Beta-tricalcium Phosphate Research Articles

CO-ADMINISTRATION OF SYSTEMIC ZOLEDRONATE PROMOTES OSTEOGENESIS INDUCED BY A LOCAL CO-DELIVERY OF RECOMBINANT HUMAN BONE MORPHOGENETIC PROTEIN-2 AND β-TRICALCIUM PHOSPHATE IN THE BONE MARROW OF THE RABBIT FEMUR

Purpose: Bone morphogenetic proteins (BMPs) strongly induce osteogenesis. However, BMPs also directly or indirectly stimulate catabolic osteoclast activity, leading to strong bone resorption, especially in the bone marrow. The aim of this study was to investigate whether the combination of a local recombinant human BMP-2 (rh-BMP-2)/beta-tricalcium phosphate ([Formula: see text]-TCP) composite with systemically administrated bisphosphonate, zoledronate (ZOL) could promote osteogenesis in a rabbit model. Methods: [Formula: see text]-TCP columns, with or without rh-BMP-2 (30 [Formula: see text]g/column), were implanted into the left femur canal of 20 rabbits. The animals were injected with 0.4[Formula: see text]mg of ZOL or saline 1 week after implantation. The implants were evaluated by micro-computed tomography ([Formula: see text]-CT) and histology 6 weeks after implantation. Results: [Formula: see text]-CT data revealed that the bone volume/tissue volume ratio of bone nodules inside [Formula: see text]-TCP columns in combination with rh-BMP-2 and ZOL was significantly higher than that of [Formula: see text]-TCP columns treated with rh-BMP-2, ZOL, or neither. Histological evaluation also revealed that significantly more new bone formed inside [Formula: see text]-TCP columns treated with rh-BMP-2 and ZOL than inside [Formula: see text]-TCP columns treated with rh-BMP-2, ZOL, or neither. Conclusion: This combination therapy contributed to the maintenance of the newly formed BMP-2-induced bone structure in the bone marrow.

Evaluation of europium-doped HA/β-TCP ratio fluorescence in biphasic calcium phosphate nanocomposites controlled by the pH value during the synthesis

Europium-doped hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP) and biphasic phosphate nanopowders were synthesized by co-precipitation method and their crystal structures and fluorescence properties were investigated depending on the pH of the starting solution. In the range of pH 6–10, HA and β-TCP phases coexist. The β-TCP proportion increased as the pH of the solution decreased, while HA yields decreased. At pH below 6, monophasic β-TCP powder was obtained after thermal treatment. In particular, HA and β-TCP can be used as luminescent materials when activated by Eu3+ ions in substitution of Ca2+ ions. Herein, the Eu3+ ions doped HA and β-TCP phase composition were analyzed in order to investigate the fluorescence emission of the HA, β-TCP and biphasic compounds. Eu-doped HA exhibited a red-orange emission at 575nm with several minor peaks at 610–640nm, while Eu-doped β-TCP had an unexpected strong red emission at 610–620nm and a secondary band at 590–600nm. In fact, the Eu:β-TCP integrated emission area is almost 20-fold higher than Eu:HA for the same europium ion concentration. These results demonstrate the potential of Eu:β-TCP as biomarker for medical applications, as drug release and targeting based on their luminescent properties.

The Importance of Sufficient Graft Material in Achieving Foot or Ankle Fusion.

