Acellular Bone Research Articles

Enhancing osteogenesis and mandibular defect repair with magnesium-modified acellular bovine bone matrix

An acellular bovine bone matrix modified to release Magnesium ions (Mg2+) (ABBM-Mg) was prepared and evaluated for its potential in osteogenesis and mandibular defect repair. Mg2+ was incorporated into ABBM using an ion exchange method. The microstructure and mechanical properties of both ABBM and ABBM-Mg were analyzed using SEM and a biomechanical testing machine. Cytocompatibility, cell adhesion, and osteogenic differentiation were assessed using various methods including CCK-8, Live/Dead staining, SEM, ALP staining, and qPCR analysis in MC3T3-E1 cells. Additionally, a mandibular defect model in rats was established. The bone defect repair outcomes were evaluated using Micro-CT, histological HE staining, and Masson staining. The study showed that mineralization containing magnesium was redeposited on the surface of the three-dimensional porous ABBM, and the ABBM-Mg scaffold promoted cell proliferation and osteogenic differentiation compared to the ABBM scaffold. In the rat mandibular defect model, the ABBM-Mg scaffold demonstrated superior bone repair ability. This study successfully incorporated Mg2+ into ABBM without significantly affecting its microstructure and compressive strength. Furthermore, ABBM-Mg showed sustained release of Mg2+ which enhanced cell proliferation, adhesion, and osteogenic differentiation in vitro, and promoted mandibular defect healing in rats. This research opens up new possibilities for the clinical application of functionalized acellular bone matrix.Graphical

Efficacy of positive space acquiring membrane and antimicrobial membrane combined with granular bone substitute implantation in guiding oral bone regeneration.

Augmentation of the alveolar bone is important before oral implantation. For large bone defects, it becomes necessary to apply guided bone regeneration (GBR) materials, accompanied by filling defect sites with autologous or allogeneic bone, or bone substitutes such as acellular bone powder. In this study, we tested a granular bone substitute and GBR membrane combination therapy in treating MC3T3-E1 and L929 cells in vitro and rat calvarial and alveolar defects in vivo. The recovery conditions of bone defects were monitored by micro-CT, and 3D reconstruction of the CT images was applied to evaluate the bone augmentation semi-quantitatively. Test GBR materials could support the proliferation of MC3T3-E1 cells, poly (p-dioxanone-co-L-phenylalanine) (PDPA)-based membrane could induce apoptosis of L929 cells. Among GBR membranes applied groups, the regeneration condition of defected calvarial defects of PDPA based membrane applied group was the best and this may be caused by its excellent positive space acquiring effect. However, in a complex bacteriogenic environment, the oral bone regeneration-guided efficacy of the PDPA membrane decreased in the post-repair stage with the aggravation of infections. By contrast, the antimicrobial membrane combined with the PDPA membrane exhibited continually increasing GBR efficacy at the later stage of repair owing to its multifunctional properties, which are infection-inhibiting and positive space acquiring. Therefore, multifunctional GBR membranes are preferable for GBR in complex oral environments, and further research should be conducted to determine their efficacy in other models.

Treated Pierre Robin Sequence Using Placed Allogenic Acellular Bone Matrix and Mandibular Distraction Osteogenesis in the Neonate

ObjectiveThe aim of the study was to report our experience with placed allogenic acellular bone matrix and mandibular distraction osteogenesis in Pierre Robin sequence (PRS), and explore the role of distraction in the osteogenesis of acellular bone.Materials and MethodsA total of 428 neonates with severe PRS managed with placing allogenic acellular bone and bilateral mandibular distraction osteogenesis were included in the study. The procedure included using oblique-shaped osteotomy, fixing bilateral mandibular distractor, instantly extending a 4–6 mm gap, and placing allogenic acellular bone into the gap. The length of allogenic acellular bone was 4–5 mm. Although the surgical techniques, distraction, and consolidation periods were similar, the allogenic acellular bone matrix we placed was quite different from the traditional distraction. With the technology we used, tracheal intubation could be immediately removed, thus quickly improving breathing conditions compared to traditional methods after the surgery. The jaw extending and oral feeding could begin on the 5th day. The jaw was extended 0.6 mm twice a day until the mandible was overcorrected by 20%.ResultsAll 428 cases included in this study were successfully extubated after the operation, and the difficulty in breathing was instantly relieved. Total mandibular distraction was 15–20 mm. Oral feeding was started at 6 h to 6 days postoperatively, while hospital stay ranged from 18 to 20 days postoperatively. No major complications were reported. Medium to long-term results was good. Mandibular distractors were removed after 3 months.ConclusionsBilateral mandibular distraction osteogenesis combined with placing allogenic acellular bone in the neonate are safe and accurate procedures, which are the primary treatment options for cases of severe PRS. It can be considered that the tension of distraction can promote osteogenesis in acellular bone and thus improve distractive effect of the mandible.

