OVEREXPRESSION OF HUMAN METHYLMALONYL COA MUTASE IN MICE AFTER IN-VIVO GENE-TRANSFER WITH ASIALOGLYCOPROTEIN POLYLYSINE DNA COMPLEXES

Methylmalonic acidemia resulting from genetic deficiency of methylmalo nyl CoA mutase (MCM) is an often fatal metabolic disease. Somatic gene therapy for this disorder may require gene replacement in the liver. We describe overexpression of MCM in the liver of mice after in vivo g ene delivery using asialoglycoprotein/polylysine/DNA (ASO/PL/DNA) targ eted delivery to the liver of plasmids expressing recombinant MCM. Aft er intravenous administration of the ASO/PL/DNA complex, the vector se quences are cleared from the blood with t(1/2) = 2.5 min and >95% of t he vector is taken up by the liver. Vector sequences are cleared from the liver with t(1/2) = 1.0-1.3 hr. MCM enzyme activity in the liver i ncreases to levels 30-40% over baseline 6-24 hr after injection. No ac ute or chronic toxicity was observed. This net level of expression is likely to be therapeutic for MCM if the complex could be administered repetitively to treat acute episodes of life-threatening acidosis or e stablish a steady-state level of MCM activity. Repetitive administrati on of the ASO/PL/DNA complexes in mice was associated with formation o f antibodies against asialo-orosomucoid and the asialo-orosomucoid com plex but not against DNA.