β-TCP Granules Research Articles

Performance of β-tricalcium phosphate granules and putty, bone grafting materials after bilateral sinus floor augmentation in humans

Sinus floor augmentation (SFA) using bone grafting materials, and in particular calcium phosphates (CaP), is a well-established pre-implantology procedure. The use of CaP simplifies SFA procedures. β-tricalcium phosphate (β-TCP) is amply used for SFA. This study evaluated the clinical and osteogenic performance of β-TCP granules (TCP-G) and a β-TCP putty (TCP-P) bone graft material. TCP-P consisted of TCP-G in a hyaluronic acid (HyA) carrier. Bone formation, volume stability and osteogenic marker expression after bilateral SFA in patients was assessed. Eight patients were selected for a split-mouth design. Biopsies obtained six months after SFA, were processed for immunohistochemical analysis of collagen type I (Col I), alkaline phosphatase (ALP), osteocalcin (OC) and bone sialoprotein (BSP). Histomorphometric analysis determined bone, grafting material and marrow space percentages. Cone-beam computed tomography was used to calculate the graft volume and its stability. Both materials allowed excellent bone regeneration and volume stability. TCP-P displayed better surgical handling properties, greater bone formation, higher expression of Col I, ALP, OC and BSP; as well as significantly lower grafting volume reduction values. HyA had no adverse effect on TCP-P performance. Due to its clinical and osteogenic performance, TCP-P can be regarded as excellent bone grafting material for SFA.

β-TCP–polylactide composite scaffolds with high strength and enhanced permeability prepared by a modified salt leaching method

A modified particulate leaching method for fabrication of strong calcium phosphate–polymer composite scaffolds with improved pore interconnectivity is reported. The scaffolds were produced by mixing precompacted composite granules (β-TCP with 40vol% PLA) of different size and density with salt particles followed by high pressure consolidation (at room temperature or 120°C) and porogen dissolution. The scaffolds' compressive strength and Darcy's permeability were found to be inversely related and to be strongly dependent on the processing parameters. The use of precompacted granules instead of the loose β-TCP–PLA powder allowed us to increase permeability by three orders of magnitude while maintaining load bearing characteristics. Scaffolds with 50% porosity prepared from large (300–420μm) composite granules of β-TCP–40vol% PLA and salt porogen particles of comparable size exhibited the best combination of compressive strength (4–6MPa) and permeability (1.3–1.6×10−10m2) falling within the range of trabecular bone.

β-TCP granules mixed with reticulated hyaluronic acid induce an increase in bone apposition

β beta-tricalcium phosphate (β-TCP) granules are suitable for repair of bone defects. They have an osteoconductive effect shortly after implantation. However, dry granules are difficult to handle in the surgical room because of low weight and lack of cohesion. Incorporation of granules in a hydrogel could be a satisfactory solution. We have investigated the use of hyaluronic acid (HyA) as an aqueous binder of the granules. β-TCP granules were prepared by the polyurethane foam technology. Commercially available linear (LHya) and reticulated hyaluronic acid (RHyA) in aqueous solution were used to prepare a pasty mixture that can be handled more easily than granules alone. Thirteen New Zealand White rabbits (3.5–3.75 kg) were used; a 4 mm hole was drilled in each femoral condyle. After flushing, holes were filled with either LHyA, RHyA, dry β-TCP granules alone, β-TCP granules + LHyA and β-TCP granules + RHyA. Rabbits were allowed to heal for one month, sacrificed and femurs were harvested and analysed by microCT and histomorphometry. The net amount of newly formed bone was derived from measurements done after thresholding the microCT images for the material and for the material+bone. LHyA and RHyA did not result in healing of the grafted area. LHyA was rapidly eluted from the grafted zone but allowed deposition of more granules, although the amount of formed bone was not significantly higher than with β-TCP granules alone. RHyA permitted the deposition of more granules which induced significantly more bone trabeculae without inducing an inflammatory reaction. RHyA appears to be a good vehicle to implant granules of β-TCP, since HyA does not interfere with bone remodeling.

