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1.
Angiogenesis of tissue-engineered bone remains a limited factor for the engineering of larger bone tissue constructs. Attempts to stimulate angiogenesis, using recombinant protein or gene transfer of angiogenic growth factors, have been proposed; however, these approaches have been associated with some problems regarding such as complex technique, expensive prices as well as safety problems and short half-life of angiogenic growth factors. This study was performed to determine the ability of strontium-doped calcium polyphosphate (SCPP) to induce angiogenesis via researching its effect on the mRNA expressions and protein secretion of VEGF and bFGF in/from cultured osteoblasts (ROS17/2.8 cells). We cultured osteoblasts with SCPP scaffolds containing various doses of strontium as well as calcium polyphosphate (CPP) scaffold. Through the detection of MTT and SEM, we have found that SCPP could promote cell proliferation and maintain their morphology. The results of RT–PCR and ELISA indicated that, compared with those in CPP group, the mRNA expression as well as protein levels of VEGF and bFGF in/from cultured osteoblasts were dose-dependent increasing in response to increasing strontium before reaching the peak in SCPP groups, and 8% SCPP showed the optimal promoting role. Therefore, SCPP containing proper dose of strontium could be served as a potential biomaterial with stimulating angiogenesis in bone tissue engineering and bone repair.  相似文献   

2.
This work describes the preparation and characterization of porous 3D-scaffolds based on chitosan (CHI), chitosan/silk fibroin (CHI/SF) and chitosan/silk fibroin/hydroxyapatite (CHI/SF/HA) by freeze drying. The biomaterials were characterized by X-ray diffraction, attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and energy dispersive spectroscopy. In addition, studies of porosity, pore size, contact angle and biological response of SaOs-2osteoblastic cells were performed. The CHI scaffolds have a porosity of 94.2 ± 0.9%, which is statistically higher than the one presented by CHI/SF/HA scaffolds, 89.7 ± 2.6%. Although all scaffolds were able to promote adhesion, growth and maintenance of osteogenic differentiation of SaOs-2 cells, the new 3D-scaffold based on CHI/SF/HA showed a significantly higher cell growth at 7 days and 21 days and the level of alkaline phosphatase at 14 and 21 days was statistically superior compared to other tested materials.  相似文献   

3.
Scaffolds fabricated by current methods often lack the combination of high strength and high porosity for skeletal substitution of load-bearing bones. In this work, freeze extrusion fabrication (FEF), a solid freeform fabrication technique, was investigated for the creation of porous and strong bioactive glass (13–93) scaffolds for potential applications in the repair of loaded bone. The process parameters for forming three-dimensional (3D) scaffolds with a pre-designed, grid-like microstructure by FEF were determined. Following thermal treatment of the as-formed constructs at temperatures up to 700 °C, scaffolds consisting of dense glass struts and interconnecting pores (porosity  50%; pore width  300 μm) were obtained. These scaffolds showed an elastic mechanical response in compression, with a compressive strength of 140 ± 70 MPa and an elastic modulus of 5.5 ± 0.5 GPa, comparable to the values for human cortical bone. The scaffolds supported the proliferation of osteogenic cells in vitro, showing their biocompatibility. These results indicate that 13–93 bioactive glass scaffolds created by the FEF method could have potential application in the repair and regeneration of load-bearing bones.  相似文献   

