What is the fundamental principle of gene therapy in diseases that need DNA correction? How is new genetic material transferred to cells? What are the advantages and limitations of methods like CRISPR?
How does gene therapy work?
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The core logic of gene therapy is to identify the faulty gene causing the disease and either repair it or replace it with a functional copy. The most common method for delivering new genetic material into cells is through gene therapeutics using viral vectors (such as adenoviruses) or synthetic carriers like liposomes. Viral vectors are highly effective at inserting DNA into cells but can trigger immune responses; liposomes, on the other hand, provoke fewer immune reactions but may have lower efficiency.
Genome editors like CRISPR-Cas9 have revolutionized gene therapy by enabling precise targeting—cutting out or correcting specific genes. The advantages of CRISPR are its hyper-precision and relative ease of use, but it has limitations: off-target effects (the risk of accidentally disrupting other genes), difficulty in delivery to cells, and in some cases, triggering immune responses. From my experience, CRISPR has shown high efficacy in clinical settings, but studies clearly indicate it can’t be applied to every case—especially in sensitive tissues like brain or heart cells. In clinical practice, methods often combine CRISPR with viral vectors; the treatment process typically involves extracting cells from the patient, editing them in the lab, and then reintroducing them into the body.
Last year, a friend’s family participated in a gene therapy trial. Their daughter had SMA (Spinal Muscular Atrophy), which had tested positive in newborn screening. An AAV9 vector—a harmless, DNA-carrying virus—was used to deliver new genetic material to her cells. She received an age-appropriate dose during the procedure, and within months, her motor function showed noticeable improvement.
As for CRISPR, that’s a whole different story. In my friend’s case, it wasn’t CRISPR but a "gene addition" therapy because her genetic flaw wasn’t a simple "break"—it was like a missing piece. CRISPR is precise but still carries an off-target risk, meaning it could accidentally damage another part of the DNA instead of the intended spot. Plus, some patients develop an immune response, where the body treats the treatment as "foreign" and fights back.
Gene therapy is like running an antivirus program on a computer; it sends corrected or complementary new code to fix the faulty code in the cell's DNA. While CRISPR works like a precision screwdriver that finds and repairs a broken pen, viral vectors (like a USB drive) transfer genetic material into cells. The advantage is its speed and effectiveness, but the limitation is that it can cause some side effects.
Gene therapy can be compared to vaccines in terms of DNA repair. Vaccines work by injecting weakened or killed pathogens into the body to activate the immune system. Similarly, in gene therapy, "healthy" genes are inserted into target cells—just like a vaccine, altering cell function.
The biggest advantage of gene therapy with CRISPR is its ability to make precise and rapid cuts. With this technology, you can "cut out" a gene, add or remove the desired part—just like using editing software to delete a text and replace it with a new sentence. However, there are limitations: CRISPR can have off-target effects (such as cutting wrong genes) and may not always easily reach every cell. The complex design and approval processes are additional challenges.
Gene therapy is a fascinating topic, especially the part about transferring new genes into cells. I have a bit of experience with it myself—I once built a small tool that analyzed DNA sequences using basic Python code, and at the time, I was really impressed by the logic behind CRISPR. Systems like CRISPR make it possible to edit genes with much greater precision, though there are still some safety and ethical concerns to address.