DNA delivery to 'ex vivo' human liver segments

Hydrodynamic injection is an efficient procedure for liver gene therapy in rodents but with limited efficacy in large animals, using an 'in vivo' adapted regional hydrodynamic gene delivery system. We study the ability of this procedure to mediate gene delivery in human liver segments obtained by surgical resection. Watertight liver segments were retrogradely injected from hepatic vein with a saline solution containing a plasmid bearing the enhanced green fluorescent protein (eGFP) gene, under different conditions of flow rate (1, 10 and 20 ml s(-1)) and final perfused volume. Samples were cultured for 1 to 2 days and used for microscopy and molecular analysis of gene expression. The fluorescent and immunohistochemistry studies indicated that in segments injected at ≥10 ml s(-1), good and wide gene expression was present in the liver sections and the molecular analysis reinforced the histological observation in a quantitative manner (index of apparent gene delivery: 10(2)-10(4) eGFP DNA copy per 100 pg of total DNA; transcription index: 10(5)-2 × 10(6) eGFP RNA copy per 100 ng of total RNA). In addition, injected gold nanoparticles (15 nm diameter) suggested that DNA delivery to hepatocytes must involve a facilitated permeation process without membrane disruption. In summary, we show that retrograde venous injection of watertight human liver segment is an anadromous procedure that results in wide liver gene delivery and good gene expression. However, additional studies will be necessary to clarify the influence of the prolonged ischemia injury to hepatocytes in our model.