4.
The key factor for regenerating large segmental bone defects through bone tissue engineering is angiogenesis in scaffolds. Attempts to overcome this problem, it is a good strategy to develop a new scaffold with bioactivity to induce angiogenesis in bone tissue engineering. In our previous research, the ability of strontium-doped calcium polyphosphate (SCPP) to stimulate the release of angiogenic growth factors from cultured osteoblasts was studied. This study was performed to determine the ability of SCPP to induce angiogenesis within in vitro co-culture model of human umbilical vein endothelial cells (HUVEC) and osteoblasts co-cultured. The bioactivity of developed scaffolds to induce angiogenesis in vivo was also researched in this paper. Co-cultured model has been developed in vitro and then cultured with SCPP scaffold as well as calcium polyphosphate (CPP) scaffold and hydroxylapatite (HA) scaffold. The results showed that the optimal ratio of HUVEC and osteoblasts co-cultured model for in vitro angiogenesis was 5:1. The model could maintain for more than 35 days when cultured with the scaffold and show the best activity at 21st day. Compared with those in CPP and HA scaffold, the formation of tube-like structure and the expression of platelet endothelial cell adhesion molecule in co-cultured model is better in SCPP scaffold. The in vivo immunohistochemistry staining for VEGF also showed that SCPP had a potential to promote the formation of angiogenesis and the regeneration of bone. SCPP scaffold could be served as a potential biomaterial with stimulating angiogenesis in bone tissue engineering and bone repair.  相似文献   

5.
According to previous reports, a large volume of bone marrow cells (1 × 107 cells/ml) is required for bone regeneration in the pores of a scaffold in vivo. We theorized that immersion of a porous hydroxyapatite (HA) scaffold in hyaluronic acid solution would facilitate bone formation in the scaffold at 1 × 106 cells/ml density of bone marrow cells. The cells were respectively seeded into pores of the cylindrical HA scaffolds with a hollow center after immersion in hyaluronic acid solution or in culture medium. The scaffolds were implanted in the dorsal subcutis of rats for 4 weeks. Thereafter, serially sectioned paraffin specimens were made and observed histologically. Bone formation was observed in many pores of HA scaffold by immersion in hyaluronic acid solution. However, there were no or less pores with new bone formation in the scaffold by immersion in culture medium. The cells were cultured with and without hyaluronic acid in vitro. There was no significant difference in bone formation in vitro with and without hyaluronic acid. The results of this study suggest that hyaluronic acid binds to the cells on the wall of three-dimensional structure and effectively promotes new bone formation.  相似文献   

6.
The surface of porous three-dimensional (3D) calcium polyphosphate (CPP) scaffold was modified by treatment of quenching-after-sintering in the fabrication process. Scanning electron microscopic examination and degradation tests confirmed a new type of surface modification. A rotary-shaking culture was compared to that of a stationary culture and the results showed that rotary shaking led to enhanced extracellular matrices (ECM) secretion of both proteoglycans and collagen. Rotary-shaking cultured results showed that the quenching-treated CPP scaffold produced a better cartilage tissue, with both proteoglycans and collagen secretions enhanced, than the air-cooled-after-sintering scaffolds. Moreover, β-CPP scaffolds were better for the ECM secretion of both proteoglycans and collagen than the β-CPP + γ-CPP multiphase scaffold. However, the multiphase scaffold led to higher growth rate than that of β-CPP scaffold; the quenching-after-sintering treatment reversed this. In addition, the ECM secretions of both proteoglycans and collagen in the quenching-treated β-CPP scaffold were higher than those in the air-cooled one. Thus, the novel treatment of quenching-after-sintering has shown merits to the porous 3D CPP scaffolds for articular cartilage tissue engineering.  相似文献   

7.
The aims of this study were to fabricate biopolymer and biocomposite scaffolds for bone tissue engineering by an air pressure-aided deposition system and to carry out osteoblast cell culture tests to validate the biocompatibility of fabricated scaffolds. A mPEG–PCL–mPEG triblock copolymer was synthesized as a biopolymer material. Biocomposite material was composed of synthesized biopolymer and hydroxyapatite (HA) with a mean diameter of 100 μm. The weight ratio of HA added to the synthesized biopolymer was 0.1, 0.25, 0.5 and 1. The experimental results show that the maximum average compressive strength of biocomposite scaffolds, made of weight ratio 0.5, with mean pore size of 410 μm (porosity 81%) is 18.38 MPa which is two times stronger than that of biopolymer scaffolds. Osteoblast cells, MC3T3-E1, were seeded on both types of fabricated scaffolds to validate the biocompatibility using methylthianzol tetrazolium (MTT) assay and cell morphology observation. After 28 days of in vitro culturing, the seeded osteoblasts were well distributed in the interior of both types of scaffolds. Furthermore, MTT experimental results show that the cell viability of the biocomposite scaffold is higher than that of the biopolymer scaffold. This indicates that adding HA into synthesized biopolymer can enhance compressive strength and the proliferation of the osteoblast cell.  相似文献   

