Optimizing manufacturing conditions of polymer microspheres as cell carriers for modular tissue engineering
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AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Department of Biomaterials and Composites, Al. A. Mickiewicza 30, 30-059 Kraków, Poland
Engineering of Biomaterials 2020;(156):2–9
Microspheres (MS) made of biostable polymer, namely polystyrene, have been used as substrates for cell culture enabling rapid cell expansion in dynamic conditions. However, due to non-resorbability, polystyrene (PS) MS when repopulated with cells cannot be directly used in tissue engineering. Our concept was to produce MS from resorbable polymer – poly(L-lactide-co-glycolide) (PLGA) as a support for adherent cells, e.g. osteoblasts. We hypothesize that such MS can be applied to the injured site to act as cell carriers or as modules for modular tissue engineering (MTE). In this article, we present the results of optimizing the PLGA MS manufacturing conditions via oil-in-water emulsification. Due to such a technique, MS with the required size, size distribution and properties suitable for cell culturing can be obtained. Three parameters of the oil-in-water emulsification were examined: the stirring speed of a water phase during MS manufacturing, the surfactant concentration, i.e. poly(vinyl alcohol) (PVA) in a water phase and concentration of PLGA in dichloromethane (DCM) as an oil phase. The results proved that the 7.5% PLGA concentration in DCM solution as an oil phase, the 0.5-2% concentration of PVA solution as a water phase and the stirring speed of water phase of 1000 rpm provided MS with the 160 µm mean diameter, which is suitable for cell culture. Moreover, the developed sieving and cleaning procedures were efficient to collect MS with the mean diameter of 280 µm, the more coherent size distribution and the ability to sink in the cell culture medium. The presence on the bottom of cell culture wells is crucial for MTE.