Nonunion, an important complication following foot and ankle arthrodesis, causes substantial morbidity and disability. In patients undergoing hindfoot and ankle arthrodesis, autogenous bone graft (autograft) or a suitable alternative is often used to promote osseous fusion across the joint. This study assessed the importance of adequate graft material in the fusion space to achieve joint fusion during ankle and hindfoot arthrodesis. This study used data from a previously published clinical trial of grafting material (recombinant human platelet-derived growth factor-BB with beta-tricalcium phosphate [rhPDGF-BB/β-TCP] or autograft) for healing in hindfoot and ankle arthrodesis to correlate the amount of graft fill at 9 weeks with ultimate healing. Patients who received supplemental graft material for ankle or hindfoot arthrodesis for end-stage ankle or hindfoot arthritis were stratified according to nonunion risk factors and surgical fusion site. Patients underwent arthrodesis using standard rigid internal fixation. Graft fill was defined as "adequate" if the material occupied ≥50% of the cross-sectional area of the fusion space on a computed tomography (CT) scan made at 9 weeks. Fusion was defined as osseous bridging of ≥50% of each articulation on a CT scan made at 24 weeks. Three hundred and seventy-nine patients with 573 joints (383 managed with rhPDGF-BB/β-TCP and 190 managed with autograft) that underwent arthrodesis had complete follow-up with 9-week and 24-week CT scans available. Overall, 472 (82%) of 573 joints had adequate graft fill; of those, 383 (81%) were successfully fused at 24 weeks compared with 21 (21%) of 101 joints without adequate graft fill (p < 0.0001). Absolute fusion rate differences (joints with adequate fill minus those without adequate fill) were consistent across joints (61% to 63%) and for graft materials. The overall odds ratio (OR) of successful fusion in joints with adequate graft fill compared with those without adequate graft fill was 16.4 (95% confidence interval, 9.6 to 27.9). This study demonstrates an association between the amount of graft material and successful hindfoot and ankle arthrodesis. Graft material filling of ≥50% of the fusion space at 9 weeks, regardless of type or origin, was associated with significantly higher fusion rates at 24 weeks. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

In Vitro Biocompatibility Assessment and In Vivo Behavior of a New Osteoconductive βTCP Bone Substitute

Beta-tricalcium phosphate (βTCP) granules (OsproLife) exhibit a pure crystalline phase and a rough microporous surface for promoting cell adhesion and microsized intragranule porosity for improving wettability and resorption necessary for bone regeneration. OsproLife is a fully resorbable, space-maintaining, and osteoconductive synthetic material for the filling of bone defects. To asses OsproLife properties, a similar synthetic biomaterial, already on the market, has been chosen as reference: Cerasorb has the same chemical composition, but different crystal structure, surface morphology, and granule size. The aim of this study is to compare the properties of OsproLife and Cerasorb. Chemical purity, composition and physical properties, in vitro cytotoxicity, and in vivo bone performance in a rabbit model were analyzed. βTCP OsproLife granules (test) were compared with Cerasorb (control). Histological and μCT analyses were performed at 6, 12, and 56 weeks after implantation. βTCP OsproLife and Cerasorb granules result to be both biocompatible and characterized by the same osteoconductivity and resorption rate. βTCP OsproLife granules are a promising bone substitute for dental and orthopedic applications.

Biocompatibility, resorption and biofunctionality of a new synthetic biodegradable membrane for guided bone regeneration

Membranes for guided bone regeneration (GBR) were prepared from the synthetic biodegradable polymer poly-D,L-lactic/glycolic acid (PLGA). This GBR membrane has a bi-layered structure with a dense film to prevent gingival fibroblast ingrowth and ensure mechanical function, and a micro-fibrous layer to support colonization by osteogenic cells and promote bone regeneration. Hydrolysis and biodegradation were both studied in vitro through soaking in phosphate buffered saline (PBS) and in vivo by implantation in the subcutis of rats for 4, 8, 16, 26, 48 and 52 weeks. Histology revealed an excellent colonization of the micro-fibrous layer by cells with a minimal inflammatory reaction during resorption. GBR using the synthetic PLGA membrane was evaluated on critical-size calvaria defects in rats for 4 and 8 weeks. Radiographs, micro-computed tomography and histology showed bone regeneration with the PLGA membrane, while the defects covered with a collagen membrane showed a limited amount of mineralized bone, similar to that of the defect left empty. The biofunctionality of the PLGA membranes was also compared to collagen membranes in mandible defects in rabbits, associated or not with beta-tricalcium phosphate granules. This study revealed that the bi-layered synthetic membrane made of PLGA was safer, more biocompatible, and had a greater controlled resorption rate and bone regeneration capacity than collagen membranes. This new PLGA membrane could be used in pre-implantology and peri-odontology surgery.

