Combined mononuclear phagocyte system depletion and blockade permits functional adenoviral hepatic insulin gene transfer in pigs

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 758-775-Beta Cells, Glucose Control & Complications
Basic/Translational
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-762
Peter Martin Thule*1, Dingwu Jia2, Adam G Campbell2, Sara Paveglio3 and Darin Erik Olson4
1VA Medical Center (111), Decatur, GA, 2Atlanta VA Medical Center, Decatur, GA, 3University of Connecticut, 4Emory Univ and the Atlanta VA, Decatur, GA
Assessing hepatic transgene function in pigs may provide a more accurate indication of human responses to gene therapy than rodent studies. However, obtaining robust gene transfer into pig liver is difficult, requiring partial hepatectomy and ex vivo transfection, hepatic circulatory isolation, or segmental hepatic catheterization. Adenoviral gene transfer in pigs is complicated by circulatory collapse induced by virus activating pulmonary and hepatic mononuclear phagocyte system (MPS). We performed a series of experiments in 12 pigs to determine if MPS depletion and/or blockade enhances adenoviral (Ad5) hepatic gene transfer. Under general anesthesia, Hanford barrow swine (10-20kg body weight) were administered increasing doses of recombinant Ad5 by mesenteric vein infusion with or without gadolinium chloride (GdCl3) or liposome encapsulated clodronate (Lipo-Cl) infusion induced MPS depletion. Most Lipo-Cl pigs also received MPS blockade with poly-inosinic acid (pI). MPS depletion with GdCl3 reduced pulmonary MPS uptake of particulate copper and Ad5, and increased vector uptake in liver and persistence in blood. However, GdCl3 failed to protect against Ad induced circulatory collapse. In contrast, Lipo-Cl pretreatment alone prevented Ad5 induced circulatory collapse (3.5x1011Vp/kg). Combining screening to exclude Ad5 serum neutralizing factors (SNF), Lipo-Cl treatment, and MPS blockade with pI permitted survival, and diffuse pan-hepatic transduction (0.5-5%) in 5 pigs, as determine by green fluorescent protein microscopy. In a STZ-diabetic pig administration of Ad G3 2xfur, a metabolically responsive, liver specific insulin transgene produced hepatic transduction sufficient to lower blood sugars from >300mg/dl to <100mg/dl and induce weight gain without exogenous insulin. We conclude that in pigs, MPS depletion with Lipo-Cl combined with pI mediated blockade permits administration of Ad at doses sufficient to obtain functionally significant hepatic gene transfer without inducing circulatory collapse.

Disclosure: DEO: Clinical Researcher, Amylin Pharmaceuticals, Clinical Researcher, Novo Nordisk, Clinical Researcher, Lilly USA, LLC, Clinical Researcher, Roche Pharmaceuticals, Clinical Researcher, PhaseBio. Nothing to Disclose: PMT, DJ, AGC, SP

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Juvenile Diabetes Research Foundation Research Grant, VA Merit Award awarded to PMT