A myeloid cell-binding adenovirus efficiently targets gene transfer to the lung and escapes liver tropism

Abstract

Specific and efficient gene delivery to the lung has been hampered by liver sequestration of adenovirus serotype 5 (Ad5) vectors. The complexity of Ad5 liver tropism has largely been unraveled, permitting improved efficacy of Ad5 gene delivery. However, Kupffer cell (KC) scavenging and elimination of Ad5 still represent major obstacles to lung gene delivery strategies. KC uptake substantially reduces bioavailability of Ad5 for target tissues and compensatory dose escalation leads to acute hepatotoxicity and a potent innate immune response. Here we report a novel lung-targeting strategy through redirection of Ad5 binding to the concentrated leukocyte pool within the pulmonary microvasculature. We demonstrate that this leukocyte-binding approach retargets Ad5 specifically to lung endothelial cells and prevents KC uptake and hepatocyte transduction, resulting in 165 000-fold enhanced lung-targeting, compared to Ad5. Additionally, myeloid cell-specific binding is preserved in single cell lung suspensions and only Ad.MBP-coated myeloid cells achieved efficient endothelial cell transduction ex vivo. These findings demonstrate that KC sequestration of Ad5 can be prevented through more efficient uptake of virions in target tissues and suggest endothelial transduction is achieved by leukocyte-mediated “hand-off” of Ad.

The myeloid-binding peptide adenoviral vector enables multi-organ vascular endothelial gene targeting

“…Our initial work with the Ad.MBP.CMV vector focused on differential liver and lung transduction 1 . Here we sought to test the multiorgan biodistribution of Ad.MBP.CMV using semi quantitative tissue section immunofluorescence analysis.…”

“…The Ad.MBP.CMV vector containing the sequence WTLDRGY on a T4 fibritin chimeric fiber knob was created as described previously 1, 17 . Recombinant viruses were purified by two rounds of CsCl density ultracentrifugation and dialyzed in storage buffer containing 10 mmol/L HEPES, 1 mmol/L MgCl 2 , pH 7.8 with 10% glycerol as previously described 19 .…”

“…However, standard Ad5 vectors predominantly transduce liver but not the vasculature following intravenous administration. We recently developed an Ad5 vector with a myeloid cell-binding peptide (MBP) incorporated into the knob-deleted, T4 fibritin chimeric fiber (Ad.MBP) 1 .This vector was shown to transduce pulmonary ECs presumably via a vector handoff mechanism. Here we tested the body wide tropism of the Ad.MBP vector, its myeloid cell necessity, and vector-EC expression dose response.…”

“…Ad.MBP was engineered for MBP display at the tip of a “de-knobbed” chimeric fiber 5, 17 . This vector was shown to bind specifically to myeloid cells ex vivo but predominantly transduced lung vascular endothelium following systemic administration 1 . Here, we discovered that the Ad.MBP vector affected multi-organ EC specific expression.…”

The Consideration of Viral Vector in Gene Therapy to Potential Lung Injury

“…The ideal virus vector for gene therapy is to transfer target gene to a location with effective gene expression; and it should not cause significant toxicity on its own [1,2]. During the study on gene therapy from 2002 at University of Pennsylvania School of Medicine, we observed the first finding of potential lung injure from viral vector delivery to mice.…”