Double immunofluorescent staining of P63 and CK14 in the tracheal allografts treated intratracheally with PMSCs or PBS on day 14 after transplantation. Red color indicates positive staining of CK14; green color shows positive staining of P63; blue color indicates nuclei stained with DAPI. The magnification of all images is 40×. The merged images are indicated on the side. +PMSCs, Intratracheally treated with PMSCs (1×106); +PBS, treated with 1 × PBS as control. PMSC, Placenta-derived human mesenchymal stem cells; PBS, phosphate-buffered saline; DAPI, 4,6-diamidine-2-phenylindole dihydrochloride.