Three-dimensional (3D) culture models such as spheroids better resemble the in vivo situation compared to 2D models, and more realistically recapitulate the tumor microenvironment offering advantages of resembling in vivo tumor microenvironment, enabling thereby a better understanding of molecular and cellular mechanisms and cell-matrix interactions. Furthermore, they can facilitate better screening of nanomedicines. 3D in vitro models also yield more predictive in vitro data and support the reduction of animal studies which are costly and suffering from high failures rates; for all these reasons, 3D in vitro models are particularly attractive for screening of clinically relevant properties of nanomedicines.
Various platforms have been proposed for generating 3D cell models and for 3D cell cultures, using scaffolds based on different polymers, hydrogels, microwell arrays, hanging drop method, and microfluidic devices, or combinations thereof. In particular, Sridhar et al. reported a hot-embossed polystyrene-based microwell array in a conventional Petri dish for production of homogenously-sized spheroids, which is rapid and easy to handle while being suitable for in situ microscopic examination.
In this study, we developed a 3D spheroid array by co-culturing tumor cells and fibroblasts to mimic tumor stroma in vitro, which we subsequently applied for studying nanoparticle penetration. Spheroid arrays were generated in a microwell array which are hot embossed in a polystyrene dish. Homospheroids (single cell type) and heterospheroids (tumor cells and fibroblasts) were prepared, subsequently characterized for cellular re-organization using confocal laser scanning microscopy as well as for the expression of tumor stromal biomarkers at the transcription and protein levels, and compared to tumor biopsies from patients.