PSGL-1/SLEX MSCs exhibit a robust rolling response on P-selectin-coated substrates in vitro and on inflamed endothelium in vivo. (A) Representative images showing PSGL-1/SLeX MSCs (yellow arrows) roll on a P-selectin surface in vitro at a substantially lower velocity than a native MSC. Shear stress in these images: 0.75 dyn/cm2. (B) Simultaneous expression of both PSGL-1 and SLeX is required to induce robust rolling of MSCs on P-selectin surface. Data are shown as mean velocity (calculated from 20 cells per group) ± SD. (C) Representative in vivo confocal microscopy images show a rolling (yellow arrows) and adhered (white arrows) PSGL-1/SLeX MSCs. (D) Histogram showing a representative velocity distribution of native MSCs and PSGL-1/SLeX MSCs on inflamed ear endothelium in vivo (representative analyzed population; velocity was calculated for at least 50 cells per group). Vcrit calculated as described in the “Methods” section.