The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid)

Orthophosphates are bioactive crystals with similar structure, in terms of elemental composition and crystal nature, to human bone. In this work, biocomposite materials were prepared with poly(lactic acid) (PLA) as matrix, and beta-tricalcium phosphate (β-TCP) as osteoconductive filler by extrusion-compounding followed by conventional injection molding. The β-TCP load content was varied in the 10–40 wt% range and the influence of the β-TCP load on mechanical performance of PLA/β-TCP composites was evaluated. Mechanical properties of composites were obtained by standardized tensile, flexural, impact, and hardness tests. Thermal analysis of composites was carried out by means of differential scanning calorimetry; degradation at high temperatures was studied by thermogravimetric analysis; and the effect of the β-TCP load on dynamical response of composites was studied by mechanical thermal analysis in torsion mode. The best-balanced properties were obtained for PLA composites containing 30 wt% β-TCP with a remarkable increase in the Young’s modulus. These materials offer interesting properties to be used as base materials for medical applications such as interference screws due to high stiffness and mechanical resistance.

Cytokine Production by SaOS-2 and Mononuclear Cells Cultivated on Alginate Titanium Surfaces Doped with Calcium Phosphates

The immune response of the host tissue to the tested biomaterial predicts the success of implantation therapy success. Connective tissue cell line SaOS-2 and mononuclear cells isolated from “buffy coat” testing determines the overall immune response to the implanted biomaterial. Alginate hydrogel coatings doped with inorganic hydroxyapatite (Ti/Alg/HAP) or beta-tricalcium phosphate (Ti/Alg/TCP) nanoparticles on Titanium grade 2 were prepared. Both cell types mentioned above were used to evaluate the cytokine production when cultivated on the proposed coatings. The pristine Ti and alginate (Alg) served as control surfaces. Cytokine production was assessed by the multiplex proteomic analysis of 40 cytokines. Mononuclear cell testing revealed differences between control (Ti, Ti/Alg) and alginate hydrogel surfaces doped with calcium phosphates (Ti/Alg/TCP and Ti/Alg/HAP). Cytokine production declines from the highest found on the mononuclear cells treated by Ti/Alg/HAP through control Ti and Ti/Alg/TCP surface to control Ti/Alg surface with lowest cytokine production. Mononuclear cells produced mostly IL-6 and IL-8. No significant differences between Ti/Alg/TCP and Ti/Alg/HAP were found in cytokines produced by cell line SaOS-2. Cell line SaOS-2 produced a wide spectrum of cytokines, but the production was low, with the exception of TIMP-2. The comparison of cytokines produced by cell line SaOS-2 and mononuclear cells from “buffy coat” indicated that mononuclear cells have much better potential to show differences between the monitored materials. The immune response of mononuclear cells showed differences between tested materials, whereas SaOS-2 cells were not sufficiently sensitive. Therefore, besides SaOS-2 cells, mononuclear cells should also be considered for in vitro evaluation of overall immune response induced by the presence of an implant. Keywords: Cytokine production, SaOS-2 cells, peripheral blood mononuclear cells, alginate titanium surfaces, calcium phosphates, nanoparticles.

Preservación de alvéolos mediante fosfato tricálcico beta, con y sin membrana

The present study evaluated the results of the post-extraction socket preservation technique using Beta-Tricalcium Phosphate with and without the use of a non-resorbable membrane. A total of 18 teeth with indication of extraction and socket preservation were selected, with 10 alveoli being treated with Beta-Tricalcium Phosphate combined with a non-resorbable membrane, and the other 8 with Beta-Tricalcium Phosphate only. The width and height of each socket was evaluated using computed tomography, prior to the extraction, and 6 months after the surgery. At the time of performing the surgical technique for installing the implants, histological specimens were taken from the implant site in order to study the graft site 6 months after the dental extraction surgery and alveoli preservation.The use of Beta-Tricalcium Phosphate, whether a membrane is used or not, maintained the alveolar height 6 months after the extraction, while the width of the alveolus only remained in the group without membrane. Histological results showed varying amounts of bone regeneration.

