Gene therapy: understanding the medicine that acts directly on our genes

Gene therapy: understanding the medicine that acts directly on our genes

For several decades, medicine has sought to go further than simply treating symptoms. The goal: to correct the cause of a disease directly.

With gene therapy, that goal becomes reality. This innovative medical approach no longer just supports a patient or slows the progression of a pathology; it aims to fix the problem at its root: in the DNA itself.

What is gene therapy?

Gene therapy involves introducing, replacing, or modifying genetic material (genes) in a patient's cells.

• When a gene is missing or defective, a healthy copy can be provided to restore its function.

• When a gene produces an abnormal protein, it can be inactivated.

• Finally, a new gene can be added that provides a useful function (for example, enabling immune cells to recognize and destroy cancer cells).

This approach is particularly promising for rare genetic diseases, but its applications already go beyond that scope.

The different types of gene therapy

There are several strategies:

1. Replacement gene therapy

   
   A functional gene is introduced to replace a defective gene. Example: certain severe immunodeficiencies in children.

2. Corrective gene therapy

   
   The defective gene is modified directly to correct the genetic error. Editing technologies like CRISPR-Cas9 open immense possibilities here.

3. Additive gene therapy

   An additional gene is added to give the cell a new capability. Example: anticancer immunotherapy with CAR-T cells (modified lymphocytes).

How is a gene introduced into the body?

One of the major challenges of gene therapy is successfully delivering the genetic material into the right cells. For this, vectors are used:

• Viral vectors:
  Modified viruses (adenovirus, lentivirus, AAV) are rendered harmless but retain their ability to introduce genetic material into cells.

• Non-viral vectors:
  Liposomes, nanoparticles, or electroporation, which allow DNA or RNA to enter cells without using a virus.

Each method has its advantages and limitations: efficacy, safety, durability.

Current medical applications

1. Rare diseases

• Infantile spinal muscular atrophy: treatment by injection of a functional gene that saves children who were once doomed.

• Severe immunodeficiencies: children nicknamed "bubble babies" have been able to leave isolation thanks to gene therapy.

2. Cancer

• CAR-T cells are a dramatic example: T cells are collected from the patient, genetically modified so they recognize a specific protein on tumor cells, and then reinfused into the patient. These cells become true "cancer hunters".

3. Ophthalmology

• Some forms of genetic blindness (e.g. Leber congenital amaurosis) can be partially corrected by gene therapy, restoring sight to people who lived in darkness.

4. More common diseases (in research)

• Diabetes, Parkinson's, cardiovascular diseases: clinical trials are already exploring how modifying DNA or gene expression could improve management.

The promises of gene therapy

• Addressing the root cause: symptoms are no longer masked; the origin is targeted.

• Durability: in some cases, a single injection can be enough to change a patient's life.

• Hope for the incurable: rare diseases without treatments become accessible to therapeutic solutions.

Limitations and challenges

Despite its potential, gene therapy still faces several obstacles:

• Safety: there is a risk that the gene inserts in the wrong place in the DNA.

• Duration of effect: some therapies need to be repeated.

• Cost: several treatments are marketed at prices exceeding a million euros per patient.

• Accessibility: only a few countries and specialized centers currently offer these therapies.

Ethical aspects

Modifying DNA raises fundamental questions:

• Where should the line be drawn between treatment and enhancement of humans?

• Should gene therapies concern only serious diseases, or also more common conditions?

• How can equal access be ensured in the face of such expensive treatments?

A medical revolution underway

Gene therapy is already a reality for some patients. It opens a new medical era where we no longer treat only the visible effects of a disease, but where we rewrite the biological program that is responsible.

For laboratories engaged in innovation, like RENASCOR in its field of hair care, the approach is similar: make science understandable, accessible and useful to as many people as possible. Popularize, support, and make hope concrete.

Conclusion

Gene therapy is not yet a universal treatment, but it illustrates the future of medicine: precision, personalized medicine that acts directly at the heart of our genes. If the challenges remain considerable (cost, accessibility, safety), its current successes prove that humanity has passed a turning point

FAQ – Gene therapy

1. What is gene therapy in medicine?

Gene therapy is an innovative medical technique that involves introducing, correcting, or replacing genes in a patient's cells. It allows certain diseases to be treated at their source, acting directly on the DNA rather than only on symptoms.

2. How does gene therapy work?

It uses vectors, often viruses rendered harmless, to carry a therapeutic gene to the patient's cells. Once integrated, this gene enables the production of a functional protein or corrects the anomaly responsible for the disease.

3. Which diseases can be treated by gene therapy?

Today, gene therapy is used for certain rare diseases (spinal muscular atrophy, immunodeficiencies, genetic blindness), but also in some cancers via CAR-T cells. Clinical trials are exploring its effectiveness in diabetes, Parkinson's, and heart diseases.

4. What are the advantages of gene therapy?

• It acts on the root cause of the disease.

• Its effects can be durable, sometimes after a single injection.

• It represents a source of hope for diseases that were previously untreatable.

5. What are the risks and limits of gene therapy?

Gene therapy can present risks (incorrect insertion of the gene, immune side effects). It remains costly, sometimes more than a million euros per patient, and is only available in certain specialized centers.

6. Is gene therapy already available in France?

Yes, several gene therapies are authorized in Europe and in France, notably for certain rare diseases and in oncology. However, access remains limited to specific protocols in specialized hospitals.

7. What is the difference between gene therapy and cell therapy?

• Gene therapy acts directly on genes inside cells.

• Cell therapy involves taking cells (from the patient or a donor), modifying or cultivating them, and then reinjecting them.
  Some approaches combine both, such as CAR-T cells in oncology.