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An analysis of the emerging patent landscape of gene therapies under development, focusing on non-viral vectors.The possibility of persistently modifying mammalian cells represents an attractive field for molecular and cell biologists. A system that provides efficient, persistent and stable expression of transferred genes in mammalian cells may be a useful tool for a variety of applications, such as gene regulation, disease modeling, drug testing and gene supplementation for therapeutic correction. In 1990, researchers at the US National Institutes of Health conducted the first licensed gene therapy on an individual born with a rare genetic disease called severe combined immunodeficiency. This trial was a success and encouraged the expansion of the gene therapy field with the aim of treating other patients. However, in the following years, patients treated with gene therapy presented substantial adverse events. In 1999, the first severe adverse event was reported when an individual suffering from ornithine transcarbamylase deficiency had received a dose of an adenoviral vector carrying a

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BackgroundHemophilia A is a bleeding disorder caused by deficiency in coagulation factor VIII. Recombinant factor VIII (rFVIII) is an alternative to plasma-derived FVIII for the treatment of hemophilia A. However, commercial manufacturing of rFVIII products is inefficient and costly and is associated to high prices and product shortage, even in economically privileged countries. This situation may be solved by adopting more efficient production methods. Here, we evaluated the potential of transient transfection in producing rFVIII in serum-free suspension HEK 293 cell cultures and investigated the effects of different DNA concentration (0.4, 0.6 and 0.8 μg/106 cells) and repeated transfections done at 34° and 37°C.ResultsWe observed a decrease in cell growth when high DNA concentrations were used, but no significant differences in transfection efficiency and in the biological activity of the rFVIII were noticed. The best condition for rFVIII production was obtained with repeated transfections at 34°C using 0.4 μg DNA/106 cells through which almost 50 IU of active rFVIII was produced six days post-transfection.ConclusionSerum-free suspension transient transfection is thus a viable option for high-yield-rFVIII production. Work is in progress to further optimize the process and validate its scalability.