INTRAAMNIOTIC ADMINISTRATION OF AN ADENOVIRAL VECTOR FOR GENE-TRANSFER TO FETAL SHEEP AND MOUSE-TISSUES

Replication-deficient adenoviruses have been used to transfer various genes of interest to mammalian tissues in vivo. Effective therapy for inborn genetic defects presenting with significant morbidity and morta lity at birth will require correction of the defect prenatally. To tes t the hypothesis that intraamniotically administered adenovirus transf ers gene expression to fetal tissues, replication-deficient human type 5 adenovirus carrying the lacZ gene which encodes nuclear-targeted ba cterial beta-galactosidase (Av1LacZ4) was instilled into the amniotic cavity of fetal sheep (10(10) to 1.5 x 10(11) pfu) and fetal mice (10( 9) pfu) at 0.8 term gestation. Amniotic membranes and gastrointestinal and respiratory tract tissues were harvested after 3 d, bacterial bet a-galactosidase activity was determined by 5-bromo-4-chloro-3-indoyl-b eta-D-galactopyranoside (X-gal) enzyme-histochemistry, and tissue inte grity was assessed in sections stained with hematoxylin and eosin. Bac terial beta-galactosidase activity was abundant in amniotic membranes and present in lower levels in esophagus, stomach, and small intestine as well as in conducting airways and pulmonary alveoli. To determine whether gene transfer by intraamniotic injection of adenovirus was dos e-dependent, Av1Luc1, an adenoviral vector carrying the gene for lucif erase (10(5)-10(9) pfu), was injected intraamniotically into fetal mic e at 0.8 term gestation. Luciferase activity measured after 3 d in tis sue homogenates of Av1Luc1-treated fetal mice revealed a linear dose r esponse in amniotic membranes and gastrointestinal and respiratory tra ct organs. Intraamniotic administration of an adenoviral gene vector l eads to expression of the transferred gene in amniotic membranes as we ll as in fetal gastrointestinal and respiratory tract tissues in a dos e-dependent manner.