FIG. 1.

Isolation of cancer stem cells (CSCs) from cultured primary cells from 17 ovarian serous carcinomas (OSCs) by spheroid formation assay. (A) Phase-contrast image of primary culture of OSC cells (a) and spheroid morphology with low (b) and high (c) power view. (B) The spheroid-forming capacity of the primary cancer cells was consistent (2.17%–2.37%) between the first and second generations, indicating that the spheroid-forming cells (SFCs) had self-renewing characteristics. (C) Significant expression of stem cell markers was detected in SFCs (*P<0.05). Known markers of stem cells were used, and all markers, except CD117, were significantly overexpressed in SFCs, indicating that the SFCs are enriched in CSCs compared with the cultured primary cells.