Dynamic Imaging of Marrow-Resident Granulocytes Interacting with Human Mesenchymal Stem Cells upon Systemic Lipopolysaccharide Challenge
Figure 2
Distribution of CTO-labeled hMSCs in the calvarium of a mouse. A total of 8 × 106 CTO-labeled hMSCs (red) were injected i.v. into a recipient mouse containing LysM+ (green) neutrophils and monocytes. Intravital TPM was performed through intact calvarium of live recipient mice 20 hours after i.v. injection of hMSCs. (a) Distribution of labeled hMSCs in the calvarium bone marrow within the general vicinity of bone marrow-resident LysM+ myeloid-lineage cells. Vessels were highlighted with Qtracker-655 (magenta). Scale bar = 50 μm. (b) Same image as in (a) after channel subtraction to remove CTO signal inclusions inside of the LysM+ GFP signals, showing close association of the hMSCs with the vessels (inset). (c) Zoomed-in view of the inset in (a), showing that many hMSCs (red) remain intact in the bone marrow and do not colocalize with the GFP signal (yellow arrows). However, a small number of LysM+ granulocytes can be seen to harbor CTO+ inclusions inside the cell body (white arrows). Channel subtraction of the micrograph in the left column removed CTO signal that resided within LysM+ cell body, further supporting the presence of CTO signal inside a few LysM+ cells (right column; white arrows). Scale bars = 20 μm.
