalcium phosphate conduits combined with collagen filaments and nerve growth factor promote facial nerve regeneration in miniature swine: an in vivo study.

OBJECTIVE: The aim of this study was to investigate the efficiency of a novel biomedical system that repairs facial nerve gaps in a miniature swine model. STUDY DESIGN: A collagen (COL)/nano-sized ß-tricalcium phosphate (nß-TCP) conduit combined with COL filaments and nerve growth factor (NGF) was prepared and used to bridge a 35-mm-long facial nerve gap in miniature swine. The functional recovery and axonal regeneration were evaluated by electrophysiologic and histologic assessments in the different groups at 6 months postoperatively. RESULTS: Morphologic analysis revealed that the COL+NGF, COL/nß-TCP+NGF, and autograft groups exhibited a superior recovery compared with the COL and COL/nß-TCP groups. The compound muscle action potential ratios were significantly greater in the COL/nß-TCP+NGF group compared to the COL+NGF and COL/nß-TCP groups (P < .01). Moreover, transmission electron microscopy demonstrated significantly larger axon diameters and myelin sheath thicknesses in the COL/nß-TCP+NGF group compared with the COL, COL+NGF, and COL/nß-TCP groups (P < .05). The expression of S-100 was significantly greater in the COL/nß-TCP+NGF group than in the COL+NGF and COL/nß-TCP groups (P < .05). CONCLUSIONS: The functional nerve biomedical system containing the COL/nß-TCP conduit combined with COL filaments and NGF could promote facial nerve regeneration, thus offering promising potential for clinical applications.

Microarray gene expression of periosteum in spontaneous bone regeneration of mandibular segmental defects.

Spontaneous bone regeneration could occur to reestablish mandibular bony continuity in patients who underwent partial or total mandibulectomy for tumors with periosteum-preserving. However, scarce data is available related to the precise role of periosteum in this bone regeneration. Therefore we aimed to investigate the gene expression of periosteum that were involved in the mandibular bone regeneration. Mandibular segmental defects were created in six mini-pigs with periosteum preserved. The periosteum of defects and control site were harvested at 1 and 2 weeks. Gene ontology (GO) analysis showed that the mechanisms concerning immature wound healing were clearly up-regulated at week 1. In contrast, by week-2, the GO categories of skeletal development, ossification and bone mineralization were significantly over-represented at week-2 with several genes encoding cell differentiation, extracellular matrix formation, and anatomical structure development. Furthermore, Tgfß/Bmp, Wnt and Notch signaling were all related to the osteogenic process in this study. Besides osteogenesis, genes related to angiogenesis and neurogenesis were also prominent at week-2. These findings revealed that the gene expression profile of the periosteum's cells participating in bone regeneration varied in different time points, and numbers of candidate genes that differentially expressed during early healing stages of intramembranous bone regeneration were suggested.

Individualized treatment for the mandibular segmental defect: a case report.

Ameloblastomas are slowly growing, locally invasive tumors with high recurrence rate and more common in the mandible, if not treated they can grow to enormous size. Radical resection is the only predictable form of treatment for ameloblastomas. However, mandibular resection can lead to dysfunctions in appearance, speech, mastication, and deglutition, which severely impair the patients' quality of life. The reconstruction of extensive bone defects in the maxillofacial area is still challenging. To meet the demands of functional reconstruction, minimizing the negative influence of mandibular malformation, and disability on patients, the individualized systematic treatment plans highlight denture prosthodontics and require much consideration of multidisciplinary cooperation, with such related fields as maxillofacial surgery, oral implantology, prosthodontics, and radiology taken into account. In this report, we will present a case of reconstructing the mandibular segmental defect after the resection of a rarely giant ameloblastoma. In the case, we took the restoration of the missing teeth and the rehabilitation of the masticatory function as well as restoring bony continuities and facial appearance into consideration, communicated well with prosthodontists and implantologists before surgery, making the individualized systematic treatment plan more effective and efficient.

Comparison of cell-loading methods in hydrogel systems.

