Figure 4.

Pericyte-specific deletion of Mettl3 alleviates pericyte dysfunction and retinal vascular complication in vivo. (A and B) Mettl3^f/f; Pdgfrβ-Cre (Mettl3^f/f) mice or Mettl3^+/+; Pdgfrβ-Cre (Mettl3^+/+) mice (Ctrl group) were intraperitoneally injected with STZ for diabetes induction. The flat-mounted retinas were stained by IB4 (in green, endothelial cells) and NG2 (in red, pericytes) to detect pericyte coverage on retinal vessels (n = 6 retinas per group, Scale bar: 100 µm). The multiple overlapping images of flat-mounted retinas were captured by a ×10 lens and the individual images were arrayed to obtain the composite images of a leaf of retina vessels. The representative composite images after 6 months of treatment and statistical result was shown. (C and D) Evans blue assay was conducted to detect retinal vascular leakage. Evans blue dye was injected and circulated for 2 h. After fixation, the whole flat-mounted retinas were tiled and observed under a fluorescence microscope at a × 4 lens to take tile-scanning images. The representative composite images of flat-mounted retinas and the quantification results were shown. The red fluorescent is Evans blue signaling (n = 6 retinas per group, Scale bar: 500 µm). (E-H) Retinal trypsin digestion was conducted to detect the number of microaneurysms (F, n = 6 retinas per group, per mm² retina), pericyte ghosts (G, n = 6 retinas per group, per 1000 capillary cells), and acellular capillaries (F, n = 6 retinas per group, per mm² retina). The representative images of acellular capillary, pericyte ghost, and microaneurysm were shown (E, Scale bar: 100 µm). *P < 0.05 versus Ctrl group; ^#P < 0.05 between the marked groups; Kruskal-Wallis test, Bonferroni test.