Figure 2.

Mitochondria are transported from EBI macrophages to early erythroblasts upon stress. (A) Schematic illustration of the experiment to examine the mitochondrial dynamics in EBI macrophage-mediated erythroid regeneration following PHZ-induced stress. (B) Frequency of mitochondria transfer, as indicated by the percentage of mito-Dendra2⁺ events, among various stages of erythroid populations in spleen. Mitochondria transfer frequency is also shown among early erythroblasts in spleen of PHZ-treated mice infused with either control (F4/80⁺CD106⁻CD169⁻) or EBI (F4/80⁺CD106⁺CD169⁺) macrophages from mito-Dendra2 mice. Representative FACS plots are shown. Mean ± SEM; n = 5; ***, P ≤ 0.001; ****, P ≤ 0.0001 by Student’s t test. (C) Confocal microscopy images showing native early splenic erythroblasts (Ter119⁺CD44⁺) from mito-Dendra2 mice (left) and mito-Dendra2⁺ early splenic erythroblasts from wildtype mice administered EBI macrophages from mito-Dendra2 mice (right). Scale bar, 10 μm. (D) Representative Z-stack and iso-surface rendering of super-resolution images of native early splenic erythroblasts from mito-Dendra2 mice (left) and mito-Dendra2⁺ early erythroblasts from wildtype mice administered EBI macrophages from mito-Dendra2 mice (right). Scale bar, 5 μm. (E) Frequency of mitochondria transfer as indicated by the percentage of mito-Dendra2⁺ events among early erythroblast in the spleens (left) and BM (right) of untreated or PHZ-treated mice infused with EBI macrophages from mito-Dendra2 mice. Schematic illustration of the experiment is shown. Mean ± SEM; n = 3; **, P < 0.01 by Student’s t test. (F) Confocal microscopy images showing the presence of mito-Dendra2–labeled mitochondria in recipient erythroblasts (isolated from PHZ stressed tdTomato-Vav-Cre mice) in close contact with donor EBI macrophages (isolated from mito-Dendra2 mice) after coculture for 3 d. A schematic illustration of the experiment is shown. Scale bar, 10 μm.