The tree · Replacing lost cells and parts
Cells grown from stem cells restore a lost organ function in people
The promise of stem cells was always this: grow the cells an organ has lost and put them back. Insulin-making cells were grown from embryonic stem cells in bulk in 2014 and cured diabetic mice; in June 2025 a Vertex Pharmaceuticals trial reported that twelve people with type 1 diabetes given an infusion of such cells into the liver all had their blood sugar back in the target range a year later, and ten of them no longer needed insulin. They take anti-rejection drugs, and the company planned to file for approval in 2026. Parkinson's disease is close behind: dopamine-making cells grown the same way were reported safe in 2025 and a late-stage trial began in 2025. It is the first time grown cells have replaced a lost function, not just survived.
What would count
A person given cells grown from stem cells afterwards regains a lost organ function (makes their own insulin, moves without dopamine drugs, sees) in a peer-reviewed report, with the function measured. The animal rung is the same in a living animal. For the clinic rung: a regulator approves such a cell therapy for use outside a trial.
Who settles it: The peer-reviewed trial report; the trial registry; the regulator's approval record for the clinic rung.
Where it stands
First human. Reached June 2025, on the record of doi.org. Next rung within 1 to 5 years.
When it reaches the clinic: the project's estimate
This is the one thing on this page that is a judgment rather than a record. The project's estimate of the year it reaches the clinic is 2028, no earlier than 2027 and no later than 2036; the model draws from that range every run, with the likely year the most probable draw. Set 16 October 2026, a first pass awaiting an outside review.
| Rung | No earlier than | Most likely | No later than | |
|---|---|---|---|---|
| In clinical use | 2027 | 2028 | 2036 | feeds the year at the top |
| In wide use | 2030 | 2035 | 2055 |
Why. The diabetes therapy was due to be filed in 2026 on data from a late-stage trial that finished dosing in 2025; the likely year for approval is 2028, the earliest 2027 if the filing is made this year and reviewed fast, and the latest allows for a manufacturing or safety setback and the Parkinson's therapy, due to read out in 2027, carrying the rung instead in the mid 2030s.
Changes to this record
None since it was written on 16 October 2026. Every change to the stage or the estimate lands here with its date, the old value, the new one and the reason, and a change to the estimate never happens because a number looked wrong: it needs a dated reason and a source.
The last readings
- 17 October 2026 Quiet
Nothing in the window. No filing for approval of Vertex's zimislecel, no acceptance by a regulator and no new peer-reviewed readout was found; the newest item seen was a third-party explainer dated 2026-06 saying a filing in 2026 was still expected, which matches the record's verify note (no filing as of 2026-08-03). The Parkinson's late-stage trial (bemdaneprocel, NCT06944522) showed no update after its 2025 start. Vertex's and BlueRock's newsrooms could not be opened because the session's web fetching was refused, so a release in the window cannot be ruled out by this searcher.
What the story so far says about it
On the record
Notes
The branch's own line asks for a stem cell therapy restoring a lost function in a controlled trial; the 2025 diabetes result had no control group, and the Parkinson's trial is the first with one. The anti-rejection drugs are the catch for ageing: a treatment that needs them trades one failing system for another, and the encapsulated version that would avoid them was dropped in 2025.
Not yet verified
These facts in the record were written from memory or from a secondary source and have not yet been checked against the paper, the regulator's record or the registry. Nothing here is presented as settled until it is cleared, by checking it and either deleting the line or correcting the record.
- Vertex's results releases show no filing for approval as of 2026-08-03; it said in 2025-08 it expected to file in 2026, postponed completing dosing from 2025-11 to about 2026-05 for a manufacturing review, and promised updated timelines later in 2026. Whether it has filed since was not found.