Open Porous Microscaffolds for Cellular and Tissue Engineering by Lipid Templating

Porous microspheres fabricated from biodegradable polymers have great potential as microscaffolds in tissue engineering applications, especially for novel strategies such as microtissue fabrication in vitro and microtissue assembly in vivo. Fabrication techniques for microparticulate scaffolds with surface and bulk pore sizes relevant for effective cell intrusion, however, are scarce. This study presents two techniques for the fabrication of open porous microscaffolds from poly(lactide-co-glycolide) in which lipid templating is used for pore formation and combined with either dispersion spraying or a double emulsion technique to determine the size and shape of the particulate structures generated. Both techniques yield microscaffolds with an average size of between 500 and 800 μm, high bulk porosities and open surface pores larger than 50 μm in diameter. Microscaffold morphology was investigated microscopically, particle size distribution was determined and porosity was quantified by intrusion measurements. Particle size and morphology was controlled by the processing parameters and the content and type of lipid porogen. Efficient extraction of the lipid template was shown by thermal analysis. Microscaffold cytocompatibility and in vitro cell culture performance was evaluated with L929 fibroblasts and rat adipose-derived stromal cells (ADSC), respectively. Extracts of different formulations were cytocompatible. Rat ADSC proliferated on the microscaffolds and were differentiated along the adipogenic lineage.