781. Adenoviral Gene Transfer of Angiopoietin-1 Corrects Post-Pneumonectomy Compensatory Lung Growth in the MMP-9-/- Mice Via Mobilization of Endothelial Progenitor Cells
Authors: A. Marwan, S. Vaikunth, J. Parvadia, U. Harkness, A. Maldonado, M. Ripberger, B. Kalinowska, D. Alaee, E. Uzvolgyi, T. Crombleholme
Journal: Molecular Therapy (2006)

Previous work in our lab demonstrated that post-pneumonectomy compensatory lung growth (PPCLG) is an endothelial progenitor cell(EPC)dependent process. MMP-9-/-mice have a defect in mobilization of EPCs and a defect in PPCLG. Restoring EPC mobilization in these mice using stem cell factor(SCF) administration corrects the defect in lung growth. Similar results are seen when the mice are directly injected with exogenously isolated EPCs. Angiopoietin-1(Ang-1) is a potent stimulus to EPC mobilization. We hypothesized that adenoviral gene transfer of Ang-1 to the MMP-9-/-mice might bypass the mobilization defect, increase the mobilization of EPCs, and correct the defect in compensatory lung growth. Female FVBN mice 6–10 weeks old(n=5 each group) were divided into wild type (WT), MMP-9-/-mice, and MMP-9-/-mice with adenoviral vector gene transfer. The mice were subjected to a left pneumonectomy. Gene transfer was accomplished through tail vein injection of 1x109 pfu of an E1 or E1E3 deleted Ad-Ang-1 or Ad- lacZ under control of CMV promoter. Three days after surgery, CD133+/Flk-1+ cells, consistent with EPC containing subpopulation, were measured by flow-cytometry. The lungs were harvested at day 10, and inflation fixed for morphometry. Analysis included the Lung Body Weight Ratio(LBWR), Tissue-Airspace Ratio(TAR), and Airway Branching(AB). Serum SCF was measured using ELISA. Results are expressed as mean ± Standard error and analysis was done using ANOVA. Ad-Ang-1 gene transfer to the MMP-9-/-mice corrects the defect in compensatory lung growth with respect to LBWR, TAR, and AB. Ad-Ang-1 results in a significantly increased LBWR and AB in the MMP-9-/-mice compared to normal levels in control mice (p=0.021, and p=0.017 respectively). Flow-cytometric analysis demonstrates that Ang-1 significantly increases the mobilization of EPCs in the treated MMP-9-/-mice. Serum SCF ELISA demonstrates that the Ang-1 treated MMP-9-/-mice have no increase in serum SCF levels compared to untreated mice. Results of Gene transfer to the MMP-9-/- mice Tabled 1LBWRTARAB# of EPCs in 200μl bloodSerum SCF pg/mlWT0.023±0.00138.76±0.813.47±0.1225.82±15.3333.03±17.3MMP-9-/-0.018±0.001**33.33±1.61**2.58±0.16**138.48±33.2242.66±20.8**MMP-9-/- LacZ0.019±0.00129.43±0.893.04±0.05191.84±48.2225.89±20.8MMP-9-/- Ang-10.028±0.001****37.9±0.82*4.18±0.19***575.52±43***157.23±9.33* Open table in a new tab * p=0.02 - ** p≥0.003 - *** p=0.0001. Adenoviral gene transfer of Ang-1 not only corrects the defect in compensatory lung growth in the MMP-9-/-mice, but enhances it to levels greater than WT controls. This is mediated through an SCF independent pathway of EPC mobilization as evidenced by an increase in the number of peripheral EPCs despite no chnage in SCF levels. These results hold promise for the development of novel therapeutic strategies using gene transfer techniques to manipulate lung growth in different clinical scenarios.