Gene transfer involves introducing new DNA into a cell. This is typically achieved using vectors such as plasmids or modified viruses.
Here's a breakdown of common methods:
-
Vectors:
- Plasmids: These are small, circular DNA molecules often used to transfer genes into bacteria. Researchers insert the desired gene into the plasmid, which then gets taken up by the bacterial cell.
- Modified Viruses (Viral Vectors): Viruses are naturally adept at entering cells and delivering genetic material. Scientists modify viruses to carry therapeutic genes without causing disease. Adenoviruses, adeno-associated viruses (AAVs), and retroviruses are commonly used as viral vectors.
-
Ex Vivo vs. In Vivo Gene Transfer:
- Ex Vivo Gene Transfer: Cells are modified outside the body. For example, a patient's cells may be extracted, genetically modified in a lab, and then reintroduced into the patient.
- In Vivo Gene Transfer: Genes are directly delivered into the body. This approach often uses viral vectors injected directly into the bloodstream or targeted tissues.
-
Gene Therapy Examples:
- Luxturna: This is an example of in vivo gene therapy using an AAV vector to deliver a functional gene to retinal cells, treating a form of inherited blindness.
- CAR-T cell therapy: This utilizes ex vivo gene transfer, where a patient's T cells are modified to express a chimeric antigen receptor (CAR) which helps them target and kill cancer cells.
-
Methods of Gene Transfer:
- Transfection: This involves introducing DNA into eukaryotic cells (e.g., mammalian cells). It can be achieved through chemical methods, electroporation (using electrical pulses to create temporary pores in the cell membrane), or lipofection (using lipids to encapsulate DNA).
- Transduction: This method uses viruses to deliver genes into cells. The modified virus infects the target cell and delivers the desired gene.
- Transformation: This process is generally used for bacteria, where they take up naked DNA from the environment.
In summary, gene transfer is accomplished by using vectors, like plasmids or modified viruses, to deliver new DNA into a cell, either directly in the body (in vivo) or after modification outside the body (ex vivo).
