○ Human lifespan benefit: not established by the compiled studies. Included records: none

Two caveats govern every page on this site. (1) Telomere length is a contested aging biomarker — it is measured differently by different methods, varies between tissues, and "longer" is not straightforwardly "healthier"; changing a telomere-length or telomerase-activity number in a trial is not the same as slowing human aging. (2) Activating telomerase is not risk-free — telomerase expression is low in many differentiated normal tissues, while some normal proliferating cells can express it. Cancer can also use telomere maintenance; the included human records do not resolve long-term cancer risk from pharmacological activation. Tellingly, the FDA-approved telomerase inhibitor — imetelstat (RYTELO, 2024) — inhibits telomerase to treat cancer (lower-risk MDS), the opposite direction from the anti-aging "activation" narrative.

What it is

Class: Adeno-associated-virus vector expressing TERT (preclinical)

Also known as: AAV9-Tert, AAV-TERT, telomerase gene therapy

Relationship to telomere biology: Telomerase gene therapy delivers the TERT gene via an AAV vector so that treated cells express telomerase and extend their telomeres. It is the intervention behind the striking mouse-lifespan result — the outcome evidence in these included records is mouse evidence, not established human benefit.

Regulatory status

Experimental; the AAV9-TERT intervention represented by the two included mouse studies is not an approved human aging therapy. Registered human research, if present, must not be conflated with published outcome evidence.

Mechanism

In mice, a single AAV9-TERT treatment in adult/old animals lengthened telomeres, delayed several aging phenotypes, and increased lifespan without a reported rise in cancer incidence (Bernardes de Jesus/Blasco 2012); a related mouse study showed benefit in a short-telomere pulmonary-fibrosis model (Povedano/Blasco 2018). See /telomerase-cancer-paradox.

Animal lifespan evidence

Animal lifespan evidence: yes

A single intravenous dose of AAV9-TERT in adult and aged mice increased median lifespan and delayed several age-related conditions, without increased cancer incidence in that study (Bernardes de Jesus et al., EMBO Mol Med 2012;4(8):691-704). A mouse gene therapy, not an approved human treatment.

This is separate from human lifespan evidence, which is none for every intervention on this site. A mouse lifespan result is not a human lifespan result, and a telomere change is not a lifespan result in either species.

Evidence — Animal (mouse lifespan / disease model) verify: source publication identified; see evidence and limitations

Species / population	Adult (1-year) and old (2-year) mice; and a separate bleomycin/short-telomere mouse model of pulmonary fibrosis.
Exposure, route, schedule	Single intravenous dose of an AAV9 vector expressing mouse TERT (AAV9-Tert).
Comparator / duration	The 2012 lifespan study compared AAV9-mTERT with AAV9-eGFP reporter-vector and untreated controls; the separate fibrosis experiment used its reported AAV9 control.
Endpoint / numeric result	Median lifespan increased ~24% when treated at 1 year and ~13% when treated at 2 years, with delayed aging markers and NO reported increase in cancer incidence (2012); improved lung function and reduced fibrosis in the pulmonary-fibrosis model (2018).
What it did NOT establish	These are mouse results. Mouse telomere biology differs substantially from human; there is no human lifespan, disease-outcome, or safety evidence, and the cancer-risk question is unresolved in humans.

Negative or null findings

The two gene-therapy outcome studies included here are preclinical mouse studies; they do not establish human benefit or safety.
Mouse telomeres are much longer than human telomeres and mouse cells regulate telomerase differently, so the lifespan result does not transfer to a human claim.

Telomerase gene therapy (AAV-TERT)