In Vivo Gene Editing: Scientists Use CRISPR Technology to Modify DNA Inside a Person’s Body

In a groundbreaking innovation in genetic engineering, a team of researchers has used the CRISPR gene editing tool inside a person's body for the first time, opening a new frontier in modifying DNA to treat diseases.

(Photo: Unsplash/ CDC)

Potential of In Vivo Gene Editing

Over recent years, genome editing has been well-established as an engineering tool with the potential to treat various diseases. Existing gene therapies that use non-viral vectors for therapeutic delivery usually require ex vivo editing. In this procedure, the cells are extracted from the patient, transported to a laboratory for editing, and then infused back into the body afterward.

While ex vivo editing is effective, it also has its drawbacks. One disadvantage is the additive immune response triggered by the viral vector. In addition, experts should consider the variability of cytokine production upon in vivo transduction.

In vivo gene transfer has the advantage of preventing the cumbersome and costly process of removing cells from the patient's body. In vivo gene therapy produces new genetic material in the laboratory and then directly inserts it into the cells. A vector typically delivers the new genetic material into the body through injection in the blood or by targeting the organ directly.

In vivo method is usually preferred for genetic disorders that affect a particular gene in the body. This strategy requires the target cells or tissues to be easily accessible for injection of the new genetic material.

Novel Technique in Genomic Editing

This breakthrough was carried out at the Casey Eye Institute at Oregon Health & Science University in Portland for a patient with an inherited form of blindness. It may take up to a month to see if the procedure restored their vision.

Experts first tried in-the-body gene editing for an inherited disease in 2017 using a tool known as zinc fingers. However, most scientists believe CRISPR is a much easier tool for locating and cutting DNA at a specific spot.

In this new research, the participant suffers from Leber congenital amaurosis, a condition caused by a gene mutation that keeps the body from producing a protein required to convert light into brain signals that enable sight. People with this medical condition are usually born with little vision, which can be lost within a few years.

Leber congenital amaurosis cannot be treated with standard gene therapy, which involves supplying a replacement gene. This is because the needed gene is too big to fit inside the disabled viruses used to deliver it into cells. Because of this, the scientists tried to edit or delete the mutation by making two cuts on either side of it. Then, the ends of DNA strands were reconnected and allowed to work as they should.

The procedure was done in an hour-long surgery under general anesthesia. Using a tube as wide as a hair strand, the doctors dripped three drops of fluid that contained the gene editing machinery beneath the retina.

Once the cell is edited, it is permanent and anticipated to persist throughout the patient's life. The gene editing tool is expected to stay in the eye without traveling to other body parties. This is an excellent first step for conducting gene editing in the body.

According to the team who performed the procedure, about one-tenth to one-third of the cells must be fixed to restore vision. In animal tests, scientists successfully corrected half of the cells with the treatment.

Gene editing expert Dr. Kiran Musunuru from the University of Pennsylvania noted that the treatment seems likely to work based on trials conducted in human tissue, mice, and monkeys. According to Dr. Jason Comander from Massachusetts Eye and Ear in Boston, in vivo gene editing marks a new era in medicine, where technology is used to make DNA editing easier and more effective.