Gene therapy is a fundamentally new approach, representing a combination of biomedical technologies for treating gene defects by introducing new genetic constructs into the body that can restore or replace a defective gene. Such therapy allows people to fix errors caused by mutations in the DNA structure or DNA damage by viruses. Treatment with this method is based on the principle of replacement or restoration of a damaged gene. Having received a copy of the gene, the cell is able to use it to synthesize the necessary proteins. Various mechanisms can be used in gene therapy, such as replacing a pathogenic gene with a healthy copy, turning off the gene that causes the disease, and introducing a new or modified gene into the body to help treat the condition.
Viruses are used to introduce new genes, and they have the natural ability to deliver genetic material to cells. Before using the virus to transfer therapeutic genes into cells, it is modified to eliminate the ability to cause disease. After this, DNA is introduced into the non-pathogenic virus through a chemical reaction, and then human cells are infected with this virus, which leads to the movement of DNA into the nuclei of these cells. This method of correction began to be applied after approaches for obtaining isolated genes were developed. Another way to insert genes is to use liposomes, microscopic sacs containing DNA that are absorbed by human cells, thus delivering their DNA to the cell nucleus (Ramamoorthy & Narvekar, 2015). Therefore, there are a number of available vectors for providing the gene therapy.
The testing of the genetic correction of hereditary disease is carried out on the primary cultures of the patient’s cells, in which this gene is normally functionally active. On these cell models, the effectiveness of the selected exogenous DNA transfer system is evaluated, the expression of the introduced genetic construct is determined, its interaction with the cell genome is analyzed, and correction methods are developed at the biochemical level. Using cell cultures, it is possible to create a system for targeted delivery of recombinant DNA, but the reliability of this system can be checked only at the level of the whole organism.
The next step is to solve the problem of a vector that provides efficient, and if possible, even targeted gene delivery to target cells. Then, transfection is carried out, that is, transfer of the obtained construct to target cells, the transfection efficiency, the degree of correctability of the primary biochemical defect in cell cultures in vitro, and, most importantly, in vivo in animal biological models are evaluated. One of the main disadvantages of the method is that when the virus is introduced, a potential reaction to it similar to infection can occur (Dunbar et al., 2018). In addition, new normal DNA may be lost, or it may not be able to invade new cells after some time, which will lead to a relapse of a genetic disease.
In conclusion, it is important to note that the overall development of a gene therapy program is preceded by a thorough analysis of tissue-specific expression of the corresponding gene, identification of the primary biochemical defect, study of the structure, function and intracellular distribution of its protein product, as well as biochemical analysis of the pathological process. All these data are taken into account when drawing up the appropriate medical protocol.
Dunbar, C. E., High, K. A., Joung, J. K., Kohn, D. B., Ozawa, K., & Sadelain, M. (2018). Gene therapy comes of age. Science, 359(6372), 1-10. Web.
Ramamoorth, M., & Narvekar, A. (2015). Non viral vectors in gene therapy – an overview. Journal of Clinical and Diagnostic Research: JCDR, 9(1), 1-6. Web.