In this type of somatic cel Gene therapy the functional gene introduced in addition so the defective gene endogenous to the cells the modified cell contain both the defective well as the normal copies of the gene. There are two general approaches to augmentation therapy. The first approach was used in the two general approaches to augmentation therapy. The first approach was used into the first two patients on whom gene therapy was attempted to correct the genetic disorder called Servere Combined Immune Deficiency syndrom produced by adenosine deaminase deficiency (1) normal gene copies was produced by cloning and the (2) packing into a defective retrovirus most of the viral genes were replaced by ADA gene(3) Lymphocytes were isolated from the patients and (4) the infected cells expressing the ADA gene were injected back the patients. The normal ADA gene was expressed the patients and ADA deficiency was portially corrected this resulted in an improvement in the patients immune system.
The variety of viral vectors have been used to deliver genes into the stem cells bone marrow cells cultured in vitro.
The second approach is the direct injection of DNA into the tissues either protein complexes into order to bring about receptor mediated transfer of DNA into specific tissue or even flaked DNA into muscle skin. Exciting result have been obtained with experimental hypercholesrolemia where IDI receptor levels have been augmented by injection of the gene as s sialoglycoprotein complex. THe problems in this approach as well related to the frequency of cells taking up and expressing the gene and more particularly the duration of expression. The gene delivery methods used for gene therapy can also be used for treatment of cancer. In case of cancer a toxin encoding gene can be delivered into the cancer cells. Similarly, appropriate interleukin genes can be delivered to boos the body defence mechanism.