How gene therapy works
Gene therapy is the general name of technologies (as well as relevant drugs) aimed at amending the genetic apparatus of human somatic cells for the treatment of various diseases. The genes are encoded in deoxyribonucleic acid (DNA) and contain all the information needed to form and live the cells. The history of the development of gene therapy began in 1972, when American scientists from Stanford University discovered the phenomenon of direct transfer of DNA fragments from one E. coli bacterium to another by direct contact of these cells.
Minor changes in the DNA of genes - so-called genetic variations - can provoke the development of serious diseases. Such changes occur when incorrect copying of information encoded in genes: this leads to the formation of incomplete proteins, which cause diseases. Gene therapy is used to eliminate the root cause of the disease, which allows tissues and organs to begin to function normally. In simple words, the method focuses on correcting defects caused by changes in the structure of DNA, for example, as a result of a virus lesion.
Gene Therapy Indications
Gene therapy is seen as a potentially one-size-fits-all approach to treating a wide range of ailments. These can be hereditary, multifactorial and infectious diseases, malignancies, etc. Among the diseases for which gene therapy methods are being developed, a significant part falls on various types of cancer. Malignant transformation of the cell occurs as a result of the accumulation of genetic defects leading to abnormal growth. The immediate cause is an imbalance in cell proliferation and death. Therefore, the development of methods for correcting these defects is the basis of gene therapy for malignancies.
 | One of the newest technologies in cancer gene therapy is "silent genes" technology. This type of gene therapy uses the phenomenon of so-called RNA interference or RNA silencing. The patient is injected with a certain cocktail of small interfering RNAs that silence those genes that actively work in the tumor. This causes either knockout of these genes or a pronounced decrease in their expression, for example, proto-oncogenes or growth or polypherization genes of any tissue. Thus, there is a genetic suppression of tumor progression, - said Zdrav.Expert the geneticist of a large medical company, doctor of medical sciences Lilya Dzhemileva. |  |
Gene therapy technologies
The types of genes used in the appropriate therapy are diverse, and their choice is determined by the mechanisms of development of the disease. One of the most difficult problems in gene therapy is the delivery of the required gene to the desired tissues while minimizing its contact with the biological media of the body before reaching the target cell, as well as ensuring the delivery of the gene to the desired cell in order to operate it efficiently and safely.
Virus transfection
In this case, full-fledged DNA is introduced into the virus through a chemical reaction, and then human cells are infected (transfected) with this virus, which leads to the movement of DNA into the nuclei of these cells. However, with this approach, a serious side effect can be observed: there is a risk of the body's reaction to the virus, similar to the reaction to infection.
| | The main way to deliver the desired genetic material into the cell is a viral vector. Adenoviruses are most often used for this, since they are widespread in the human population in the form of an adenovirus infection, which each of us can carry in childhood. A copy of the desired gene is injected into this modified virus, in which viral DNA has been removed, but the viral envelope has been preserved. This version of the therapeutic material is often used for gene therapy of diseases, - notes Dzhemileva. | |
Liposomes
This method of gene insertion is based on the use of liposomes - spherical vesicles having one or more lipid bilayers. They are taken up by cells, allowing DNA to be delivered to certain parts of the body.
Using antisense nucleic acids
This method is aimed at disabling the functions of pathological genes. Special drugs connect to certain DNA fragments, preventing the affected genes from functioning. Method is aimed primarily at therapy of malignant formations. However, this technique has the potential for greater efficacy and safety compared to gene insertion therapy.
Transplant therapy
This approach changes genes in transplanted organs. This reduces the likelihood of rejection in the recipient, which increases the chances of surgical success. As a result, the transplant recipient may not need to take special drugs that suppress the immune system.
Chemical modification
The essence of the method is to increase or decrease the activity of certain genes by changing cellular chemical reactions that control gene expression. Thanks to this method, it is possible, for example, to control the production of certain proteins. The method is suitable for the treatment of certain types of malignancies.
CRISPR/Cas9
Main article: CRISPR (gene editing system)
These are powerful tools of gene modification that open up new opportunities in terms of eliminating the causes of hereditary diseases and increasing the body's resistance to senile ailments. The desired effect is achieved by correcting the original DNA or inserting a new gene at a specific DNA location.
Gene therapy products
Main article: Gene therapy drugs
By August 2023, biological drugs have been developed in which the active substance contains or consists of recombinant nucleic acid used to regulate, replace, add or remove the genetic sequence. An example is Zolgensma, which is used to treat spinal muscular atrophy (SMA) in children under two years of age. However, such drugs are extremely expensive: the dose price (administered once) exceeds $2 million.
| | Like any therapy or drug, gene therapy also has side effects, dangers and contraindications. The first is the danger of delivering genetic material to the wrong type of cell and, accordingly, the inefficiency of administering a gene therapy drug. Second, if these drugs are somehow modified and specifically make changes to the patient's genome, then this is fraught with the emergence of various clones of malignant cells due to a modification of the patient's genetic material. The third is the risk of manifestation of viral infections when using various viral constructs, says Dzhemileva. | |
Chronicle
2024
Developed by the American Bluebird bio gene therapy for diseases of the nervous system led to seven cases of blood cancer
In mid-October 2024, it became known that seven cases of blood cancer were detected during studies of the gene therapy Skysona manufactured by Bluebird bio. Read more here
Glaucoma began to be treated with gene therapy
In mid-September 2024, scientists at Trinity College Dublin unveiled a promising gene therapy to treat glaucoma. Earlier, the same team discovered the possibility of gene therapy for the dry form of age-related macular degeneration, another eye disease leading to blindness. Read more here
A revolutionary gene therapy method has been developed that has improved the vision of patients by 10,000 times
In mid-September 2024, the results of a trial of a new gene therapy for Leber congenital amaurosis, which allows patients to improve their vision 100 or even 10,000 times, were published.