Evaluation of microstructure effect of the porous spherical β-tricalcium phosphate granules on cellular responses

We have developed spherical β-tricalcium phosphate (β-TCP) granules with outer pores and internal micro-channels for the use of filling bone voids. In this study, we describe the cellular behaviors associated with the variations in granule structure. By utilizing the biodegradability properties of β-TCP, we documented four different modifications of the internal structures and the outer pores, which were based on β-TCP concentration (between 0.25 and 0.67g/mL). Pore size, specific surface area and compressive strength of the granules were also evaluated. These results were then compared with the biodegradability of β-TCP using phosphate buffered saline (PBS). The significant reduction in the mass of the granules was demonstrated from the lowest β-TCP concentration group at 7 days. To ascertain the interactions between biodegradability and cellular behaviors, proliferation and osteogenic differentiation of preosteoblasts were evaluated by 3D culture configuration. A significant difference in cell proliferation was demonstrated between the highest and the lowest β-TCP concentration group at day 1 (P<0.036), and steady increment was observed in all groups thereafter. The alkaline phosphatase (ALP) activity, which is known as the early stage of osteogenic differentiation marker, showed the typical increase during cultivation. However, the specific β-TCP concentration (0.33–0.50g/mL) showed remarkable activity compared to the lowest and highest β-TCP concentration groups at day 21. Based on these findings, we posit that the porous spherical β-TCP granules using the β-TCP concentration at 0.33–0.50g/mL are of clinical interest, especially for bone regeneration.

Effects of porous beta-tricalcium phosphate-based ceramics used as an E. coli-derived rhBMP-2 carrier for bone regeneration

Recombinant human bone morphogenetic protein-2 (rhBMP-2) requires carriers for clinical effectiveness. In this study, whether porous beta-tricalcium phosphate (β-TCP)-based ceramics are ideal carriers for rhBMP-2 was investigated. Hydroxyapatite (HA), β-TCP, TCP/HA (80%/20%), HA with rhBMP-2, TCP with rhBMP-2, and TCP/HA (80%/20%) with rhBMP-2 were manufactured by a sponge method with a pore size of 300μm or more and macro-porosity of 83%. The alkaline phosphatase (ALP) activity and ALP expression of the cells with 100% β-TCP granules were more increased than the those of cells with 100% HA and TCP/HA (80%/20%) at the baseline or when treated with 15ng/ml of rhBMP-2. In an SD rat calvarial defect model, new bone formation was evidently shown in the TCP 100%-rhBMP-2 and TCP/HA (80%/20%)-rhBMP-2 groups, showing that the most affected area was filled with newly-formed bone, that the percent bone volume and trabecular number were larger when compared to the groups without rhBMP-2 treatment at both 4 and 8weeks after surgery using micro-CT and histology. Porous TCP-based ceramic granules enhanced the osteoblastic differentiation in the hMSC system when treated with 15ng/ml of rhBMP-2 and accelerated bone-healing by trabecular number in a rat calvarial defect model. Thus, in this study it was proposed that TCP-based ceramics might be useful carriers of rhBMP-2.

Prefabrication of a Vascularized Bone Graft With Beta Tricalcium Phosphate Using an In Vivo Bioreactor

We aimed to introduce an in vivo bioreactor-vascular pedicle threaded through the central portion of a scaffold in which a vascularized bone graft was prefabricated using adenoviral human BMP-2 gene (AdBMP2)-modified bone marrow mesenchymal stem cells (BMSCs), beta tricalcium phosphate (β-TCP), a vessel bundle, and muscularis membrane(group A). As controls, Adβgal-BMSCs/β-TCP granules, vessel bundle, and the muscularis membrane (group B); BMSCs/β-TCP granules, vessel bundle, and muscularis membrane (group C); and β-TCP granules, vessel bundle, and muscularis membrane (group D) were prepared. Formation of bone tissue and a vascular network was assessed by microangiography and histological methods 4 weeks after prefabrication. New cartilage and bone tissue in the space between β-TCP granules (mainly endochondral bone) were confirmed by histology, and a de novo vascular network circulating from the vessel bundle through newly formed bone tissue was observed in group A. Formation of bone or cartilage was not observed in the control groups. We concluded that the in vivo bioreactor is a promising method for prefabrication of vascularized functional bone.

