Phenotype of podoplanin-positive cells in the fibrotic tissue.

<p>Thin cardiac sections were indirectly immunolabeled with antibodies that recognize podoplanin (red) and either fibronectin and vimentin (<b>A</b>; green and grey, respectively), VEGFR-2 and CD34 (<b>B</b> and <b>C</b>; green and grey, respectively), or α-SMA (<b>D</b>; grey). Nuclei, blue. Time after MI is indicated. Areas in rectangles are shown at higher magnifications in the adjacent images for each color channel. Note that vimentin (<b>A</b>) or α-SMA (<b>D</b>) labeling is rarely detectable in podoplanin-expressing cells (examples are pointed by yellow arrowheads). In <b>B</b> and <b>C</b>, the podoplanin-presenting cells show minimal VEGFR-2 labeling. At 2 days after MI, the podoplanin-bearing cells mostly do not co-stain with CD34 (exemplified by yellow arrowheads). Starting 2 weeks after MI, the CD34 staining is present in irregular capillary-like structures (examples are indicated by white arrows). In <b>C</b>, quantitative image analysis demonstrating changes in the podoplanin co-labeling with CD34 at indicated times after MI is included in the graph (lower panel). Data represent mean and SD of the co-localization coefficient; n = 5–6 image fields per group. By one-way ANOVA, *P < 0.02 for 2 weeks vs. 2 days; **P < 0.0001 for 1 month vs. 2 days; ns, not-significant for 1 month vs. 2 weeks.</p>