Leber type 1 congenital amaurosis (LCA1) is a rare inherited retinal disease that develops as a result of mutations in the GUCY2D gene and leads to almost complete loss of vision starting in infancy. The new gene therapy ATSN-101 directly affects the cause of the disease, that is, the defective GUCY2D gene: in this type of treatment, a functional copy of this gene is delivered directly to the photoreceptor cells of the retina, thereby restoring their functionality and allowing the cerebral cortex to receive and analyze data about the environment. The study, published in the journal Lancet, included 15 patients with the disease who were given the drug once in one eye and then compared the improvement over the other eye. All patients had a qualitative jump.
A 10,000-fold improvement in vision is tantamount to "a patient now being able to see their surroundings on a moonlit night outside, although before treatment he needed bright indoor lighting to see something," said lead author Arthur Sidesiyan, director of the Center for Inherited Retinal Degenerations.
It is important to note that the observed improvement in vision turned out to be quite persistent - the improvement was recorded as early as the 28th day of the study and persisted until the 12th month. One of the patients was even able to move outside at midnight, using only a bonfire as a light source, the researchers said. Scientists hope this revolutionary drug can be a true panacea for patients with Leber's congenital amaurosis.[1]
New revolutionary gene therapy successfully restored hearing in deaf baby
On May 9, 2024, British researchers from Addenbrooke's Hospital in Cambridge reported the successful use of revolutionary gene therapy, which allowed the hearing of a deaf baby to be restored. This event, according to doctors, marks a new era in the treatment of deafness.
The patient was Opal Sandy, who was born with auditory neuropathy. This is a pathological condition in which the passage of a nerve pulse from the inner ear to the brain is disturbed. Normally, this function is performed by the auditory nerve, but when it is affected, signaling is disrupted.
Auditory neuropathy can be caused by a defect in the OTOF gene, which produces a protein called otoferlin. This allows ear cells to interact with the auditory nerve. The new therapy, developed by biotech firm Regeneron, involves "sending" a working copy of the gene to the ear to fix a signaling problem.
Four weeks after undergoing gene therapy in her right ear, Opal Sandy began responding to sounds even when a special implant in her left ear was turned off. Clinicians noted a stable improvement in hearing in the girl, who turned 18 months old as of May 2024. Moreover, the hearing level of silent sounds, such as whispers, approached normal. The baby can react to the voices of her parents and utter simple words.
Gene therapy is specifically designed for children with OTOF mutations. A harmless virus is used to transfer the working gene into the patient's body. Dr. Richard Brown, one of the study participants, says that the development of genomic medicine and alternative treatments is vital for patients around the world. This approach gives hope to children with previously incurable diseases.[2]
They began to apply a new gene therapy that restores hearing in people with congenital deafness
On January 24, 2024, the Massachusetts Ophthalmic and Otolaryngological Hospital (MEE) reported that American and Chinese specialists successfully introduced gene therapy to restore hearing in children suffering from congenital deafness. We are talking about a DFNB9 mutation in the OTOF (otoferlin protein) gene, which leads to the impossibility of transmitting sound signals from the ear to the brain.
It is noted that hearing loss affects more than 1.5 billion people worldwide, with about 26 million of them suffering from congenital deafness. Hearing disorders in children in more than 60% of cases are due to genetic causes. For example, DFNB9 is an inherited disease in which a child is born deaf.
The study involved 6 children with DFNB9 who were followed for 26 weeks at Fudan University Hospital in Shanghai. All patients aged 1 to 6 years had two mutant copies of the OTOF gene and experienced complete hearing loss prior to treatment. The gene therapy they received contained adeno-associated viruses whose genes were removed and replaced by the OTOF gene. The therapy was performed through the membrane separating the middle ear from the inner ear.
All but one of the children were reported to have a stable hearing recovery within 26 weeks of the procedure. Improvements began to show up about four to six weeks after treatment, along with improved speech perception. According to experts, the treatment did not cause any serious side effects, although fever and changes in the number of white blood cells were observed. In general, as noted, the study confirms the safety and effectiveness of gene therapy in the treatment of DFNB9, and also speaks of the possibility of using the method in other forms of genetic hearing loss.[3]
2023: Chronic pain started being treated with gene therapy
On July 27, 2023, American researchers from New York University announced the development of a new method for treating chronic pain based on gene therapy. Read more here.
See also
- Genetic engineering (genetic engineering)
- National Genetic Information Base
- Genome
- Genetic data banks (biobanks, biorepositories, storing biological samples)
- Genomics and Bioinformatics in Russia
- Chromosomes
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