Isolation of spheroid-forming cells is important to investigate cancer stem cell (CSC) characteristics. However, conventional tumor spheroid culture methods have not proven suitable because the aggregated spheroids generally maintain their original heterogeneity and harbor multiple cells with various characteristics. Here we cultured spheroids using a polydimethylsiloxane microwell-based method and a limiting dilution protocol. We then isolated and enriched for CSCs that formed single cell-derived spheroids from gastric cancer cell lines. Cells from the microwell demonstrated higher self-renewal, increased expression of stem cell markers and resistance to apoptosis compared with spheroid cells made by the traditional method. This novel approach allows efficient cancer stem cell isolation and represents a step forward in cancer stem cell studies.
Cancer stem cells (CSCs) have been hypothesized to drive tumor initiation, metastasis and chemoresistance. The American Association for Cancer Research defines CSCs as subpopulations of cells within a tumor that possess the capacity for self-renewal and that differentiate into heterogeneous lineages of cancer cells that constitute a tumor. Emerging evidence suggests that CSCs contribute to disease recurrence after completion of initial treatment.