Decline in exogenous gene expression in primate brain following intravenous administration is due to plasmid degradation.
OBJECTIVE
Nonviral gene transfer to the brain of adult Rhesus monkeys is possible with a single intravenous administration of plasmid DNA that is encapsulated in the interior of pegylated immunoliposomes, which are targeted across membrane barriers in vivo with a monoclonal antibody to the human insulin receptor.


METHODS
The present studies measure the rate of decay of luciferase gene expression in the Rhesus monkey with luciferase enzyme assays, Southern blotting, and real-time polymerase chain reaction.


RESULTS
Luciferase enzyme activity in frontal cortex, cerebellum, and liver decays with a t(1/2) of 2.1 +/- 0.1, 2.6 +/- 0.2, and 1.7 +/- 0.01 days, respectively. Luciferase plasmid in brain and liver was detectable by Southern blotting at 2 days, but not at 7 or 14 days. The concentration of luciferase plasmid DNA in brain and liver was measured by real-time polymerase chain reaction, and decayed with t(1/2) of 1.3 +/- 0.3 and 2.7 +/- 0.5 days, respectively.


CONCLUSIONS
The maximal concentration of luciferase plasmid DNA in Rhesus monkey brain was 3-4 molecules/cell following an i.v. administration of 12 microg/kg pegylated immunoliposome encapsulated plasmid DNA. These results demonstrate that the rate of loss of exogenous gene expression in the primate in vivo correlates with the rate of DNA degradation of the exogenous plasmid DNA.
Chu
Chun
C
Department of Medicine, UCLA, UCLA Warren Hall 13-164, 900 Veteran Avenue, Los Angeles, CA 90024, USA.
Zhang
Yun
Y
Boado
Ruben J
RJ
Pardridge
William M
WM
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000276:immunology; D015703:Antigens, CD / Q000235:genetics* / Q000276:immunology; D001921:Brain / Q000378:metabolism*; D004247:DNA / Q000032:analysis / Q000302:isolation & purification; D005260:Female; D018390:Gene Targeting; D017930:Genes, Reporter; D005822:Genetic Vectors; D006207:Half-Life; D008081:Liposomes; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008156:Luciferases / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics*; D008253:Macaca mulatta; D010957:Plasmids / Q000008:administration & dosage* / Q000032:analysis / Q000302:isolation & purification; D011092:Polyethylene Glycols; D011972:Receptor, Insulin / Q000235:genetics* / Q000276:immunology; D013997:Time Factors
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D008081:Liposomes; D011092:Polyethylene Glycols; D004247:DNA; D008156:Luciferases; C435941:INSR protein, human; D011972:Receptor, Insulin