Massive bone reconstruction with heat-treated bone graft loaded autologous bone marrow-derived stromal cells and β-tricalcium phosphate composites in canine models

Bone marrow-derived stromal cells (BMSCs) contain mesenchymal stem cells that are capable of forming various mesenchymal tissues. We hypothesized that BMSCs and β-tricalcium phosphate (β-TCP) composites would promote the remodeling of large-sized autologous devitalized bone grafts; therefore, the aim of this study was to evaluate the effects of the composites on the remodeling of autologous devitalized bone grafts. Autologous BMSCs cultured in culture medium containing dexamethasone (10(-7) M) were loaded into porous β-TCP granules under low-pressure. Theses BMSC/TCP composites were put into the bone marrow cavity of autologous heat-treated bone (femoral diaphysis, 65-mm long, 100°C, 30 min) and put back to the harvest site. In the contralateral side, β-TCP without BMSC were used in the same manner as the opposite side as the control. Treatment with the BMSC/TCP composites resulted in a significant increase in thickness, bone mineral density, and matured bone volume of the cortical bone at the center of the graft compared to the control. Histological analysis showed matured regenerated bone in the BMSC loaded group. These results indicate that BMSC/TCP composites facilitated bone regeneration and maturation at the graft site of large-sized devitalized bone. This method could potentially be applied for clinical use in the reconstruction of large bone defects such as those associated with bone tumors.

Porosity of β-Tricalcium Phosphate Affects the Results of Lumbar Posterolateral Fusion

Clinical case-control and cross-sectional study. To determine the influence of different porosities of β-tricalcium phosphate (β-TCP) as a bone substitute combined with local autograft bone obtained from decompression for lumbar posterolateral fusion (PLF). Several reports have documented a high bone fusion rate using β-TCP as a bone substitute. β-TCP is increasingly used to supplement autograft in lumbar PLF, but the influence of different porosities of β-TCP for the lumbar PLF has not been reported. Sixty patients who were diagnosed with lumbar degenerative diseases and treated with 2-level noninstrumented lumbar PLF were divided into 2 groups. Thirty patients were treated with 75% porous β-TCP (β-TCP-75 group), and the others were treated with 60% porous β-TCP (β-TCP-60 group). The clinical and radiographic results of each patient were assessed at 2 years postoperatively. Both the groups showed a good improvement rate of the Japanese Orthopaedic Association score (JOA score) at 2 years postoperatively, but there were no significant differences between them. The β-TCP-75 group represented a bone fusion rate of 70.0% (64.7% in men, 76.9% in women) and the β-TCP-60 group was 93.3% (87.5% in men, 100.0% in women). The latter exhibited a significantly better bone fusion rate than the β-TCP-75 group (P<0.05). In lumbar PLF, 60% porous β-TCP granules achieved a higher bone fusion rate than 75% porous β-TCP granules.

Adipose Stem Cell Tissue–Engineered Construct Used to Treat Large Anterior Mandibular Defect: A Case Report and Review of the Clinical Application of Good Manufacturing Practice–Level Adipose Stem Cells for Bone Regeneration

Large mandibular resection defects historically have been treated using autogenous bone grafts and reconstruction plates. However, a major drawback of large autogenous bone grafts is donor-site morbidity. This report describes the replacement of a 10-cm anterior mandibular ameloblastoma resection defect, reproducing the original anatomy of the chin, using a tissue-engineered construct consisting of β-tricalcium phosphate (β-TCP) granules, recombinant human bone morphogenetic protein-2 (BMP-2), and Good Manufacturing Practice-level autologous adipose stem cells (ASCs). Unlike prior reports, 1-step in situ bone formation was used without the need for an ectopic bone-formation step. The reconstructed defect was rehabilitated with a dental implant-supported overdenture. An additive manufactured medical skull model was used preoperatively to guide the prebending of patient-specific hardware, including a reconstruction plate and titanium mesh. A subcutaneous adipose tissue sample was harvested from the anterior abdominal wall of the patient before resection and simultaneous reconstruction of the parasymphysis. ASCs were isolated and expanded ex vivo over the next 3 weeks. The cell surface marker expression profile of ASCs was similar to previously reported results and ASCs were analyzed for osteogenic differentiation potential in vitro. The expanded cells were seeded onto a scaffold consisting of β-TCP and BMP-2 and the cell viability was evaluated. The construct was implanted into the parasymphyseal defect. Ten months after reconstruction, dental implants were inserted into the grafted site, allowing harvesting of bone cores. Histologic examination and in vitro analysis of cell viability and cell surface markers were performed and prosthodontic rehabilitation was completed. ASCs in combination with β-TCP and BMP-2 offer a promising construct for the treatment of large, challenging mandibular defects without the need for ectopic bone formation and allowing rehabilitation with dental implants.