8.
Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which has been extensively used in medicine as implantable materials, owing to its good biocompatibility, bioactivity high osteoconductive, and/or osteoinductive properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL), a newly remarkable biocompatible and biodegradable polymer, was employed as a matrix and hydroxyapatite nanoparticles were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by a new in situ sol–gel process using calcium hydroxide and phosphoric acid precursors in the presence of Tetrahydrofuran (THF) as a solvent. Chemical and physical characteristics of the nanocomposite were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) analyses. The results indicated that pure HA nanoparticles were well-incorporated and homogenously dispersed in the PCL matrix. It was found that the mechanical property of PCL was improved by addition of 20 wt.% HA nanoparticles. Furthermore, the biological property of nanocomposites was investigated under in vitro condition. For this purpose, HA/PCL scaffolds were prepared through a salt leaching process and immersed in a saturated simulated body fluid (SBF) after 3 and 7 days. It was found that a uniform layer of biomimetic HA could be deposited on the surface of HA/PCL scaffolds. Therefore, the prepared HA/PCL scaffolds showed good potential for bone tissue engineering and could be used for many clinical applications in orthopedic and maxillofacial surgery.  相似文献   

9.
Compounds belonging to the calcium phosphate (CaP) system are known to be major constituents of bone and are bioactive to different extents in vitro and in vivo. Their chemical similarity makes them prime candidates for implants and bone tissue engineering scaffolds. CaP nanoparticles of amorphous hydroxyapatite (aHA) and dicalcium phosphate dihydrate (DCPD) were synthesized using chemical precipitation. Uniaxially pressed aHA and DCPD powders were subjected to microwave radiation to promote solid state phase transformations resulting in crystalline hydroxyapatite (HA), tricalcium phosphate (TCP) and biphasic compositions: HA/TCP and TCP/calcium pyrophosphate (CPP) and their subsequent densification. Phase composition of microwave sintered compacts was confirmed via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Solution pH during crystal growth was found to have a profound effect on particle morphology and post-sintered phases, despite constant sintering temperature.Cytocompatibility assessment using 7F2 cells, corresponding to adult mouse osteoblasts, on microwave and conventional, furnace sintered samples demonstrated that manufacturing method does not impact cellular viability after 24 h or proliferation over 7 days. New CaP deposition and extracellular matrix components were observed in vitro via scanning electron microscopy (SEM).  相似文献   

10.
Hydroxyapatite (HA) powder was prepared by wet chemical method. The hydroxyapatite phase was stable up to 1250 °C without decomposition to beta-tricalcium phosphate. Interconnected porous hydroxyapatite scaffold resembling trabecular bone structure was developed from polymeric replica sponge method. The prepared scaffold has 60 vol.% porosity having a major fraction of ~ 50–125 μm pore diameter. The pore content, pore morphology, pore interconnectivity of scaffold and their compressive strength were dependent on the solid loading and binder content. In-vitro bioactivity and bioresorbability confirmed the feasibility of the developed scaffolds.  相似文献   

