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. 2015 Dec 14;15(2):279–290. doi: 10.1111/acel.12434

Figure 1.

Figure 1

Morphological abnormalities of mitochondria in HGPS fibroblasts. (A) Representative fluorescence images of the mitochondria stained by MitoTracker Green FM in two normal fibroblast lines and two HGPS fibroblast lines. R: reticular mitochondria; I: intermediate mitochondria; F: fragmented mitochondria; S: swollen mitochondria. Scale bar, 20 μm. (B) Representative fluorescence images of normal fibroblasts transduced with lentivirus expressing either GFP‐lamin A (GFP‐LA) or GFP‐progerin (GFP‐Pr). The mitochondria were stained by MitoTracker Red CMXRos. Scale bar, 20 μm. (C) Representative transmission electron micrographs (TEM) of mitochondria taken from either normal‐1 (control) or HGPS‐1 (G608G) fibroblasts showing various morphological alterations ranging from ‘normal mitochondria’ (a‐b), ‘minor defective mitochondria’ (c‐d) to ‘severe defective mitochondria’ (e‐h). These three general categories for phenotype grading were classified based on the intactness of membrane (outer, inner and cristae), matrix integrity and overall organelle shape: mitochondria with intact membrane and matrix were considered as ‘normal mitochondria (a‐b); mitochondria with broken membrane or with small vacuole areas in matrix (<20% of the total area) were considered as ‘minor defective mitochondria’ (c‐d); and mitochondria that were either morphologically abnormal (swollen or budding) or with large vacuole areas (over 20% of the total area) were defined as ‘severe defective mitochondria’ (e‐h). Over 300 mitochondria in either normal‐1 or HGPS‐1, fibroblasts were blindly scored according to these criteria. Arrows pointed to abnormalities. (D) Percentages of mitochondria with different types of abnormalities in normal‐1 or HGPS‐1 fibroblasts. The number of mitochondria that were blindly scored in each group is indicated in the parentheses (***P < 0.001 by chi‐squared test).