Three-Dimensional Engineered Matrix to Study Cancer Stem Cells and Tumorsphere Formation: Effect of Matrix Modulus

Maintenance of cancer stem cells (CSCs) is regulated by the tumor microenvironment. Synthetic hydrogels provide the flexibility to design three-dimensional (3D) matrices to isolate and study individual factors in the tumor microenvironment. The objective of this work was to investigate the effect of matrix modulus on tu-morsphere formation by breast cancer cells and maintenance of CSCs in an inert microenvironment without the interference of other factors. In that regard, 4T1 mouse breast cancer cells were encapsulated in inert polyeth-ylene glycol diacrylate hydrogels and the effect of matrix modulus on tumorsphere formation and expression of CSC markers was investigated. The gel modulus had a strong effect on tumorsphere formation and the effect was bimodal. Tumorsphere formation and expression of CSC markers peaked after 8 days of culture. At day 8