Generation of MCF-7 Spheroids in Polyethylene Glycol-Dextran Droplets for Cancer Niche Studies Using Aqueous Two-Phase System-3D Platforms.

Cell-based aqueous two-phase system (ATPS) applications involve the construction of 3D cultures encapsulating cells in polyethylene glycol (PEG)-dextran (DEX) droplets due to their low interfacial tension. This technology has enabled cell patterning in a controlled-defined shape giving rise to specific cell microenvironments. The present work aims to encapsulate MCF-7 cancer cells in ATPS droplets evaluating four different compositions of PEG-DEX, construction Strategies A (droplet added), B (immersed), or C (covered), and two cell densities (5000 and 10,000 cells/µL) during a 24 h incubation time using 96-well plates. The smallest cell-containing DEX droplets showed a mid-range value of 1.05 ± 0.33 mm using Strategy C whereas the largest of 1.46 ± 0.49 mm in Strategy B. However, Strategy A was associated with higher rates of circularity. After 24 h, MCF-7 spheroids were formed in all PEG-DEX systems showing a diameter size ranging from 0.10 to 0.65 mm. Their circularity was higher in low cell densities. Higher rates of cell viability were obtained in PEG 35,000-DEX 500,000 systems for a period of 4 days showing tumor-specific traits compared to 2D control. This work demonstrates practical strategies for 3D model construction for cancer niche for future drug screening studies using basic laboratory equipment.