Improvement of Polycaprolactone Nanofibers Topographies: Testing the Influence in Osteoblastic Proliferation
A. Martins, J. Cunha, F. Macedo, R.L. Reis and N.M. Neves
University of Minho, PT
electrospinning, polycaprolactone, osteoblastic cells, nanofiber membrane
The nanofiber technology of present interest focuses on the electrospinning technique, which conveniently allows the preparation of fibrous materials with very fine diameters ranging from submicron to several nanometers. With the ability to form nanofibrous structures, a drive to mimic the extracellular matrix (ECM) and form scaffolds that are an artificial ECM suitable for tissue formation has begun. In addition, nanofibrous scaffolds have a high surface area-to-volume ratio, which is thought to enhance cell adhesion. Cell migration, proliferation and differentiation are dependent on adhesion and should be enhanced on nanofibrous scaffolds. Based on these, the main goals of the present work were to produce biodegradable nanofiber meshes with different topographies by electrospinning, in order to obtain diverse porosities and texture; to perform in vitro studies with an established cell line of Human primary osteogenic sarcoma (SaOs-2 cells), in order to observe cellular performance over these nanofiber meshes.
A polymeric solution was electrospun. Collectors with diverse topographies (namelly flattened aluminium foil, a metallic net with 1.0 mm spacing and a semi-aluminium tube with 5mm spacing) were used. Results demonstrated a random distribution of nanofibers, when a flattened aluminium foil was used as collector, as expected. However, when a metallic net was used as collector, it was possible to observed two distinct areas: fibers appeared align and collapse where the wire was present and randomly distributed in the spacing between wires. Inversely, random collapsed fibers were present in protuberances of the semi-aluminium tube and aligned nanofibers occurred in the spacing between protuberances.
SaOs-2 cells were seeded and their viability and adherence evaluated by methylene blue staining and scanning electronic microscopy (SEM), respectively. Results from these in vitro studies indicate that osteoblastic cells maintained their normal phenotype shape and preferred a structure where the fibers are not collapsed, independently if the nanofibers are random or align. It was also possible to observe that these cells integrate with the surrounding fibers and migrate into the nanofibrous structure to form a three-dimensional cellular network at long-time periods. In addition, some cells were found into the nanofibrous structure, indicating that these meshes had adequate porosity and interconnectivity to cell migration, and oxygen and metabolites exchanges.
In conclusion, we developed collector-dependent polycaprolactone (PCL) nanofiber meshes, with different topographies, where it was possible to identify two distinct areas of nanofiber deposition: random and aligned fibers. These patterned nanofiber meshes contained good features for bone tissue regeneration, once osteoblasts proliferated and maintained a normal phenotype shape, suggesting that these cells function biologically within these structures processed by electrospinning. This effect of collector geometry over cellular growth is still under study, using human bone marrow-derived stem cells (hBMSCs).
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Nanotech 2006 Conference Program Abstract