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

Figure 2

Neutrophils and other granulocytes were recruited to the lungs within 2 hr of hUC-MSC IV administration. (a) Flow cytometry showed that Cd11c⁻ CD24^hi granulocytes and Siglec F⁻ CD11b^hi CD103⁻ Ly6G^hi neutrophils increased 2 hr after hUC-MSC injection, and decreased at the 24 hr time point. Kruskal–Wallis test with multiple comparisons; control n = 8, hUC-MSC group n = 4, ; . (b) MPO⁺ granulocytes/monocytes (green) clustered around the hUC-MSCs (red) in the lungs 2 hr after cell injection (yellow arrows); their levels decreased at 24 hr. Scale bar = 30 µm. (c) Immunofluorescence quantification of MPO⁺ cells. Kruskal–Wallis test with multiple comparisons. n = 3, ; . (d) Ly6G + MPO (magenta + cyan) neutrophils surrounded the hUC-MSCs (red) in the lungs 2 hr after cell injection (yellow arrows). 24 hr later, neutrophil numbers had lowered but Ly6G⁺ cells were still present in the lung. (e) Immunofluorescence quantification of Ly6G⁺ MPO⁺ neutrophils. Kruskal–Wallis test with multiple comparisons. n = 3, ; . The number of fields of view counted per condition was 27.

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