Gene delivery to the placenta is one potential way of specifically modifyin
g placental biological processes and fetal development, The aim of this stu
dy was to determine the most efficient and least invasive route of placenta
l adenovirus delivery, The feasibility of adenovirus-mediated gene transfer
to the rat placenta was addressed by maternal intravenous or direct intrap
lacental injection of adenoviral vectors expressing the glucose transporter
GLUT3, a noncirculating integral membrane protein. Both routes led to tran
sgene expression in the placenta. However, direct intraplacental delivery o
n day 14 of gestation yielded a higher transduction efficiency than materna
l intravenous administration, and markedly reduced transgene expression in
maternal liver, Most importantly, the amount of the GLUT3 transgene and the
adenovirus itself in fetal tissues was only 1 to 3% of that found in the p
lacenta. These results indicate that the nature of the transgene and the ro
ute of adenovirus administration are key parameters in selective placental
somatic gene transfer. This novel strategy may prove useful for modifying a
placental function without altering the fetal genome.