TRANSEURO fetal grafts

The research record

This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".

Who

Roger Barker (University of Cambridge) coordinated the TRANSEURO consortium, with Anders Björklund, Stephen Dunnett and others (co-authors of the paper; the two grafting centres were Cambridge and Lund). EU-funded under its 7th Framework Programme, launched January 2010. Results: Nature Biotechnology 2026;44:70–78 (online 2 May 2025).

What happened

• An observational study (recruiting from 2011) followed patients who might later be grafted. Thirty-six were recruited into the transplant trial and randomly allocated to transplant or control; six withdrew and three did not finish screening before any intervention, and 11 of the remaining 27 were grafted. The 16 controls had the same scans and exams but no sham surgery and no immunosuppression, so the design was open-label with an unblinded comparison group.
• Because human fetal tissue was hard to get, only 11 people were grafted between 2015 and 2018: 8 in Cambridge and 3 in Lund. The tissue preparation was the same but the implantation devices differed. Ten had bilateral grafts (tissue from three fetuses per side) and one had a single-sided graft. All had 12 months of triple immunosuppression.
• The primary endpoint was the change in the UPDRS Part III motor score off medication (the standard Parkinson's rating scale) 36 months after surgery. It showed no overall difference from baseline or from the controls. The authors used no inferential statistics because of the small numbers.
• Three patients developed off-state dyskinesias assumed to be graft-induced; all were mild and not disabling. Outcomes differed by device or site. Five of 11 grafted (45.5%) and 3 of 16 controls (18.8%) had serious adverse events, including two intracerebral haemorrhages that left no lasting effect.
• Dopamine uptake on fluorodopa PET improved at 18 months in seven people, but returned to near-normal in only one.
• The registry record (NCT01898390, "TRANSEURO Open Label Transplant Study", University of Cambridge, completed, last updated May 2023) lists the start as May 2012 and 13 enrolled, which does not match the paper's 11 grafted and 16 controls.

Why it moved us toward a cure

It was the last large attempt to make fetal grafts work, using lessons from the earlier trials (landmarks 317 and 318) and the serotonin finding (landmark 215). Its own conclusion is that a stem-cell source of dopamine neurons is needed, the route taken in landmark 10. The first-generation grafts it builds on are in landmark 3.

Outcome

Dead end: no overall clinical gain in the 11 grafted people; the field moved to stem-cell-derived dopamine neurons.

Sources

• Barker et al., Nat Biotechnol 2026;44:70–78, DOI 10.1038/s41587-025-02567-2 (abstract via Europe PMC, PMID 40316701; open-access full text PMC12807853, read 19 Oct 2026)
• ClinicalTrials.gov NCT01898390 (read 19 Oct 2026; record last updated May 2023)
• CORDIS, TRANSEURO launch (launch January 2010, observational recruitment from 2011)
• Not yet verified: the exact primary-endpoint scores (the paper gives them mainly in figures); the date of the first graft (the paper says grafting took place between 2015 and 2018); how the 13 registry participants relate to the 11 grafted and 16 controls.