Researchers from the Hebrew University and University College London have developed an antioxidant therapy based on AAV vectors. The therapeutic sequence is activated in response to abnormal electrical activity in the brain. More than half of the treated rats were prevented from having seizures, and in the remaining animals they were significantly reduced.
Garden healing Experimental, activated in response to abnormal electrical activity in the brain, prevented Convulsions in more than half of the treated rats and significantly reduced seizures in the remaining animals. The treatment was developed by researchers from the Hebrew University of Jerusalem, in collaboration with researchers from University College London.
The treatment is based on viral vectors of the type AAV, which are designed to deliver a genetic sequence to brain cells that increases the defense mechanisms against Oxidative stressThe system was designed so that the therapeutic sequence would be activated mainly in the cells participating in the abnormal electrical activity, and would not operate at a constant intensity in all brain cells.
The results were obtained in the model of epilepsy In rats. This is a preclinical stage, and it is not yet known whether the treatment will be safe and effective in humans.
Epilepsy is one of the most common neurological diseases in the world. It is characterized by recurrent seizures, caused by increased and uncontrolled electrical activity in groups of nerve cells in the brain.
The manifestation of the seizure depends on the area where the abnormal activity begins and the extent of its spread. A seizure may manifest itself in convulsions, muscle twitches, visual or sensory disturbances, temporary detachment from the environment, or loss of consciousness.
According to Dr. Tawfiq Sheikh Ahmed of the Hebrew University School of Pharmacy, approximately one-third of epilepsy patients do not have drug treatment that prevents seizures or reduces them sufficiently. Therefore, there is a need to develop new treatment approaches.
The vicious cycle of oxidative stress
Dr. Sheikh Ahmed's laboratory is investigating the link between epilepsy and oxidative stress. This is a condition in which cells produce a large amount of active molecules called free radicals, and the cell's defense systems are unable to neutralize them.
Free radicals are also formed as part of normal cell activity, including during energy production processes. When they are formed in excessive amounts, they can damage proteins, cell membranes, and genetic material.
The abnormal electrical activity that occurs during an epileptic seizure increases energy consumption and metabolic load in nerve cells. This may result in increased production of free radicals and oxidative damage.
The damage may impair the function of nerve cells and increase the tendency of the neural network to further abnormal activity. Thus, a cycle may develop in which seizures increase oxidative stress, which in turn contributes to the worsening of the disease.
According to Dr. Sheikh Ahmed, the question of whether seizures initially increase the production of free radicals, or whether the radicals themselves contribute to the development of further seizures, is still being investigated. The existing evidence suggests that the two processes may feed each other.
Two key targets in the cell's defense system
The researchers focused on two factors that affect the oxidative balance in cells.
The first is nrf2, a transcription factor protein. When activated, it promotes the expression of many genes related to the defense systems against oxidative stress. In this way, it helps cells produce enzymes and proteins that neutralize oxidizing molecules and help repair damage.
The second factor is NADPH Oxidase, a family of enzymes that produce reactive oxygen molecules. During abnormal electrical activity, their activity may contribute to increased production of free radicals.
A possible therapeutic approach could therefore work in two directions: increase Nrf2 activity and antioxidant defense mechanisms, or reduce NADPH Oxidase activity and free radical generation.
Garden care Operated on demand
In the study, supported by a grant from the National Science Foundation, the researchers examined a treatment based on Adeno-associated virus vectors, known as AAV for short.
These carriers are engineered to be used to deliver genetic material into cells. They are not intended to replicate in the body or cause disease.
In conventional gene therapy, the therapeutic sequence may continue to operate in cells for a long time. This may be an advantage, but it can also cause the system to operate when it is not needed.
To improve control of the treatment, the researchers developed an on-demand system. The AAV carriers carried a genetic switch that was sensitive to increased neural activity.
When the electrical activity in the cell is normal, the expression of the therapeutic sequence remains low. When abnormal activity similar to that which occurs in an epileptic seizure begins, the switch is activated and increases the antioxidant defense mechanisms.