Extracellular vesicles derived from neural EGFL-Like 1-modified mesenchymal stem cells improve acellular bone regeneration via the miR-25-5p-SMAD2 signaling axis.

Stem cell based transplants effectively regenerate tissues; however, limitations such as immune rejection and teratoma formation prevent their application. Extracellular vesicles (EVs)-mediated acellular tissue regeneration is a promising alternative to stem cell based transplants. Although neural EGFL-like 1 (Nell1) is known to contribute to the osteogenic differentiation of bone marrow stem cells (BMSCs), it remains unknown whether EVs are involved in this process. Here, we present that EVs derived from Nell1-modified BMSCs (Nell1/EVs) have a stronger ability to promote BMSC osteogenesis owing to miR-25–5p downregulation. MiR-25–5p inhibits osteogenesis by targeting Smad2 and suppressing the SMAD and extracellular signal-related kinase 1 and 2 (ERK1/2) pathway activation. In addition, we demonstrate that the 3D-Nell1/EV-hydrogel system is beneficial for bone regeneration in vivo, probably stemming from a slow, continuous release and high concentration of EVs in the bone defect area. Thus, our results have shown the potential of Nell1/EVs as a novel acellular bone regeneration strategy. Mechanistically, the identification of miR-25-5p-SMAD2 signaling axis expands the knowledge of Nell1/EVs induced osteogenesis.

Highly effective induction of cell-derived extracellular matrix by macromolecular crowding for osteogenic differentiation of mesenchymal stem cells

The extracellular matrix (ECM) is the non-cellular component that exists in all tissues and provides dynamic microenvironment that initiates crucial biochemical and biophysical cues, including cell adhesion, proliferation, migration, and differentiation. Although the cell-derived ECM mimics the native cellular microenvironment, the long-term maintenance of cells is required to harvest a sufficient amount of ECM for the intended application. In this study, we evaluated the biophysical properties of fucoidan as a macromolecular crowding (MMC) agent to accelerate ECM synthesis and deposition in human dermal fibroblasts and found that the accumulated cell-derived ECM by fucoidan (fCDM) influenced the osteogenic differentiation of mesenchymal stem cells (MSCs). The treatment of fucoidan resulted in significantly higher ECM deposition at 5 days compared with the treatment of dextran sulfate (DxS), a potent MMC agent. The advantages of fCDM were demonstrated in vitro by the promotion of multiple cellular behaviors of MSCs, osteogenic differentiation, and signal transduction pathway. In addition, the PLGA scaffold containing fCDM had significantly higher alkaline phosphatase activity than the PLGA scaffold containing acellular bone tissue ECM. Based on these results, the fCDM can support the development of human cell-derived, xeno-free biomaterials for tissue engineering applications.

Application of Bovine Acellular Cancellous Bone Matrix in Alveolar Ridge Preservation Following Tooth Extraction

