September 2015. Liz Parrish was nervous. She was on a plane to Colombia, where she was about to undergo gene therapy that had not been tested in humans.
She and her colleagues had spent two years developing the treatment and making preparations, but they couldn't know how it would turn out.

It is important to clarify from the outset: Everything described here is a self-experiment on a single subject (n=1), who reported her own results, without a control group, without regulatory oversight, and without peer-reviewed publication. No medical conclusions should be drawn from this, and all the numbers presented below are claims reported by Parrish and her company, not established facts.

The treatment consisted of two intravenous injections and proceeded without immediate complications.
Before the treatment, commercial telomere tests (performed at SpectraCell Laboratories) indicated, according to Parrish, that the telomere length in her white blood cells was shorter than expected for her age, a condition translated by the test to a reported biological age of about 62, while her chronological age at the time was 44. That is a reported gap of about 17 to 18 years, not 22 years as sometimes stated.

The first report of a change did not come within weeks but about six months later, in March 2016: a follow-up test at the lab indicated, according to the company, a lengthening of the telomeres. In the years that followed, Parrish published additional reports stating that her reported biological age continued to decrease, allegedly at an average rate of about five years per calendar year, reaching particularly low values.

And here, great scientific caution is required. All these data are based on self-reporting, on a single subject, and on commercial telomere tests, and have not undergone peer review. A major problem is that telomere length measurements suffer from significant measurement inaccuracy: common methods (like qPCR) show variability on the order of about 10 percent or even more between measurements, depending on the test day and the lab. This means that a significant portion of the reported "change" may be due to measurement noise rather than a true biological change. Additionally, telomere length within the normal range is not considered a reliable indicator for determining an accurate "biological age." Therefore, the impressive numbers reported by Parrish should be viewed with healthy skepticism, as unverified claims, not proven results.

Liz publishes this data publicly, but her approach is controversial.
George Martin, a professor of pathology at the University of Washington, was a consultant for Liz Parrish's company BioViva but resigned when he heard about the trip to Colombia and the administration of the treatment outside a controlled trial framework.
Maria Blasco, the Spanish scientist whose pioneering work on telomerase underlies the rationale for the treatment, insists that such treatments should not be administered without rigorous trials validated by the FDA and other regulatory agencies.

Liz has no regrets. She does not dispute the need to make medical treatment as safe as possible but notes that it can never be completely risk-free.
"People are killed by regulated drugs all the time," she argues. The type of treatment she took had shown results in mice for over a decade.
But it must be emphasized: mice and humans are very different species, and there are no real human safety data beyond her single self-experiment. In other words, the treatment has not been proven safe in humans; at most, it can be said that in her single case, no harm has been observed so far.

In the years since her treatment, Liz has met presidents, health ministers, and policymakers around the world.
There is great interest in her arguments, but also a reluctance to deviate from the status quo.
Liz hopes one way to overcome this resistance is to make new treatments available to end-of-life patients without the usual testing, patients who have tried every approved approach and have no alternative left.

It takes many years and billions of dollars to bring a new drug to market, meaning many promising treatments never get a chance.
One result of this is the rise of medical tourism, with patients traveling to clinics outside the jurisdiction of the FDA and similar agencies.
Many of these clinics are reputable institutions with professional management, but others are less so.
Liz argues that the existence of medical tourism is a sign that something is wrong with the medical establishment, and she claims (an unverified claim) that a significant portion of medical trials conducted by large pharmaceutical companies take place outside US shores.

There is no way to know how many people have followed Liz Parrish's path, but she believes there are quite a few. Given that the results she reports have not been independently verified or peer-reviewed, it is not surprising that the broader scientific community remains cautious and reserved.

The Scientific Background: Telomeres and Telomerase
The primary gene therapy Liz underwent was intended to lengthen her telomeres. (She also received a myostatin inhibitor aimed at combating muscle mass loss.)
Our genes are composed of intertwined strands of DNA molecules called chromosomes.
When our cells divide, the ends of these strands would erode without the protection provided by telomeres.
Telomeres are segments of repetitive DNA at the ends of chromosomes, serving as a kind of disposable buffer.
When a cell divides more than a certain number of times (the Hayflick limit, typically between 50 and 70 divisions), the telomeres shorten significantly, and chromosome stability is compromised.
An enzyme called telomerase can re-lengthen telomeres and maintain the cell's genetic stability, making it a focus of aging research.

Liz Parrish's reported biological age was estimated based on the telomere length in her white blood cells, particularly in T lymphocytes, a type of white blood cell that plays an important role in the body's immune response.

Gene therapy is typically delivered using viruses, known as "vectors."
The treatment Liz Parrish used in 2015 employed a vector called AAV, and her company later worked on another vector based on cytomegalovirus (CMV).
Both technologies are based on viruses that occur naturally in humans and monkeys, and both are designed to deliver genes that produce telomerase without altering the chromosome sequence itself.
The advantage of CMV is that it can carry larger genetic payloads than AAV, and BioViva sought to develop treatments using multiple genes to influence the aging process.
Within this framework, BioViva collaborated with researchers from Rutgers University to develop the technology.

Significant Caveat: This research collaboration produced a paper published in the journal PNAS in 2022 (Jaijyan et al., "Gene therapy for healthy life extension"). This paper was retracted in August 2025, at the request of the Rutgers University Research Regulatory Office, following an internal investigation that found data discrepancies (including issues with duplicate images). This is a significant caveat regarding the reliability of some scientific publications related to this technology, and it must be considered when evaluating the claims.

Liz Parrish herself does not believe (and rightly so) that telomere lengthening alone is sufficient to conquer aging.
There are different species whose telomeres shorten quickly, and vice versa.
Human biology is highly complex, and aging will not be defeated by a single "silver bullet."
But Parrish believes (like many other scientists) that telomere lengthening may play a role in combating aging. However, translating this promising idea into a safe and proven treatment in humans is still far from established, and the path to that goal lies through controlled clinical trials, not unsupervised self-experiments.