Modulation of release kinetics by plasma polymerization of ampicillin-loaded β-TCP ceramics

Beta-tricalcium phosphate (β-TCP) bioceramics are employed in bone repair surgery. Their local implantation in bone defects puts them in the limelight as potential materials for local drug delivery. However, obtaining suitable release patterns fitting the required therapeutics is a challenge. Here, plasma polymerization of ampicillin-loaded β-TCP is studied for the design of a novel antibiotic delivery system. Polyethylene glycol-like (PEG-like) coating of β-TCP by low pressure plasma polymerization was performed using diglyme as precursor, and nanometric PEG-like layers were obtained by simple and double plasma polymerization processes. A significant increase in hydrophobicity, and the presence of plasma polymer was visible on the surface by SEM and quantified by XPS. As a main consequence of the plasma polymerisation, the release kinetics were successfully modified, avoiding burst release, and slowing down the initial rate of release leading to a 4.5 h delay in reaching the same antibiotic release percentage, whilst conservation of the activity of the antibiotic was simultaneously maintained. Thus, plasma polymerisation on the surface of bioceramics may be a good strategy to design controlled drug delivery matrices for local bone therapies.

Development of PLGA-coated β-TCP scaffolds containing VEGF for bone tissue engineering

Bone tissue engineering is sought to apply strategies for bone defects healing without limitations and short-comings of using either bone autografts or allografts and xenografts. The aim of this study was to fabricate a thin layer poly(lactic-co-glycolic) acid (PLGA) coated beta-tricalcium phosphate (β-TCP) scaffold with sustained release of vascular endothelial growth factor (VEGF). PLGA coating increased compressive strength of the β-TCP scaffolds significantly. For in vitro evaluations, canine mesenchymal stem cells (cMSCs) and canine endothelial progenitor cells (cEPCs) were isolated and characterized. Cell proliferation and attachment were demonstrated and the rate of cells proliferation on the VEGF released scaffold was significantly more than compared to the scaffolds with no VEGF loading. A significant increase in expression of COL1 and RUNX2 was indicated in the scaffolds loaded with VEGF and MSCs compared to the other groups. Consequently, PLGA coated β-TCP scaffold with sustained and localized release of VEGF showed favourable results for bone regeneration in vitro, and this scaffold has the potential to use as a drug delivery device in the future.

Collagen/chitosan porous bone tissue engineering composite scaffold incorporated with Ginseng compound K

In this study, suitable scaffold materials for bone tissue engineering were successfully prepared using fish scale collagen, hydroxyapatite, chitosan, and beta-tricalcium phosphate. Porous composite scaffolds were prepared by freeze drying method. The Korean traditional medicinal ginseng compound K, a therapeutic agent for the treatment of osteoporosis that reduces inflammation and enhances production of bone morphogenetic protein-2, was incorporated into the composite scaffold. The scaffold was characterized for pore size, swelling, density, degradation, mineralization, cell viability and attachment, and its morphological features were examined using scanning electron microscopy. This characterization and in vitro analysis showed that the prepared scaffold was biocompatible and supported the growth of MG-63 cells, and therefore has potential as an alternative approach for bone regeneration.

Bioinspired Collagen-Apatite Nanocomposites for Bone Regeneration

IntroductionNatural bone has a complex hierarchical nanostructure composed of well-organized collagen fibrils embedded with apatite crystallites. Bone tissue engineering requires scaffolds with structural properties and functionality similar to the natural bone. Inspired by bone, a collagen-apatite (Col-Ap) nanocomposite was fabricated with bonelike subfibrillar nanostructures using a modified bottom-up biomimetic approach and has a potential role in the healing of large bone defects in unresolved apical periodontitis. MethodsThe bone regeneration potential of the Col-Ap nanocomposite was investigated by comparing it with inorganic beta-tricalcium phosphate and organic pure collagen using a critical-sized rodent mandibular defect model. Micro–computed tomographic imaging and histologic staining were used to evaluate new bone formation in vivo. ResultsWhen compared with the beta-tricalcium phosphate and collagen scaffolds, the Col-Ap nanocomposite scaffold exhibited superior regeneration properties characterized by profuse deposition of new bony structures and vascularization at the defect center. Immunohistochemistry showed that the transcription factor osterix and vascular endothelial growth factor receptor 1 were highly expressed in the Col-Ap group. The results indicate that the Col-Ap nanocomposite activates more bone-forming cells and stimulates more vascular tissue ingrowth. Furthermore, the Col-Ap nanocomposite induces extracellular matrix secretion and mineralization of rat bone marrow stem cells. The increased expression of transforming growth factor beta 1 may contribute to the formation of a mineralized extracellular matrix. ConclusionsThe present study lays the foundation for the development of Col-Ap nanocomposite–based bone grafts for future clinical applications in bone regeneration of large periapical lesions after apical curettage or apicoectomy.

