Multiscale 3d scaffolds for soft tissue engineering via multimodal electrospinning

Periodical: Acta Biomater ISBN: 1878-7568 (Electronic)  Date: 2009/11/06  Language: Eng

Authors:Soliman, S., Pagliari, S., Rinaldi, A., Forte, G., Fiaccavento, R., Pagliari, F., Franzese, O., Minieri, M., Nardo, P. D., Licoccia, S., Traversa, E.

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Abstract
A novel (scalable) electrospinning process was developed to fabricate bio-inspired multiscale 3D scaffolds endowed with a controlled multimodal distribution of fiber diameters and geared towards soft tissue engineering. The resulting materials finely mingle nano- and microscale fibers together. rather than simply juxtapose as commonly found in literature. A detailed proof-of-concept study was conducted on a simpler bimodal poly(epsilon-caprolactone) (PCL) scaffold with modes of the fiber distribution at 600 nm and 3.3 mum. Three conventional unimodal scaffolds with mean diameters of 300 nm, 2.6 mum, and 5.2 mum respectively were used as controls to evaluate the new materials. The characterization of microstructure (i.e. porosity, fiber distribution, and pore structure) and mechanical properties (i.e. stiffness, strength, and failure mode) indicated that the multimodal scaffold had superior mechanical properties (Young`s modulus approximately 40 MPa and strength approximately 1 MPa) in comparison to the controls, despite the large porosity ( approximately 90% on average). A biological assessment was conducted with bone marrow stromal cell type (mesenchymal stem cells, mTERT-MSCs). While the new material compared favourably against the controls as far as cell viability (on the outer surface), it outperformed them in terms of cell colonization within the wall. The latter result, which could neither be practically achieved in the controls nor be expected based on current models of pore size distribution, demonstrated the greater openness of the pore structure of the bimodal material that remarkably did not come at the expense of mechanical properties. Furthermore nanofibers were seen to form a nanoweb bridging across neighbouring microfibers, which contributed to boost cell motility and survival. At last standard adipogenic and osteogenic differentiation tests served to demonstrate that the new scaffold does not hinder the multilineage potential of stem cells.