Follistatin gene therapy
What is follistatin gene therapy?
Follistatin gene therapy delivers a gene that makes cells produce more follistatin, a protein that blocks myostatin, the body's brake on muscle growth. It builds muscle in mice and monkeys and has been tested in a few people with muscle-wasting diseases. It is not approved anywhere for aging, and no human trial has tested it for that.
Listed here because well-known people have tried it on themselves. Trying something is not recommending it; each entry says whether the person tells others to do it.
Who has tried it
Tried by 2 people we can source: 2 testing.
Testing
Bryan JohnsonEntrepreneur, founder of BlueprintBlueprint (Bryan Johnson)
Started Oct 2023 · Does not recommend it to others
A one-time, unapproved follistatin gene therapy from Minicircle in Roatan, Honduras, aimed at more muscle and slower aging; he reported a 160% rise in follistatin and has not reported an end result.
“I am now a genetically enhanced human”
Fortune, Bryan Johnson is a human guinea pig for unproven gene therapy (December 2023) · Status checked October 31, 2026 · Suggest a correction
Liz ParrishFounder and CEO of BioViva
Started Sep 2015 · Does not recommend it to others
Had injections of the follistatin gene into her muscles in 2015, alongside a telomerase gene therapy, as an unapproved self-experiment aimed at age-related muscle loss.
“We are attempting to reverse aging at a biological level.”
MIT Technology Review, A Tale of Do-It-Yourself Gene Therapy (October 2015) · Status checked October 14, 2015 · Suggest a correction
What the evidence shows
No human study has tested follistatin gene therapy for aging, longevity or muscle in healthy people. The only published human results come from two small trials at one US center, in which a virus vector carried the gene into the thigh muscles. In six people with Becker muscular dystrophy, four walked farther in six minutes afterwards [1]. In six people with inclusion body myositis, walking distance improved over a year compared with untreated patients [2]. Neither trial had a placebo group.
The reasoning comes from animals. Mice without myostatin have muscles two to three times heavier than normal [3], and a single dose of a follistatin gene raised muscle mass and strength in mice for more than two years [4] and in monkeys [5]. A 2022 mouse study reporting that a follistatin gene therapy extended median lifespan by about a third was retracted by the journal in 2025 [6].
Almost everything that matters for a healthy person is unknown: whether it extends life or healthspan, how long the gene keeps working, and what it does over years to the heart, hormones or cancer risk. The FDA has not approved any follistatin gene therapy [7].
Safety
- No follistatin gene therapy is approved by the FDA or any major regulator. Offshore clinics sell it outside clinical trials, without independent checks on what the product contains.
- A gene therapy may be hard or impossible to reverse once the gene is in cells.
- Risks of gene delivery include immune reactions to the vector or the product, inflammation at the injection site and unknown long-term effects.
- Follistatin also blocks activin, which helps control reproductive hormones, so effects beyond muscle are possible and have not been studied in healthy people.
- The published human safety data come from 12 patients with muscle disease in supervised trials, not from healthy people.
Common questions
Did Bryan Johnson get follistatin gene therapy?
Yes. In September 2023 he had a one-time, unapproved follistatin gene therapy from Minicircle in Roatan, Honduras. He reported a 160% rise in follistatin but has not reported an end result such as more muscle or slower aging.
Did Liz Parrish get follistatin gene therapy?
Yes. In September 2015 she had follistatin gene injections into her muscles, along with a telomerase gene therapy, reportedly in Colombia and outside any approved trial.
Does follistatin gene therapy work in humans?
Is follistatin gene therapy FDA approved?
No. No follistatin product is on the FDA's list of approved cell and gene therapies [7].
Does follistatin extend lifespan?
Not shown in people. The main mouse study reporting longer lifespan was retracted by the journal in 2025 [6].
Sources
- 1.Mendell JR, Sahenk Z, Malik V, et al. A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy. Mol Ther, 2015. doi:10.1038/mt.2014.200
- 2.Mendell JR, Sahenk Z, Al-Zaidy S, et al. Follistatin Gene Therapy for Sporadic Inclusion Body Myositis Improves Functional Outcomes. Mol Ther, 2017. doi:10.1016/j.ymthe.2017.02.015
- 3.McPherron AC, Lawler AM, Lee SJ. Regulation of skeletal muscle mass in mice by a new TGF-beta superfamily member. Nature, 1997. doi:10.1038/387083a0
- 4.Haidet AM, Rizo L, Handy C, et al. Long-term enhancement of skeletal muscle mass and strength by single gene administration of myostatin inhibitors. Proc Natl Acad Sci U S A, 2008. doi:10.1073/pnas.0709144105
- 5.Kota J, Handy CR, Haidet AM, et al. Follistatin gene delivery enhances muscle growth and strength in nonhuman primates. Sci Transl Med, 2009. doi:10.1126/scitranslmed.3000112
- 6.Jaijyan DK, Selariu A, Cruz-Cosme R, et al. New intranasal and injectable gene therapy for healthy life extension. Proc Natl Acad Sci U S A, 2022. doi:10.1073/pnas.2121499119
- 7.U.S. Food and Drug Administration. Approved Cellular and Gene Therapy Products. U.S. Food and Drug Administration, 2026. Link