Objective: In this article, we explored the microscopic structure and composition of the decellular-ized cancellous bone matrix of the calf, and established the animal model of Beagle dog extraction. By applying different bone substitute materials in the extraction of teeth, we observed the new collagen-rich in the preservation of the site after tooth extraction. The protein bone matrix maintained the three-dimensional shape of the alveolar ridge compared to other biological materials. Methods: The microstructure of the new collagen-rich bone matrix was observed by scanning electron microscopy. The porous structure, porosity and distribution of collagen fibers were observed. XRD and infrared spectroscopy were used to further detect the inorganic and organic components in the new collagen-rich bone matrix. The premolar extraction and site preservation model of Beagle dogs were constructed. The changes of collagen-rich bone matrix, Bio-oss bone powder, CGF filling and blank control alveolar ridge volume were compared by CBCT. HE staining was used to observe and compare new bone formation, bone remodeling and bone resorption between groups, and to observe the formation of blood vessels, osteogenic mineralization, trabecular bone formation and inflammatory response in different periods. Results: (1) The acellular bone matrix of bovine cancellous bone completely removes the immunogenicity of the cells and has good histocompat-ibility; the pore diameter and porosity closest to the physiological structure, the main component is hydroxyapatite and collagen. (2) Site preservation can reduce the absorption of alveolar ridge following tooth extraction, preserve sufficient bone mass for alveolar fossa, and retain a good width of attachment, which provides further protection for implant surgery. (3) In the post-extraction site preservation, the CGF group has better bone composition than the BABM group and Bio-oss bone powder. Conclusion: Bovine Acellular Cancellous Bone Matrix is a new type of biological bone matrix. The main components are collagen and hydroxyapatite, which can promote bone formation in the extraction socket.

Impact of dietary phosphorus on turbot bone mineral density and content

Fish are largely dependent on dietary phosphorus for skeletal development and mineralization. In aquaculture, commercial diets commonly have higher phosphorus concentration than the basal requirements in most fish species to ensure growth and prevent bone mineral disorders. Excessive phosphorus in feeds is harmful for metabolism and results in an increase of wastes in farm effluents, which impact aquatic ecosystems. Previous studies have shown that depletion/excess of dietary phosphorus cause skeletal malformations and reduced/enhanced mineralization in fish. There is scarce information on dietary phosphorus requirements for optimal bone mineralization in species with different types of bone (cellular vs. acellular bone), which is particularly relevant for sustainable aquaculture. Thus, the aim of our study was to analyse the effect of dietary phosphorus concentrations on bone mineralization of turbot, a demersal acellular-boned fish and valuable aquaculture species. Our results show that the dietary phosphorus concentration did not cause changes to the bone mineral density and the phosphate/calcium concentrations. No apparent skeletal malformations were detected. Additionally, we did not find an altered expression of genes involved in bone mineral metabolism. Taken together, our data show that the phosphorus requirements for optimum growth and bone mineralization in turbot are below those currently used commercially at least for the time period examined: 55–195 days postfertilization (dpf).

Fabrication of Biomolecule-Loaded Composite Scaffolds Carried by Extracellular Matrix Hydrogel

Fabrication of multifunctional scaffolds with biomimicking physical and biological signals play an important role in enhancing tissue regeneration. Multifunctional features come from the composite scaffold with various bioactive molecules. However, simple, biocompatible, and controllable hybridization strategy is still lacking. In this study, we leverage naturally derived extracellular matrix (ECM) as chemically controllable hydrogel carrier to effectively load functional biomolecules. The use of ECM hydrogel takes advantage of both native functionality of ECM components and tunability of hydrogel in controlling release of loaded molecules. As a proof of concept, porous acellular bone scaffold was selected as the solid pristine scaffold to be composited with BMP-2 and VEGF, which are loaded by spinal cord-derived ECM (SC-ECM) hydrogel. Crosslinking degree of SC-ECM hydrogel is tuned by changing genipin concentration, which renders the control over release kinetics of BMP-2 and VEGF. The mechanical strength of scaffold maintained after hybridization and is not significantly decreased in wet condition. In vitro evaluations of scaffolds cocultured with osteoblasts and mesenchymal stem cells (MSCs) demonstrate the biocompatible and bioactive features resulting from the composite scaffolds. Evidenced by alkaline phosphatase test, immunofluorescence, and real-time polymerase chain reaction, differentiation of MSCs towards osteoblast lineage is significantly enhanced by composite scaffolds. Therefore, our strategy in fabricating composite scaffold enabled by biomolecule-loaded ECM hydrogel holds great promise in regenerating diverse tissue types by appropriate combinations of solid pristine scaffolds, ECM, and bioactive molecules. Impact statement We developed a bioactive molecule (e.g., growth factor, protein) loading method using extracellular matrix hydrogel as a carrier. It brings a new strategy to fabricate composite scaffolds with unique biofunctions.