11.
Free form fabrication and high resolution imaging techniques enable the creation of biomimetic tissue engineering scaffolds. A 3D CAD model of canine trabecular bone was produced via micro CT and exported to a fused deposition modeler, to produce polybutylene terephthalate (PBT) trabeculated scaffolds and four other scaffold groups of varying pore structures. The five scaffold groups were divided into subgroups (n = 6) and compression tested at two load rates (49 N/s and 294 N/s). Two groups were soaked in a 25 °C saline solution for 7 days before compression testing. Micro CT was used to compare porosity, connectivity density, and trabecular separation of each scaffold type to a canine trabecular bone sample. At 49 N/s the dry trabecular scaffolds had a compressive stiffness of 4.94 ± 1.19 MPa, similar to the simple linear small pore scaffolds and significantly more stiff (p < 0.05) than either of the complex interconnected pore scaffolds. At 294 N/s, the compressive stiffness values for all five groups roughly doubled. Soaking in saline had an insignificant effect on stiffness. The trabecular scaffolds matched bone samples in porosity; however, achieving physiologic connectivity density and trabecular separation will require further refining of scaffold processing.  相似文献   

12.
We synthesized poly(ε-caprolactone) (PCL)/hydroxyapatite (HA) composite microspheres with an aligned porous structure and evaluated their potential applications in bone tissue engineering. A range of HA particles (0, 5, 10 and 20 wt.% in relation to the PCL polymer) were added to a PCL solution in order to improve the biocompatibility of the porous PCL/HA composite microspheres. All the synthesized microspheres showed that the HA particles were distributed well in the PCL matrix, while preserving their aligned porous structure. The average size of the PCL/HA composite microspheres increased from 62 ± 7 to 179 ± 95 μm with increasing HA content from 0 to 20 wt.%. The incorporation of the HA particles to the PCL polymer led to a considerable improvement in in vitro bioactivity, which was assessed by immersing the PCL/HA composite microspheres in simulated body fluid (SBF). A number of apatite crystals could be precipitated on the surface of the aligned porous PCL/HA composite microspheres after soaking in the SBF for 7 days.  相似文献   

13.
《Composites Part A》2007,38(1):114-123
In order to improve fracture toughness, carbon nanofibers (CNF) were used as reinforcement for hydroxyapatite (HA) composites. The powder mixture of CNF/HA were obtained with ball-milling technique. CNF/HA composites were sintered by hot-pressing with 7.81 and 15.6 MPa sintering pressure. Maximum sintering pressure was 1200 °C. Mechanical and physiological bio-compatibility were evaluated by four-point bending tests, indentation tests and immersion tests in simulated body fluid (SBF). The strength values of 10 vol.% CNF/HA composites sintered at 15.6 MPa is 90 MPa, which is within those of cortical bone. The fracture toughness values for CNF/HA composites are around 1.6 times higher than those obtained for HA. Equal bioactivity are obtained for CNF/HA composites.  相似文献   

14.
The purpose of this study was to investigate in vivo biocompatibility and osteogenesis as well as degradability of the porous strontium-doped calcium polyphosphate (SCPP) scaffolds as a biomaterial for bone substitute applications. The evaluation was performed on a rabbit model over a period of 16 weeks by histology combined with image analysis, X-ray microradiography and immunohistochemistry methods. The histological and X-ray microradiographic results showed that the SCPP scaffold exhibited good biocompatibility and extensive osteoconductivity with host bone. Moreover, a significant more bone formation was observed in the SCPP group compared with that in the CPP group, especially at the initial stage after implantation. New bone volumes (NBVs) of the SCPP group determined at week 4, 8 and 16 were 14, 27 and 45%, respectively. Accordingly, NBVs of the CPP group were 10, 19 and 40%. Immunohistochemical results revealed that both the expression of collagen type I and bone morphogenetic proteins in the SCPP group were higher than that in the CPP group, which might be associated with the release of strontium ions during the implantation. In addition, during 16 weeks implantation the SCPP scaffold exhibited similar degradability with the CPP scaffold in vivo. Both scaffolds showed the greatest degradation rate for the first 4 weeks, and then the degradation rate gradually decreased. The results presented in this study demonstrated that SCPP scaffold can be considered as a biocompatible material, making it attractive for bone substitute application purposes.  相似文献   

