Partially resetting cells reverses ageing in a living animal

Four genes can turn an adult cell back into something like an embryonic one. Switched on briefly and then off, in a live animal, they turn back some of the marks of age without erasing what the cell is. In 2016 mice with a premature-ageing disease lived longer when this was done to them, and in 2020 old mice regained sight after the nerve from the eye was reset. It is the most direct attempt yet to reverse ageing rather than slow it. The first person was given it, in one eye, in June 2026, with no result yet reported.

What would count

A living animal given a brief, controlled dose of reprogramming genes afterwards has a measured marker of biological age (an epigenetic clock, a restored tissue function) moved towards youth, compared with untreated controls, in a peer-reviewed report. The first-human rung needs the same in a person.

Who settles it: Peer-reviewed reports; the trial registry entry and report when the first person is treated

Where it stands

Shown in animals. Reached on 15 December 2016, on the record of doi.org. Could move a stage within 1 to 5 years.

Outrunning Ageing tracks when this reaches the clinic: the same upgrade on that site, which keeps its own record of the same test and is checked against this one every week.

The last 2 readings

Once a week every upgrade is read against the news, against what would count above. Open a line to see what that week held. Every reading of this upgrade is on this week's reading.

• 18 October 2026 Nothing new

  Nothing dated 2026-10-11 to 2026-10-18 turned up. The company's 2026-06-09 announcement that the first participant was dosed is already in the entry's notes; a dose is not a measured reversal in a person, which the next rung needs, and no trial result was found. The sibling site Outrunning Ageing agrees on the stage.

• 16 October 2026 Nothing new

  Nothing in the window. Life Biosciences' trial of ER-100 in two optic nerve diseases, which the entry's notes say dosed its first participant on 2026-06-09, has reported no measured result; the searches found only the company's 2024 and 2025 animal presentations and secondary coverage of the trial's start. The first-human rung needs a measured marker moved toward youth in a person.

Changes to this entry

• 2026-10-17, sibling: none → partially-resetting-cells-reverses-ageing-in-an-animal. Cross-link to the matching entry on Outrunning Ageing, 'Partially resetting cells reverses ageing in a living animal', which has pointed at this entry since 2026-10-16; the two sites keep their own records of the same test and the weekly reading compares the stages (Outrunning Ageing kickoff, item 7, ruled by John 2026-10-16).

Notes

The record is the 2016 Salk Institute report of partial reprogramming in live mice. The 2020 Harvard report that restored vision in old mice by resetting cells in the eye is the clearest reversal of a lost function. A company founded on that work announced on 9 June 2026 that the first participant in its trial for two optic nerve diseases had been dosed. Under this entry's test the first-human rung needs a measured reversal in a person, not a dose, so the entry stays at shown in animals until the trial reports; if John would rather count the dose, the stage moves to first human on the company's own release. Outrunning Ageing keeps its own record of this upgrade under the same name, linked from here on 2026-10-17, and holds the June 2026 dose as a separate entry of its own; the weekly reading checks that the two stages agree.