Evaluation of Acellular Bovine Cancellous Bone Matrix Seeded with Foetal Rabbit Osteoblasts for Segmental Bone Defects in Rabbits

The present work was assessed the restoration of segmental bone gap defect in rabbits by application of composite bone grafts. Composite bone grafts were prepared by seeding of rabbit foetal osteoblast on the bovine acellular cancellous bone matrix and evaluated in the segmental gap defect of 20 mm in rabbits. Thirty six adult New Zealand White rabbits of either sex were allotted to three groups of 12 each. Autograft (group A), Acellular cancellous bone matrix (group B) and composite graft seeded with fetal osteoblasts (group C) were implanted in the defects. Radiography, gross observations and histopathology at different intervals were done to evaluate healing. It was concluded that the seeded foetal osteoblasts in the composite grafts augment regeneration of the new bone leading to better integration of graft in host in comparison to bovine acellular cancellous bone matrix graft.

Can IV Infusions Of Bone Marrow Derived Mesenchymal Stem Cell Extracellular Vesicles Be The Fountain Of Youth?

There is increasing published literature to support the safety and efficacy of IV infusions of bone marrow-derived expanded allogeneic mesenchymal stem cells (MSCs) for the treatment of various auto-immune diseases. Frailty Syndrome was created to provide a way of objectively measuring aging with physical activity scales and bio-inflammatory markers. IV infusions of allogeneic MSCs have been reported to statistically significantly increase physical function and decrease inflammatory biomarkers in Frailty Syndrome. Replacing cellular allogeneic IV infusions with acellular bone marrow-derived MSC extracellular vesicle isolate products (EVIP) containing active growth factors (GFs) and exosomes has numerous advantages. Regenerative medicine researchers and clinicians now realize that living MSCs are not required to achieve clinical efficacy. The clinical efficacy of MSCs is due to their paracrine release of GFs and exosomes. Living MSCs are not required to accomplish the paracrinesignaling of GFs and exosomes. Acellular MSC EVIP containing active GFs and exosomes are the future of regenerative medicine.Acellular exosomesderived from bone marrow MSCs provide a consistent product that has extensive characterization, which includes advanced particle analysis, proteomic evaluation and USP<71> sterility assurance. The future “Fountain of Youth” will be the frequent (3 to 4 times per year) IV infusion of bio pharmacologic quality bone marrow-derived MSC EVIP. These active GF and exosome infusions will result in a continual down regulation of systemic inflammation and based on published research reverse many of the inflammatory effects of aging.

Human Bone Marrow-Derived Mesenchymal Stromal Cell-Seeded Bone Biomaterial Directs Fast and Superior Mandibular Bone Augmentation in Rats

Atrophic maxillary ridges present a challenge in the field of oral implantology. Autologous bone is still considered the gold standard grafting material, but the increased morbidity and surgical complications represent a major drawback for its use. The aim of this study was to assess the efficacy of an off-the-shelf cell-seeded bone biomaterial for mandibular bone augmentation, compared to its acellular counterpart. We used a rat model to test the osteogenic properties of bone marrow-derived mesenchymal stromal cells (MSCs)-seeded bone microparticles compared to acellular bone microparticles alone. Rats were euthanized at 4 and 8 weeks, and results analyzed using micro-CT imaging, histology (H&E, Masson’s Trichrome), histomorphometry and immunohistology (Tartrate-Resistant Acid Phosphatase-TRAP, Osteocalcin and human specific anti-mitochondria antibodies). Micro-CT analysis demonstrated that the cell-seeded biomaterial achieved significantly more bone volume formation at 4 weeks (22.75 ± 2.25 mm3 vs 12.34 ± 2.91 mm3, p = 0.016) and at 8 weeks (64.95 ± 5.41 mm3 vs 42.73 ± 10.58 mm3, p = 0.029), compared to the acellular bone microparticles. Histology confirmed that the cell-seeded biomaterial was almost completely substituted at 8 weeks, in opposition to the acellular biomaterial group. Immunohistochemical analysis showed a significantly higher number of TRAP and Osteocalcin positive cells at 4 weeks in the cell-seeded group compared to the acellular group, thereby demonstrating a higher rate of bone remodeling in the presence of MSCs. The grafted human cells remained viable and were detected up to at least 8 weeks, as observed using the human specific anti-mitochondria antibody. This off-the-shelf material available in unlimited quantities could therefore represent a significant advance in the field of mandibular bone augmentation by providing a larger volume of new bone formation in a shorter time.