Fabrication of silver/beta‐tricalcium phosphate particle by a simple liquid chemical reduction method

Using beta-tricalcium phosphate (beta-TCP), silver nitrate and glucose as the carrier, silver resource and reducing agent, silver/beta-TCP particle was successfully fabricated by a novel liquid chemical reduction method to overcome the infection problem of beta-TCP. The X-ray diffraction pattern of the as-obtained sample confirmed the existence of metallic silver in the particle. The addition of silver nanoparticle affected the thermal stability of beta-TCP and prevented the transformation from beta-TCP to alpha-TCP. Transmission electron microscopy images and the corresponding calculation result proved the mean size and size distribution of silver nanoparticles in the silver/beta-TCP particle could be controlled by varying the molar ratio between beta-TCP and silver nitrate. Moreover, the mean size and size distribution of silver nanoparticles also could be changed by using different stabilisers. The prepared silver/beta-TCP particle is a potential biomaterial to replace pure beta-TCP particle and utilise for coating material and other applications.

Mandibular Jaw Bone Regeneration Using Human Dental Cell-Seeded Tyrosine-Derived Polycarbonate Scaffolds.

Here we present a new model for alveolar jaw bone regeneration, which uses human dental pulp cells (hDPCs) combined with tyrosine-derived polycarbonate polymer scaffolds [E1001(1k)] containing beta-tricalcium phosphate (β-TCP) [E1001(1k)/β-TCP]. E1001(1k)/β-TCP scaffolds (5 mm diameter × 1 mm thickness) were fabricated to fit a 5 mm rat mandibular ramus critical bone defect. Five experimental groups were examined in this study: (1) E1001(1k)/β-TCP scaffolds seeded with a high density of hDPCs, 5.0 × 10(5) hDPCs/scaffold (CH); (2) E1001(1k)/β-TCP scaffolds seeded with a lower density of hDPCs, 2.5 × 10(5) hDPCs/scaffold (CL); (3) acellular E1001(1k)/β-TCP scaffolds (SA); (4) acellular E1001(1k)/β-TCP scaffolds supplemented with 4 μg recombinant human bone morphogenetic protein-2 (BMP); and (5) empty defects (EDs). Replicate hDPC-seeded and acellular E1001(1k)/β-TCP scaffolds were cultured in vitro in osteogenic media for 1 week before implantation for 3 and 6 weeks. Live microcomputed tomography (μCT) imaging at 3 and 6 weeks postimplantation revealed robust bone regeneration in the BMP implant group. CH and CL groups exhibited similar uniformly distributed mineralized tissue coverage throughout the defects, but less than the BMP implants. In contrast, SA-treated defects exhibited sparse areas of mineralized tissue regeneration. The ED group exhibited slightly reduced defect size. Histological analyses revealed no indication of an immune response. In addition, robust expression of dentin and bone differentiation marker expression was observed in hDPC-seeded scaffolds, whereas, in contrast, BMP and SA implants exhibited only bone and not dentin differentiation marker expression. hDPCs were detected in 3-week but not in 6-week hDPC-seeded scaffold groups, indicating their survival for at least 3 weeks. Together, these results show that hDPC-seeded E1001(1k)/β-TCP scaffolds support the rapid regeneration of osteo-dentin-like mineralized jaw tissue, suggesting a promising new therapy for alveolar jaw bone repair and regeneration.

