Figure 5.

TBI and Aβ₄₂ protofibril exposure cause mitochondrial damage in astrocytes. (A) The health of mitochondria in astrocytes (GFAP) in response to the TBI and Aβ₄₂ protofibril exposure was investigated. Representative images show mitochondria labeled with CellLight Mitochondria-GFP and cell nuclei with DAPI. The sites of the injury are indicated by the dashed lines. (B) Mitochondrial network fragmentation was assessed and quantified. While control cells possess a predominately healthy-looking mitochondrial network with strands of branching mitochondria, exposed cells display various states of mitochondrial network disruption. Increasing fragmentation can be observed and at late stages defective mitochondrial membranes causes the release of labeled mitochondrial proteins that become visible in the cytosol. Fifteen images per independent cell culture (n = 3) and experimental group were analyzed and reported. (C) Representative TEM images showing examples of mitochondria observed in control cells and cells undergone TBI, Aβ₄₂ protofibril exposure or the combination of both. Abnormal fusion events were primarily observed in exposed cells and some mitochondria possessed marked lesions. (D) Quantification of the aspect ratio (mitochondrial length/width) confirmed these observations. Five cells per experimental group were analyzed; quantifying the mitochondria in a total of 55–68 TEM images per group. Statistical analyses were performed with the Kruskal–Wallis test followed by Dunn’s multiple comparisons test, *p ≤ 0.05 **p ≤ 0.01 ***p ≤ 0.001. Scale bars 50 µm (A) and 20 µm (B).