[Producing recombinant adenovirus encoding green fluorescent protein (Ad-GFP) by suspension cultured HEK-293 N3S cells].

Adenovirus vectors are one of the most promising gene transfer systems. They are of great value for gene therapy because these vectors achieve temporal high-level transgene expression and high gene transfer efficiency. To meet increasing needs of adenovirus vectors for gene therapy programs, parallel development of efficient, scalable and reproducible production processes is required. Perfusion cultivation of 293 cells is one of the most commonly used methods to produce adenovirus vectors and it is suitable for industrialized production specially. Experimental studies had been carried out to produce recombinant adenovirus containing the green fluorescent protein gene (Ad-GFP) by perfusion cultivation of HEK-293 N3S cells in a 5L stirring bioreactors. Perfusion rate was 1-2 volume/day. To infect the 293 N3S cells with Ad-GFP at the density of (2-4) x 10(6) cells/ ml. The time of collecting cells was 48 hours post infection. After three rounds of freeze/thaw and centrifugation, the crude viral lysates were stored at--80 degrees C until use. Then to get the Ad-GFP products by 2 x CsCl-gradient purification. The purity of the products was determined by the A260/A280 ratio and a high performance liquid chromatography (HPLC) assay. The infective titer was determined by a TCID50 assay. The culture term was 10-12 days. The infectious titer, the number of virus particle and the ratio of infectious titer to virus particle for the product were 1.0 x 10(11) IU/mL, 1.68 x 10(12) VP/mL and 6.0% IU/VP respectively. The A260/A280 ratio was 1.33, and the purity determined by HPLC was 99.2%. The cell specific productivity was around 1000 IU/cell. By perfusion cultivation of 293 N3S cells in a 5L stirring bioreactors, we established the production process for Ad-GFP, which paves a way to produce other recombinant adenovirus for gene therapy.

[Plasmid pUDKH gene therapy of rat acute hindlimb ischemia: an experimental study].

OBJECTIVE: To investigate the effect of plasmid pUDKH carrying human hepatocyte growth factor (HGF) gene on rat acute limb ischemia and to find the lowest effective dosage. METHODS: Ligation of femoral artery of one hindlimb in Wistar rats was performed. The rats were randomly divided into 5 groups of 10 rats: pUDKH 50 microg, 100 microg, 200 microg, and 400 microg groups and a vacant vector pUDK group (control group). The plasmids were injected once directly into the ischemic limb muscle (5 sites around ligation position) immediately after ligation. At day 10, the muscles were removed and stained with H.E. to assess histologically the blood vessel formation. HGF expression was detected in the muscle tissue of another 12 rats on days 3, 5, 10, 14, 21, 30 after injection of pUDKH or pUDK, 200 microg each per animal. RESULTS: HGF expression was detected clearly in muscle tissue on days 3, 5, 10, 14 in pUDKH groups. In HGF-transfected animals (except for 50 microg group) neoformation of blood vessels in muscles and soft tissues was found, while it was not seen in controls. By semi-quantitation of the degree of vessel formation, significant differences between pUDKH groups (0.96 +/- 0.07, 1.97 +/- 0.91, 2.26 +/- 1.00 for 100 microg, 200 microg, 400 microg, respectively) and the control group (0.27 +/- 0.04) (P < 0.05) were noted. In addition, injection of pUDKH could alleviate the severity of degeneration of muscular tissue due to ischemia. CONCLUSION: Human HGF gene therapy is effective in treating rat acute limb ischemia with the lowest effective dose of 100 microg.