GMP-level adipose stem cells combined with computer-aided manufacturing to reconstruct mandibular ameloblastoma resection defects: Experience with three cases

Background:The current management of large mandibular resection defects involves harvesting of autogenous bone grafts and repeated bending of generic reconstruction plates. However, the major disadvantage of harvesting large autogenous bone grafts is donor site morbidity and the major drawback of repeated reconstruction plate bending is plate fracture and difficulty in reproducing complex facial contours. The aim of this study was to describe reconstruction of three mandibular ameloblastoma resection defects using tissue engineered constructs of beta-tricalcium phosphate (β-TCP) granules, recombinant human bone morphogenetic protein-2 (rhBMP-2), and Good Manufacturing Practice (GMP) level autologous adipose stem cells (ASCs) with progressively increasing usage of computer-aided manufacturing (CAM) technology.Materials and Methods:Patients’ three-dimensional (3D) images were used in three consecutive patients to plan and reverse-engineer patient-specific saw guides and reconstruction plates using computer-aided additive manufacturing. Adipose tissue was harvested from the anterior abdominal walls of three patients before resection. ASCs were expanded ex vivo over 3 weeks and seeded onto a β-TCP scaffold with rhBMP-2. Constructs were implanted into patient resection defects together with rapid prototyped reconstruction plates.Results:All three cases used one step in situ bone formation without the need for an ectopic bone formation step or vascularized flaps. In two of the three patients, dental implants were placed 10 and 14 months following reconstruction, allowing harvesting of bone cores from the regenerated mandibular defects. Histological examination and in vitro analysis of cell viability and cell surface markers were performed and prosthodontic rehabilitation was completed.Discussion:Constructs with ASCs, β-TCP scaffolds, and rhBMP-2 can be used to reconstruct a variety of large mandibular defects, together with rapid prototyped reconstruction hardware which supports placement of dental implants.

The use of Reamer Irrigator Aspirator (RIA) autograft harvest in the treatment of critical-sized iliac wing defects in sheep: Investigation of dexamethasone and beta-tricalcium phosphate augmentation

Bone grafts are commonly used for the treatment of segmental bone defects and fracture non-unions. Recently, osseous particles obtained during intermedullary canal reaming (using a Reamer-Irrigator-Aspirator (RIA) device) have been evaluated as graft material during in vitro and clinical studies. The aim of this study was to evaluate and quantify new bone formation after implantation of bone graft material obtained after reaming of the tibia in a bilateral critical-sized iliac wing defect in sheep and to investigate the effect of the augmentation of this graft. A reamer bone graft alone, or after short term incubation in a dexamethasone enriched solution, and a reamer graft collected using beta-tricalcium phosphate (β-TCP) granules in the filter of the RIA collection device were compared to autologous iliac wing graft. In addition, reamer graft was combined with the cellular fraction collected from the irrigation fluid with and without short-term incubation in a dexamethasone enriched solution. It was hypothesized that the amount of physical bone in the reamer bone graft groups would be higher than the amount in the autologous iliac wing graft group and that augmentation of a reamer bone graft would increase bone formation. Three months after implantation, the amount of new bone formation (as percentage of the total defect volume) in the defects was evaluated ex-vivo by means of micro-CT and histomorphometry. The mean amount of bone in the autologous iliac wing graft group was 17.7% and 16.8% for micro-CT and histomorphometry, respectively. The mean amount of bone in all reamer graft groups ranged between 20.4–29.2% (micro-CT) and 17.0–25.4% (histomorphometry). Reamer graft collected using β-TCP granules (29.2±1.7%) in the filter produced a significantly higher amount of bone in comparison to an autologous iliac wing graft evaluated by micro-CT. RIA bone grafts added a small increase in bone volume to the 3month graft volume in this preclinical sheep model. The current model does not support the use of short-term high concentration dexamethasone for augmentation of a graft volume. If avoidance of an iliac wing graft is desirable, or a reaming procedure is required, then a RIA graft or RIA graft plus β-TCP granules are as good as the current gold standard for this model.

