Tumorigenicity testing of primate cell lines in nude mice, muscle organ culture and for colony formation in soft agarose

Highly Sensitive In Vitro Methods for Detection of Residual Undifferentiated Cells in Retinal Pigment Epithelial Cells Derived from Human iPS Cells

“…Table 1 summarizes the advantages and disadvantages of the assays associated with product tumorigenicity. The soft agar colony formation assay is known to be more sensitive in the detection of certain types of tumorigenic cells, compared to in vivo methods using immunocompromised mice [27]. However, we found the soft agar colony formation assay unsuitable for detecting residual undifferentiated hiPSCs, presumably attributable to the dissociation-induced apoptosis of hiPSCs [18].…”

Immortalization of human WI38 cells is associated with differential activation of the c‐myc origins

“…Here again, we found increased activities of all origins at the c‐myc locus in WI38 cells transformed by SV40 by comparison to their normal counterparts. Since WI38(SV40) cells are immortalized, but not malignant [Levenbook et al, 1985], we conclude that the higher origin activities are associated with cell immortalization, one of multi‐steps leading to malignant transformation.…”

In vitro and in vivo evaluation of discogenic cells, an investigational cell therapy for disc degeneration

“…Two concentrations are used because at the high concentration, adjacent cells can be mistaken for a colony, but at the lower concentration, the cells may be too diffuse to result in tumor formation. Three groups were tested: discogenic cells, positive control cells that form tumors (HT-1080 cells from Wuxi Apptec), and negative control cells that do not form tumors (WI-38 cells from Wuxi Apptec) [21]. The cells were then incubated at 37˚C in an atmosphere of 5% CO 2 .…”