Fig 1: Histopathological analyses of MSCs in DMM-operated mice at 1, 2, and 4 weeks post-injection.(A) Mouse knee sections were co-stained with Sca-1 (Purple) and Prussian Blue (PB, blue) to indicate persistence of DiR+Fe-MSC at 1, 2 and 4 weeks post-injection. Co-staining of F4/80 (purple) and Prussian Blue (blue) demonstrated some co-localization of DiR+Fe-MSC cells with macrophages. (Black Arrows.) Scalebar = 50 µm. (B) Mouse knee sections were triple-labeled with Sca-1 (Purple), cleaved Caspase-3 (brown), and Prussian Blue (blue), to indicate presence of apoptotic DiR+Fe-MSCs in synovium. Scalebar = 50 µm.