Influence of different calcium phosphate ceramics on growth and differentiation of cells in osteoblast-endothelial co-cultures

Strategies for improvement of angiogenesis and vasculogenesis using different cells and materials are paramount aims in the field of bone tissue engineering. Thereby, the interaction between different cell types and scaffold materials is crucial for growth, differentiation, and long-term outcomes of tissue-engineered constructs. In this study, we evaluated the interaction of osteoblasts and endothelial cells in three-dimensional tissue-engineered constructs using beta tricalciumphosphate (β-TCP, [ß-Ca3 (PO4 )2 ]) and calcium-deficient hydroxyapatite (CDHA, [Ca9 (PO4 )5 (HPO4 )OH]) ceramics as scaffolds. We focused on initial cell organization, cell proliferation, and differential expression of osteoblastic and endothelial markers employing monocultures and co-cultures of endothelial cells of two different origins [human umbilical vein endothelial cells (HUVECs) and outgrowth endothelial cells (OECs)] with primary human osteoblasts (hOBs). Despite different chemical and physical characteristics of CDHA and β-TCP ceramics, similar patterns in cell growth, differentiation, and gene expression were detected in tissue-engineered constructs consisting of hOB, HUVEC, and HUVEC/hOB-co-cultures. Under dynamic cell culture conditions we found proliferation of these cells with stable endothelial and osteoblastic differentiation patterns. Both material types are highly biocompatible with these cells providing a promising perspective for the future research. In this study, both materials did not support growth and differentiation of OEC. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1950-1962, 2017.

Autogenous Bone Marrow Aspirate Coated Synthetic Hydroxyapatite for Reconstruction of Maxillo-Mandibular Osseous Defects: A Prospective Study.

This prospective study was conducted to evaluate the bone regeneration capacity of synthetic hydroxyapatite mixed with autogenous bone marrow aspirate when used as a bone graft substitute in maxillo-mandibular osseous defects. This study included nine patients with histopathalogically proven benign osteolytic lesions in maxilla and mandible that were treated with enucleation or marginal resection followed by bone marrow aspirate coated synthetic biphasic hydroxyapatite (hydroxyapatite and beta tricalcium phosphate) graft placement. Incorporation of graft was assessed based on Irwin's radiologic staging. The efficacy of graft to form new bone was radiologically evaluated by observing the sequential changes of density at grafted site using gray scale level histogram which was processed in adobe photoshop 7.0 elements. Clinical assessment of recipient and donor sites was done. Based on Irwin's radiologic staging, at 6month follow up period, obvious incorporation of graft with new bone was observed. Sequential changes in bone density measured by gray scale histogram revealed initial resorption followed by replacement of BMA coated hydroxyapatite with new bone formation. None of the patients eventually had complications like infection, wound dehiscence, graft loss at recipient sites at 6months follow up period. Autogenous bone marrow aspirate in combination with synthetic hydroxyapatite is an effective option for accelerating bone regeneration in small to moderate sized jaw bone defects. This mixture provides all the three critical elements needed for bone regeneration (osteogenesis, osteoinduction and osteoconduction) with an added advantage of obviating donor site morbidity.

Purmorphamine increased adhesion, proliferation and expression of osteoblast phenotype markers of human dental pulp stem cells cultured on beta-tricalcium phosphate.

