الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 172 |  |  |
| | | from | 172 | | |
Abstract
gene therapy is a medical procedure in which the cell genetic structure is manipulated or modified by adding one or more genes to achieve a desired result. It can be used to cure or treat diseases or illnesses that have been caused either by malfunctioning genes or by the absence of certain essential genes in the cells.
The liver has become an important target organ for gene therapy because it has the ability to synthesize large amounts of different proteins and performs many posttranslational modifications required for proper function of those proteins. It is also able to regenerate after partial injury.
Many systemic inherited disorders such as hemophilia, familial hypercholesterolemia, Crigler Najjar syndrome, Alpha-1 antitrypsin deficiency and other metabolic diseases could be treated by addressing the underlying genetic defect in liver cells. In addition, gene therapeutic strategies could theoretically be used to treat acquired diseases such as viral infections of the liver, liver cirrhosis and heptocelular carcinoma.
Gene therapy protocols can be categorized into two procedural approaches, ex vivo approach which involves the use of autologus cells where the transduction of therapeutic gene is carried out in the laboratory then modified cells are returned and reinfused via the portal vein in the same patient’s liver and in vivo approach in which the therapeutic nucleic acid sequence complementary to the defective gene is directly inoculated into the patient without premanipulation in laboratory and without utilizing harbouring cells.
In the process of gene therapy, gene transfer vectors are used to transfer the gene or genes of interest (transgene) to the target cells. Numerous viral and nonviral vectors have been designed.
Gene therapy involves many therapeutic concepts including gene repair, gene substitution, hepatocyte transplantation, block of gene expression or function (by using of ribozymes, small interfering RNA, antisense oligonucleotides and interfering peptides or proteins), DNA vaccination, gene augmentation (as suicide gene therapy and antiangiogenic gene therapy), oncolytic viruses and immune therapy.