Detection of Active Caspase-3 in Mouse Models of Stroke and Alzheimer’s Disease with a Novel Dual Positron Emission Tomography/Fluorescent Tracer [⁶⁸Ga]Ga-TC3-OGDOTA

Figure 5

Fluorescence microscopy in brains extracted from [⁶⁸Ga]Ga-TC3-OGDOTA-injected MCAO and sham-operated mice. (a, b) [⁶⁸Ga]Ga-TC3-OGDOTA fluorescence in 20-µm coronal brain sections. (a) Representative images of MCAO (top left and right panels) and sham-operated (bottom left panel) brains. (b) Quantification of fluorescence integrated over the left (operated) vs. right (nonoperated) brain halves. Data were averaged over 4 sections for each brain collected from 4 MCAO and 3 sham-operated mice and analyzed by Student’s t-test. (c, d) Sections of the same brains immunostained for CC3 (red) and Hoechst (blue). [⁶⁸Ga]Ga-TC3-OGDOTA presence was probed in Oregon Green channel (OG, green). (c) Representative images of MCAO (top left and right panels) and sham-operated (bottom left panel) brains. (d) Quantification of CC3-positive cells in the left (operated) vs. right (nonoperated) brain halves. Data were averaged over 4 sections collected from 3 brains for each condition and analyzed by two-way ANOVA followed by Bonferoni post hoc test. ; (E-G) [⁶⁸Ga]Ga-TC3-OGDOTA fluorescence (OG, green) in optically cleared 2 mm brains sections. (e) Representative images of 1 mm z-stack images of coronal sections of MCAO (top) and sham-operated (bottom) brains. (f, g) Representative images of the MCAO brain sections immunostained for CC3 and imaged for both [⁶⁸Ga]Ga-TC3-OGDOTA and CC3 (red). Cells positive for both [⁶⁸Ga]Ga-TC3-OGDOTA and CC3 are marked with white arrows, blood vessels—with red arrows. (f) Thalamus, 20x objective, ipsilateral side. (g) Cortex (top) and thalamus (bottom), 60x objective, ipsilateral side.