Loss of epithelial cells in allografts after intratracheal injection of PMSCs or PMSCCM on day 14 after transplantation. A, Representative images of H&E-stained histopathologic sections of allografts at 14 days after transplantation. All images are 40× magnification. +PMSCs, Treated with PMSCs (1 × 106); +PBS, treated with 1× PBS as control; +PMSCCM, treated with PMSCCM; +CONM, treated with blank medium as the control. B, Bar graph depicting percentage allograft luminal epithelial loss with each type of injection (n=7–13). Data shown are the mean ± standard error of mean. PMSC, Placenta-derived human mesenchymal stem cells; PBS, phosphate-buffered saline; PMSCCM, PMSC-conditioned medium; CONM, control media.