Figure 4.

Histological characteristics of homotypic and heterotypic co-culture spheroids. (A) Monoculture spheroids of HCC827 parental cells, the erlotinib-resistant clone ER3, and the fibroblast cell line SV80 were cultured for seven days in ultra-low attachment plates before fixation, paraffin embedding, and sectioning. Spheroids are stained with hematoxylin and eosin (H&E). ER3 cells formed only loosely attached clusters of cells captured in a thrombin gel before paraffin embedding. (B) Heterotypic co-culture spheroids consisting of SV80 fibroblasts and HCC827 parental or ER3 cells in a 2:1 ratio. Spheroids were cultured for seven days in ultra-low attachment plates before fixation, paraffin embedding, and sectioning. Spheroids are stained with H&E. The light pink matrix surrounding the loosely attached cell clusters of ER cells, and the spheroids is the serum-thrombin clot used to cast the spheroids. Magnification is indicated.