Gene delivery

Gene delivery is the process of introducing foreign DNA into host cells. Gene delivery occurs throughout nature as horizontal gene transfer from one organism to another and is a mechanism of evolution. It is also one of the steps necessary for gene therapy and, for example, has applications in the genetic modification of crops. There are many different methods of gene delivery for various types of cells and tissues, from bacterial to mammalian.

For gene delivery to be successful, foreign DNA must survive long enough in the host cell to integrate into its genome. This requires foreign DNA to be synthesized as part of a vector, which is designed to enter the desired host cell and deliver the transgene to that cell's genome. Vectors utilized as the method for gene delivery can be divided into two categories, non-viral and viral.

In complex multicellular eukaryotes (more specifically Weissmanists), if the transgene is incorporated into the host's germline cells, the resulting host cell can pass the transgene to its progeny. If the transgene is incorporated into somatic cells, the transgene will die with the somatic cell line, and thus its host organism.

Non-viral methods of gene delivery can be divided into transformation, where a cell incorporates foreign DNA from its surroundings, and conjugation, where gene transfer is a result of direct contact between two cells. Both methods utilize plasmids, which carry DNA inside a cell that can replicate independently of chromosomal DNA. This is the DNA that can be transferred to another organism. Artificial non-viral gene delivery can be mediated by physical methods such as electroporation, microinjection, gene gun, impalefection, hydrostatic pressure, continuous infusion, sonication and lipofection. It can also include the use of polymeric gene carriers (polyplexes).

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