Thermo-responsive polymer aided spheroid culture in cryogel based platform for high throughput drug screening

Abstract

In high throughput cell culture, the paradigm is now shifting from 2D to 3D systems. However, in 3D cell culture systems, it is important that the cells form spheroids with robust cell–cell interactions. We fabricated poly(N-isopropylacrylamide-co-gelatin) cryogel scaffolds for cell culture and inserted them into open-ended 96-well plates that formed a drainage and leakage protected, easy to handle high throughput platform. This platform was used to screen for the optimal concentration of poly(N-isopropylacrylamide) (pNIPAAm) as an external aid to the formation of cellular spheroids. It was found that hepatic cells (Hep G2) seeded in the presence of 0.03% pNIPAAm formed better hepatic spheroids in terms of morphology (as assessed by microscopic analysis and formation of bile canaliculi-like structures) and functionality by day 5 of culture. An increase of 44.22%, 15.75%, 36.44%, 32.05% and 27.02% was observed in glucose consumption (1.925 mM per day per 10⁴ cells), albumin synthesis (164.18 ng per day per 10⁴ cells), CYP1A1 (304.92 pg per min per 10⁴ cells), CYP2A6 (441.23 nM per min per 10⁴ cells) and phase II metabolic activity (386.18 nM per min⁻¹ per 10⁴ cells), respectively, upon using 0.03% pNIPAAm, as compared to the 3D control. The platform was tested with other cells such as breast and lung cancer cells and found to be compatible. The cell spheroids were subjected to drug toxicity screening in cryogel based open-ended platforms. It was observed that the spheroids were more resistant to anticancer drugs, as compared to 2D and 3D controls, with approximately 11%–67% increase in the IC₅₀ values of tamoxifen and paclitaxel. The platform also showed dose dependent and reproducible responses to drugs.