INTRAPERITONEAL IN-VIVO GENE-THERAPY TO DELIVER ALPHA-1-ANTITRYPSIN TO THE SYSTEMIC CIRCULATION

The utility of replication-deficient recombinant adenovirus vector-med iated transfer and expression of the alpha-antitrypsin (alpha 1AT) cDN A to peritoneal mesothelial tissues was evaluated as a means of delive ring alpha 1AT to the systemic circulation. Preliminary studies with A d. RSV beta gal, an adenovirus vector expressing the Escherichia coli lacZ gene (beta-galactosidase), showed that intraperitoneal injection of 10(9) plaque-forming units (pfu) to cotton rats resulted in beta-ga lactosidase activity in mesothelial cells lining the peritoneal cavity . After intraperitoneal administration of 10(9) pfu of Ad alpha 1AT (a n adenovirus vector containing the human alpha 1AT cDNA), human alpha 1AT was detectable in serum for up to 24 days, with a maximal level of 3.4 mu g/ml at 4 days. Expression of the exogenous gene was localized to the peritoneal mesothelium as PCR analyses detected no evidence of expression of the exogenous gene in any other tissues evaluated. Anti -adenovirus vector antibodies were detectable in serum after intraperi toneal administration of the recombinant vectors, including antibodies with neutralizing activity. Repeat administrations of adenovirus vect ors to the peritoneal cavity at 1 wk and 1 mo after the initial dose f ailed to show gene expression, but repeat administration 3 mo after de monstrated measurable gene transfer and expression. Together these obs ervations suggest replication-deficient adenovirus-mediated gene trans fer to the peritoneal mesothelium offers a promising means to transfer alpha 1AT to the systemic circulation, although immunity induced agai nst the adenovirus may limit frequent repetitive dosing.