94 research outputs found
Incorporation of a sequential BMP-2/BMP-7 delivery system into chitosan-based scaffolds for bone tissue engineering
The aim of this study was to develop a 3-D construct carrying an inherent sequential growth factor
delivery system. Poly(lactic acid-co-glycolic acid) (PLGA) nanocapsules loaded with bone morphogenetic
protein BMP-2 and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanocapsules loaded with
BMP-7 made the early release of BMP-2 and longer term release of BMP-7 possible. 3-D fiber mesh
scaffolds were prepared from chitosan and from chitosan–PEO by wet spinning. Chitosan of 4%
concentration in 2% acetic acid (CHI4–HAc2) and chitosan (4%) and PEO (2%) in 5% acetic acid (CHI4–
PEO2–HAc5) yielded scaffolds with smooth and rough fiber surfaces, respectively. These scaffolds were
seeded with rat bone marrow mesenchymal stem cells (MSCs). When there were no nanoparticles the
initial differentiation rate was higher on (CHI4–HAc2) scaffolds but by three weeks both the scaffolds had
similar alkaline phosphatase (ALP) levels. The cell numbers were also comparable by the end of the third
week. Incorporation of nanoparticles into the scaffolds was achieved by two different methods: incorporation
within the scaffold fibers (NP–IN) and on the fibers (NP–ON). It was shown that incorporation
on the CHI4–HAc2 fibers (NP–ON) prevented the burst release observed with the free nanoparticles, but
this did not influence the total amount released in 25 days. However NP–IN for the same fibers revealed
a much slower rate of release; ca. 70% released at the end of incubation period. The effect of single,
simultaneous and sequential delivery of BMP-2 and BMP-7 from the CHI4–HAc2 scaffolds was studied in
vitro using samples prepared with both incorporation methods. The effect of delivered agents was higher
with the NP–ON samples. Delivery of BMP-2 alone suppressed cell proliferation while providing higher
ALP activity compared to BMP-7. Simultaneous delivery was not particularly effective on cell numbers
and ALP activity. The sequential delivery of BMP-2 and BMP-7, on the other hand, led to the highest ALP
activity per cell (while suppressing proliferation) indicating the synergistic effect of using both growth
factors holds promise for the production of tissue engineered bone.This project was conducted within the scope of the EU FP6 NoE Project Expertissues (NMP3-CT-2004-500283). We acknowledge the support to PY through the same project in the form of an integrated PhD grant. We also would like to acknowledge the support from Scientific and Technical Research Council of Turkey (TUBITAK) through project METUNANOBIOMAT (TBAG 105T508)
3D plotted PCL scaffolds for stem cell based bone tissue engineering
The ability to control the architecture and strength of a bone tissue
engineering scaffold is critical to achieve a harmony between the scaffold and the
host tissue. Rapid prototyping (RP) technique is applied to tissue engineering to
satisfy this need and to create a scaffold directly from the scanned and digitized
image of the defect site. Design and construction of complex structures with
different shapes and sizes, at micro and macro scale, with fully interconnected pore
structure and appropriate mechanical properties are possible by using RP techniques.
In this study, RP was used for the production of poly(e-caprolactone) (PCL) scaffolds.
Scaffolds with four different architectures were produced by using different configurations
of the fibers (basic, basic-offset, crossed and crossed-offset) within the
architecture of the scaffold. The structure of the prepared scaffolds were examined by
scanning electron microscopy (SEM), porosity and its distribution were analyzed by
micro-computed tomography (m-CT), stiffness and modulus values were determined
by dynamic mechanical analysis (DMA). It was observed that the scaffolds had very
ordered structures with mean porosities about 60%, and having storage modulus
values about 1!107 Pa. These structures were then seeded with rat bone marrow
origin mesenchymal stem cells (MSCs) in order to investigate the effect of scaffold
structure on the cell behavior; the proliferation and differentiation of the cells on
the scaffolds were studied. It was observed that cell proliferation was higher on offset
scaffolds (262000 vs 235000 for basic, 287000 vs 222000 for crossed structure) and
stainings for actin filaments of the cells reveal successful attachment and spreading
at the surfaces of the fibers. Alkaline phosphatase (ALP) activity results were higher
for the samples with lower cell proliferation, as expected. Highest MSC differentiation
was observed for crossed scaffolds indicating the influence of scaffold structure on
cellular activities
Nano/microparticle incorporated chitosan fibers as tissue engineering scaffolds
[Excerpt] The aim of this study was to develop a bone tissue engineering scaffold with an inherent bone morphogenetic proteins BMP-2 and BMP-7 sequential delivery system. BMPs were encapsulated
in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(lactic acid-co-glycolic acid) (PLGA) nano/microparticules which are then introduced to a chitosan matrix by two methods:
embedding in the chitosan fibers and then forming the scaffold or by forming the chitosan scaffold and then introducing the nano/microparticules. [...]info:eu-repo/semantics/publishedVersio
Effect of scaffold architecture and BMP-2/BMP-7 delivery on in vitro bone regeneration
The aim of this study was to develop 3-D tissue engineered constructs that mimic the in vivo conditions through a self-contained growth factor delivery system. A set of nanoparticles providing the release of BMP-2 initially followed by the release of BMP-7 were incorporated in poly(ε-caprolactone) scaffolds with different 3-D architectures produced by 3-D plotting and wet spinning. The release patterns were: each growth factor alone, simultaneous, and sequential. The orientation of the fibers did not have a significant effect on the kinetics of release of the model protein BSA; but affected proliferation of bone marrow mesenchymal stem cells. Cell proliferation on random scaffolds was significantly higher compared to the oriented ones. Delivery of BMP-2 alone suppressed MSC proliferation and increased the ALP activity to a higher level than that with BMP-7 delivery. Proliferation rate was suppressed the most by the sequential delivery of the two growth factors from the random scaffold on which the ALP activity was the highest. Results indicated the distinct effect of scaffold architecture and the mode of growth factor delivery on the proliferation and osteogenic differentiation of MSCs, enabling us to design multifunctional scaffolds capable of controlling bone healing.This project was conducted within the scope of the EU FP6 NoE Project Expertissues (NMP3-CT-2004-500283). We acknowledge the support to PY through the same project in the form of an integrated PhD grant. We also would like to acknowledge the support from Scientific and Technical Research Council of Turkey (TUBITAK) through project METUNANOBIOMAT (TBAG 105T508)
Comparative pharmacokinetics and bioavailability of albendazole sulfoxide in sheep and goats, and dose-dependent plasma disposition in goats
Adenovirus-mediated siRNA targeting TNF-α and overexpression of bone morphogenetic protein-2 promotes early osteoblast differentiation on a cell model of Ti particle-induced inflammatory response in vitro
Use and efficacy of bone morphogenetic proteins in fracture healing
Signal transduction in aging related disease
Natural decomposition of hornbeam wood decayed by the white rot fungus Trametes versicolor
Mechanoresponsive musculoskeletal tissue differentiation of adipose-derived stem cells
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