The tree · Replacing lost cells and parts
A person's own cells are grown outside the body and used to rebuild a worn joint surface
Cartilage, the smooth surface that lets a joint glide, does not heal; a hole in it is for life and is where osteoarthritis starts. In 1994 a Swedish group reported taking a little cartilage from a patient's knee, growing the cells for weeks in the laboratory, and putting them back under a flap of tissue to fill the hole; most of the 23 patients had good knees two years on. The cells-on-a-membrane version, MACI, was approved by the United States regulator on 13 December 2016 after a controlled trial of 144 people in which it beat the standard operation on pain and function. It is the oldest approved therapy made from a person's own grown cells, and the branch's one leaf in the clinic. It repairs injuries in younger knees; whether grown cells can resurface an old, worn joint is the open question.
What would count
A person's own cells are grown outside the body and placed into a joint, and the joint's pain and function are afterwards measurably better than with the standard treatment in a controlled trial, in a peer-reviewed report. For the clinic rung: a regulator approves such a product. For wide use: the product is available in several countries and used in a substantial share of eligible cases, including worn joints in older people, not only injuries in younger ones.
Who settles it: The peer-reviewed trial report; the regulator's approval record; published use figures for the wide-use rung.
Where it stands
In clinical use. Reached 13 December 2016, on the record of web.archive.org. Next rung within 5 to 20 years. The year the model reads for it is 2016, the year it reached the clinic; what has happened is not drawn.
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. It is already in the clinic, so the model reads a known year; the estimate below is for the rungs still above it and feeds nothing. Set 16 October 2026, a first pass awaiting an outside review.
| Rung | No earlier than | Most likely | No later than | |
|---|---|---|---|---|
| In wide use | 2028 | 2036 | 2065 |
Why. The product has been sold for a decade and a next-generation version that needs one operation instead of two was in trials; wide use under the test needs use in worn older joints, which needs a trial in osteoarthritis that nobody had run. The likely year assumes such a trial reads out in the early 2030s and use widens through the decade; the earliest assumes use figures already meet the bar once counted; the latest allows for grown cells never working in an arthritic joint.
Changes to this record
- 17 October 2026, stage_reached_on: 2016-12-14 became 2016-12-13. The regulator's own release is dated 13 December 2016; 14 December was the company's notice. The stage itself is unchanged.
The last readings
- 17 October 2026 Quiet
Nothing in the window. The searches returned the 2016-12-13 approval, the 2024-08 arthroscopic-delivery label expansion (MACI Arthro) and older trial extensions, none of which bears on the wide-use rung (use in worn older joints); no osteoarthritis trial of grown cartilage cells and no new use figures were found. Vericel's own newsroom could not be opened because the session's web fetching was refused.
What the story so far says about it
No promise, self-experiment or logged paper names this one yet.
Notes
This leaf is on the tree with a caveat said plainly: the approved use is for defects in otherwise healthy knees, mostly in people under fifty-five, and osteoarthritis of old age is excluded from the label. It counts toward the branch under the test as written because the test is about grown cells rebuilding a worn surface; the wide-use rung is where the age question is asked, and the yearly review may decide the leaf should be narrower.
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.
- Carticel was first licensed in the United States in 1997 (its label says 'Initial U.S. Approval: 1997'); the month, and whether the licence rested on a controlled trial, were not checked. John ruled on 2026-10-17 that this stays open as written: the clinic date stays 2016-12-13 and the description stands until the 1997 licence basis is checked.