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. 2019 Apr 28;11(5):594. doi: 10.3390/cancers11050594

Figure 1.

Figure 1

Characterization of pheochromocytoma cell spheroids. (A) Tumor cell spheroids are characterized by a necrotic core surrounded by hypoxic cell layers and an external zone of proliferating cells. This structure encourages the formation of an oxygen, pH and nutrient gradient and leads to accumulation of extracellular matrix proteins. Complexity and comparability with the structure of a metastasis offers an important tool for drug screening. (B) Growth pattern of MPC and MTT cell spheroids generated by using methylcellulose method. Four independent experiments (n = 15–20). Mean ± SEM. (C) Impact of spheroid cultivation on the amount of protein produced by 500 cells over a time-period of eight days in comparison to monolayer conditions. Four independent experiments (n = 16). Mean ± SEM. ANOVA and Bonferroni post hoc test comparison vs. monolayer, * p < 0.05. (D) Representative section of pheochromocytoma cell spheroids stained with Hematoxylin and Eosin (nuclei: blue, cytosol: violet). (E) Covalent binding of pimonidazole confirmed the development of a hypoxic region (red) surrounding the necrotic core of the spheroids (nuclei: blue). Scale bar: 200 µm.