Gene transfer techniques

Gene transfer techniques Success of gene therapy lies in efficient gene transfer into the cell. The gene (cDNA) is generally cloned into a vector to be able to deposit the foreign gene into the target cell. Selection of the right vector is crucial to gene ther-apy. An ideal vector should be able to protect and deliver DNA easily across the cell membrane into the nucleus, should have the ability to regulate expression of the gene of interest and minimize toxicity by targeting gene delivery to specific cells. It should be easy and inexpensive to produce in large quantities. Once the therapeutic gene is cloned into a vector with appropriate regulatory sequences (promoter/enhancer), it is introduced into the target cells. The genes can be delivered either ex vivo –where cells from a selected tissue of the patient are removed, exposed to the gene-transfer vector, selected forthe transgene using markers, and then the genetically cor-rected cells are reintroduced into the patient’s body; or in vivo where the vector DNA is injected directly into the body, generally into the tissue to be treated. Physical and chemical methods of gene transfer Various methods have evolved in the past few years to transfer genes to the target cells. Physical methods such as (a) microinjection of DNA into the cells or (b) electroporation, although very efficient, have their drawbacks in delivering genes in vivo. Also they are expensive as they involve use of specialized instruments. Chemical methods such as (a) calcium phosphate precipitation, where DNA in trapped in a fine precipitate which is endocytosed by the cell, or (b) DNA bound to the positively charged molecules such as DEAE-dextran or polybrene which then bind to the negatively charged cell membrane, are commonly used in the laboratories. DNA encapsulated in synthetic cationic lipid vesicles which fuse with the cell membrane and release DNA into the cell are being used in a number of gene therapy trials 2. Cationic liposome-mediated gene transfer is a safe and effective means of delivering genes directly into tumours. This approach prevents undesirable side effects.

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Gene Therapy for Cancer

Gene therapy, the latest development in the field of medicine, is based on manipulating, or changing the genetic material to treat and prevent the appearance of certain diseases that are difficult to heal with normal treatment. Gene therapy involves the introduction of genes, the biological unit of heredity, in cells or tissues of people who suffer from diseases like cancer. Gene therapy is done for the first time on September 14, 1990 by a group of physicians, consisting of W. French Anderson, MD and his colleagues Michael R. Blaese, MD, Bouza C. Institute and Kenneth Culver, MD, U. S. National Health. Performed in a four-year-old child suffering from "severe immunodeficiency combined, a rare genetic disease. Gene therapy can be classified into two main types of germ-line gene therapy and somatic gene therapy. Germline gene therapy involves the introduction of functional genes in the germ or reproductive cells (sperm and eggs) from the body, while in the case of somatic gene therapy, therapeutic genes are introduced into somatic cells. Gene therapy consists primarily in changing the genetic material (DNA and genes), and plays a key role in determining individual traits and characteristics. It has added a new dimension to cancer treatment, which is caused by mutation or DNA damage that leads to uncontrolled growth of abnormal cells. Most research was conducted and some are still underway to discover the potential of gene therapy in the treatment of breast, lung, prostate, bone, and leukemia. Different approaches for gene therapy to treat cancer, mainly concentrated or destroy or prevent growth of cancer cells or improve the ability of normal cells to fight cancer cells. If cancer is caused due to missing or changed genes, then gene therapy is the replacement of these genes with healthy ones. In addition, gene therapy can be done to stimulate the immune system to attack cancer cells. Through this technology, genes can be inserted into the patient's body, which, to instruct the cancer cells to produce certain proteins to inhibit stimulated Oncogenes cause cancer or tumor suppressor genes. Several other studies also underway to introduce genes into cancer cells, which can help make cancer cells more sensitive to various cancer treatments, including chemotherapy and radiotherapy. In addition, investigations are also underway to reduce the side effects of anticancer drugs to different cells increased resistance to flow. However, gene therapy, genes are introduced directly into the patient's body, but the virus used for this purpose. The virus is generally used for this therapy are retrovirus, adenovirus, herpes virus, lentivirus and poxviruses. Sometimes, liposomes (a small vesicle in a cell to shops and transport of substances in a cell) is also used as carriers in gene therapy. The virus can be used for both ex vivo and in vivo gene therapy. Ex vivo gene therapy involves the collection of blood or less bone marrow cells of the patient. Then the virus to insert genes into cells are needed in a laboratory, then injected into the patient's body. Furthermore, in vivo gene therapy involves the direct introduction of viruses or liposomes containing the desired gene in the patient's body. However, gene therapy is not without its drawbacks. One of the potential risks associated with gene therapy on the possibility of infection of healthy cells caused by the virus used to deliver the gene. Moreover, if genetic material is accidentally introduced into germ cells, then changes induced by it, will become the next generation. Again, this is very important to insert the desired gene in the right place, which can lead to failure and cause genetic mutations and cancer. More research is needed to eliminate the shortcomings of gene therapy, so you can truly revolutionize the treatment of life-threatening diseases like cancer.

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