Gene Delivery Using Physical Methods - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 91

gene expression, and elevated serum IL-12 and IFN- levels significantly prolonged
the survival periods by both growth inhibition of orthotopic HCC and inhibition of
spontaneous lung metastasis [55] . Based on these various studies, phase I clinical
trial of IL-12 plasmid for treatment of metastatic melanoma was conducted, and the
results indicated that the method was safe, effective, reproducible, and titratable, with
significant metastasis inhibition [56] .
The liver is one of the most assessable organ for gene transfer because of its
vasculature and portal vein structure. Naked DNA delivery for treatment of various
liver disorders followed by EP demonstrated significant DNA expression. In vivo
electropermeabilization of the liver tissue of rats in the presence of genes encoding
luciferase or -galactosidase resulted in the strong expression of these genetic mark-
ers in rat liver cells. About 30-40% of the rat liver cells electroporated expressed the
-galactosidase genetic marker 48 h after EP [57] . In vivo electrotransfection effi-
ciency and manner of transferred gene expression were also investigated by fluores-
cence microscopic image analysis, using the GFP gene as the genetic marker in rats.
EP was carried out on the liver of live rats, using disk electrodes mounted in the tips
of tweezers, which were directly pressed onto the surface of a liver lobe in situ . Bright
fluorescence of GFP appeared as dots, which were scattered around the area damaged
by EP [58] . GFP gene delivery by portal vein infusion of DNA into liver followed by
EP has also demonstrated significant transgene expression [59] . The results were fur-
ther extrapolated to delivery of the hepatocyte growth factor (HGF) gene by EP into
liver for treatment of rat liver cirrhosis, with significant DNA expression, thus sug-
gesting a role of this method in liver disorder management [59] .
To increase the levels of pulmonary gene transfer by nonviral vectors, EP was
used for the treatment of lung disorders. Delivery of saline solution containing dis-
solved plasmids expressing luciferase, or -galactosidase under control of the cyto-
megalovirus (CMV) immediate-early promoter and enhancer followed by EP have
shown significant transgene expression up to 7 days without any significant lung
toxicity [60] . The gene expression appeared to be concentrated in the periphery of
the lung but was also present throughout the parenchyma. Further, delivery of HGF,
which shows antiapoptotic and fibrinolytic activity, was achieved by delivering it to
the quadriceps skeletal muscles of mice, followed by EP, in bleomycin-induced lung
fibrotic animals. The results indicated that HGF gene therapy with a single skeletal
muscle-targeting EP has a therapeutic potential for bleomycin-induced lung fibro-
sis, and this strategy can be applied as a practical gene therapy protocol for various
organs [61] .
By using in vivo EP, treatment of renal disorders has also been achieved. The
EPO production system using naked plasmid and in vivo EP using plasmids encod-
ing the chimeric gene switch protein and inducible transgene for human EPO was
developed. Modulation of the level of secretion of EPO into the serum was achieved
by intraperitoneal administration of mifepristone (MFP). The delivery of plasmids in
skeletal muscles of the thigh, followed by EP, was carried out, and the level of serum
EPO was estimated to determine gene expression efficiency [62] . These results dem-
onstrated that EPO gene transfer with the gene switch system using in vivo EP is
a beneficial procedure for efficient and drug-dependent regulated delivery of EPO.