Magnesium incorporation into β‐TCP reduced itsin vivoresorption by decreasing parathormone production

Beta-tricalcium phosphate (β-TCP), one of the most widely used bioresorbable materials for bone therapy, can be doped with magnesium ions, generating β-TCMP. The objectives of this work were to evaluate, on a murine dental alveolus grafting model, the biocompatibility of β-TCP and β-TMCP granules by histomorphometric analysis, as well as the impact on plasmatic levels of receptor activator of nuclear factor κB ligand (RANK-L), osteoprotegerin (OPG), osteocalcin, osteopontin, and parathormone (PTH) during bone repair, using Luminex multiplexing technology. After grafting for 42 days, β-TCP grafted group presented higher bioresorption and induced more newly formed bone than β-TCMP (p < 0.05). β-TCP grafting also induced higher plasmatic levels of RANK-L, compared to β-TCMP and control (blood clot) groups at 21st day (p < 0.05). PTH, which remained at low levels in control group, presented a time-dependent increase in grafted groups, attaining significantly higher levels with β-TCP by the 42nd day (p < 0.05). RANK-L/OPG ratio increased on β-TCP group and attained a peak on the 21st day. In conclusion, β-TCP granules were more bioresorbable and osteogenic than β-TCMP granules, and the resorption of both materials might have been affected by osteoclastogenesis modulated by changes in the plasmatic levels of PTH and RANK-L.

Use of an Injectable Complex of β-Tricalcium Phosphate Granules, Hyaluronate, and Fibroblast Growth Factor-2 on Repair of Unstable Intertrochanteric Fractures

We evaluated effects of an injectable complex of β-tricalcium phosphate (β-TCP) granules, hyaluronate, and recombinant human fibroblast growth factor-2 (rhFGF-2) on repair of unstable intertrochanteric fractures in elderly patients. Twenty-five patients (range, 76-91 years) having 31.A2 fractures (AO classification) were treated with injection of the complex followed by intramedullary nails. Bone regeneration and β-TCP resorption, unions of intertrochanteric fractures and displaced lesser trochanters to the shaft, and varus deformity of the femoral neck were assessed by X-ray and CT scans. Fracture union occurred in all cases and union of the displaced lesser trochanter to the shaft was obtained in 24 cases by 12 weeks. It is of interest that β-TCP granules were completely replaced by bone and marked new bone formation around the lesser trochanter was observed in all cases compared to cases not treated with the complex. This complex is a paste-like material that is easy to handle, and it may be of considerable use in treatment of both unstable intertrochanteric fractures and other cortical bone defects with minimal surgical invasion.

The Effect on Implant Fixation of Soaking Tricalcium Phosphate Granules in Bisphosphonate

The use of bone grafting is a well-established way to enhance initial implant fixation in situations with reduced bone stock. Ceramic bone substitutes are inferior alternatives to autogenous or allogeneic bone graft. Improvement of bone graft substitutes is needed. We investigated whether biomechanical implant fixation and osseointegration of experimental implant grafted with β-TCP granules (Conduit) could be improved by soaking the β-TCP granules in bisphosphonate (zoledronate). In 10 dogs, a pair of titanium coated implants surrounded by a 2.5 mm gap was inserted into the proximal part of each tibia. The gap was grafted with β-TCP granules either soaked with zoledronate or saline. At 12 weeks, the implants were evaluated with biomechanical push-out test and histomorphometrical analysis. We found that bisphosphonate increased one of the three biomechanical parameters, but found no difference in the amount of new bone or β-TCP granules between the two treatment groups. This study indicates that local treatment of β-TCP granules with zoledronate not only has the potential to increase implant fixation but also calls for further experimental research in order to optimize the dose of zoledronate.

