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Open Access Research

Intracardiac injection of a capsid-modified Ad5/35 results in decreased heart toxicity when compared to standard Ad5

Raine Toivonen123, Juha Koskenvuo45, Mari Merentie6, Mirva Söderström7, Seppo Ylä-Herttuala6 and Mikko Savontaus128*

Author Affiliations

1 Turku Centre for biotechnology, University of Turku, Tykistökatu 6B 5th floor, Turku, FIN-20520, Finland

2 Department of Medical Biochemistry and Molecular Biology, University of Turku, Turku, Finland

3 Turku Graduate School of Biomedical Sciences, University of Turku, Turku, Finland

4 Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland

5 Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku, Finland

6 Department of Biotechnology and Molecular Medicine, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland

7 Department of Pathology, University of Turku and Turku University Hospital, Turku, Finland

8 Department of Medicine, University of Turku and Turku University Hospital, Turku, Finland

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Virology Journal 2012, 9:296  doi:10.1186/1743-422X-9-296

Published: 29 November 2012

Abstract

Background

Clinical gene therapy trials for cardiovascular diseases have demonstrated the crucial role of efficient gene delivery and transfection technologies in achieving clinically relevant results. We hypothesized that the use of tropism-modified adenoviruses would improve transduction efficacy and to this end we analyzed the transduction efficiency and toxicity of standard Ad5 and tropism-modified Ad5/35 in combination with ultrasound-guided intramyocardial gene delivery.

Methods

Ultrasound-guided intracardiac injections were used to deliver 1 × 1010 pfu/ml Ad5-lacZ and Ad5/35-lacZ vectors into mouse left ventricle wall. Since Ad5/35 uses human CD46 as its primary receptor, we used transgenic hCD46Ge mice expressing human CD46 at levels comparable to man. Mice were sacrificed 6 or 14 days post-injection and immunohistochemistry and X-gal staining were used to detect transgene and viral receptor expression. Virus-induced cardiac toxicity was evaluated by a pathologist.

Results

The intramyocardial injection was well tolerated and both Ad5-lacZ and Ad5/35-lacZ were able to give robust transgene expression after a single injection. Interestingly, while Ad5-lacZ was able to generate greater transgene expression than Ad5/35-lacZ, it also evoked more severe tissue damage with large areas of interstitial inflammatory cell infiltration and myocyte necrosis.

Conclusions

Ultrasound-guided intramyocardial injection is an effective and safe way to deliver vectors to the heart. The observed severe tissue damage of Ad5-lacZ greatly undermines the efficient transgene expression and suggests that Ad5/35 capsid modification can result in safer adenoviral vectors for cardiovascular gene therapy, although at the cost of some vector transduction efficacy.

Keywords:
Adenovirus; Intracardiac injection; CAR; CD46; Targeting