This study investigates the influence of the porosity of fiber mesh scaffolds obtained from a blend
of starch and poly(-caprolactone) on the proliferation and osteogenic differentiation of marrow
stromal cells cultured under static and flow perfusion conditions. For this purpose, biodegradable
scaffolds were fabricated by a fiber bonding method into mesh structures with two different porosities–
50 and 75%. These scaffolds were then seeded with marrow stromal cells harvested from Wistar
rats and cultured in a flow perfusion bioreactor or in 6-well plates for up to 15 days. Scaffolds
of 75% porosity demonstrated significantly enhanced cell proliferation under both static and flow
perfusion culture conditions. The expression of alkaline phosphatase activity was higher in flow cultures,
but only for cells cultured onto the higher porosity scaffolds. Calcium deposition patterns
were similar for both scaffolds, showing a significant enhancement of calcium deposition on cellscaffold
constructs cultured under flow perfusion, as compared to static cultures. Calcium deposition
was higher in scaffolds of 75% porosity, but this difference was not statistically significant. Observation
by scanning electron microscopy showed the formation of pore-like structures within the
extracellular matrix deposited on the higher porosity scaffolds. Fourier transformed infrared spectroscopy
with attenuated total reflectance and thin-film X-ray diffraction analysis of the cell-scaffold
constructs after 15 days of culture in a flow perfusion bioreactor revealed the presence of a
mineralized matrix similar to bone. These findings indicate that starch-based scaffolds, in conjunction
with fluid flow bioreactor culture, minimize diffusion constraints and provide mechanical stimulation
to the marrow stromal cells, leading to enhancement of differentiation toward development
of bone-like mineralized tissue. These results also demonstrate that the scaffold structure, namely,
the porosity, influences the sequential development of osteoblastic cells and, in combination with the
culture conditions, may affect the functionality of tissues formed in vitro.
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