The development of reliable preclinical systems for anticancer drug testing has become an imperative considering that over 96% of oncology drugs that reach clinical trials ultimately fail . Traditional cancer models comprising monolayer cell cultures (2D) where the cells adhere to the flat surface of a culture flask cannot recapitulate the complex 3D structure of in vivo cancers. To overcome this problem, significant effort has been put into the development of more adequate biomimetic 3D model systems for anticancer drug testing. In this study we demonstrate the potential of alginate microfibers with immobilized cancer cells as a 3D cancer model for anticancer drug research.
Immobilization of cancer cells (NCI-H460 cell line) in alginate microfibers was achieved by simple extrusion. A mixture of Na-alginate solution and cell suspension (4×106 cells/ml, 2.8 % Na-alginate) was manually extruded through a blunt edge stainless steel needle (25G) into the gelling solution containing 0.18 M Ca2+. Formed alginate microfibers with immobilized cells were then cultured for 48 h in the culture medium after which period the cells were treated with the anticancer drug cisplatin at concentrations of 1, 5, 10, 25 and 50 µM. Untreated cells immobilized in alginate microfibers served as a control. Simultaneously, the same cisplatin concentrations were applied to the cells in 2D monolayer cultures, with untreated cells as a control. After another 48 h, cell viability was assessed by the MTT assay based on the reduction of the MTT dye into formazan in metabolically active cells. After the addition of the dye (0.5 mg/ml MTT), cells in both 3D and 2D cultures were incubated for 4 h at 37°C, followed by dissolution of the formed formazan crystals with dimethyl sulfoxide and measurement of the absorbance of the obtained solutions at 570 nm. The cells in microfibers were also examined regarding morphology by optical and fluorescence microscopy.
Cancer cells were successfully immobilized in alginate microfibers retaining their normal morphology and viability, confirmed by optical microscopy and MTT staining. After the treatment with anticancer drug different cell viability results were obtained in 3D cultures compared to 2D cultures. In 2D cultures, the half-maximal inhibitory concentration (IC50) of cisplatin was shown to be 5 µM, while in 3D cultures the concentration of 5 µM reduced the cell viability by only 24 %. Furthermore, the IC50 value in the 3D culture was not achieved in the applied range of concentrations, with a reduction in cell viability of 43 % at the highest applied cisplatin concentration, 50 µM. In comparison, the cisplatin concentration of 50 µM in 2D cultures reduced the cell viability by 76 %.
The preliminary study of anticancer drug testing in the 3D cancer model comprising cancer cells immobilized in alginate microfibers showed increased resistance of the cells to the anticancer drug cisplatin compared to cells in 2D cultures. This result indicates that such 3D systems could be used as more reliable cancer models in anticancer drug research.
1. Wong, C. H. et al., Biostatistics 20, 273-286 (2019)