A new mineralized tissue in the early vertebrate Astraspis.

The dermoskeleton of the earliest vertebrates is well known but their endoskeleton is thought to have been largely cartilaginous until the Late Silurian. We confirm that the dermal plates of Astraspis are three-layered, with a superficial layer of enameloid and orthodentine, a middle layer of aspidin and a basal layer of lamellar acellular bone. This dermoskeleton is found in association with globular calcified cartilage, indicating the presence of a partially mineralized endoskeleton. In addition to the classical three-layered organization, some dermal plates exhibit alignments of chondrocyte-like lacunae, very similar to a pattern typical of chondroid metaplastic bone, previously unknown in early vertebrates. This discovery implies the presence of a proliferative cartilage, hitherto only known in Osteichthyans. This discovery indicates that a pattern similar to the first step of endochondral ossification was already present in the earliest vertebrates.

Osteomimetic matrix components alter cell migration and drug response in a 3D tumour-engineered osteosarcoma model

Osteosarcoma management continues to lack the appropriate prognostic tools to assign personalised treatment. This leaves non-responders to standard care vulnerable to recurring disease and pulmonary metastases. Developing 3D in vitro disease models to serve as a test bed for personalised treatment is a promising approach to address this issue. This study describes the generation of 3D osteosarcoma models termed “tumouroids”, which are geometrically compartmentalised to reproduce the bone cancer mass and its surrounding. Although the tumour microenvironment impacts osteosarcoma in many ways, this model focussed on interrogating the influence of a biomimetic matrix on tumour cell behaviour. The 3D matrix was supplemented with the bone-marrow proteins laminin, fibronectin and NuOss® bone granules. This led to increased invasion of osteosarcoma cell aggregates from within the bone-like matrix into the surrounding acellular bone marrow-like ECM. The presence of bone granules also yielded an atypical molecular profile of osteosarcoma cells, suggesting malignant metabolic reprogramming. Changes include decreased MMP-9 (p < 0.05) and increased PTEN (p < 0.05), MCP-1 (p < 0.01) and MCT-4 (p < 0.05) gene expression. This complex 3D biomimetic composition also changed cellular responses to doxorubicin, a common chemotherapeutic agent used to treat osteosarcoma, and reproduced key issues of in vivo treatment like drug penetrance and doxorubicin-induced bone toxicity. This work highlights the importance of a biomimetic matrix in 3D osteosarcoma models for both basic and translational research. Statement of SignificanceThis study describes the generation of 3D osteosarcoma models termed “tumouroids”, which are geometrically compartmentalised to reproduce the bone cancer mass and its environment. Utilising this novel model, specific parameters of osteosarcoma growth and invasion were investigated. Osteosarcoma cell lines proliferate at a slower rate, exhibit malignant metabolic reprogramming, and respond to drug intervention at lower concentrations of doxorubicin hydrochloride in matrix-complex compared to basic tumouroids. As such, this study provides evidence that the tumour microenvironment impacts osteosarcoma in many ways. The osteosarcoma tumouroid described herein may form the basis of a personalised-medicine strategy, which will allow the testing of drug effectiveness similar to that used for antibiotic selection for pathogenic bacteria.

Effects of micro-osteoperforations on tooth movement and bone in the beagle maxilla.

