3-D Scaffold Platform for Optimized Non-viral Transfection of Multipotent Stem Cells

Optimization of non-viral gene delivery from biomaterials is of critical importance, as several material parameters are known to influence non-viral transfection efficiency. A series of previous studies have achieved screening of gene delivery vectors on two dimensional (2D) substrates, which have direct relevance to cell culture applications. There is an additional need to create screening systems that are 3-dimensional (3D), and can thus be applied to emerging tissue engineering applications. Here, we report an enhanced throughput, 3D scaffold platform to screen for the influence of mineral coating properties on stem cell transfection. Mineral coatings with a range of physicochemical properties were formed on the scaffolds within a 96-well plate format, while maintaining an interconnected macroporous scaffold structure. A series of general gene delivery parameters, including plasmid amount, N/P ratio, and cell density, were efficiently screened in scaffolds using a luciferase-encoding plasmid as a reporter. In addition, human mesenchymal stem cell (hMSC) transfection with a plasmid encoding bone morphogenetic protein-2 (BMP-2) was successfully optimized by screening a library of mineral coatings, resulting in over 5-fold increases in BMP-2 production when compared to standard techniques. Notably, the majority of BMP-2 was incorporated into the mineral coating following secretion from the cells. The 3D mineral coated scaffold platform described here may accelerate gene delivery optimization and improve the predictability of the screening systems, which could facilitate translation of gene delivery to clinical applications.