Characterisation of systemic dissemination of nonreplicating adenoviral vectors from tumours in local gene delivery

Abstract

Systemic virus dissemination is a potential problem during local gene delivery in solid tumours. However, the kinetics and pathways of the dissemination have not been well characterised during the first 24 h after the infusion is started. To this end, we infused adenoviral vectors for luciferase or enhanced green fluorescence protein into three different tumour models in mice. During and/or after the infusion, we determined the amount of adenoviruses in the tumour, blood, and liver, and examined the transgene expression in the liver, lung, blood, and tumour. In addition, we intravenously injected tumour cells expressing luciferase and examined the biodistribution of these cells in the body. We observed transgene expression in the liver and tumour at 24 h after the infusion, but could not detect transgene expression in the blood and lung. The peak concentration of viral vectors in the plasma occurred during the intratumoral infusion. At 10 min after the infusion, few viral vectors remained in the blood and the ratio of copy numbers of adenoviruses between liver and tumour was 42 in 80% and X10 in 40% of the mice. Most tumour cells injected intravenously accumulated in the lung within the first 24 h. Taken together, these data indicated that systemic virus dissemination occurred mainly during the first 10 min after the intratumoral infusion was started, and that the dissemination was due to infusion-induced convective transport of viral vectors into leaky tumour microvessels.

Effects of rate, volume, and dose of intratumoral infusion on virus dissemination in local gene delivery

“…As a result, adenoviral vectors accumulate mainly in the liver after they disseminate from the tumor following intratumoral infusion, and the amount of luciferase (a nonsecretable transgene product) in the liver should correlate with the number of disseminated adenoviruses (13,15). Meanwhile, luciferase expression in other tissues was negligible and thus not examined in our study.…”

“…Luciferase expressions in the liver and tumor were quantified at different time points after intratumoral infusion of AdCMVLuc, using the Xenogen In vivo Imaging System (Xenogen Corp., Alameda, CA; ref. 15).…”

“…The Ad5-based recombinant system was used to produce an adenoviral vector, AdCMVLuc, encoding luciferase (15). Adenoviruses were propagated in 293 cells (American Type Culture Collection, Manassas, VA), harvested at 48 hours after infection, and purified by cesium chloride gradient centrifugation according to a standard protocol (19).…”

“…The infusion was done via a 30-gauge needle mounted on a syringe pump (model 22, Harvard Apparatus Co., Cambridge, MA; ref. 15). Luciferase expressions in the liver and tumor were quantified at different time points after intratumoral infusion of AdCMVLuc, using the Xenogen In vivo Imaging System (Xenogen Corp., Alameda, CA; ref.…”

“…However, data in the literature has shown that a fraction of infused viral vectors could disseminate from tumors during and after the infusion (10 -16). In a mouse study, up to 90% of adenoviral vectors are observed in the liver 10 minutes after intratumoral infusion (15). The dissemination reduces transgene expression in the tumor and leads to the accumulation of viruses and transgene products in normal tissues.…”