Biochemical and functional characterization of nitric oxide synthase III gene transfer using a replication-deficient...

Nitric oxide (NO) produced in endothelial cells has been implicated in the regulation of blood pressure, regional blood flow, inhibition of platelet aggregation, and endothelial and vascular smooth muscle cell proliferation. In a variety of cardiovascular disease states, such as atherosclerosis, arterial hypertension, and restenosis, expression of endothelial NO synthase (NOS-III) and endothelial NO production appear to be altered. Thus, NOS-III is an attractive target for cardiovascular gene therapy for which adenoviral vectors are one of the most effective vector systems. Therefore, a recombinant adenoviral vector expressing NOS-III (adenovirus type 5 [Ad5] cytomegalovirus [CMV] NOSIII) was constructed and biochemically and pharmacologically characterized both in vitro and in intact cells. Ad5CMVNOSIII-derived recombinant NOS-III was successfully expressed, as shown by immunoprecipitation and immunocytochemistry, and biologically active, as shown by functional assays in human primary umbilical vein and EA.hy926 endothelial cells, as well as 293 human embryonic kidney and Chinese hamster ovary cells. The Km values for NADPH and L-arginine and the Ka for tetrahydrobiopterin as well as the enzyme's dependency on other cofactors were similar to recombinant reference enzyme and literature values. NOS-III expression levels correlated linearly with the multiplicity of infection with Ad5CMVNOSIII and lasted for at least 8 days. NOS-III transfection inhibited endothelial cell proliferation. In conclusion, adenovirus-mediated gene transfer of Ad5CMVNOSIII to vascular and nonvascular cells resulted in the dose-dependent expression of intact, physiologically regulated, and functionally active NOS-III.