Nearly 60% of children who undergo fetal surgery for spina bifida still cannot walk [Mayo Clinic]. That statistic has haunted prenatal medicine for over a decade, ever since fetal repair became the gold standard. On February 26, 2026, a Phase 1 study published in 『The Lancet』 offered something the field hadn’t seen before: evidence that adding stem cells during fetal surgery may meaningfully improve neurological outcomes. The CuRe Trial, conducted at UC Davis Health, marks the world’s first application of stem cells during in-utero spina bifida repair. The FDA has already approved progression to the next phase. This isn’t a theoretical promise. It’s early clinical evidence that fetal medicine may be shifting from damage control to active neural repair.
What Spina Bifida Does Before Birth
Spina bifida occurs when the neural tube fails to close during early fetal development, leaving the spinal cord exposed to amniotic fluid.
Photo by That exposure is progressive. The longer the spinal cord remains unprotected, the more nerve damage accumulates, leading to paralysis, bladder dysfunction, and cognitive challenges. Up to 80% of affected children develop hydrocephalus, a dangerous fluid buildup in the brain that often requires surgical shunt placement.
Fetal surgery, established as superior to postnatal repair by the landmark MOMS Trial in 2011, was a genuine breakthrough. It closes the defect before birth, shielding the cord from further harm. Yet it has a fundamental limitation: it halts damage but doesn’t reverse what’s already occurred. For families receiving a prenatal diagnosis, the difference between stopping the clock and turning it back carries enormous weight.
This is the gap the CuRe Trial set out to address.
How the CuRe Trial Was Built
The trial centered on an ambitious question: could placental mesenchymal stem cells, applied directly to the exposed spinal cord during fetal surgery, improve neurological repair beyond what surgery alone achieves?
Researchers at UC Davis Health enrolled pregnant women carrying fetuses with spina bifida, performing procedures between 19 and 26 weeks of gestation. The stem cells were chosen for three specific biological properties:
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Anti-inflammatory action: reducing the immune response that compounds nerve damage
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Growth factor secretion: supporting neural tissue repair at the cellular level
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Immune modulation: creating a more favorable environment for healing
Outcomes were tracked at birth and again at 12 months, measuring motor function, brain development, and shunt placement rates. The phased design prioritized safety first, then signal detection. A deliberate, methodical approach rather than a rush toward broad claims.
What the Results Actually Show
The Phase 1 findings are cautiously encouraging.
Photo by Infants who received stem cell-augmented surgery showed stronger lower-limb motor function at 12 months compared to historical controls from surgery-only cohorts. Motor level outcomes were, on average, one to two neurological levels better than predicted, a clinically meaningful difference that could translate into greater mobility and independence.
The stem cell group also showed a reduced need for postnatal shunt placement. This matters. Shunt surgery carries serious risks, including infection and mechanical failure, and many children with spina bifida undergo multiple shunt revisions throughout their lives.
Critically, no significant increase in maternal or fetal complications was observed. Adverse event rates stayed comparable to standard fetal surgery, a threshold any adjunct therapy must clear before advancing.
Real Limitations Worth Weighing
Promising early evidence is not proof.
Photo by Several considerations temper the optimism:
- Small sample size: Phase 1 trials are designed for safety and signal detection, not population-level conclusions. The statistical power to draw definitive generalizations isn’t there yet.
- Short follow-up window: Neurological development in spina bifida continues evolving through childhood. Whether early motor gains persist, plateau, or expand beyond the 12-month mark remains unknown.
- Access barriers: Fewer than 30 U.S. centers perform open fetal surgery. Adding stem cell preparation raises complexity, potentially narrowing access for families outside major academic medical centers.
Skeptics in the maternal-fetal medicine community rightly note that historical controls, rather than a randomized concurrent control group, limit the strength of comparisons. Larger, randomized Phase 2 trials will need to address this directly. The FDA’s approval to proceed reflects confidence in the safety profile, but the efficacy question remains open.
A Shift From Protection to Regeneration
What makes the CuRe Trial significant isn’t just the data.
Photo by It’s the conceptual shift it represents. For decades, fetal surgery operated under one philosophy: stop the damage before it gets worse. The CuRe approach introduces a different idea, that regenerative medicine can be applied before birth, not just after.
This has implications well beyond spina bifida. Researchers and bioethicists are already exploring whether stem cell augmentation could apply to other fetal conditions involving in-utero tissue or nerve damage. The door, at least conceptually, has opened.
Still, the measured response from the medical community reflects appropriate caution. Early-phase results in a small cohort deserve attention, not celebration. The difference between a signal and a standard of care is years of rigorous validation. What the CuRe Trial offers is something rarer than a cure. It offers a credible new direction.
The CuRe Trial provides early but compelling evidence that stem cells may improve fetal spina bifida surgery, with better motor outcomes and potentially reduced hydrocephalus burden. Questions around scale, long-term durability, and equitable access remain unresolved. Larger trials will determine whether these findings hold. For families navigating a prenatal spina bifida diagnosis, this research represents a reason for cautious hope, not a guarantee, but a genuine shift in what prenatal medicine may one day achieve. Watching for Phase 2 results from the UC Davis team is well worth the attention.
