Figure 4. An optimized dye pair allows quantification of MSC cytokine pre-treatment impact on delivery to an inflamed site.

Systemic infusion of MSCs pretreated with TNF-α/IFN-γ (blue, stained with Vybrant DiD) increases cell trafficking to the inflamed ear vs. control MSCs (green, stained with Vybrant DiI) (a). When quantified, this yields an average increase in cells/mm² of ear surface area of 22±2% (p<0.05, Students unpaired t-test) (b). The increase in trafficking is of a consistent magnitude across a range of injected cell numbers with a commensurate range of detected counts (p<0.05, 2-way ANOVA) (c). If the increase in homing for each cell dose is plotted, consistent evaluation of the homing increase is observed, even with a wide range of injected cell numbers (d). Scale bar = 100 µm.