15.
3D porous scaffolds are relevant biomaterials to bone engineering as they can be used as templates to tissue reconstruction. The aim of the present study was to produce and characterize in vitro 3D magnesium-carbonate apatite/collagen (MCA/col) scaffolds. They were prepared by using biomimetic approach, followed by cross-linking with 0.25% glutaraldehyde solution (GA) and liofilization. Results obtained with Fourier-transform infrared spectroscopy (FT-IR) confirmed the type-B carbonate substitution, while by X-ray diffraction (XRD), a crystallite size of ~ 10 nm was obtained. Optical and electron microscopy showed that the cylindrical samples exhibited an open-porous morphology, with apatite nanocrystals precipitated on collagen fibrils. The cross-linked 3D scaffolds showed integrity when immersed in culture medium up to 14 days. Also, the immersion of such samples into an acid buffer solution, to mimic the osteoclastic resorption environment, promotes the release of important ions for bone repair, such as calcium, phosphorus and magnesium. Bone cells (SaOs2) adhered, and proliferated on the 3D composite scaffolds, showing that synthesis and the cross-linking processes did not induce cytotoxicity.  相似文献   

16.
In this study, the effects of bioactive glass nanoparticles' (nBGs) size and shape incorporated into hydroxyapatite/β-tricalcium phosphate (BCP) scaffolds were investigated. We prepared a highly porous (> 85%) BCP scaffold and coated its surface with a nanocomposite layer consisted of polycaprolactone (PCL) and rod (~ 153 nm in height and ~ 29 nm in width) or spherical (~ 33 nm and 64 nm in diameter) nBGs. Osteogenic gene expression by primary human osteoblast-like cells (HOB) was investigated using quantitative real time polymerase chain reaction (q-RT-PCR). We demonstrated for the first time that in vitro osteogenesis is dramatically affected by the shape of the nBGs, whereby rod shaped nBGs showed the most significant osteogenic induction, compared to spherical particles (regardless of their size). Importantly, the good biological effect observed for the rod shaped nBGs was coupled by a marked increase in the modulus (~ 48 MPa), compressive strength (~ 1 MPa) and failure strain (~ 6%), compared to those for the BCP scaffolds (~ 4 MPa, ~ 1 MPa and ~ 0.5% respectively). The findings of this study demonstrated that the shape of the nBGs is of significant importance when considering bone regeneration.  相似文献   

17.
In the current study PCL/HA composites were fabricated using SLS as two- and three-dimensional lattice structures and exposed to a cellular component (MC 3T3 osteoblast-like cells). The main aims were to determine the mechanical differences due to powder composition and to observe the physical and mechanical changes pertaining to cell presence. These structures were characterized by compressive mechanical testing, and the effects of cell culturing and degradation on mechanical properties of the scaffolds with different PCL/HA compositions were determined. Moreover, changes in the scaffold morphology due to the cell culture conditions were determined by μ-CT analysis.Cells steadily grew on the scaffolds for 21 days with preferential distribution around the macropores and initially PCL/HA(15%) composites had higher cell numbers. Removal of loosely sintered parts was observable during the culturing period. Cell culture conditions did not change the compressive moduli significantly but had a distinct effect on compressive strength. For PCL/HA(15%) composites, an initial loss in strength caused by cell culture was reversed by longer cell exposure, with compressive strength of the structures restored to the initial properties (p  0.05). μ-CT measurements showed widespread morphological changes in the scaffolds, such as a decrease in the roughness of the struts. In general, in the initial period composites with lower HA content (15 wt.%) showed better metabolic activity compared to the higher HA content, however by day 14 the performance of the two compositions was equal. These results suggest that changes in sintering due to the differences in powder composition can have profound effects on the short and long term mechanical properties of the scaffold particularly under cell culture conditions, and this should be closely considered for SLS processing of scaffolds.  相似文献   