Bone regenerative medicine, based on the combined use of cells and scaffolds, represents a promising strategy in bone regeneration. Hydrogels have attracted huge interests for application as a scaffold for minimally invasive surgery. Collagen and oligo(poly(ethylene glycol)fumarate) (OPF) hydrogels are the representatives of two main categories of hydrogels, that is, natural- and synthetic-based hydrogels. With these the optimal cell-loading (i.e., cell distribution inside the hydrogels) method was assessed. The cell behavior of both bone marrow- and adipose tissue-derived mesenchymal stem cells (BM- and AT-MSCs) in three loading methods, which are dispersed (i.e., homogeneous cell encapsulation, D), sandwich (i.e., cells located in between two hydrogel layers, S), and spheroid (i.e., cell pellets encapsulation, Sp) loading in two hydrogel systems (i.e., collagen and OPF), was compared. The results suggested that the cell behavior was influenced by the hydrogel type, meaning cells cultured in collagen hydrogels had higher proliferation and osteogenic differentiation capacity than in OPF hydrogels. In addition, AT-MSCs exhibited higher proliferation and osteogenic properties compared to BM-MSCs. However, no difference was observed for mineralization among the three loading methods, which did not approve the hypothesis that S and Sp loading would increase osteogenic capacity compared to D loading. In conclusion, D and Sp loading represents two promising cell loading methods for injectable bone substitute materials that allow application of minimally invasive surgery for cell-based regenerative treatment.

The in vivo performance of CaP/PLGA composites with varied PLGA microsphere sizes and inorganic compositions.

Enrichment of calcium phosphate (CaP) bone substitutes with poly(lactic-co-glycolic acid) (PLGA) microspheres to create porosity overcomes the problem of poor CaP degradation. The degradation of CaP-PLGA composites can be customized by changing the physical and chemical properties of PLGA and/or CaP. However, the effect of the size of dense (solid rather than hollow) PLGA microspheres in CaP has not previously been described. The present study aimed at determining the effect of different dense (i.e. solid) PLGA microsphere sizes (small (S) ~20µm vs. large (L) ~130µm) and of CaP composition (CaP with either anhydrous dicalcium phosphate (DCP) or calcium sulphate dihydrate (CSD)) on CaP scaffold biodegradability and subsequent bone in-growth. To this end mandibular defects in minipigs were filled with pre-set CaP-PLGA implants, with autologous bone being used as a control. After 4weeks the autologous bone group outperformed all CaP-PLGA groups in terms of the amount of bone present at the defect site. On the other hand, at 12weeks substantial bone formation was observed for all CaP-PLGA groups (ranging from 47±25% to 62±15%), showing equal amounts of bone compared with the autologous bone group (82±9%), except for CaP with DCP and large PLGA microspheres (47±25%). It was concluded that in the current study design the difference in PLGA microsphere size and CaP composition led to similar results with respect to scaffold degradation and subsequent bone in-growth. Further, after 12weeks all CaP-PLGA composites proved to be effective for bone substitution.

Determination of critical size defect of minipig mandible.

The critical size defect (CSD) of bone can provide a standard for evaluating the usefulness of bone repair materials or methods. The present study aimed to determine the CSDs of the minipig mandible with and without the periosteum. Ten 18 month-old female minipigs were used. First, the premolars and the first molar in the right mandible of each minipig were extracted. Two months later, the animals were randomly divided into two groups, with six animals in group A and four in group B. In group A, bone segments of 4, 5 and 6 cm were removed from the right mandible and the neighbouring periosteum was preserved. In group B, bone segments of 1 and 2 cm were removed from the right mandible and the periosteum was removed. The defects were retained with two reconstructive titanium plates. The mandibles underwent X-ray examinations at 4, 8 and 12 weeks after the operation. The animals were sacrificed at 12 weeks after the operation, and specimens were evaluated by gross and histological examinations. For defects retained by two reconstructive plates, the CSDs in the minipig mandible models with and without periosteum were determined as 6 and 2 cm, respectively.

[Research of immunization with recombinant plasmid pcDNA3-pacA and pcDNA3-pacP against dental caries in gnotobiotic rats. I: Measurement of specific anti-PAc S-IgA, IgG, valence].

OBJECTIVE: In this study, rats were immunized with pcDNA3-pacA and pcDNA3-pacP through submandibular gland, the valence of specific anti-PAc S-IgA,IgG were measured. METHODS: Gnotobiotic rats were vaccinated with pcDNA3-pacA, pcDNA3-pacP and combination use of pcDNA3-pacA and pcDNA3-pacP through submandibular gland. The valence of specific anti-PAc S-IgA in salivary, IgG in serum were measured. RESULTS: The specific anti-PAc S-IgA, IgG could be detected in all of recombinant plasmid groups. The level of salivary specific anti-PAc S-IgA and IgG in pcDNA3-pacA, pcDNA3-pacP, combination use of pcDNA3-pacA and pcDNA3-pacP groups were higher than negative control groups (P < 0.05). CONCLUSION: The recombinant plasmid pcDNA3-pacA and pcDNA3-pacP could provoke specific mucosal immune responses as a novel immunogen against dental caries.