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. 2022 Aug 21;71(8):1679–1693. doi: 10.2337/db21-1104

Figure 4.

Figure 4

Activation of pericytes with blue light affects vascular perfusion of islet grafts. A: Mice with intraocular islet grafts from NG2-ChR2+ and NG2-ChR2− mice were housed together in cages equipped with a blue LED around their perimeter and subjected to the same light stimulation protocol. B: Stimulation with blue light pulses for 4 h (1 min on, 4 min off) increased levels of the hypoxia marker pimonidazole (Pimo) (60 mg/kg, green) in mice with NG2-ChR2+ islets (bottom) but not in mice with NG2-ChR2− islets (top). C: Quantification of results as in B showing the density of Pimo immunostaining (immunostained area/graft area) in islet grafts (n = 4–6 grafts per six mice). *P < 0.05 between ChR2+ mice Pimo injected and exposed to blue light and all other groups by one-way ANOVA with Tukey multiple comparisons test. D: Optogenetic activation of islet pericytes increased NADPH-diaphorase activity (black staining) in grafts from NG2-ChR2+ mice upon stimulation with blue light (right) but not in the absence of light (left). Note ChR2-tdTomato–expressing pericytes in red and background NADPH-diaphorase activity in iris vessels. E: Quantification of the density of diaphorase activity in ChR2− and ChR2+ grafts (n = 4–6 grafts per six mice). *P < 0.05 between ChR2+ exposed to blue light and the other two groups by one-way ANOVA with Tukey multiple comparisons test. Data are shown in box and whisker plots (min to max) (C and E). Scale bar = 10 μm (B).