Intravenous Administration of Human Umbilical Cord Mesenchymal Stromal Cells Leads to an Inflammatory Response in the Lung

Figure 4

Monocytes and M0 macrophages in the lung show a two-step polarization response to IV injection of hUC-MSCs. (a) Flow cytometry showed that the CD11b^hi MHC II^+/− CD64^+/− monocyte and M0 macrophage populations increased at 2 hr and presented a classically activated M1 phenotype. At 24 hr there was an increase in alternatively activated M2 monocytes/macrophages. Kruskal–Wallis test with multiple comparisons. control n = 8, hUC-MSC group n = 4, . (b) Proinflammatory monocytes were immunostained for CD11b (white) and Ly6C (green). They were found evenly distributed throughout the lungs as well as close to the hUC-MSCs (yellow arrows). Scale bar = 30 µm. (c) Immunofluorescence quantification of Ly6C⁺ CD11b⁺ proinflammatory monocytes. Kruskal–Wallis test with multiple comparisons. n = 3, ; . (d) Proinflammatory macrophage (F4/80 [green] + CD16/32 [white]) distribution in the lung after cell therapy (yellow arrows). Scale bar = 30 µm. (e) Immunofluorescence quantification of F4/80⁺ CD16/32⁺ proinflammatory macrophages. Kruskal–Wallis test with multiple comparisons. n = 3, ; . (f) (F4/80 [green] + CD206 [white]) anti-inflammatory macrophage distribution (yellow arrowheads). Scale bar = 30 µm. (g) Immunofluorescence quantification of F4/80⁺ CD206⁺ anti-inflammatory macrophages. Kruskal–Wallis test with multiple comparisons. n = 3, . The number of fields of view counted per condition was 27.

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