Figure 2. hIDO improved histological appearance and inhibited collagen deposition in lung allografts. Samples of Masson’s trichrome stained sections from normal lung (A), isograft (B), untreated allograft (C), allograft treated with empty vector (D), pMSZ-hIDO/pTRUF-hSB17/PEI (E), or lung section from a patient with interstitial pneumonitis as a positive control (F). The untreated allograft has pronounced peribronchiole collagen deposition (blue coloration) along with widespread destruction of alveolar architecture that was notably absent in the pMSZ-hIDO/pTRUF-hSB17/PEI treated allograft. Photomicrographs are representative of five rats in each group (original magnification: x400). In (G), quantification of lung collagen content in all groups. Results are mean ± SEM (n=5 in each group). *P < 0.05, **P < 0.01 vs. normal lungs or isografts (Iso); P < 0.01 vs. untreated allografts (Allo) or pMSZ-null treated allografts (Allo/vehicle).