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Paper Title Page
Abstract: Grafting of autologous iliac crest and decortication approach in posterior spinal fusion
surgery has been the “gold standard”. However, the limited source of autograft has prompted
extensive research into bone substitute and biological enhancement of the fusion mass. In this study,
the application of stem cell therapy by tissue engineering method was investigated to enhance
posterior spinal fusion with -tricalcium phosphate ceramics in rabbit model. Rabbit bone marrow
derived mesenchymal stem cells were aspirated from trochanter region of proximal femur. The
mesenchymal stem cells were grown and directed to differentiate into osteogenic cells by
osteogenic supplement (ascorbic acid, -glycerophosphate and dexamethasone) in basal medium
(10% FBS in DMEM). The osteogenic cells were seeded on tricalcium phosphate ceramics for one
day (MSC group, n=6). The cell-ceramics composite was implanted onto autologous L5 and L6
transverse processes with decortication approach in posterior spinal fusion. The cell free ceramics
acts as control (Control group, n=6) and iliac crest autograft as positive control (Autograft group).
The spinal segments were harvested at week 7 post-operation. Manual palpation was performed
with spinal segments to assess any movement of L5-L6 vertebral joint. The stiffness of the joint was
considered as solid fusion. The specimens then were fixed by formalin and transferred to 70%
ethanol. The BMC and volume of fusion transverse processes of L5 and L6 was measured by
peripheral quantitative computed tomography.
In manual palpation, 50% solid fusion was found in MSC group, 60% in autograft group but
none in control group. Moreover, the BMC of L5 and L6 transverse processes in MSC group was
greater than autograft and control group (45%, 40% respectively, p<0.01). The volume of transverse
processes in MSC group was greater than autograft by 45% (p<0.01) and control group by 26%
(p<0.05). In conclusion, the mesenchymal stem cells derived osteogenic cells augmented spinal
fusion and bone mineralization.
1201
Abstract: Porous calcium phosphate ceramics have been widely investigated in orthopaedic
surgery as bone extensor. Attention has been given to manufacturing of a porous bioceramic that
mimics the trabecular bone structure for proper bone regeneration and integration. Although
different methods have been applied to manufacture the porous structure, it was unable to visualize
the pores and their interconnections within the ceramic and had objective measurement of the
calcium phosphate ceramics. With the advance of biomedical imaging through micro-computed
tomography (microCT), the study attempted to quantify the pore structure of different calcium
phosphate ceramics. Three kinds of bioceramic blocks, namely BSC, ChronOS, and THA, were
synthesized by three methods and tested in the study. Six blocks of each bioceramic were evaluated
by conventional water immersion method and microCT. The pore size and connectivity of the pores
were evaluated with standardized protocols. The three-dimensional analysis of the pores and their
distribution by microCT was presented. The ChronOS had more functional pores (200-400μm in
diameter) than the BSC and THA did (p<0.05). Providing objective information on the functional
pores, the microCT evaluation serves as a good standard for specification of the bioceramic-related
implants.
1205
Abstract: PEG-modified ZnGd0.1Fe1.9O4 ferrite nanoparticles were synthesized by a coprecipitation
process combined with a microemulsion technique. The effect of modification on the structure,
magnetic properties of ZnGd0.1Fe1.9O4 nanoparticles was also investigated by XRD, FTIR, TEM
and VSM. The results showed immobilizing PEG on the surfaces of magnetic nanoparticles
effectively improved their dispersibility. Magnetic measurements indicated that the as-prepared
PEG-modified nanoparticles exhibited relatively high magnetic properties, although a slight
reduction in saturation and remanent magnetization were observed compared with unmodified
samples. Therefore, with promising high magnetic behavior and potentially good biocompatibility,
PEG-modified ZnGd0.1Fe1.9O4 ferrite nanoparticles would be feasible as thermoseeds for interstitial
hyperthermia to tumor.
