FIGURE SUMMARY
Title

Human macrophages survive and adopt activated genotypes in living zebrafish

Authors
Paul, C.D., Devine, A., Bishop, K., Xu, Q., Wulftange, W.J., Burr, H., Daly, K.M., Lewis, C., Green, D.S., Staunton, J.R., Choksi, S., Liu, Z.G., Sood, R., Tanner, K.
Source
Full text @ Sci. Rep.

Human macrophages survive in vivo for up to two weeks post-injection following brain injection. (a) Schematic of experimental design: primary monocytes were differentiated into macrophages before injection into the zebrafish brain at age 2 days post fertilization (dpf) and imaged at 1, 7 and 14 days post injection (dpi). (b) Micrographs of representative whole larva at 3 dpf (left) and 3D projections showing distribution and survival of human primary macrophages (blue) injected into the hind brain of transgenic mpx:GFP (neutrophils-green)/flk:mCherry (vessels-red) zebrafish larvae at 1 dpi (3 dpf) (right). (c) Micrographs of representative whole larva at 9 dpf (left) and 3D projections showing distribution and survival of human primary macrophages (blue) injected into the hind brain of transgenic mpx:GFP (neutrophils-green)/flk:mCherry (vessels-red) zebrafish larvae at 7 dpi (9 dpf) (right). (d) Micrographs show that cells can persist for up to 2 weeks after injection at 16 dpf. Top panel: representative zebrafish at 16 dpf. Left panel: micrograph shows tiled image of transgenic mpx:GFP (neutrophils-green)/flk:mCherry (vessels-red) 16 dpf zebrafish, white square highlights region of interest in the zebrafish brain. Right panel: micrograph of the inset where the white arrows indicate human cells. Scales are indicated on each image.

 

Human macrophages survive and interact with zebrafish stromal cells post-injection following brain injection. (a) Schematic of experimental design: primary monocytes were differentiated into macrophages before injection into the zebrafish brain at age 2 days post fertilization (dpf) and imaged at 1 and 2 days post injection (dpi). (b) 3D projections of whole head at 3 dpf (left) and 4 dpf (middle) showing distribution and survival of human primary macrophages (blue) injected into the hind brain of flk:mCherry (vessels-red) (top) and GFAP:GFP (astrocytes-green)/flk:mCherry (vessels-red) (bottom) zebrafish larvae. Boxes indicate positions of insets shown in right panels. Scales are indicated.

 

Human macrophages survive in vivo for up to two weeks post-injection following injection directly into the circulation of the zebrafish. (a) Schematic showing experimental set up, where human macrophages were directly injected into the circulation of 2 days post-fertilization (dpf) larvae, after being differentiated from primary human monocytes. Injected larvae were imaged at 1, 7 and/or 14 days post injection (dpi). (b,c) Micrographs of whole larva at 3 dpf (left) showing distribution and survival of human primary macrophages (blue) differentiated at either at physiological temperature of zebrafish (28.5 °C) or at physiological temperature of humans (37 °C) before injection into the caudal vein of transgenic fli:GFP (vessels-red) zebrafish larvae. Micrographs display macrophage distribution at 1 dpi. Bottom panels: Micrographs of 3D projections at higher magnification of insets highlighted in tiled images showing distribution and survival of human primary macrophages (blue). (d) Top panel: micrograph shows tiled image of the 9 dpf zebrafish, 7dpi, showing distribution and survival of human primary macrophages differentiated at human physiological temperature (37 °C) (blue) injected into transgenic fli:GFP (vessels-red) zebrafish larva. Bottom panel: Micrographs of 3D projections at higher magnification of insets highlighted in tiled image showing distribution and survival of human primary macrophages (blue). (e) Top panel: micrograph shows representative tiled image of a 16 dpf zebrafish. Bottom panel: Micrographs of 3D projections showing distribution and survival of human primary macrophages (blue) at 14 dpi following injection to transgenic mpx:gfp (neutrophils-green)/flk:mCherry (vessels-red) zebrafish larvae at 2 dpf. Arrows indicate macrophage positions.

 

Primary human monocytes survive at physiological temperature of the zebrafish in vitro and in vivo. (a) Primary human monocytes (blue) were injected into the hind brain of transgenic GFAP:GFP (astrocytes-green)/flk:mCherry (vessels-red) zebrafish larvae at 2 dpf. Micrographs show representative images where zebrafish was imaged serially over the course of 3 days post-injection at interval of 24 hours. (b) Plot (mean ± 95% CI) of average in vivo survival calculated for primary human monocytes obtained from larvae where the numbers of cells that survived over the course of 3 days for each larvae were normalized to the initial numbers measured one day post injection. Statistical analysis where * indicates a p value of p < 0.025 and *** indicates a p value of p < 0.0005 by successive t tests with Bonferroni correction, with n = 41 larvae for Day 1, n = 41 larvae for Day 2, and n = 4 larvae for Day 3. Scatter plots show values for individual zebrafish. Not all zebrafish survived to 5 days post injection. (c) Cells were either cultured at physiological temperature of humans (37 °C) or at physiological temperature of zebrafish (28.5 °C). Plot (mean ± SD) of average survival calculated for primary human monocytes obtained from n = 4 donors where the numbers of cells that survived over the course of 7 days were normalized to the original seeding density. Days in culture was a statistically significant factor in survival by two-way ANOVA with one degree of freedom (P < 0.0001), as was the temperature of culture (P = 0.0018).

 

Primary human macrophages can survive at physiological temperature of the zebrafish in vivo and do not cause a sustained inflammatory response. (a) Representative light sheet micrographs of uninjected, control whole larva at 3 days post-fertilization (dpf). Both transgenic mpeg:GFP (macrophages-green)/flk:mCherry (vessels-red) (top) and mpx:GFP (neutrophils-green)/flk:mCherry (vessels-red) (bottom) are shown. (b) Representative lightsheet micrographs of head regions of uninjected, control larvae at 3 dpf. Both transgenic mpeg:GFP (macrophages-green)/flk:mCherry (vessels-red) (top) and mpx:GFP (neutrophils-green)/flk:mCherry (vessels-red) (bottom) are shown. (c) Schematic of experimental design: primary monocytes were differentiated into macrophages before injection into the zebrafish brain at age 2 dpf and imaged at 1 and 7 days post injection (dpi). (d) Plot (mean ± SD) of average in vivo survival calculated for primary human macrophages differentiated at physiological temperatures of the zebrafish or human obtained from 3 larvae each, where the numbers of cells that survived over the course of 7 days were normalized to the initial numbers measured one day post injection. Differences in survival were not significant by two-way ANOVA with Tukey’s multiple comparisons post-test. The temperature of macrophage differentiation (P = 0.3072), fish line injected (P = 0.4822), and interaction between factors (P = 0.4575) were not significant sources of variation by two-way ANOVA with one degree of freedom. Monocytes that had been cultured in the presence of human macrophage colony stimulating factor (H-M-CSF) for eight days (e) at physiological temperature of (28.5 °C) and (f) at physiological temperature of humans (37 °C). Primary human macrophages (blue) were injected into the hind brain of transgenic mpeg:GFP (macrophages-green)/flk:mCherry (vessels-red) or mpx:GFP (neutrophils-green)/flk:mCherry (vessels-red) zebrafish larvae at 2 dpf. Micrographs of 3D projections showing distribution and survival of human primary macrophages 1 dpi, when larvae are 3 dpf, and 7 dpi, when larvae are 9 dpf. The same fish is shown in the left and right panels.

 

Acknowledgments
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