Three-dimensional cryogel matrix for spheroid formation and anti-cancer drug screening

Spheroid-based systems have been developed as alternatives to two-dimensional (2D) monolayer cultures for understanding 3D cell behavior and conducting in vitro drug screening tests. However, spheroids are easily disrupted while handling and do not mimic the presence of extracellular matrix (ECM) components. To address that, we have developed a cost-effective, polyethylene glycol diacrylate (PEGDA), and gelatin methacryloyl (GELMA) based semi-synthetic cryogel matrix system, which can be used to grow spheroids and conduct studies while providing architectural support and mimicking in vivo ECM components. These matrices are macroporous and support formation of tumor-like spheroids of breast tumor epithelial (MCF-7) cells in the absence of additional growth factors otherwise required for spheroid formation. Difference in morphology of cells as a function of matrix composition and increase in size and number of spheroids as a function of time was observed. Spheroids grown in cryogel matrices showed more drug resistance than their 2D counterparts, which can partially be explained by the epithelial to mesenchymal transition (EMT) observed in spheroids. We believe that spheroids formed through these PEGDA-GELMA cryogel matrices better represent in vivo pathological conditions and can help develop cost-effective in vitro assays for screening new pharmacological drug candidates and performing cell mechanistic studies.