Growth factors play a significant role in cell proliferation and differentiation during different stages of the bone repair. However, several limitations have been brought researchers attention to an osteoinductive small molecule including Purmorphamine. In this study, we aimed to evaluate the effect of Purmorphamine on adhesion, proliferation and differentiation of human dental pulp stem cells (hDPSCs) seaded on beta-tricalcium phosphate (β-TCP) granules. hDPSCs were established from extracted wisdom teeth of healthy volenteers. Cells at passage 3 were seeded on β-TCP in the presence or absence of Purmorphamine. Cell adhesion and proliferation were assessed using scanning electeron microscopy (SEM) and DNA counting assay, respectively, after 1, 3 and 5days. Then, hDPSCs seeded on β-TCP were subjected to osteogenic medium with or without Purmorphamine. After 7 and 14days osteogenic diffrentiation capability of hDPSCs were determined using real-time RT-PCR and alkaline phosphatase (ALP) activity assay. The significant increase in amount of DNA was observed at day 3 and 5 in the presence of Purmorphamine. SEM imaging also was confirmed the DNA counting assay; in all given time points, hDPSC attachment and growth was significantly higher in the presence of Purmorphamine. ALP activity was increased by Purmorphamine at both 7 and 14days of induction. Purmorphamine showed to effect on osteopontin expression at earlier stage of osteogenic differentiation, whereas for osteocalcin expression, this effect was more evident at later stage of differentiation. Purmorphamine had a promotive effect on adhesion, proliferation and osteogenic differentiation of hDPSCs cultured on β-TCP. The outcome of the current study would help in development of in vitro culture conditions for better osteogenic differentiation of hDPSCs prior to transplantation.

Characterization of Three-Dimensional Printed Composite Scaffolds Prepared with Different Fabrication Methods

Abstract An optimal method for composites preparation as an input to rapid prototyping fabrication of scaffolds with potential application in osteochondral tissue engineering is still needed. Scaffolds in tissue engineering applications play a role of constructs providing appropriate mechanical support with defined porosity to assist regeneration of tissue. The aim of the presented study was to analyze the influence of composite fabrication methods on scaffolds mechanical properties. The evaluation was performed on polycaprolactone (PCL) with 5 wt% beta-tricalcium phosphate (TCP) scaffolds fabricated using fused deposition modeling (FDM). Three different methods of PCL-TCP composite preparation: solution casting, particles milling, extrusion and injection were used to provide material for scaffold fabrication. The obtained scaffolds were investigated by means of scanning electron microscope, x-ray micro computed tomography, thermal gravimetric analysis and static material testing machine. All of the scaffolds had the same geometry (cylinder, 4×6 mm) and fiber orientation (0/60/120°). There were some differences in the TCP distribution and formation of the ceramic agglomerates in the scaffolds. They depended on fabrication method. The use of composites prepared by solution casting method resulted in scaffolds with the best combination of compressive strength (5.7±0.2 MPa) and porosity (48.5±2.7 %), both within the range of trabecular bone.

Polyethylene glycol-assisted preparation of beta-tricalcium phosphate by direct precipitation method

Beta-tricalcium phosphate (β-TCP) was obtained by calcining the precursor calcium deficient hydroxylapatite (CDHA). The CDHA was synthesized via direct precipitation method using calcium hrdroxide and phosphoric acid assisted with polyethylene glycol ((CH2CH2OH)n; PEG). The X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetry-differential scanning calorimetry (TG/DSC), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to investigate the phase composition and morphology of obtained powders. The results showed that the PEG played an important role on improving the purity and dispersity of β-TCP. The size of β-TCP particles with nearly spherical shape was in the range of 0.2–0.5μm when the CH2CH2O/H+ molar ratio was equal to 1:17. According to the TG/DSC, the formation of the β-TCP from the CDHA phase was about 770°C. Meanwhile, a plausible synthetic mechanism has been proposed.

Sintering of Beta-Tricalcium Phosphate Scaffold Using Polyurethane Template

Porous beta-tricalcium phosphate (β-TCP) bioceramic has been reported as synthetic graft for cancellous bone substitute due to its biocompatibility and biodegradability properties. A highly porous and interconnected porosity architecture of bone scaffold facilitates attachment and in-growth of new bone tissue. β-TCP foam, a porous 3-dimensional scaffold was fabricated by employing polymeric foam replica method in this study. Polyurethane (PU) foam was used as the sacrificial template, in which β-TCP slurry with powder to water ratio of 10g:10ml was coated on PU template and sintered to 1100, 1200, 1250 and 1300°C. Observation on architecture of the foam, macrostructure and microstructure of pores and surface topography of porous strut showed that sintering at 1250°C produced sufficient densification of grains and micropores on the β-TCP strut. The β-TCP foams exhibited high porosity (92 – 97%) and large pore size (200 - 750um) that resemble cancellous bone structure.