Background & objective: Replicating adenovirus, with the favorable features of efficient transduction and multiple in malignant cells, represent a promising option for gene therapy. Its influence on vascular endothelia in vivo is an important indicator for safety evaluation. This study was to explore the effects of conditionally replicating adenovirus Adv5/dE1A-Aschk1 on proliferating and resting endothelial cells.
Methods: Human umbilical vein endothelial cells (HUVECs) were isolated by filling umbilical veins with digestive enzyme solution. HUVECs were cultured and observed with immunofluorescent staining and under electron microscope to identify endothelial cells. The oncolytic effects of Adv5/dE1A-Aschk1 on HeLa and endothelial cells were measured by cytopathic effect assay (CPE)û its effect on the proliferation of endothelial cells was measured by MTT assay. Cell apoptosis after treatment of Adv5/dE1A-Aschk1 alone or in combination with irradiation was measured by flow cytometry (FCM).
Results: Highly purified endothelial cells were isolated. Adv5/dE1A-Aschk1 lysed HeLa cells in a replication-dependent fashion, but did not exhibit detectable cytopathic effects on resting endothelial cells at a multiplicity of infection (MOI) of 500. The inhibitory effect of Adv5/dE1A-Aschk1 on the proliferation of endothelial cells increased with the increase of viral titer. When treated with Adv5/dE1A-Aschk1 at a MOI of 100 for 96 h, the proliferation inhibition rate of proliferating HUVECs was (22.0+/-2.5)%, but that of resting HUVECs was (13.0+/-2.3)%. When treated with Adv5/dE1A-Aschk1 combined irradiation, the apoptosis rate of resting HUVECs was (23.1+/-2.5)%, and that of proliferating HUVECs was (35.7+/-3.0)%.
Conclusions: HUVECs may be taken as a good target for the research of conditionally replicating adenovirus. The viral titer for injuring endothelial cells is much higher than that for killing tumor cells, so Adv5/dE1A-Aschk1 has a wide range of therapeutic dosage. As compared with resting HUVECs, proliferating HUVECs are more likely to be lysed by Adv5/dE1A-Aschk1.