The purpose of this study was to determine how micro-osteoperforations (MOPs) affect tooth movements, bone turnover, bone density, and bone volume. A split-mouth experimental design with 7 beagle dogs was used to evaluate bone surrounding maxillary second premolars that had been retracted for 7weeks. One month after the maxillary third premolars were extracted, 8 MOPs (1.5mm wide and 7mm deep) were created without flaps with the use of the Propel device (6 were placed 3mm distal to the second premolar and 2 were placed in the premolar furcation) on one randomly chosen side. The maxillary second premolars were retracted bilaterally with the use of 200g nickel-titanium closed coil springs. Tooth movements were measured intraorally and radiographically. Microscopic computed tomography was used to evaluate the material density and volume fraction of bone distal to the premolars. Hematoxylin and eosin-stained and fluorescent sections were used to examine the bone remodeling. Neither the intraoral (P=0.866) nor radiographic (P=0.528) measures showed statistically significant side differences in tooth movements. There also were no statistically significant differences in the density (P=0.237) or volume fraction (P=0.398) of bone through which the premolars were being moved. Fluorescent and histologic evaluations showed no apparent differences in osteoblasts, osteoclasts, or mineralization of bone near the teeth being moved. Bone healing was evident in and near the MOP sites, which had nearly but not completely healed after 7weeks. Regions of acellular bone were evident extending ∼0.8mm from the MOP sites. MOPs placed 3mm away from teeth do not increase tooth movements and have limited and transitory effect on bone.

The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolism.

Vertebrate bone is composed of three main cell types: osteoblasts, osteoclasts and osteocytes, the latter being by far the most numerous. Osteocytes are thought to play a fundamental role in bone physiology and homeostasis, however they are entirely absent in most extant species of teleosts, a group that comprises the vast majority of bony 'fishes', and approximately half of vertebrates. Understanding how this acellular (anosteocytic) bone appeared and was maintained in such an important vertebrate group has important implications for our understanding of the function and evolution of osteocytes. Nevertheless, although it is clear that cellular bone is ancestral for teleosts, it has not been clear in which specific subgroup the osteocytes were lost. This review aims to clarify the phylogenetic distribution of cellular and acellular bone in teleosts, to identify its precise origin, reversals to cellularity, and their implications. We surveyed the bone type for more than 600 fossil and extant ray-finned fish species and optimised the results on recent large-scale molecular phylogenetic trees, estimating ancestral states. We find that acellular bone is a probable synapomorphy of Euteleostei, a group uniting approximately two-thirds of teleost species. We also confirm homoplasy in these traits: acellular bone occurs in some non-euteleosts (although rarely), and cellular bone was reacquired several times independently within euteleosts, in salmons and relatives, tunas and the opah (Lampris sp.). The occurrence of peculiar ecological (e.g. anadromous migration) and physiological (e.g. red-muscle endothermy) strategies in these lineages might explain the reacquisition of osteocytes. Our review supports that the main contribution of osteocytes in teleost bone is to mineral homeostasis (via osteocytic osteolysis) and not to strain detection or bone remodelling, helping to clarify their role in bone physiology.

Minimally Manipulative Method for the Expansion of Human Bone Marrow Mesenchymal Stem Cells to Treat Osseous Defects.

Lack of standardization of clinically compliant culture protocols of mesenchymal stem cells for re-implantation in humans have hindered clinical progress in the field of tissue regeneration to repair maxillofacial and orthopedic defects. The goal of this study was to establish a clinically relevant osteogenic protocol for collection and expansion of autologous stem cells to be used at Marshall University for re-implantation and repair of maxillofacial and orthopedic conditions. Human bone marrow (hBM) samples were collected from patients undergoing intramedullary nail fixation for closed femoral fractures. hBM mesenchymal cells were expanded by growing them first in Petri dishes for two weeks, followed by a week of culture using Perfecta 3D Hanging Drop Plates®. Various scaffold materials were tested and analyzed for cellular integration, vitality, and differentiation capacity of harvested hBM-MSCs including: 60/40 blend of hydroxyapatite biomatrix; Acellular bone composite discs; Allowash®, cancellous bone cubes; PLGA (poly lactic-co-glycolic acid); and Woven chitin derived fiber. We found that the 3D spheroid culture allowed production of hBM mesenchymal cells that retained osteoblast differentiation capacity over a monolayer culture of hBM-MSCs without the need to use chemical or hormonal modulation. We also observed that hydroxyapatite and Allowash cancellous bone scaffolds allowed better cell integration and viability properties as compared to other materials tested in this study. In conclusion, the multimodal culture methodology we developed creates actively differentiating stem-cell spheroids that can then be readily utilized in clinical practices to improve the regeneration of tissues of the head and the body.

