Dependence of the optimum gel modulus for CSC growth on tissue origin of cancer cells.

<p>(A) DAPI (blue) and phalloidin (red) stained images of MCF10A, MCF7, MDA231, HCT116, U2OS, and AGS cancer cells encapsulated in the un-patterned gels after 2, 6, and 9 days of incubation (scale bars in A are 50 μm). Cell number (B), tumorsphere number (C), tumorsphere diameter (D), and tumorsphere size distribution (E) as a function of cancer cell type after 9 days of encapsulation for gel moduli of 2 (pink), 5 (blue), 25 (brown), 50 (purple), and 70 (green) kPa. The gel modulus in (A and E) was the optimum PEGDA modulus of 5 kPa for MCF7 and MDA231 cells; 25 kPa for HCT116 and AGS; 50 kPa for U2OS. (F) mRNA expression of CSC markers for MCF7 (CD44 and ABCG2), MDA231 (CD44 and EGFR), HCT116 (CD44 and TGF-β), U2OS (CD44 and CD133), and AGS (CD44 and OCT4) after 6 and 9 days of encapsulation for gel moduli of 2 (pink), 5 (blue), 25 (brown), 50 (purple), and 70 (green) kPa. An asterisk in (B-D) indicates a statistically higher (p<0.05) cell number, sphere number and size for the test modulus compared to all other moduli for a given cell type. An asterisk in (F) indicates a statistically higher (p<0.05) marker expression level for the test modulus compared to all other moduli for a given cell type and at a given time. The p-values for the asterisks in (B-D,F) are listed in Tables I-U in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132377#pone.0132377.s001" target="_blank">S1 File</a>. Error bars correspond to mean±1 SD for n = 3.