1209
Abstract: Bonelike apatite coating was formed on poly(L-lactic acid) (PLLA) scaffolds and poly(glycolic acid)
(PGA) scaffolds in 24 hours through an accelerated biomimetic process. The ion concentrations in the
simulated body fluid (SBF) were nearly 5 times of those in human blood plasma. The apatite formed
in 5SBF was similar in morphology and composition to that formed in the classical biomimetic
process employing SBF or 1.5SBF, and similar to that of natural bone. To facilitate coating into
scaffolds, the flowing condition was introduced into the accelerated biomimetic process. It was found
that the accelerated biomimetic process performed in the flowing condition yielded more uniform
spatial distribution of apatite particles than that in the regular shaking condition.
1213
Abstract: Two series of bioactive and biodegradable composite materials consisting of particulate
β-tricalcium phosphate (β-TCP) and polyhydroxybutyrate (PHB) and its copolymer
polyhydroxybutyrate-co-hydroxyvalerate (PHBV) were produced and investigated for bone tissue
repair. A manufacturing route employing injection moulding was established for producing the
biomedical composites. In the process, plates of composites containing 10%, 20%, 30% or 40% by
volume of micro-sized TCP particles were successfully injection moulded for both TCP/PHB and
TCP/PHBV composites. Thermal properties of as-produced TCP/PHB and TCP/PHBV composites
were systematically evaluated using differential scanning calorimetry (DSC). The mechanical
performance of TCP/PHB and TCP/PHBV composites was assessed using dynamic mechanical
analysis (DMA).
1217
Abstract: Nano-sized carbonated hydroxyapatite (CHAp) particles were firstly synthesized using a
nanoemulsion method. TEM analyses revealed that as-synthesized nanoparticles were
calcium-deficient and spherical in shape (diameter: 16.8±2.6nm). Biocomposite microspheres
comprising CHAp nanoparticles and poly(L-lactide) (PLLA) were fabricated using the single
emulsion solvent evaporation technique. SEM images showed that composite microspheres were
mainly 5-30 μm in size despite the change of CHAp nanoparticle content. When the CHAp
nanoparticle content in composite microspheres was below 10 wt%, all nanoparticles were
encapsulated within the microspheres which possessed a nanocomposite structure. DSC results
showed that the crystallinity of the PLLA matrix of microspheres increased from 38 to 42% when the
CHAp nanoparticle content was increased from 0 to 20 wt%. The biocomposite microspheres should
be a suitable material for constructing bone tissue engineering scaffolds.
1221
Abstract: This paper reports a study on the modification of a commercial selective laser sintering
(SLS) machine for the fabrication of tissue engineering scaffolds from small quantities of
poly(L-lactide) (PLLA) microspheres. A miniature build platform was designed, fabricated and
installed in the build cylinder of a Sinterstation 2000 system. Porous scaffolds in the form of
rectangular prism, 12.7×12.7×25.4 mm3, with interconnected square and round channels were
designed using SolidWorks. For initial trials, DuraFormTM polyamide powder was used to build
scaffolds with a designed porosity of ~70%. The actual porosity was found to be ~83%, which
indicated that the sintered regions were not fully dense. PLLA microspheres in the size range of 5-30
μm were made using an oil-in-water emulsion solvent evaporation procedure and they were suitable
for the SLS process. A porous scaffold was sintered from the PLLA microspheres with a laser power
of 15W and a part bed temperature of 60oC. SEM examination showed that the PLLA microspheres
were partially melted to form the scaffold. This study has demonstrated that it is feasible to build
tissue engineering scaffolds from small amounts of biomaterials using a commercial SLS machine
with suitable modifications.
1225
Abstract: This paper reports the fabrication and characterization of three-dimensional, highly porous
polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-valerate (PHBV) and composite scaffolds
made by the emulsion freezing / freezing-drying technique. Freeze-drying of the polymer/solvent/
water phase emulsions produced hard and tough scaffolds with interconnected pores. The effects of
the fabrication parameters such as polymer concentration in emulsions and emulsion stabilizer were
examined and optimized. The density of polymer scaffolds was found to increase with an increasing
polymer concentration. Structural analyses of selected samples using scanning electron microscopy
indicated that the scaffolds had pore sizes ranging from several microns to a few hundred microns.
The porosity of scaffolds of up to 85% was achieved and it increased with a decreasing polymer
concentration. It was found that mechanical properties of composite scaffolds increased with the
increasing amount of hydroxyapatite (HA) incorporated in the scaffolds.
1229