Poly(L-lactide-co-glycolide) microparticles emulsified by mixing and in a microfluidic device for potential bottom-up bone tissue engineering

The aim of this study was to obtain degradable poly(Llactide-co-glycolide) (PLGA) microparticles (MPs) with a controlled size for bottom-up bone tissue engineering. The particles were produced using the classical single water/oil emulsification method by mixing with a magnetic stirrer and by using a novel approach based on the application of a microfluidic device. This study involved a thorough investigation of different concentrations of PLGA and poly(vinyl alcohol) (PVA) during microparticle fabrication. The oil phase was PLGA dissolved in dichloromethane or ethyl acetate at 1%, 2% and 4% w/v concentrations. The water phase was an aqueous solution of PVA at concentrations of 0.5%, 1%, 2%, 2.5%, 4% and 5% w/v. The size and size distribution of the MPs were evaluated with an optical microscope. Obtained MPs were incubated in contact with osteoblast-like MG-63 cells and after days 1 and 3, the cell viability was evaluated using the reduction of resazurin and the fluorescence live/dead staining. The results showed that for each concentration of PVA, the size of the MPs increased with an increase in the concentration of PLGA in the oil phase. The MPs obtained with the use of the microfluidic device were characterized by a smaller size and lower polydispersity compared to those obtained with emulsification by mixing. Both methods resulted in the generation of MPs cytocompatible with MG-63 cells, what paves the way to consider them as scaffolds for bottom-up tissue engineering.