18.
The aim of this study was to use CO2 at sub-critical pressures as a tool to sinter 3D, macroporous, microsphere-based scaffolds for bone and cartilage tissue engineering. Porous scaffolds composed of ~ 200 μm microspheres of either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) were prepared using dense phase CO2 sintering, which were seeded with rat bone marrow mesenchymal stromal cells (rBMSCs), and exposed to either osteogenic (PLGA, PCL) or chondrogenic (PLGA) conditions for 6 weeks. Under osteogenic conditions, the PLGA constructs produced over an order of magnitude more calcium than the PCL constructs, whereas the PCL constructs had far superior mechanical and structural integrity (125 times stiffer than PLGA constructs) at week 6, along with twice the cell content of the PLGA constructs. Chondrogenic cell performance was limited in PLGA constructs, perhaps as a result of the polymer degradation rate being too high. The current study represents the first long-term culture of CO2-sintered microsphere-based scaffolds, and has established important thermodynamic differences in sintering between the selected formulations of PLGA and PCL, with the former requiring adjustment of pressure only, and the latter requiring the adjustment of both pressure and temperature. Based on more straightforward sintering conditions and more favorable cell performance, PLGA may be the material of choice for microspheres in a CO2 sintering application, although a different PLGA formulation with the encapsulation of growth factors, extracellular matrix-derived nanoparticles, and/or buffers in the microspheres may be advantageous for achieving a more superior cell performance than observed here.  相似文献   

19.
Nutrient depletion within three-dimensional (3D) scaffolds is one of the major hurdles in the use of this technology to grow cells for applications in tissue engineering. In order to help in addressing it, we herein propose to use the controlled release of encapsulated nutrients within polymer microspheres into chitosan-based 3D scaffolds, wherein the microspheres are embedded. This method has allowed maintaining a stable concentration of nutrients within the scaffolds over the long term. The polymer microspheres were prepared using multiple emulsions (w/o/w), in which bovine serum albumin (BSA) and poly (lactic-co-glycolic) acid (PLGA) were regarded as the protein pattern and the exoperidium material, respectively. These were then mixed with a chitosan solution in order to form the scaffolds by cryo-desiccation. The release of BSA, entrapped within the embedded microspheres, was monitored with time using a BCA kit. The morphology and structure of the PLGA microspheres containing BSA before and after embedding within the scaffold were observed under a scanning electron microscope (SEM). These had a round shape with diameters in the range of 27–55 μm, whereas the chitosan-based scaffolds had a uniform porous structure with the microspheres uniformly dispersed within their 3D structure and without any morphological change. In addition, the porosity, water absorption and degradation rate at 37 °C in an aqueous environment of 1% chitosan-based scaffolds were (92.99 ± 2.51) %, (89.66 ± 0.66) % and (73.77 ± 3.21) %, respectively. The studies of BSA release from the embedded microspheres have shown a sustained and cumulative tendency with little initial burst, with (20.24 ± 0.83) % of the initial amount released after 168 h (an average rate of 0.12%/h). The protein concentration within the chitosan-based scaffolds after 168 h was found to be (11.44 ± 1.81) × 10? 2 mg/mL. This novel chitosan-based scaffold embedded with PLGA microspheres has proven to be a promising technique for the development of new and improved tissue engineering scaffolds.  相似文献   

20.
The major goal of this research was to investigate and characterize the deposition of a biomimetic apatite-like coating onto the surface of 3D porous calcium-silicate-hydrate scaffolds with suitable bioactivity for potential application in bone tissue engineering. Basically, Portland cement, water, sand and lime were mixed for preparing the slurry which was poured into molds, and fine aluminum powder was added as foaming agent resulting on the formation of porous 3D structures. After aging for 28 days, these porous inorganic scaffolds were immersed in calcium chloride supersaturated solution in PBS for 7 days at 37 °C for the biomimetic layer deposition. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR) techniques were used in order to characterize the porous scaffolds and the apatite-like biomimetic coating. The results have showed that 3D constructs were successfully produced with interconnected porosity, compressive strength and cytocompatibility appropriate for potential use as an alternative in trabecular bone repair.  相似文献   

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