ADENOVIRAL-MEDIATED GENE-TRANSFER TO FETAL PULMONARY EPITHELIA IN-VITRO AND IN-VIVO

Vector-mediated gene transfer offers a direct method of correcting gen etic pulmonary diseases and might also be used to correct temporary ab normalities associated with acquired, nongenetic disorders, Because th e fetus or newborn may be a more immune tolerant host for gene transfe r using viral vectors, we used replication defective recombinant adeno viral vectors to test the feasibility of gene transfer to the fetal pu lmonary epithelium in vitro and in vivo, Both proximal and distal epit helial cells in cultured fetal lung tissues from rodents and humans di ffusely expressed the lacZ transgene 3 d after viral infection, In viv o gene delivery experiments were performed in fetal mice and lambs, De livery of Ad2/CMV-beta Gal to the amniotic fluid in mice produced inte nse transgene expression in the fetal epidermis and amniotic membranes , some gastrointestinal expression, but no significant airway epitheli al expression, When we introduced the adenoviral vector directly into the trachea of fetal lambs, the lacZ gene was expressed in the trachea l, bronchial, and distal pulmonary epithelial cells 3 d after viral in fection, Unexpectedly, reactive hyperplasia and squamous metaplasia we re noted in epithelia expressing lacZ in the trachea, but not in the d istal lung of fetal lambs, 1 wk after infection, adenovirus-treated fe tuses developed inflammatory cell infiltrates in the lung tissue with CD?, CD8, IgM, and granulocyte/macrophage positive immune effector cel ls, Transgene expression faded coincident with inflammation and serolo gic evidence of antiadenoviral antibody production, While these studie s document the feasibility of viral-mediated gene transfer in the pren atal lung, they indicate that immunologic responses to El-deleted reco mbinant adenoviruses limit the duration of transgene expression.