Repair of segmental bone defects in rabbit tibia promoted by a complex of β-tricalcium phosphate and hepatocyte growth factor

BackgroundSegmental bone defect repair remains a clinical and scientific challenge with increasing interest focused on bone tissue engineering. Clinical studies are ongoing to address application of hepatocyte growth factor (HGF) for treatment of some diseases; however, the use of HGF in bone tissue engineering has not been addressed. This study was performed to evaluate the effect of HGF in a complex of β-tricalcium phosphate (β-TCP) and collagen in repairing segmental bone defects. MethodsSegmental bone defects 5mm long were created in the middle of the tibial shafts of rabbits. The defect was stabilized with external fixators and implanted with a complex of β-TCP granules and collagen, with or without 100μg recombinant human HGF. Biweekly, bone regeneration and β-TCP resorption were assessed radiographically and histologically. At 4 and 8weeks, bone regeneration was evaluated by use of micro-computed tomography and mechanical tests. ResultsCompared with the bone tissue treated with β-TCP and collagen, mineralization, angiogenesis, new bone formation, and absorption of β-TCP were promoted 4weeks postoperatively by treatment with HGF in the β-TCP and collagen group. These changes were associated with promoting biomechanical regeneration. By 8weeks, the formation of bone marrow in newly generated bone and absorption of the β-TCP granules were completed in a shorter period by combining HGF with β-TCP and collagen, compared with tissues without HGF. ConclusionsThe combined application of HGF in a β-TCP and collagen matrix promoted histological bone healing and augmented mechanical strength of the healing bone, particularly in the early stages. The combined use of HGF and β-TCP for treatment of bone defects made a substantial difference.

Enhanced bone regeneration by gelatin-β-tricalcium phosphate composites enabling controlled release of bFGF

The objective of this study was to investigate the feasibility of biodegradable gelatin-β-tricalcium phosphate (β-TCP) composites as a cell scaffold and controlled-release carrier of basic fibroblast growth factor (bFGF) suitable for inducing bone regeneration at a segmental bone defect. The composite of gelatin sponge and β-TCP granules had an interconnected pore structure with an average size of 340 µm. The composite provided the controlled release of bFGF over 2 weeks. Segmental, critical-sized, bone defects of 20 mm length were created in the ulnas of New Zealand white rabbits and the gelatin-β-TCP composites, with or without incorporated bFGF, were implanted into the defects. Bone regeneration and β-TCP resorption profiles were evaluated by microcomputed tomography scanner analysis and haematoxylin and eosin staining. The composites incorporating bFGF promoted significantly higher bone regeneration at the defect site as compared to the bFGF-free composites. The controlled release of biologically active bFGF from the composites may possibly be achieved through the biodegradation of the composites, resulting in the promotion of bone regeneration. We conclude that the biodegradable gelatin-β-TCP composite is a promising scaffold for bone regeneration that enables the controlled release of bFGF.

Apert syndrome mutant FGFR2 and its soluble form reciprocally alter osteogenesis of primary calvarial osteoblasts

Apert syndrome is characterized by craniosynostosis and syndactyly, and is predominantly caused by mutation of either S252W or P253W in the fibroblast growth factor receptor (FGFR) 2 gene. In this study, we characterized the effects of one of the mutations (S252W) using primary calvarial osteoblasts derived from transgenic mice, Ap-Tg and sAp-Tg, that expressed an Apert-type mutant FGFR2 (FGFR2IIIc-S252W; FGFR2IIIc-Ap), and the soluble form (extracellular domain only) of the mutant FGFR2 (sFGFR2IIIc-Ap), respectively. Compared to WT-derived osteoblasts, osteoblasts from Ap-Tg mouse showed a higher proliferative activity and enhanced differentiation, while those from sAp-Tg mouse exhibited reduced potential for proliferation and osteogenic differentiation. When transplanted with β-tricalcium phosphate (β-TCP) granules into immunodeficient mice, Ap-Tg-derived osteoblasts showed a higher bone forming capacity, whereas sAp-Tg-derived osteoblasts were completely deficient for this phenotype. Phosphorylation of extracellular signal-regulated kinase (ERK), MEK, PLCγ, and p38 was increased in Ap-Tg-derived osteoblasts, whereas phosphorylation of these signaling molecules was reduced in sAp-Tg-derived osteoblasts. Interestingly, when these experiments were carried out using osteoblasts from the mice generated by crossing Ap-Tg and sAp-Tg (Ap/sAp-Tg), which co-expressed FGFR2IIIc-Ap and sFGFR2IIIc-Ap, the results were comparable to those obtained from WT-derived osteoblasts. Taken together, these results indicate that osteoblasts expressing FGFR2IIIc-Ap proliferate and differentiate via highly activated MEK, ERK, and p38 pathways, while these pathways are suppressed in osteoblasts expressing sFGFR2IIIc-Ap. Our findings also suggest that altered FGFR2IIIc signaling in osteoblasts is mostly responsible for the phenotypes seen in Apert syndrome, therefore these osteoblast cell lines are useful tools for investigating the pathogenesis of Apert syndrome.

