Figure 5.

Differentiation of gene-edited PSCs towards CMs. (A) After 8 days of CM differentiation, spontaneous beating of the cells could be observed in vitro. No significant difference in beating frequency was seen between the different cell lines. (B) Differentiation towards CMs was also indicated by qRT-PCR, as there was a decrease in SOX2 expression at day 15 and upregulation of an early (TBX5) and late (cMHC) marker of cardiomyogenesis (*p<0.05; **p<0.01; ***p<0.001). (C) This was also confirmed at the protein level, as cells stained positive for CX-43 (green) and αSMA (red) at day 15 of differentiation (scale bar: 50 µm for CX-43 and 100 µm for αSMA). (D) Differentiation had no influence on reporter gene expression, as similar BLI signals were obtained from undifferentiated and differentiated ESCs (**p<0.01). (E) The uptake of ^99mTcO₄^- was significantly reduced after differentiation, although the uptake was still significantly higher than in WT ESCs (***p<0.001). (F) Similar uptake results were found for undifferentiated and differentiated hSSTr2⁺ ESCs after incubation with ⁶⁸Ga-DOTATATE. This was significantly higher than in WT ESCs (***p<0.001).