Figure 7. Dyshomeostatic human-induced pluripotent stem cell (iPSC)-derived microglial cells in the mouse retina phagocytose dead photoreceptor cells/debris after retinal pigment epithelial (RPE) cell injury.

(A) Dyshomeostatic human microglial cells (tdtomato+) accumulated in the photoreceptor cell layer after 3 days of sodium iodate (NaIO₃)-induced RPE cell injury compared with no NaIO₃ administration. The photoreceptor cells stained with cone arrestin (green) and autofluorescence showed in magenta. Scale bar = 60 µm. (B) High-magnificent images and the side view showed human microglial cells (red) co-labeled with photoreceptor cells arrestin staining (green) after 3 days of NaIO₃ injury. The yellow arrowhead showed the colocalized tdT+ human microglia cell and arrestin+ cone photoreceptor cell. Scale bar = 40 µm. (C) The number of tdtomato+ human microglial cells in the photoreceptor layer. (D) The mean gray autofluorescence value in each human microglia cell. ****p < 0.0001.

Figure 7—figure supplement 1. The inflammation, phagocytosis, adhesion and migration, neurotrophic factors, and microglia signature gene expression in human-induced pluripotent stem cell (hiPSC)-derived microglia cells of grafted retinas.

The gene coding sequences were compared between humans and mice, a human-specific sequence was chose to make the oligos (Supplementary file 5), and ran a quantitative reverse transcription-PCR (qRT-PCR) on 8-month hiPSC-derived microglia cells grafted retinas with/without sodium iodate (NaIO₃)-treated retinas. The results revealed that hiPSC-derived microglia cells expressed more inflammatory factors and phagocytosis genes and promoted cell migration but decreased microglia cell signature genes and neurotrophic factors in NaIO₃-treated retina (3 biological replicates in each group).