The controlled release of vancomycin in gelatin/β‐TCP composite scaffolds

Osteomyelitis remains a difficult infection to treat for orthopaedic surgeons regardless of the continuous advances in surgical techniques and antimicrobial agents. The controlled release of vancomycin from local delivery system is a promising method for eliminating infection. In this study, biodegradable gelatin sponge containing different contents of β-tricalcium phosphate ceramic (β-TCP) was prepared for the controlled-release of vancomycin. We aimed to confirm the composite scaffolds could be used as a vancomycin sustained-release system. Examinations of scanning electron microscopy, Fourier transform infrared spectroscopy, mechanical properties, and in vivo drug release were performed. The results showed that the composite scaffolds could achieve local therapeutic drug levels over an extended duration. Taking consideration of porosity, interconnection, mechanical properties, and controlled release performance, the composite gelatin scaffold containing 30% β-TCP granules may be a good candidate for the controlled release of vancomycin in the treatment of chronic osteomyelitis.

Development and evaluation of tetrapod-shaped granular artificial bones

We have developed a novel form of granular artificial bone “Tetrabones” with a homogeneous tetrapod shape and uniform size. Tetrabones are four armed structures that accumulate to form the intergranular pores that allow invasion of cells and blood vessels. In this study we evaluated the physicochemical characteristics of Tetrabones in vitro, and compared their biological and biomechanical properties in vivo to those of conventional β-tricalcium phosphate (β-TCP) granule artificial bone. Both the rupture strength and elastic modulus of Tetrabone particles were higher than those of β-TCP granules in vitro. The connectivity of intergranular pores 100, 300, and 400μm in size were higher in Tetrabones than in the β-TCP granules. Tetrabones showed similar osteoconductivity and biomechanical stiffness to β-TCP at 2months after implantation in an in vivo study of canine bone defects. These results suggest that Tetrabones may be a good bone graft material in bone reconstruction.

Cytocompatibility of Porous Biphasic Calcium Phosphate Granules With Human Mesenchymal Cells by a Multiparametric Assay

This work aims to evaluate the cytocompatibility of injectable and moldable restorative biomaterials based on granules of dense or porous biphasic calcium phosphates (BCPs) with human primary mesenchymal cells, in order to validate them as tools for stem cell-induced bone regeneration. Porous hydroxyapatite (HA) and HA/beta-tricalcium phosphate (β-TCP) (60:40) granules were obtained by the addition of wax spheres and pressing at 20 MPa, while dense materials were compacted by pressing at 100 MPa, followed by thermal treatment (1100°C), grinding, and sieving. Extracts were prepared by 24-h incubation of granules on culture media, with subsequent exposition of human primary mesenchymal cells. Three different cell viability parameters were evaluated on the same samples. Scanning electron microscopy analysis of the granules revealed distinct dense and porous surfaces. After cell exposition to extracts, no significant differences on mitochondrial activity (2,3-bis(2-methoxy-4-nitro-5-sulfophenly)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) or cell density (Crystal Violet Dye Elution) were observed among groups. However, Neutral Red assay revealed that dense materials extracts induced lower levels of total viable cells to porous HA/β-TCP (P < 0.01). Calcium ion content was also significantly lower on the extracts of dense samples. Porogenic treatments on BCP composites do not affect cytocompatibility, as measured by three different parameters, indicating that these ceramics are well suited for further studies on future bioengineering applications.