This does not mean that the virus itself awakens or begins to multiply. The carrier remains in the cell, while the genetic switch activates the therapeutic sequence.
According to the researchers, the main advantage of the method is the possibility of activating the treatment on the cells involved in the seizure, while minimizing the impact on healthy cells in their surroundings.
Fewer free radicals and less cell death
The researchers examined the effect of the treatment using microscopic, biochemical, and histological methods.
In the brain cells of the treated rats, an increase in the activity of antioxidant defense mechanisms was measured. At the same time, fewer free radicals were formed compared to rats that did not receive the treatment.
The treated cells also suffered less oxidative damage and less cell death.
Using microscopy images, the researchers were able to examine the concentration of free radicals and the activity of defense mechanisms at the individual cell level. A decrease in the concentration of radicals indicated that the treatment strengthened the cell's ability to cope with oxidative stress.
Seizures were prevented in more than half of the rats
The change at the cellular level was also accompanied by improvement in the course of the disease.
According to the researchers, more than half of the rats that received the treatment did not experience seizures. In the remaining treated rats, the frequency of seizures was significantly reduced, compared to the control group.
The material provided does not include the number of rats in each group, the duration of follow-up, or the exact rate of reduction. These data are necessary to assess the strength of the result and will be required for full presentation in the scientific publication.
A different approach from conventional medications
The new treatment is not primarily aimed at stopping the abnormal electrical activity, as many anti-epileptic drugs do.
Conventional drugs attempt to reduce the excitability of nerve cells or increase inhibitory activity in the brain. The gene therapy being studied is primarily designed to reduce the biological damage caused by seizures.
According to Dr. Sheikh Ahmed, the goal is to prevent the oxidative damage and cell death caused by free radicals. In this way, researchers hope to reduce the worsening of seizures, the development of treatment resistance, and the cognitive impairment that can result from an unbalanced disease over time.
Possible treatment in areas that cannot be removed surgically
In some patients with drug-resistant focal epilepsy, surgery to remove the area from which seizures begin may be considered.
Surgery is not possible when the focus is in an area essential for language, movement, memory, vision, or other important functions.
Targeted gene therapy may in the future allow treatment of cells located in such areas without removing the entire tissue. This is one of the potential advantages of therapy that operates at the cellular level.
The road to human trials is still long.
So far, the method has only been tested in rats and cell cultures. Results in an animal model do not guarantee that the treatment will be safe or effective in humans.
Before moving to a clinical trial, it will be necessary to determine the appropriate dosage, injection areas, duration of treatment effect, and the risk of an immune response or unwanted changes in nerve cell function.
It will also be necessary to ensure that the genetic switch is not activated in normal situations where increased brain activity occurs, such as learning, physical exertion, or emotional arousal.
The researchers say no unusual side effects have been observed in rats so far. However, safety and efficacy will need to be rigorously tested before the treatment can be tested in humans.
The study suggests a new direction for treating epilepsy: not only an attempt to suppress the abnormal electrical activity, but also targeted protection of brain cells from the damage it causes.
Questions and Answers
What is gene therapy for epilepsy?
Answer: This is an experimental approach in which genetic material is introduced into brain cells designed to change their activity, produce a therapeutic protein, or strengthen cellular defense mechanisms.
Did the researchers inject viruses that cause the disease?
Answer: No. Engineered AAV viral vectors are used, which are designed to carry genetic material and are not supposed to reproduce or cause disease.
What does on-demand care mean?
Answer: The therapeutic sequence does not operate at the same intensity all the time. It is connected to a genetic switch that responds to abnormal electrical activity and increases therapeutic expression primarily in cells that are active during a seizure.
What is Nrf2?
Answer: This is a transcription factor that activates many genes related to protection against oxidative stress and neutralization of oxidizing molecules.
Does the treatment directly stop the seizure?
Answer: Its main purpose is to reduce oxidative stress and cell damage. The
This may help reduce seizures and slow the worsening of the disease.
Has the treatment already been tested in humans?
Answer: No. The study is in the preclinical stage and was conducted in rats and cells.
