Ultrasonographically guided direct gene transfer in utero: Successful induction of beta-galactosidase in a rabbit model

OBJECTIVE: We sought to determine whether the transfer of enzyme-encoding g enes in utero can be detected after birth. STUDY DESIGN: An adenoviral vector carrying the gene for beta-gatactosidase was injected under ultrasonographic guidance into the rivers of 4 rabbit f etuses per titter (3 litters total) at 27 days' gestation. On delivery of t he pups 2 to 3 days later, the livers were analyzed for beta-galactosidase activity by using 5-bromo-4-chloro3-indolyl-beta-D-galactopyranoside (X-gal ) staining. Polymerase chain reaction was also performed on liver extracts as an additional independent measure of successful vector delivery. RESULTS: Successful targeting of the livers of fetal rabbits was demonstrat ed by beta-galactosidase activity in the nuclei of liver serosal cells, par enchymal hepatocytes, or columnar cells of the gallbladder in 7 (58%) of 12 injected pups and by polymerase chain reaction in liver extracts from 10 ( 83%) of 12 injected pups. CONCLUSIONS: These results suggest that vectors that carry genes for specif ic enzymes can be delivered to fetal organs in utero and that expression of the enzyme can be detected after delivery.