Fig. 4. Mitochondria from FRDA fibroblasts have significantly higher levels of labile iron compared to healthy fibroblasts. Cells were treated (or not) with the hexadentate chelator DFO followed by 50 μM of compound 13 as described in materials and methods. Cells were then harvested and their fluorescence was measured. Data were compiled from n = 3–5 measurements per cell line. Mitochondrial LI levels are represented as fold change relating to control FEK4 cells (taken as 1). * significantly different (p < 0.05) from healthy cells.