Vectors for gene therapy

To circumvent this problem, vectors that are based on lentiviruses have been developed. In contrast to prototypic retroviruses, lentiviruses do not require cell division for integration. Gene-therapy vectors have been developed from a broad spectrum of lentiviruses including human immunodeficiency vims (HIV), simian and feline immunodeficiency vims as well as visna/maedi vims. The most widely used lentiviral vector system is based on HIV-1. These vectors can efficiently transduce a broad spectrum of dividing and nondividing cells including neurons, hepatocytes, muscle cells, and hematopoietic stem cells [1,2]. 

Ohlfest, J.R., Freese, A.B., and Largaespada, D.A. 2005. Nonviral vectors for cancer gene therapy prospects for integrating vectors and combination therapies. Current Gene Therapy 5(6), 629-641. 

Figure 6.1 An RNA viral gene therapy vector, engineered to carry the genetic information for a protein product, is incubated with blood or bone marrow cells removed from a patient. The foreign DNA sequence integrates into the cell s genetic material and when the cells are returned to the patient, they direct the production of the protein product. RNA gene therapy vectors are engineered to be unable to direct the production of new virus particles.

Figures are not essential in a patent specification, but it is often the simplest way of including information such as a nucleotide sequence, or details of a purification process for a protein, or details of a new gene therapy vector.

PER.C6 cells have been used extensively for the production of gene therapy vectors. This cell line was derived from the immortalization of human embryonic retina cells through the use of adenovirus El gene (Fallaux et al., 1998). This cell line has been well characterized since its establishment, and no retroviruses or adventitious viruses have been detected in it. This cell line is easily adapted to different growth conditions and stably produces high levels of recombinant proteins. 

HEK-293 cells, derived from human embryo kidney, were transformed with human type 5 adenovirus (Graham et al., 1977). These cells exhibit epithelial morphology and can be adapted to suspension growth in serum-free media. In addition, this cell line is easily transfected and has been explored for viral vector production for gene therapy and for obtaining human recombinant proteins with normal glycosylation profiles. 

G. Biopanning on Cells A New Approach for Cell-Targeting Gene Therapy Vectors... 

Thorrez L, VandenDriessche L, Collen D, Chuah M. Preclinical gene therapy studies for hemophilia using adenoviral vectors. Semin Thromb Hemost 2004 30 173-83. 

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