Clinical analysis of acellular dermal matrix and acellular bone matrix in oro-antral fistula repair

This study aimed to investigate the application of acellular dermal matrix and acellular bone matrix in the management of oro-antral fistula. Nine patients with oro-antral fistula (with defect greater than 5 mm×5 mm) after maxillary cyst resection or maxillary molar extraction were selected. The defects were repaired by the simultaneous implantation of acellular dermal matrix and acellular bone matrix. The incisions of nine patients were all primary healing. After 6 months of follow-up, the oro-antral communication healed well, and no symptom such as nasal congestion or runny nose was observed. The clinical and CT examinations confirmed wound healing. The usage of acellular dermal matrix and acellular bone matrix is a reliable repairing method for ora-antral fistula.

The nature of aspidin and the evolutionary origin of bone.

Bone is the key innovation underpinning the evolution of the vertebrate skeleton, yet its origin is mired by debate over interpretation of the most primitive bone-like tissue, aspidin. This has variously been interpreted as cellular bone, acellular bone, dentine or as an intermediate of dentine and bone. The crux of the controversy is the nature of unmineralised spaces pervading the aspidin matrix, which have alternatively been interpreted as having housed cells, cell processes, or Sharpey’s Fibres. Discriminating between these hypotheses has been hindered by the limits of traditional histological methods. Here we use Synchrotron X-ray Tomographic Microscopy (srXTM) to reveal the nature of aspidin. We show the spaces exhibit a linear morphology, incompatible with interpretations that they represent voids left by cells or cell processes. Instead, these spaces represent intrinsic collagen fibre bundles that form a scaffold, about which mineral was deposited. Aspidin is thus acellular dermal bone. We reject hypotheses that it is a type of dentine, cellular bone, or transitional tissue. Our study suggests the full repertoire of skeletal tissue types was established prior to the divergence of the earliest known skeletonising vertebrates, indicating that the corresponding cell types evolved rapidly following the divergence of cyclostomes and gnathostomes.

Histology of the endothermic opah (Lampris sp.) suggests a new structure-function relationship in teleost fish bone.

Endothermy, production and retention of heat by the body, appeared convergently in mammals, birds and four spiny-rayed teleost fish lineages. Of these, red-muscle endothermy over most or all of the body has only appeared in two groups: tunas and the opah (Lampris). Hitherto, tunas have been the only spiny-rayed fishes known to have bones containing embedded osteocyte cells; others have acellular bone. We examined bone histology in Lampris for the first time, demonstrating the presence of cellular bone very similar to that of tunas. This contrasts with the acellular condition of its ectothermic close relatives. The distribution of this character suggests that it co-evolved with red-muscle endothermy, hinting at a common physiological mechanism that would link bone histology to endothermy in these distantly related teleost lineages.

Recent Progresses in Breast Reconstruction: Stem Cells, Biomaterials, and Growth Factors

Breast cancer is one of the most deadly tumors in women, and new procedures for post- surgical breast reconstruction have been developed which includes autologous stromal vascular fraction (SVF), platelet-derived growth factors, biomaterials and various stem cells. Adipose derived-stem cells (ASCs) has been reported to be one of the most widely used stem cell for breast reconstruction because of their ability to form new functional adipose tissue and vessels and in combination with stromal vascular fraction has been also reported efficient for breast reconstruction. Biomaterials include acellular dermal matrix, bone substitutes, and injectable have also been reported to be applicable for several clinical applications, including breast reconstruction surgery. Nevertheless, further studies are needed to explicitly define methodological procedures and to confirm the safety of all theses procedures during post-surgical breast reconstruction. The purpose of this mini-review is to summarize various recent and old applications of stem cells, biomaterials as well as growth factors in breast reconstruction.