PMSCs failed to integrate into the airway epithelial layer on day 14 after transplantation after intratracheal delivery. A, Representative images of immunofluorescent staining of human HLA-ABC within in vitro PMSCs. The images were taken at 20× magnification. Red color indicates positive staining of human HLA-ABC, blue color indicates nuclei stained with DAPI. B, Representative images of immunofluorescent staining of human HLA-ABC and CK14 within tracheas treated with PMSCs. The images were taken at 40× magnification. Red color indicates positive staining of human HLA-ABC molecules (left panel) and CK14 molecules (right panel); blue color indicates nuclei stained with DAPI. Right, The location of epithelial cells is seen by the area of strong CK14 signal. Left, There is essentially no HLA-ABC signal in this same location. HLA-ABC, Human leukocyte antigens-A, -B, and -C.