3.4 Cisplatin delivery to the embedded spheroids
To evaluate the exploitation of these 3D systems as a drug-screening platform, the MCF-7 spheroids embedded either in the 0.25%-0.02% or 0.125%-0.02% A-C hydrogels were treated with 100 µM cisplatin. After 24 h incubation, the Live/Dead assay was performed and the samples were analysed under the fluorescence microscope. The images of Figure 8 show that the dead cells were detected in the hydrogels administered with cisplatin, while control samples were brightly green fluorescent. The analysis of the distribution of the fluorescent pixels performed on 25 spheroids for each type of sample evidenced that the difference between the number of dead cells of the control and those of the drug-treated samples is statistically significant (p <0.01) (Figure 8, lower panel). Furthermore, it looked that the penetration of the drug depended on the agarose percentage amount, as indeed, the number of dead cells was higher in the hydrogels containing 0.125% agarose. Interestingly, when the samples, after 24 h incubation with the drug, were kept in fresh medium for additional 5 days and then observed under the microscope, the structure of the spheroids was dramatically altered. A huge number of dead cells peeled off from the spheroids and many cellular debris were spread into the matrix while small residues of the 3D structures were still visible (Figure 9S). This effect was observed in both types of matrices at 5 days post drug treatment.